A complementary study to our previous research to aid in the optimisation of the thermal bonding machine components for improved thermally bonded nonwoven production is introduced. The effect of the conveyer belt on the nonwoven’s thermo-fluid flow behaviour is investigated in detail. A hybrid model consisting of the discrete conveyer belt geometry and the continuum porous nonwoven web, is presented. A comparison study to predict the thermal and flow field differences in 3D and 2D formulations of the same problem is elucidated. The thermal and fluid flow distributions within the conveyer belt, nonwoven and the air domain are predicted with particular focus on the conveyer belt component of the Low & BONAR pilot machine. It has been shown that the developed 2D model provides accurate results for the conveyer belt temperatures. The three-dimensional flow effects on the thermal boundary have been predicted. The 3D approach is shown to be superior in depicting the wake behind the central conveyer belt thread. The amplitude of the wavy geometry is determined to be introducing different degrees of geometric three dimensionalities in the wake. The industrial partner Low & BONAR (former COLBOND bv.) provided technical data for the nonwoven and machine components.
In the current scenario, the paperboard industries are experimenting the reinforcement of their products with various natural fibers. Based on affordability, low weight, biodegradability and recyclability, natural fiber-reinforced composites have attracted the attention of industrial researchers. In the present work, investigations have been carried out to find the suitability of the Passiflora foetida fiber for paper board industry. The physico-mechanical and chemical compositions in the fiber are analyzed with the help of standard methods. The average density and diameter of the fibers were 1.22 g/cm3 and 98.48 ± 5.65 µm, respectively. The fibers showed a tensile strength of 0.32 ± 0.21 MPa, Young’s modulus of 19.42 MPa and strain-to-failure of 2.05 ± 0.18%. The maximum peak of depolymerization is obtained at 361.7℃ in DTG curve. These properties make the Passiflora foetida fibers suitable for replacing the existing fiber in the paperboard composites.
Bi-functional nanofibrous membrane composed of polyurethane in one face and poly(2-acryloylamido-2-methylpropanesulfonic acid)-graphene oxide (PAMPS-GO) in another face has been fabricated using two opposite-nozzle electrospinning set-up. The effect of graphene oxide addition on morphology of PAMPS nanofibers and performance of membrane were investigated. Besides structure of graphene oxide layers, electrospun nanofibers were studied using TEM, X-ray, FTIR, and FE-SEM methods. To evaluate the nanofibrous membrane performance, their tensile strength, water vapor permeability, and contact angle were measured. An average diameter of 500 nm and 83 nm were obtained for PU and PAMPS nanofibers, respectively, through the optimized electrospinning process. Results show that PAMPS nanofiber diameters together with pore sizes of its mat decrease by increasing the graphene oxide content. Also, the dimensional stability of electrospun fibers against water vapor was strengthened in the presence of graphene oxide nanosheets. An improvement in tensile strength of PAMPS nanofibers was observed by the addition of graphene oxide up to 0.2 wt.%, while more addition caused a negative change. Studying water vapor permeability of PAMPS nanofibers showed that increasing the graphene oxide content, the water vapor permeability increases. However, it decreases by increasing the surface density of nanofibers. From a hydrophobic–hydrophilic perspective, an excellent dual-mode behavior on two opposite faces was observed that is already proper for water proof-breathable protective clothing and wound dressing applications.
Amorphous carbon fiber from polyamide 6 (PA6) precursor was produced using a multi-step procedure consisting of oxidative stabilization in air at 180℃ in the presence of cupric chloride impregnation, pre-carbonization at 250℃ and carbonization at temperatures ranging from 500℃ to 1000℃ in nitrogen. The results obtained from thermal analysis data suggested that cupric chloride impregnation enhanced thermal stability. During the oxidative stabilization process, a polymorphic structure consisting of α- and -phases was eliminated due to the decrystallization process. The pre-carbonization step was found to be necessary to enhance the thermal stability of oxidatively stabilized PA6 fiber prior to carbonization. The results suggested that the pre-carbonization step improved the aromatization and crosslinking reactions. The results obtained from the experimental data suggested that the carbonization temperature had an effective role on the molecular structure and properties of the resulting carbon fibers. The carbon fibers obtained from stabilized and pre-carbonized PA6 fibers showed physical and structural changes with rising temperature. They were characterized by a reduction in fiber diameter, linear density, carbon fiber yield, hydrogen and nitrogen content values due to the removal of non-carbon elements together with increases in the values of density, crystallite thickness, carbon content, C/H ratio and electrical conductivity values. The results obtained from X-ray diffraction, IR spectroscopy and elemental analysis suggested that the crystalline structure was totally lost and converted to a carbonized structure at 500℃ and above due to the formation of an amorphous carbon structure during carbonization reactions.
Silk fabric was pretreated with 3-aminopropyltrimethoxysilane (silane) in supercritical carbon dioxide and then silver nanoparticles were synthesized on the pretreated silk fabric under microwave irradiation. The silver nanoparticle coated fabrics were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, and ultraviolet–visible spectroscopy. Deposition rate and color characteristics of the silver coating of samples were investigated. The results show that silver-coated silk fabric with pretreatment of the silane via supercritical carbon dioxide possesses excellent ultraviolet protection, softness and the adhesive strength between silver coating and silk fabric is improved.
In this paper, nylon 66/TiO2 composite nanofiber yarn has been developed using electrospinning method. The effect of the TiO2 nanoparticle content on the physical and tensile properties of the resulted composite nanofiber yarns has been extensively investigated using SEM, EDX, FTIR and mechanical testing machine. The probability density function is computed to model the diameter distribution of nanofibers constituent of the composite yarn for different percentages of TiO2. The addition of TiO2 nanoparticles into the electrospun composite nanofiber yarn decreases its tensile strength. The influence of thickness (diameter) and twist of the yarn on its tensile strength has been considered and the optimum conditions with improved tensile strength have been presented. Photoactivity of the composite yarns is tested against Rhodamine B (RhB). Results show that nanocomposite yarns are effective to be used as an economically and environmentally friendly photocatalyst in water remediation processes. They are not dispersed in the solution and can be removed easily without additional and costly steps of filtration or centrifuge.
A comprehensive analysis carried out on the mechanical and free vibration properties of woven natural fiber polymer composites is presented. Jute fabric with three different weave types (plain, basket and herringbone) and intra-ply woven jute-banana fabrics are considered for investigation of the effect of weave type of a fabric and its stacking sequence on mechanical, dynamic mechanical and free vibration properties. Enhancement of the properties is found with the number of layers of fabric and better properties obtained for four layers. Uniform stress distribution along warp and weft direction of fabric with basket weave type lead to better properties compared to other weave types for four-layered composites. Intra-ply hybridization of jute-banana also enhances the mechanical properties but slightly less than the jute-basket fabric composite. The investigations on effect of layer sequence of fabrics revealed improvement in mechanical properties. Layered composite with relatively strong intra-ply fabric as the facing layer and relatively weak jute plain fabrics as the core layer has higher tensile and flexural properties. Experimental modal analysis carried out on beam-like composite laminates reveal that natural frequencies and associated modal damping factor are significantly influenced by stacking sequence and weave type of a fabric. The density of the composite calculated based on Archimedes principle matches well with the theoretical values.
In the last decade, polymer nanofibers have found promising application for improving through-thickness properties of structural composite laminates through interleaving. The main advantage of inserting nanofibers in conventional composites is making the matrix between the layers tougher. In this article, the benefits of using electrospun fibrous nano-interleaves in enhancing the quasi-static indentation response of aramid/epoxy laminated composites was investigated and the effect of variables of produced nano-interleaves including interleaf thickness (17.5, 35, and 70 µm) and stacking configuration (one-side, central, and two-side interleaving) on behavior of the nano-modified composites was investigated. The results indicate that force, displacement, absorbed energy, and stiffness of these composites are significantly affected by the presence of nano-interleaves. The optimum values were observed in the composites with 35 µm thickness of nano-interleave where three first parameters were higher than their reference values, but the stiffness value had opposite trend of other parameters. On the other hand, it can be seen that only asymmetrical (back-side indentation) stacking configuration lead to improving the composite properties. The visual inspection of the indentation damaged specimens reveals that thickness and stacking configuration of interleaves controls the size of damage.
The search for sustainable renewable source of fibre is the need of the hour for the textile industry. In this aspect, milkweed fibres are considered to be one of the potential fibre crops. Plated knit fabrics are designed and engineered with correct selection of fibre and yarn constituents in the distinct bottom and top layer (next to sin) can serve well for next-to-skin applications. In this research work, the potential application of milkweed/polyester plated knitted fabrics for next-to-skin end uses were analysed by changing the inner and outer layers of plated fabrics and with different polyester/milkweed blend proportion. From the results of various moisture management indices of plated knitted fabrics, it is observed that except polyester/polyester and polyester/60% milkweed samples, which are exhibited as water penetration fabric, all other samples are showed as moisture management fabric. The hydrophobic fibre (polyester) in the top layer and hydrophilic fibres (milkweed) in the bottom layer exhibits higher bottom absorption rate, bottom spreading speed and one-way liquid transport leading to higher overall moisture management index. By considering the moisture management indices and grades of various samples, it could be observed that the plated fabric made from 40% milkweed/polyester could be an efficient moisture management fabric when used in either-way compared with other fabrics. One-way analysis of variance carried out at 95% confidence level showed that the results are statistically significant. The pair wise strength and association between various moisture management indices was analysed using Pearson correlation coefficient and observed that one-way transport capacity and overall moisture management capacity was found to be positively and linearly related to each other.
Human hairs are considered as major waste from barbershops. It contains an important protein called keratin. Keratin from human hair exhibits biocompatibility, wound-healing property, biodegradability, and antibacterial property. Silver and gold nanoparticles are commonly used in wound-healing applications. These nanoparticles possess excellent functional properties like antibacterial, wound healing and biocompatibility and applicable in biomedical field. In this study, silver and gold nanoparticles were used along with human hair keratin for the production of antibacterial materials. The functional properties of these two materials are synergized for wound-healing applications. Silver and gold nanoparticles were synthesized by chemical reduction method. The synthesized nanoparticles were characterized using UV–Visible, particle size, and zeta potential analyses. The prepared materials were characterized by scanning electron microscopy, Fourier transform infrared, and energy-dispersive X-ray spectroscopic analyses and they were measured for the physical properties such as air permeability, water contact angle, moisture content, and water absorbency. Furthermore, the antibacterial activities were evaluated against burn wound bacteria. Superior antibacterial activities and adequate physical properties found in keratin/nanoparticles immobilized cotton samples.
Today, with substantial global demand from patients suffering from wounds and burns, the wound care sector has gained great deal of interest in medical industry. Herein, coaxial electrospun poly(caprolactone)/poly(vinyl alcohol) core–shell nanofibers incorporated with Thyme extract in the core structure were prepared using coaxial electrospinning, and the effect of various operational parameters such as polymer concentration, applied voltage, flow rate, distance, and Thyme concentration on nanofiber diameter were studied. Physical and mechanical properties of the nanofibers were determined by analytical techniques. The results revealed that desired nanofibers with uniform surface morphology and acceptable tensile strength could be obtained at applied voltage of 15 kV, needle tip-target of 13 cm, core flow rate of 0.2 mL/h, and shell flow rate of l mL/h. Moreover, MTT assay shows that the nanofibers are highly biocompatible regardless of Thyme encapsulation. Antibacterial activities of the prepared core–shell nanofibers were also examined against two bacteria—gram-positive Staphylococcus and gram-negative Escherichia. Encapsulation of 5% (w/v) Thyme extract concentration in the core–shell poly(caprolactone)/poly(vinyl alcohol) nanofibers led to high antibacterial activity of the produced nanofibers.
A microscale model of multifilament reinforcement yarns made of technical carbon fibers is established based on the finite element method. The model is used to perform simulations of tensile failure. The failure behavior of dry multifilament carbon yarns is modeled using a maximum stress criterion with statistical distribution of the strength. The maximum stress is assigned to every single element and varied according to a normal distribution found in experimental tests of single filaments. The Weibull distribution is used for calculating the local failure stress. The material parameters are calculated in function of the element size to account for the volume-specific statistical breaking effect. Representative simulations of the tensile failure behavior prove the concept of the introduced assumptions.
Protection from steam burns is beneficial to reduce the nonfatal injuries of firefighters in firefighting and rescue operations. A new multifunctional testing apparatus was employed to study heat and steam transfer in protective clothing under low-pressure steam and low-level thermal radiation. Single-, double-, and triple-layered fabric assemblies were selected in this experiment. It is indicated that the existence of hot steam weakens the positive influence of the fabric’s thickness, but increases the importance of the air permeability on the thermal protection. The fabric assemblies entrapping moisture barrier can better resist the penetration of steam through the fabric system, and significantly improve the thermal protection in low steam and thermal radiation exposure due to the low air permeability. Additionally, the total transmitted energy (Qe) and dry thermal energy (Qd) under low steam and thermal radiation are dramatically larger than that under thermal radiation (p < 0.05), while hot steam insignificantly reduces the thermal energy during the cooling (p = 0.143 > 0.05). The understanding of steam heat transfer helps to provide proper guidance to improve the thermal protection of the firefighter’s clothing and reduce steam burns.
This paper presents an experimental investigation regarding the influence of the thermal and chemical treatment over the strength of one type industrially used basalt fibers. The fibers are heated at 160℃, 320℃, 480℃, 640℃, or 800℃ using a muffle furnace for 32, 64, 128, or 256 min. In the second series, the fibers are treated with 10% to 30% H2SO4, HCl and NaOH aqueous solutions for 48 h. The strength of the fibers is tested after the different treatments and is found to be decreased even after moderate heating temperatures. The fibers are as well investigated by scanning electron microscopy and energy-dispersive spectroscopy. By energy-dispersive spectroscopic method, the surface composition of the fiber is determined and significant changes in composition are observed even after treatment at 160℃. Obviously the change in surface composition is related to the change in the strength. A possible explanation can be the decomposition of the sizing on the fiber surface.
In recent years, a growing interest in flexible electronic devices has been the origin of the formation of extensive research in providing the best method for the production of these tools. In this context, manufacturing of flexible textile antennas due to opportunities to integrate unique technical attributes with their applications is highly regarded by researchers. Therefore, in this paper, using inkjet printing technology with textiles and subsequently reducing it by metal nanoparticles with various deposition techniques to develop micro-layers of fabric has been suggested. It is anticipated that this method can produce electrically conductive textiles with flexibility and signal transmission in different wavelengths. According to the method in this article, after primary preparation of polyester fabric, it will print active materials with different designs at suitable operating conditions and then it will enter into the nickel electroless bath. The antenna having a conductive nickel fabric as ground plane was tested at different angles than receivers. That indicating zero degree angle relative to a line perpendicular to the surface of the antenna has the gain equal to –5.34 dB, because most of the antenna radiation field is perpendicular to the surface of the antenna. The most unsuitable degree is 90° angle, which is equal to –14.59 dB and shows that radiation from the sides of the antenna does not occur.
Lead-shielding products, such as lead aprons, are important materials for personal protection of physicians and patients from X-ray (gamma) radiation during medical operations. However, lead has environmental disadvantages such as high toxicity. The aim of this study was to manufacture an environmentally friendly and flexible textile-based radiation shielding material. In this work, 3/1 twill and some cellular woven fabrics were produced with conductive core yarns, and gamma radiation shielding effectiveness of these cellular woven fabrics were investigated and compared with that of the 3/1 twill woven fabric, which are commonly used as uniforms and were not studied previously in any other literature. The effects of weave on the structural characteristics of fabric such as the conductive weft yarn density, fabric thickness, and fullness were analyzed graphically and statistically. It is observed that with indenting and protruding, structure cellular woven fabrics performed better gamma radiation shielding performance than the 3/1 twill woven fabrics. The sample B1, woven with cellular weave 1, has the highest gamma radiation shielding effectiveness, thanks to the highest fabric thickness. In addition, the increase in the conductive core yarn density improved the gamma radiation shielding effectiveness of the woven fabrics.
A facile method for the preparation of acid-resistant fabric with the fluoropolymer/SiO2 hybrid materials was presented. The polyester fabric was treated using a dip-dry technique and, subsequently, cured under high temperature. The results showed that the treated fabric displayed remarkable acid repellency with contact angles of 137.1°, 141.2°, and 139.5° for H2SO4 (80%), HCl (30%), and HNO3 (40%), respectively. The break force tests further confirmed the true potential of fluoropolymer/SiO2 hybrid materials to fabricate functional textile. We believe that this successful attempt offers an opportunity to fabricate acid-resistant fabric and advances the applications of protective clothing.
This article reviews the preparation, development and characteristics of conductive polymer-based electro-conductive textile composites for electromagnetic interference shielding. Modification of ordinary textile materials in the form of electro-conductive composites makes them suitable for this purpose. Various metallic and non-metallic electro-conductive textiles have been explored here as the material for electromagnetic shielding. Different approaches of preparing textile electromagnetic shield have been described here. Recent advancements of application of conductive polymers in the field of textile electromagnetic shielding are described. Conductive polymer-coated textile materials showed superior electrical property as electromagnetic shield. Different methods of applications of conductive polymers onto textile surface are described here with their relative merits and demerits. Different conductive polymer-coated woven and nonwoven fabrics prepared by various researchers for electromagnetic shielding are taken into account. The effects of different process parameters of polymer processing on electromagnetic shielding are described.
Extensive use of composite materials leads to an increase in waste materials. Therefore, it is necessary to find a proper way to recycle the composites. In this research, the powder waste of carbon-epoxy resin composites collected from the cutting and grinding process have been added into glass fiber reinforced phenolic resin composite during the preparation process in order to enhance some mechanical characteristics. Thermal behavior, tensile and flexural properties of adding powder composites have been analyzed. Results show that adding powder waste in a certain proportional range can improve the performance of the new composites.
Jute and hollow conjugated polyester fibres were blended to produce non-woven composite by using a compressive hot pressing method having a weight of 328 g/m2. Its blending ratios: 50/50, 60/40 and 70/30% are considered as one factor. Needling density of non-woven fabric: 300, 150 and 75 punches/cm2 is fixed as another factor. Thermal and mechanical properties of developed non-woven composite material such as thermal conductivity and thermal resistance, breaking force and elongation were tested. Among the developed 15 samples, optimal responses are shown on 50/50% of Jute/hollow conjugated polyester fibre proportion and 150 punches/cm2 needling density. To produce three-layered winter over coat, 50% Jute/50% hollow conjugated polyester is selected as middle layer, polyurethane coated nylon and polyester fabric is used as outer and inner layer fabric, respectively. This designed over coat shows the least thermal conductivity value of 0.0195 W/m K.
In the present work, polyester fabric with protective and magnetic properties is introduced using mixture of micro magnetic carbonyl iron powder and nano carbon black through pad-dry-cure method and sputter coating with aluminium (Al). This leads to X-band microwave absorbing properties as the great demand for protective garment. The morphology, static magnetic and X-band microwave absorbing properties of the treated fabrics were characterized by field emission scanning electron microscopy, vibrating sample magnetometer and vector network analyzer in the range of 8.2–12.4 GHz. Normal-angle X-ray diffraction was used to study the crystalline structure of treated PET fabric. Compared with the blank polyethylene terephthalate fabric without Al sputter coating, the presence of nano carbon black and carbonyl iron powder on the polyethylene terephthalate fabric sputter coated with aluminum exhibited higher microwave absorbing properties particularly in the primary range of 8.2–12.4 GHz. The results in the whole frequency range investigated were remarkable; however, the reflection loss was found to be lower than –5.9 dB in the entire frequency. The maximum reflection loss value was reached to –7.7 dB at the frequency of 8.2 GHz. Overall, the co-application of nano carbon black and carbonyl iron powders on the polyethylene terephthalate fabric opens up a new coating method for X-band microwave absorbing properties.
This study characterizes the thermal protective fabrics of firefighters’ clothing under the exposure of hot surface contact. For this, thermal protective performance of different fabrics was evaluated using a laboratory-simulated hot surface contact test, and various factors affecting the performance were statistically identified. Additionally, heat transfer mechanisms during testing were analytically and mathematically modeled. It has been found that fabric’s constructional features and properties are the key factors to affect its thermal protective performance. In this study, the presence of a thicker thermal liner in a layered fabric system resulted in higher performance; in contrast, a multi-layered fabric system incorporating a moisture barrier in its outer layer displayed the lowest performance. Furthermore, it was demonstrated that a fabric’s air permeability has a minimal impact on performance, whereas weight, thickness, and thermal resistance have a significant positive impact on performance. Based on the analytical and mathematical models developed, it was apparent that conductive heat transfer mainly occurs through fabric during testing, and this conductive heat transfer depends upon the surface roughness and thermal properties (thermal conductivity, density, and specific heat) of the tested fabric. Here, thermal contact resistance between the hot surface and fabric also plays a crucial role in the heat transfer or thermal protective performance of fabric. Moreover, the heat transfer gradually decreases across fabric thickness, which can substantially affect thermal protective performance. This study can advance the theory of textile/materials science through better understanding of heat transfer in fabrics. This understanding can help in developing an integrated knowledge of fabric properties, heat transfer through fabrics, and thermal protective performance of fabrics. The findings from this study can also assist textile/material engineers with the development of a high performance thermal protective fabric for clothing to provide better occupational safety and health for firefighters.
In this study, the compression molding process parameters for the development of silk fiber-reinforced polypropylene composites was optimized using Box–Behnken experimental Design with response surface methodology. The trimmed silk fibers from shuttleless loom silk selvedge waste were used as reinforcement in polypropylene fiber matrix. The process parameters of compression molding such as temperature (165–185℃), time (7–15 min) and pressure (35–45 bar) were optimized with respect to the mechanical properties of the silk fiber-reinforced polypropylene composite. The optimum parameters for better mechanical properties were found to be temperature, 180℃; time, 7 min, and pressure, 35 bar in compression molding. The optimised level of parameters has shown good response to the predicted model.
Intrinsically conducting polymer polypyrrole/polyester textile composites were prepared by in situ chemical oxidative polymerization of polypyrrole on a polyester fabric. As an oxidizing agent ferric chloride was used, p-toluenesulfonic acid was used as a dopant. Polymerization conditions (concentration of monomer, polymerization time and temperature) were investigated and optimized by the help of Design of experiment methodology to obtain fabric with electromagnetic shielding efficiency at least 12 dB for frequency 1.5 GHz. Moreover, weight increase, macroscopic color shade of images and scanning electron microscopy images of samples were evaluated. It was found that all selected factors and their interactions have statistically significant effect on resulting electromagnetic shielding effectiveness, whereas monomer concentration has the highest positive influence. Experimental data were used to derive an empirical model linking the output and inputs. Optimized parameters (polymerization temperature 6.7℃, polymerization time 10 h and monomer concentration 5.8 g/l) for creating polypyrrole/polyester textile composite with electromagnetic shielding ability higher than 12 dB were successfully verified.
In this study, polypyrrole was deposited separately on barium titanate, barium titanate-poly (acrylonitrile-co-methylacrylate) nanocomposite-coated textile fabrics by an in-situ chemical polymerization process. Electromagnetic shielding effectiveness, electrical conductivity, chemical structure, and morphology of fabrics were fully characterized and systematically studied for investigation of individual effects of barium titanate, pyrrole polymer, and barium titanate-poly (acrylonitrile-co-methylacrylate) on obtained fabrics’ conductivity and shielding behaviour. Electromagnetic shielding effectiveness of the fabrics was determined according to the ASTM D4935-10 protocol, by using a coaxial transmission line measurement technique in the frequency range of 15–3000 MHz. Electrical characteristics were measured by the two-end method. Electromagnetic shielding effectiveness data suggested that polypyrrole-coated fabrics had better electromagnetic shielding effectiveness than polypyrrole-barium titanate and barium titanate-poly (acrylonitrile-co-methylacrylate)-coated fabrics. On the other hand, conductivity increased due to the interaction between polypyrrole and barium titanate-poly (acrylonitrile-co-methylacrylate), with fabric conductivity values also increased with the use of barium titanate. Spectroscopic characterizations of coated fabrics were determined using Fourier transform infrared spectroscopy. Analyses demonstrated that there is a strong interaction between cotton and polypyrrole and barium titanate, and also with poly (acrylonitrile-co-methylacrylate)-barium titanate. Morphological characterizations of the coated fabrics were examined by scanning electron microscopy. Colour measurements of fabric samples were performed for determination of colour intensity as a function of polymerization efficiency.
Jute fiber has poor compatibility with hydrophobic thermosetting polymeric resin for the development of a biocomposite. In this present study, plain weave jute fabric was treated with 1% sodium hydroxide (owf) in three different time (30, 60 and 90 minutes), temperature (30, 40 and 50℃) and material-to-liquor ratio (1:5, 1:10 and 1:15) as per orthogonal array and the treated jute fabrics were used for the preparation of the biocomposite sheet by hand laying-cum-compression moulding method. Developed biocomposite sheets were evaluated for their mechanical properties as per ASTM standards and results were analyzed by Taguchi model to optimize the sodium hydroxide treatment condition. Results inferred that jute fabric reinforcement treated with 1% sodium hydroxide at 50℃ for 60 minutes in 1:10 material-to-liquor ratio could be the optimum condition to develop the biocomposite sheet with higher mechanical properties than other conditions.
In this paper, glass fiber felts are fabricated by centrifugal-spinneret-blow process. Swing cylinder is designed to obtain a micro-layer structure, and the phase difference of two swing cylinders is /2 + 2k. Tensile strength, flexural rigidity, and thermal conductivity of various glass fiber felts are investigated. The experimental results indicate that the tensile strength of micro-layer glass fiber felts and random glass fiber felts is 0.015 MPa and 0.013 MPa, respectively. In addition, the tensile strength of glass fiber felts is also improved with the increase of the density and the resin content of glass fiber felts. The micro-layer structure decreases the flexural rigidity of glass fiber felts, and the flexural rigidity of glass fiber felts with micro-layer and random structures is 43.4 g.cm and 101.3 g.cm, respectively. The mean thermal conductivity of glass fiber felts with micro-layer and random structures is 31.57 mW/m·k and 35.69 mW/m·k, respectively.
Conductive polymers with their medium level of conductivity are synthetic materials that can be used as electromagnetic wave absorber. In this work, the effect of aging and washing on the surface resistivity and also the influence of efficient doping and redoping procedure on the dielectric properties and electromagnetic radiation shielding of uniformly polyaniline coated polyester fabric are investigated in the X-band frequency range. They can affect the shielding effectiveness by changing the surface resistivity and dielectric permittivity. It is found that lightweight, flexible, and thin polyaniline-coated polyester fabric sample prepared in 1:1:7 monomer:oxidant:dopant molar ratio and redoped with concentrated HCl vapor shows the highest transmission loss (53–43%) in 8.2–12.4 GHz. Compared to single layer, double and triple layer samples attenuated 71–61% and 83–77% of incident wave, respectively. Absorption was the dominant shielding mechanism. It is also demonstrated that the increment of surface resistivity due to washing of samples is compensated by the redoping process.
Artificial antistatic fibers due to their low cost as well as providing desirable properties based on their constitutive components, have attracted considerable interests. In the present study, bicomponent antistatic fibers with various cross-sectional configurations (i.e. core/sheath and segmented-pie structures) were produced using the mixture of carbon black/dispersing agent/PBT and polyethylene terephthalate. To investigate their practical application, woven fabrics were produced and then examined upon their antistatic characteristics as well their thermal properties, wash durability and breaking strength and elongation. Moreover, the effect of dispersing agent during fiber spinning was examined. Among the produced fibers with different structural configuration, it was concluded that the core/sheath antistatic fibers exhibited higher breaking strength and elongation, as well as lower electrical resistivity. Rheological investigations based on the pressure tests indicated that the homogeneous distribution of the fillers (e.g. carbon black) within the polyester pellets is required for manufacturing the uniform fibers. Moreover, it was determined that surface resistivity of the fabrics could be kept unchangeable even after 20 times of washing, revealing their reliable wash durability. Finally, it was found out that the mixture of carbon black/dispersing agent/PBT provides such desirable conductivity; also, the fabrics comprised of fibers with core/sheath configuration could be a good candidate for antistatic applications within the textile industry.
With increased utilisation of simple fabrics in technical engineering and manufacturing environments the need for suitable, easy to implement material representations in simulation software has increased. A simple implementation of plain woven polypropylene fabric for inflation simulation of dunnage bags is developed. Only standard finite element software packages and a simple material calibration protocol based on numerical optimisation were used to generate a homogenised material representation for the in-plane properties of plain woven polypropylene undergoing both loading and unloading. This is achieved by performing a simple material test that represents the in situ loading state of the material, measuring the applied load and material deformation in response to that load, and mapping that response to a simulation of the same test by means of an inverse problem statement. Following the proposed method, a material response model for plain wove polypropylene was developed that captures the major responses of a measured woven test specimen.
Compression stockings, which constitute one of the most important groups of compression garments, are engineered to regulate blood flow in venous systems in order to use in many medical fields such as supporting muscles and preventing edema. In the present study, it was aimed to analyze the effects of production parameters such as tightness, elastane yarn feeding tension and elastane yarn counts on pressure behavior of compression stockings, which are commonly used to adjust pressure values. The results of the statistical analysis indicated that the tested parameters had significant effects on pressure characteristics of compression stockings. Moreover, multiple regression analysis was used to investigate the relationship between the fabric parameters and pressure values. The analysis exhibited the strong impact of thickness and traversal elasticity on pressure characteristics. All parameters have positive impacts except traversal elasticity.
The technology of producing a magnetized polyester fabric for controlled and accelerated release of menthol in potential biomedical applications is reported in this paper. The magnetized polyester fabric is prepared in a facile hydrothermal process and subsequently modified with aminopropyltriethoxysilane, grafted with carboxylated β-cyclodextrin, and loaded with menthol under hydrothermal conditions. The microstructure, thermal and magnetic properties of both carboxylated β-cyclodextrins and magnetized polyester fabrics grafted with β-cyclodextrins are characterized by using field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, vibrating sample magnetometry, Fourier transform infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, and diffuse reflectance spectroscopy techniques. It is evident that the carboxylated β-cyclodextrin is synthesized and successfully grafted on the surface of the modified magnetic polyester fabric. Both hyperthermia effect and controlled release behavior of the magnetized polyester fabric loaded with menthol are measured under high-frequency alternating current magnetic fields. It is found that the menthol included in β-cyclodextrin could be released in a controlled and accelerated way under external alternating current magnetic fields.
This study attempts to investigate the influence of the inlay-yarn insertion density into a knitted structure and of the area of a rigid element integrated into a knitted orthopaedic support on a compression generated by the support. The samples were made on a flat double needle-bed knitting machine with a laid-in structure knitted on a rib 1 x 1 pattern base, differing in the inlay-yarn insertion density. In general, research studies analyse compression and other properties of compressive stockings and do not investigate the influence of non-textile parts usually used in the knitted orthopaedic support. It was established that the linear density of the inlay-yarn has a visible influence on the compression generated by knitted support when inlay-yarn insertion density is every other course and less. When inlay-yarn is inserted into every course, the generated compression is the highest and the influence of inlay-yarn linear density on the generated compression is significant. It was found that compression of the support increases depending on the area of the rigid element in the knitted support. The rate of influence of the rigid area on compression rises with an increase in the inlay-yarn insertion density and in the elongation value. By designing a knitted compressive orthopaedic support, it is necessary to find an optimal ratio between an inlay-yarn insertion density and an area of a rigid element, thereby achieving the best compressive, wear comfort and economical result.
Over-braiding of superconducting Rutherford cable was used for the composite insulation in this research. Braiding was a suitable alternative to fabric tape winding for achieving ultrathin insulation with required electrical breakdown voltage. A brief overview of the superconducting magnets, their application and requirements of insulation has been covered in order to bridge the literature gap between braiding and the superconducting magnet field of studies. Organic size coating on the fibre leaves carbon residue during high temperature treatment of the cables and hence glass fibre was desized before braiding. Braiding difficulties with desized glass fibre and possibility of braiding using compatible size coating have been discussed. The requirement of ultrathin braided layer was achieved with sufficient surface coverage with a suitable braid angle and fibre. As part of the study, braid cover factor variation on the surface of the cable was investigated and it was discussed using image analysis.
Shortcomings in large deformation calculations by mesh-based numerical methods have been overcome by smoothed particle hydrodynamics method, which is a new meshless algorithm based on Lagrange description and has been widely used in simulations as blasting and impacting, but not been applied in research of engineered fabrics yet. In this paper, a fluid structure interaction method coupling smoothed particle hydrodynamics and finite element was proposed, by which the inflating process of a model parachute was investigated. In the modeling of parachute, the same nodes were shared by beam elements of reinforced belts and adjacent canopy elements to simulate the elastic constraints, while the parachute meshes model was adjusted to satisfy requirement of fluid structure interaction calculation by loading internal pressure, and surrounding flow field was described by smoothed particle hydrodynamics particles. Then, the fluid structure interaction calculating could be realized by contacting algorithm between particles and mesh nodes. The dynamic processes of expanding structure and flow field were obtained by this method. According to the analysis of numerical results, the parachute inflating process could be divided into pre-inflating stage, fully inflating stage and inflated stage; moreover, the noise occurred in wind tunnel experiment could be explained by this method. The "breathing" phenomenon and top collapsing of canopy appeared in numerical results, as corresponded to the tunnel experiment. This new method could be a good supplement in parachute design and research.
Due to the significant and harmful effect of the global warming on our communities, health, and climate, the usage of thermal insulation material in building is must to decrease the energy consumption and to improve energy efficiency. On the other hand, the utilization of waste and biomass resources for developing new bio-based composite materials is attracting much attention for the environmental and socioeconomics. Therefore, in this study, thermal insulation bio-based composite panels from Tetra Pak® waste and wool fiber waste with different ratios were manufactured. Likewise, other sandwich bio-based composite panels were manufactured using Tetra Pak waste as a core material with glass woven fabric and jute wove fabric as skin materials. Thermal conductivity and thermal resistance results showed a significant improvement on thermal insulation properties of the developed biocomposite panels compared to the control samples made of plain Tetra Pak®.
In recent years, zinc oxide nano particles coating on textiles such as polyester is considered because of UV blocking and self-cleaning properties. Alkaline hydrolysis of polyester is a method in textile industry for surface treatment in large scale to enhance wettability. In the present work, polyester fabric was treated with sodium hydroxide, then was coated with ZnO nano particles, and also polyester fabric was treated with sodium hydroxide and ZnO nano particles at the same time. The bending length, water adsorption time, bactericidal properties, atomic absorption spectroscopy, and self-cleaning effect were measured according to the standard methods. Scanning electron microscopy and Fourier transform infrared spectroscopy analysis were used for the study of surface morphology and surface chemical bonding. The results demonstrated that increasing of zinc oxide nano particles concentration increased bending length, water adsorption time, antibacterial and self-cleaning effect. Comparing with pre-alkaline and simultaneous alkali treatment showed that pre-alkaline-treated fabric had more zinc oxide nano particles, therefore more self-cleaning and bactericidal effect. The scanning electron microscopy of alkaline-treated polyester fabric showed surface hydrolysis and nano-particles on the surface of polyester, and Fourier transform infrared spectroscopy spectroscopy indicated chemical bonding.
Piezoelectrics are one of the most important materials used for harvesting energies. Several piezoelectric nanostructures have been used to construct nanogenerators (NGs). Nanofibers made by piezo-polymers, especially polyvinylidene fluoride (PVDF) because of their high flexibility, biocompatibility, and low cost, have shown wonderful growth as the key materials for NGs. Despite these favorable properties, fabricated nanofibrous devices still has low efficiency and many studies have been conducted to characterize and improve the performance of the PVDF nanofibers. Here we tried to fabricate PVDF NG device based on align nanofibers to improve the NGs output, using two different methods rotary collector and applying magnetic field. Characteristics of these structures are evaluated utilizing X-ray diffraction, Fourier transform infrared, differential scanning calorimetry, and scanning electron microscopy. Electrical response of fabricated samples is measured through utilization of an impedance analyzer at room temperature. Results demonstrate that crystalline structure increases in both methods but sample fabricated by rotary collector in magnetic field has more improvement in their outputs. This result shows that in addition to the crystalline structure, nanofibers alignment and arrangement play important roles in piezoelectric properties of sample, as well as NG efficiency. These results teach us to establish engineering design rules for wearable power harvesting devices.
The aim of this study was to produce advanced nanofiber mats by adding boron nitride to poly (-caprolactone) polymer using an electrospinning method and to characterize the resultant structures. Pure poly (-caprolactone) nanofiber mats and boron nitride-doped nanofiber mats prepared at different concentrations were compared. The morphological structures of the nanofiber mats were examined under a scanning electron microscope, spectroscopic analyses were conducted using Fourier transform infrared spectroscopy, and thermal stability was analyzed using a thermogravimetric analysis method. Successful electrospinning of boron nitride-doped nanofibers at lower voltages was achieved. The thermogravimetric analysis test found that the thermal stability of boron nitride-doped nanofiber mats is higher than that of pure nanofibers, which suggests that the produced composite material could be preferable in applications involving insulation and high temperature. On the other hand, the Fourier transform infrared spectroscopy results indicated that no chemical reaction occurred between boron nitride and the poly (-caprolactone) nanofibers.
There is a growing interest in the development of natural fiber-reinforced composites, most likely due to their wide availability, low cost, environment friendliness, and sustainability. The market size for natural fiber-reinforced composites is projected to reach $5.83 billion by 2019, with a compound annual growth rate of 12.3%. The composite materials reinforced with wood, cotton, jute, flax or other natural fibers fall under this category. Meanwhile, some major factors limiting the large scale production of natural fiber composites include the tendency of natural fiber to absorb water, degradation by microorganisms and sunlight and ultimately low strength and service life. This paper has focused to review the different natural fiber treatments used to reduce the moisture absorption and fiber degradation. The effect of these treatments on the mechanical properties of these composites has also been summarized.
This study proposes to make geotextiles from recycled materials. Polyester fibers, recycled polyester fibers, and low melting point polyester fibers are blended and needle punched to make the polyester fabrics, the mechanical properties of which are then evaluated to determine the optimal parameters. The polyester nonwoven fabrics are needle punched with various densities. Afterwards, the resulting polyester nonwoven fabrics, glass fiber woven fabrics, and polypropylene selvages are combined, needle punched, and hot pressed to form geotextiles, the properties of which are tested by tensile strength, tearing strength, burst strength, puncture strength, and water resistance tests. The test results show that polyester fabrics containing 50 wt% of polyester fibers have the optimal mechanical properties. Furthermore, needle punching at 90 needles/cm2 results in a greatest increase in mechanical properties of the polyester nonwoven fabrics. The tensile strength, tearing strength, and water resistance of the geotextiles increase as a result of hot pressing, and the bursting strength and puncture resistance are primarily associated with the needle punching densities. This study successfully creates composite geotextiles with reinforced mechanical properties by needle punching and hot pressing recycled polyester fabrics and polypropylene selvages.
The inadequacies of the currently used small diameter, non-biodegradable synthetic grafts prompt researchers to focus on the design parameters of vascular grafts. Since the purpose is to mimic the native vessel as far as possible, the design parameters are mainly determined by the layout of cell types and proteins in the layers of the vessels and the nano and micro structure of their environments. In consequence of this, the complex structure of native vessels has become a broad source of inspiration for researchers. Electrospun fibrous scaffolds with their well accepted advantages are promising candidates and researchers are able to work with various materials with differing forms, structures, dimensions, and surface modifications according to their requirements. On the other hand, both synthetic biodegradable polymers and natural proteins are the key materials that enable researchers to take one step closer to achieving the goal of creating an autologous vessel at some time after implantation. When the priority and significance of the need for small diameter vascular grafts is considered, the research field to improve vascular grafts is worthy of note. In this regard, the objective of this review is to discuss comparatively the current studies on the design parameters of electrospun vascular grafts, defined as fiber orientation, fiber diameter, pore size and porosity, wall thickness, and material selection, based on the structure of native blood vessels, the requirements of vascular grafts and electrospinning technology, and the advantages of electrospun vascular grafts, to give an outlook for further studies.
Continuous measurement of cardio-respiratory signals offers various kinds of information valuable for the diagnosis of disease and management of the disease process. The article reports the development of the Piezofilm yarn sensor for healthcare applications, and investigates its performance by monitoring cardio-respiratory signals of human body over an extended period of time. Piezofilm yarn sensor was developed by embedding the thin PVDF strips within the textile yarn. The working mechanism of the Piezofilm yarn sensor is based on voltage generation due to the applied stress. In order to deploy the Piezofilm yarn sensor in the application environment, it was integrated into the knitted textile fabric and then sewn to form belt to be placed at the chest wall and wrist area. The raw signals were acquired through the Piezofilm lab amplifier, National Instrument data acquisition device and SignalExpress software. Fast Fourier Transform analysis was performed to calculate the average cardio-respiratory signal frequencies. Based on Fast Fourier Transform analysis, an additional signal-processing step was added to eliminate the unwanted mechanical interference and body signals by using an Infinite Impulse Response band pass filter. The Piezofilm yarn sensor embedded sensing fabric was able to measure both respiratory rate and heart beat rate under static and dynamic conditions. The wrist area measurements for heart beat signals were found to be more uniform in comparison to the chest area measurements. Apart from the general healthcare, this sensing fabric could also be used in studies related to biorhythms, sports, detection of sleep apnea and heart problems.
In this paper, we investigated a functionalization process of nonwoven viscose/polyester dressings, in order to fix a wide range of drugs, using a polymer based on β-cyclodextrins. Firstly, the optimization of the treatment process was investigated. The best operating conditions were generated using Minitab 15, in order to maximize functionalization rates. Then, in order to confirm the permanent and uniform binding of cyclodextrin’s polymer, modified and virgin dressings were characterized by Fourier transformed infrared spectroscopy, thermogravimetric analysis, and the drop contact angle method used to assess the substrates hydrophilicity. The microbiological value of this chemical modification was highlighted via the application of methylene blue, used in this case as a drug model. The encapsulation properties of cyclodextrins molecules allowed its fixation into the functionalized wound dressings. The assessment of drug release kinetics confirmed a sustained release in water. Furthermore, bacteriological properties were investigated by staining and growth inhibition. Antibacterial activity of nonwoven methylene blue cyclodextrin-functionalized samples against Staphylococcus aureus and Escherichia coli before and after release are presented.
In this work, the tensile property retention characteristics of high-performance glass and carbon rovings in warp-knitted reinforced fabrics and cement-based composites used in structural applications were investigated. Three types of warp-knitted fabrics, with differing stitch patterns, and cement-based composites were produced. The tensile strength retention and Young’s modulus retention of the roving in these fabrics and their influence on the properties of cement-based composites were compared on the basis of the stitch type. Samples of warp-knitted fabrics composed of glass fibres and carbon fibres exhibit retention of 76–87% and 65–87.6%, respectively, of the initial strength of the rovings. The highest Young’s modulus retention (~80%) occurs in the case of the fabric sample composed of glass rovings. The retention of the Young’s modulus in the fabric samples composed of carbon rovings was 37–60%. In addition, the translation of strength from the roving to the fabric and retention of the Young’s modulus in the carbon rovings decreased with increasing strength and modulus, respectively, of the original roving. On the basis of the data presented, we provided guidelines for the possible application of the developed fabrics. As conclusion, it is possible to reduce the cost of the raw materials by using fabrics whose original rovings have low tensile strength and Young’s modulus, but high retention properties.
Now-a-days, natural fibers have been receiving considerable attention as the substitute for synthetic fiber reinforcement in plastics. Among various fibers, coir is the most widely used natural fiber due to its advantages like easy availability, low cost, low density, low production cost and satisfactory mechanical properties. Fiber-reinforced polymer composites often have to function in severe erosive environment in which they encounter solid particle erosion. To this end, an attempt has been made in this paper not only to study the utilization potential of coir fiber in polymer composites, but also to study the effect of various parameters on erosion wear performance of coir fiber-reinforced epoxy composites filled with Al2O3 filler. Twenty different composite samples were prepared with different length (3 mm, 6 mm, 9 mm, 12 mm, and 15 mm) and content (5 wt%, 10 wt%, 15 wt% and 20 wt%) of fiber using hand lay-up technique. The erosion wear of these composites has been evaluated at different impingement angles (30°, 45°, 60°, 75°, and 90°) and at different impact velocities (48 m/s, 70 m/s, 82 m/s, and 109 m/s). The effect of fiber length and content on the erosion wear behavior of composites is also analyzed. A comparison has been made between composites with and without Al2O3 filler. It has been observed that composites filled with Al2O3 filler show better wear resistance properties as compared to composites without filler. To characterize the morphology of eroded surfaces and the mode of material removal, the eroded specimens are observed under scanning electron microscope.
Having control on the specific area of power harvesting devices is the main controllable parameter in their fabrication. Hence, in this paper, at first a piezoelectric nanofiber is made with different dimensions and all kinds of function tests including X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry are implemented thereon. After ensuring accurate ...... responses from the device, some kinds of forces like concentration impact and distributed impact and tension creation by applying bending force are applied on the fabricated device in the laboratory. To assess the effect of electrode position, electrodes were placed in five modes within the samples and the output voltage was recorded with regard to applied forces type. The results indicated that an increase in specific area of nanofibrous mats in devices absolutely resulted in an increase in electric output, but the electric output reduced consequently when it normalized to the specific area of nanofibrous mats. These results imply promising approaches, as an enhanced efficiency energy-scavenging interface, for designing and fabricating various wearable self-powered electrical devices and systems.
The purpose of this research is to improve ignition properties and anti-dripping of polyester fabric by using adhesion promoter (AP). The ignition properties of the untreated and treated specimens with durable flame retardant coating and non-durable flame retardant coating were estimated by horizontal flame chamber (UL-94), single-flame source and limiting oxygen index (LOI). The chemical structures of the pre- and final composites have been determined by Fourier transform infrared spectra with attenuated total reflection analysis spectroscopy. The mechanical tests and thermal properties were applied to study their tensile strength and thermal behaviors. The results show that AP has improved the flame retardancy and dripping of PET fabric compared to blank. The char yield increased from 8% to 18%, LOI from 17.5% to 27.5%.
Finite element method can provide valuable results and information to evaluate and assess the mechanical behavior of tissue engineered scaffolds. In this investigation, a structurally and analytically based model is applied to analyze and to describe the mechanical properties of wire rope yarns as scaffold or other applications in textile engineering. In order to modeling the mechanical behavior of single yarn, non-linear hyperfoam model with three strain energy potential has been used. The results of finite element model are compared with an experimental approach and showed good agreement between software and experimental analysis with a maximum error at break of about 4.3%. As a result, validation of the finite element method is guaranteed for analysis of other structure of multi twisted yarn or wire ropes.
To prevent the renewed rupture of ligaments and tendons prior to the completed healing process, which frequently occurs in treated ruptured tendons, a temporary support structure is envisaged. The limitations of current grafts have motivated the investigation of tissue-engineered ligament replacements based on the braiding technology. This technology offers a wide range of flexibility and adjustable geometrical and structural parameters. The presented work demonstrates the possible range for tailoring the mechanical properties of polyester braids and a variation of the braiding process parameters. A finite element simulation model of the braiding process was developed, which allows the optimization of production parameters without the performance of further experimental trials. In a second modelling and simulation step, mechanical properties of the braided structures were virtually determined and compared with actual tests. The digital element approach was used for the yarns in the numerical model. The results show very good agreement for the process model in terms of braiding angles and good agreement for the structural model in terms of force-strain behaviour. With a few adaptions, the models can, thus, be applied to actual ligament replacements made of resorbable polymers.
Natural cellulose fiber reinforced biopolymer composites have attracted increasing attention due to environmental concerns. However, these fibers have relatively low mechanical properties and poor interfacial adhesion with matrices, limiting their composite mechanical properties. This study investigates the synergistic effect of two recently developed techniques to maximize the mechanical performance of ramie/poly (lactic acid) laminated composites, namely alkali treatment to loosen fiber molecular structure and to increase fiber surface roughness and subsequent cyclic loading treatment to fabrics to increase their tensile strength and modulus. The results show that the treated fabrics have increased crystallinity and crystal orientation factor as well as better orientation of fibers and more uniform structures, leading to 11% improvement in fabric tensile strength and 57% enhancement of tensile strength (90.9 MPa), 48% higher tensile modulus (5.6 GPa), 18% higher flexural strength (149.4 MPa), and 91% higher flexural modulus (8.2 GPa) for the corresponding composites. Meanwhile, postmortem analysis shows that better interfacial adhesion is achieved using this approach.
The present research work addressed the results of experimental investigation on the mechanical properties and free vibration behaviours of sisal/cotton fabric reinforced polyester hybrid composites. Influence of fibre content and changing layer pattern (CLP) on the mechanical properties and free vibration characteristics are analysed. Hybrid composites are fabricated with simple hand lay-up method followed by compression moulding process. Natural frequency and modal damping values of hybrid composites are analysed by experimental modal analysis. Mechanical properties of composites are measured according to ASTM standards. It is found that an increase in the lamina content in the composite increase the mechanical and damping properties. The maximum mechanical properties are obtained for 40% fibre volume fraction (Vf) in sisal and cotton direction. Maximum natural frequency is found at 40% fibre Vf. By CLP, mechanical properties and damping characteristics are found intermittence of sisal and cotton direction. Scanning electron microscopy is performed to study the interfacial mechanism. The various theoretical models are discussed with experimental results. The statistical approach is used to analyse the experimental results and give the inferences.
The epoxidized styrene–butadiene–styrene nanofibers, which were prepared by epoxidation of the styrene–butadiene–styrene in toluene with peroxyformic acid generated in situ, were successfully embedded with nanometer titania dioxide by electrospinning. The optimum blended electrospinning parameters on preparing the nanometer titania dioxide/epoxidized styrene–butadiene–styrene fibers were obtained. The morphology and antiultraviolet property of nanometer titania dioxide/epoxidized styrene–butadiene–styrene composite fiber were examined using scanning electron microscope and an antiultraviolet transmission tester according to American Association of Textile Chemists and Colorists (AATCC183-2004) standard. The scanning electron microscope results showed that nanometer titania dioxide and the epoxy group could lead to the cementation of electrospinning fibers. The ultraviolet protection factor of rutile nanometer titania dioxide/epoxidized styrene–butadiene–styrene fiber membrane is the largest one of the four fiber membranes. The epoxidized styrene–butadiene–styrene nanofibers embedded with nanometer titania dioxide have great potential in the applications of antiultraviolet textiles.
This paper presents the research on off-axial tensile behaviors of polytetrafluoroethylene-coated woven glass fibers under different loading rates. First, groups of off-axial tensile tests were carried out, and the corresponding failure mechanisms were analyzed. Then, the effect of loading rate on the tensile behaviors of off-axial specimens was studied. Finally, several current strength criteria were compared to predict the material failure strength under different loading rates. Results show the tensile behaviors of polytetrafluoroethylene-coated woven glass fibers are typical orthotropic. The material failure strength is strongly related with failure modes and yarn orientations. Three typical failure modes are observed in the tests, including interface failure, yarn breakage, and composite failure. The loading rate has significant effects on the material tensile strength and the elongation at break. With loading rate increasing, the tensile strength increases and the elongation at break decreases. The tensile strength shows a good linear correlation with the loading rate’s logarithm. Most of current quadratic strength criteria can be used to predict the material failure strength, except for the specimens of small bias angles. This is because traditional quadratic criteria are always based on the strain energy theory of homogeneous materials, which may not reflect the failure mechanisms of coated fabrics and other important details.
Geotextiles primarily provide reinforcement, and their tensile properties can resist stresses and prevent soil structure deformation. Nonwoven geotextiles are also commonly used in railways, roads, soil and water conservation, and therefore their applications are subjected to climatic environments and geographical environments where the geotextiles are used. Therefore, this study recycles and reclaims Kevlar selvages that are then incorporated with polyester fibers and low-melting-point polyester fibers in order to form nonwoven geotextiles. The tensile properties of the geotextiles in relation to various ambient environmental temperatures are examined with the test temperatures being set as 25℃ (control group), 50, 60, 70, and 80℃. Statistical analyses are performed to examine the effects of fiber blending ratios, needle punching depth, and thermal treatments on the tensile properties of the nonwoven geotextiles. The test results indicate that nonthermally treated nonwoven geotextiles have a tensile strength that is significantly increased when the ambient temperature is increased. In contrast, according to the insignificant differences obtained from statistical analyses, the tensile strength of thermally treated samples is independent of the ambient temperatures, indicating that thermal treatment allows for heat setting of the geotextiles. In particular, the thermally treated polyester/low-melting-point polyester/Kevlar nonwoven geotextiles have the maximum tensile strength when they are composed of a blending ratio of 60/20/20 wt% and a needle punching depth of 0.5 cm.
In this paper, tungsten, bismuth, tin, and copper powders were used as additives in the fabric coating to obtain lead-free and flexible x-ray shielding material. The X-ray attenuation and the flexural properties of the coated fabrics were investigated considering the medical protection requirements. The results showed that tungsten additives in silicone rubber coating had better attenuation ratios than the samples that contain tungsten–tin, bismuth, and tungsten–copper, at same additive volume ratios. Moreover, the increment of tungsten volume ratios in coating blend resulted in higher shielding performance at same effective thicknesses and the lower silicone rubber amount in coating lead to compose thinner and lighter fabrics for equal protection level. In addition to that, the samples with tungsten–tin, bismuth, and tungsten–copper showed remarkable attenuation properties, and the results were found to be coherent with the theoretical values. The flex resistance and the flexural rigidity of the samples with tungsten content were also investigated. The coated fabrics with different powder loadings and thicknesses showed good resistance against repetitive folding; on the other hand, the results showed that the increment of tungsten amount in the coating resulted in stiffer fabrics.
This paper presents an experiment-based, multi-medium heat transfer model to study thermal responses of multi-layer protective clothing with an air gap exposed to thermal radiation and hot contact surface. The model considers the dynamical changes of air gap, each layer’s fabric thickness, and air content contained in the fabric due to the pressure applied. The fabric heat transfer model developed from this study was incorporated into a human skin burn model in order to predict skin burn injuries. The predicted results from the model were well in agreement with the experimental results. A parametric study was conducted using various contact temperatures and applied pressures and design variables of firefighting protective clothing, such as physical properties of fabric layers and air gap sizes. It was concluded from the parametric study that resistance to transmission of injurious levels of heat decreases as the test temperature and contact pressure increase, and the contact heat transfer can weaken the importance of air gap under radiant heat flux(8.5 kW/m2) for 60 s and compression (pressure: 3 kPa, temperature: 316℃) for 60 s. The findings obtained in this study can be used to engineer fabric systems that provide better protection for contact heat exposure.
In the smart textile area, textile antennas integrated into people’s clothing functioning as the wireless signal transmission devices have gained increasing attention in recent decades. In this study, a textile conformal dipole antenna was designed to work at the frequency of 915 MHz. The radiation elements of the antenna were adhered directly onto the stitched polyester fabric substrate to get the conformal effect. The measured results showed that the antenna had good performance with the return loss value and typical omnidirectional radiation patterns. To investigate the effect of textile substrate on the antenna performance, models for stitched and plain weave structures were built and the value of root mean square (RMS) surface error was calculated using integration methods. Then an acceptable range of operation frequencies versus RMS was marked out for estimating the reliability of textile substrate. The calculated RMS of our designed antenna was 0.25 mm, which was in the acceptable range area indicating the proper antenna design. Finally, the relationships between the critical frequencies and fabric parameters such as yarn thickness and density were studied, which gives the direct guideline for selecting the fabric as the substrate for textile antennas.
In this study, four plied jute, carbon, E-glass fabric-reinforced and their hybridized composites are manufactured. Nine composite laminates with different stacking sequences are manufactured by vacuum infusion technique. In order to understand the structure of the composites, fiber weight and fiber volume ratios in the laminate system are initially figured out. Furthermore, void fractions of samples are calculated by using theoretical and experimental densities of the composite samples to examine the impact of amount of fiber content on the void fraction. The effect of hybridizing jute fabric-reinforced polyester composite with E-glass fabric and carbon fabric and also the effect of stacking sequence of fabric layers on the mechanical properties (tensile strength, impact strength) of composite laminates are investigated. According to the outcomes of this investigation, it is realized that incorporating high impact resistant fibers to the outer layers of the composites leads to higher impact resistance, and placing high tensile strength fibers at the inner layers results in higher tensile strength at the hybrid composite laminates.
A novel 3D braided material was found based on the traditional 3D orthogonal woven process. The mesostructure of novel 3D braided material is similar to the 3D orthogonal woven material, but only coincide in the Z-direction. The processing technique is easy to operate in automatic process. The representative volume unit has been proposed to establish geometric model. The fiber volume fraction of novel 3D braided material is analyzed and its value is higher than the traditional 3D orthogonal woven material ones. The experimental results show that the braided process of the imperfect orthogonal 3D braided material is rational and feasible.
A new flame-retardant protein viscose fiber with safely wearing performance has been prepared through blending protein solution, flame retardant (hexaphenoxycyclotriphosphazene) and viscose spinning solution, in which wool protein was used and added to spinning solution on the basis of 16% flame retardant, and the properties of the fiber were investigated. The product has more compact structure inside the fiber and evenly scattered small pores on the surface. Flame-retardant protein viscose fiber can reach the flame-retardant standard both before and after 30 times wash test, and the mechanical strength of the fiber was also improved. The introduction of hexaphenoxycyclotriphosphazene lowered the primary decomposition temperature of viscose fiber, reduced its weight loss. The flame-retardancy of the fiber can be improved by the introduction of protein. In thermal processes, the major product of thermal decomposition was CO2, no hazardous and noxious gases were released. Due to the introduction of protein, moisture regain of the fiber is a little lower than that of viscose fiber, but higher than flame-retardant viscose fiber. Warmth retention property was also improved. Friction coefficient of the product is lower than that of flame-retardant viscose fiber. Bulking intensity was increased, which is better than that of viscose fiber.
This study focuses on the development of superhydrophobic and alcohol-repellent medical nonwoven fabrics via electrohydrodynamic atomization (electrospraying). It also compares the effectiveness of electrospraying with conventional pad-dry-cure finishing application. A commercial fluorochemical finishing agent was used to prepare fluorochemical solutions at varying concentrations (0.9–9 wt%). Electrospraying characteristics of these solutions were determined with characterizing their solution properties such as viscosity, conductivity and surface tension. After the successful applications of fluorochemical solutions on nonwoven fabrics via padding and electrospraying, wet pick-up ratios and weight gains of these fabrics were calculated. Also, water and alcohol repellencies of the coated fabrics were characterized with water contact angle and alcohol contact angle measurements. According to our findings, electrospraying application yielded less chemical consumption and higher water contact angle and alcohol contact angle results than padding. Increasing solution concentration and application time for electrospraying enhanced water contact angle values, which reached a maximum level (up to 156°) and afterwards remained almost constant depending on these variables. Thus, their limits to achieve superhydrophobic surfaces were able to be determined. Electrosprayed nonwovens were also shown to be alcohol-repellent against alcohol/water mixture of 70/30 (v/v%) whereas that was 30/70 (v/v%) for padded nonwovens. The investigation of the electrosprayed surfaces revealed a very less coating on the uppermost side of surface fibres which mostly led to the enhanced water and alcohol repellencies. One of the other important outcomes of this study is that there was no significant change on the comfort properties of nonwoven fabrics after the electrospraying application.
Phoenix sp. fiber-reinforced epoxy composites have been manufactured using compression molding technique. The effect of reinforcement volume content (0%, 10%, 20%, 30%, 40%, and 50%) and size (300 µm particles, 10 mm, 20 mm, and 30 mm fibers) on quasi-static and dynamic mechanical properties was investigated. Moreover, the water absorption properties of composites were analyzed at different environmental conditions (10℃, 30℃, and 60℃). For each reinforcement size, composites loaded with 40% in volume show highest tensile and flexural properties. Furthermore, composites with 300 µm particles present the best impact properties and the lowest water absorption, regardless of the environmental condition. The dynamic mechanical properties of the composites loaded with 40% in volume were analyzed by varying the reinforcement size and the load frequency (i.e., 0.5 Hz, 1 Hz, 2 Hz, 5 Hz, and 10 Hz). It was found that the glass transition temperature of short fiber-reinforced composites is higher than that of the composite loaded with particles.
To estimate the photo-oxidation aging performance of PVC-coated membrane material in atmospheric conditions under tensile stresses, the relationship between physical and mechanical properties under accelerated weathering test and outdoor weathering test is studied with the same cumulative UV radiation energy. And then, both tensile strength and whiteness index were measured and compared to characterize the property change of membrane material after aging under four different tensile stresses (0%, 5%, 10% and 20% of the breaking strength), respectively. In addition, FTIR spectrometry was applied to characterize the chemical components of the samples under different weathering conditions, and the carbonyl index was extracted. The results show that there were significant differences of tensile strength and carbonyl index between two kinds of aging conditions, whereas with the increasing tensile stresses, the whiteness index represented a consistent increasing deviation of accelerated weathering from the outdoor weathering. However, the relationship have been built between both whiteness index and tensile strength retention of accelerated weathering and those of outdoor weathering conditions after a Schwarzschild’s modification. Therefore, the service lifespan of PVC-coated membrane materials can be evaluated by accelerated weathering tests under tensile stresses.
The principal component of any non-invasive blood pressure measurement system is an inflatable cuff. Different types of fabrics are used for inflatable cuffs construction. In this study, sphygmomanometric blood pressure measurement using inflatable cuffs was simulated in Abaqus and validated through experimental results. The purpose of the simulation is to study the effect of variation in cuff fabric geometric and mechanical properties on pressure distribution and pressure transmission during blood pressure measurement by predicting the pressure at the interface of the blood pressure cuffs and a metal cylinder. Geometric and mechanical properties of the fabrics of four different cuff types were found experimentally. Interface pressure at the cuffs and metal cylinder surface was also found experimentally using Tekscan pressure sensing system for models validation. The results of the simulation showed that the interface pressure underneath the cuffs vary with variation in geometric and mechanical properties of their fabrics. The results of the simulation were found to be in good agreement with experimental findings. This research demonstrates that the pressure distribution under the cuffs is related to the cuffs' fabric geometric and mechanical properties. This means that variation in cuffs' fabric properties could ultimately incur variations in the blood pressure values of human subjects.
The present work was aimed to develop naturally woven coconut sheath/polyester biocomposites. In these composites, montmorillonite nanoclay (5 wt%) was used as a second filler. The heat releasing rate and other flammability properties were studied using cone calorimeter. The coconut sheath reinforcement in polyester matrix significantly decreased the heat releasing rate when compared to that of the pristine polyester. However, the time to ignite the composite material was shorter than that of the pure polyester. The morphological changes on the fiber surface by the chemical modification significantly influenced the heat-releasing rate and other flammability characteristics due to better interfacial bonding. The hybridization effect of 5 wt% of nanoclay could greatly decrease the heat release rate and the mass loss rate of the composites by char formation mechanism. The characterization techniques such as the scanning electron microscopy and the transmission electron microscopy were used to study the morphological state of the fiber surface and dispersion of clay in the polyester nanocomposites. The thermogravimetric analysis was also carried out to study the effect of the nanoclay on the thermal stability of the coconut sheath/polyester composites at higher temperatures.
The development of electric circuit fabrication on flexible polymer substrates has attracted a significant interest as a pathway to low-cost, comfortable movement, and large-area electronics among direct printing techniques. In this study, the inkjet printing technique was used as a simple method to chemically deposit silver nano and micro-particles (85–500 nm) to the polyester fabrics. It is done by the ejection of silver nitrate and ascorbic acid as a reducing agent to attain nano metals on the different weave patterns with different surface roughness to measure the conductivity variations. A four-contact method was used to measure the electrical conductivity of the deposited samples which is usually employed in the electrical assessment of films. COMSOL Multiphysics® modeling software is used in order to simulate the conductivity of printed silver tracks and finally the results of simulation and experimental works have been compared. The main purpose of this study is to evaluate the effect of surface roughness on the electrical conductivity of printed silver tracks.
In this paper, a novel textile antenna with a semi elliptical ground plane is designed for ultra-wideband applications. Conductive woven fabric made of stainless steel/polyester (80/20%) spun yarn with 158 /m linear resistance is used to design the ground and the patch of antenna. Moreover, the warp density and weft density of woven fabric are selected in a way that it gets high value of surface conductivity. The surface conductivity of woven fabric was 0.088 /sq. The proposed antenna is made of triangle patch within a transmission line and its dimensions are optimized using the genetic algorithm. Results show that the proposed antenna achieves multi impedance bandwidth ranging from 1.4 to 1.6 GHz, 1.8 to 2.4 GHz, and 3.4 to 11.6 GHz (reflection coefficient <–10 dB). The antenna in both bands from 1.4 to 1.6 GHz and 1.8 to 2.4 GHz is circularly polarized. This impedance bandwidth makes it appropriate for many wireless communication systems such as GPS, Wifi, PCS-1900, IMT-2000/UMTS, and ultra-wideband applications.
In practice, the coated fabric is available in many shapes and sizes, not just rectangle and plane. In order to increase the shape-shifting abilities of coated fabrics, polyurethane-coated multi-axial warp-knitted fabric (PU-CMWKF) is developed. In this paper, the tensile characteristics of PU-CMWKF were investigated. Five groups of tensile experiments, with off-axial angles of 0°, 22°, 45°, 67.5°, and 90°, were conducted under constant velocity. The failure mechanism was explored by analyzing the damaged specimens. Additionally, the deformation behavior of PU-CMWKF in three regions was investigated by utilizing the digital image correlation (DIC) system, and an orthogonal anisotropic model was used to predict the modulus and Poisson’s ratio of 22.5° and 67.5°. Research results showed that the apparent modulus of PU-CMWKF strongly depended on the cut of directions. And the failure mechanism under in-plane direction loading suggests that tensile and shear failure act together. The analytical model is validated along five directions in the representation of elastic constant under corresponding small strain.
Alginate/psyllium and alginate/chitosan fibers have great potential for wound-care applications. However, alginate/psyllium fibers have poor tensile strength and alginate/chitosan fibers comparatively have low liquid absorption properties. The main aim was to develop a tri-component fiber with comparatively better tensile strength and liquid absorption properties using three different natural polysaccharides. Alginate, chitosan, and psyllium composite fibers were made by using two different coagulation bath compositions. In method A, psyllium-containing sodium alginate dope solution was extruded into a bath containing CaCl2 and subsequently passed through hydrolyzed chitosan bath, whereas in method B: psyllium-containing sodium alginate dope solution was directly extruded into hydrolyzed chitosan and subsequently passed through CaCl2 bath. The produced fibers were rinsed using 25–100% acetone solutions and dried in air. Tensile, antibacterial, swelling, and absorption properties of these fibers were measured. The study showed that homogeneous fibers can be extruded by using both methods. The fibers produced showed good antibacterial, absorption, and swelling properties. Antibacterial activity of the controlled and composite fibers was more or less the same. However, tensile properties of fibers produced by method A and method B were less than the control alginate–chitosan fibers. The composite fibers produced by method A showed better absorption of saline and solution A than control fiber and composite fibers produced by method B. Therefore, method A is recommended for producing the psyllium-containing alginate chitosan fibers for wound-dressing applications. The fibers produced by this method showed comparable tensile and antibacterial properties, superior absorbency, and swelling properties.
Yarn twist in textile technology is an important characteristic since it considerably affects the properties of knitted or woven fabrics. Many researchers have investigated the effect of staple-spun yarn twist on the properties of the yarns and fabrics. However, the effects of twist level of Kevlar® 29 filament yarn on the properties of yarn and its resin-impregnated self-lubricating fabric liner are not fully known yet. In this study, we have investigated the effects of Kevlar® 29 twist level on the tensile and tribological properties of the fabric liner (Kevlar® 29/polytetrafluoroethylene fabric-resin composite). Two unexpected findings about the effect of yarn twist have been observed, namely (1) asynchronous twist effect on the yarn’s and the liner’s tensile strength and (2) dissimilar yarn twist effect on the liner’s performance. These findings are mainly attributed to the synergic contributions of the yarn twist and strength and the interaction of the resin with the yarn orientation in the woven fabric structure of the liner.
In this study, polycaprolactone (PCL) was dissolved in 9:1 chloroform:ethanol mixture at 14%, 16%, 18% and 20% w/v concentrations. Then, acetic acid and formic acid were added at pre-determined amounts to 18% PCL/chloroform:ethanol solution system separately. Before production, viscosity and conductivity of prepared solutions were measured. Electrospinning technique was used for fabrication of fibrous webs. Morphology of produced webs was observed under a scanning electron microscope while fiber diameter measurements and pore analysis were realized via Image J Software System. The effect of polymer concentration and acidic solvent additions to mostly used chloroform solvent was investigated based on fiber morphology. Results indicate that the increase in polymer concentration increases the fiber diameter which leads to larger average pore area. Electrospinning of PCL with 16% to 20% polymer concentrations in chloroform:ethanol solvent system results in micro fibers. On the other hand, fiber diameter reduced from microscales to nanoscales with the addition of either acetic or formic acid. Fibers produced from PCL/chloroform:ethanol solution at 18% polymer concentration have 2.22 µm average fiber diameter, whereas 158 nm and 256 nm diameter fibers were successfully produced without a bead-like structure by 120 µl of acetic and formic acid additions to the same solution system.
This study aimed to increase the photocatalytic efficiency and durability of functional fabrics coated with TiO2/SiO2 nanoparticles. Tetrabutyl titanate and tetraethyl orthosilicate were used as precursor and ultrasonic irradiation was utilized as a tool for synthesis of TiO2/SiO2 in low temperature and loading nanoparticles onto the polyester-cotton fabric. The multifunctionality of such nanocomposite material was evaluated by analyzing its hydrophilicity, photocatalytic, and antibacterial activities. The hydrophilicity and photocatalytic activity were analyzed based on water droplet contact angle measurements and removal of methylene blue stain under UV, respectively. On the other hand, antibacterial activities were examined against the Gram-positive S. aureus and the Gram-negative E. Coli. TiO2/SiO2-coated fabrics exhibited outstanding self-cleaning, antibacterial, and superhydrophilic properties. Moreover, particle size analysis, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and UV–Visible spectrophotometry confirmed that TiO2/SiO2 nanoparticles produced higher photocatalytic activities on the treated fabrics than pure TiO2 nanoparticles. Furthermore, the self-cleaning properties remained after 30 launderings, indicating excellent washing durability. Therefore, this process had no significant negative effect on the wearability including tensile strength, whiteness index, ventilation property, and surface roughness of sonotreated fabrics.
Electrospinning has been known as an efficient method for fabrication of polymer nanofibers. In this study, an electrospun nanofibrous mats based on polylactic acid with a defined release using doxorubicin was developed. The effects of process parameters, such as concentration, distance, applied voltage, temperature and flow rate on the mean diameter of electrospun doxorubicin-loaded polylactic acid nanofibers were investigated. The fiber morphology and mean fiber diameter of prepared nanofibers were investigated by scanning electron microscopy. Differential scanning calorimetry was employed to identify the presence of doxorubicin within nanofibers. Response surface methodology based on a five-level, five-variable central composite design was used to model the average diameter of electrospun polylactic acid/doxorubicin nanofibers. Mean fiber diameter was correlated to these variables by using a polynomial function at a 95% confidence level. The coefficient of determination of the model was found to be 0.93. The predicted fiber diameter was in good agreement with the experimental result. Differential scanning calorimetry results showed that the doxorubicin was loaded into the nanofibers successfully. In vitro drug release in phosphate-buffered solution and acetate buffer for the optimized and non-optimized samples demonstrated that diffusion is the dominant drug release mechanism for drug-loaded fibers. The initial burst release was observed for non-optimized nanofibers compared to optimized nanofibers. Optimized drug-loaded polylactic acid nanofibers could be good candidates for biomedical applications.
In this study, composite nanofibers from a solution of polyacrylonitrile (PAN), functionalized multi-walled carbon nanotubes (f-MWCNTs), and silver nitrate (AgNO3) in dimethylsulfoxide were successfully produced by the electrospinning method. Aqueous solution of hydrazinium hydroxide was used for the chemical reduction of silver ions. The effects of the simultaneous use of carbon nanotubes (either pristine or amine-functionalized) and silver nitrate in different percentages and the application of chemical reduction on the properties of the nanocomposite nanowebs were investigated. FTIR, SEM, conductivity meter, tensile tester, XRD, and DSC were used for the characterization. Antibacterial activities of the nanocomposite nanowebs were determined against S. Aureus. Full factorial experimental design was utilized in order to be able to evaluate the contributions of the selected factors (f-MWCNT content, AgNO3 content, and application of reduction process) to the variations in ultimate tensile strength, elongation, and conductivity of the composite nanowebs. Analysis of variance (ANOVA) and multiple comparisons were carried out to evaluate the average nanofiber diameters and mechanical properties. PAN/f-MWCNTs/AgNPs nanowebs displayed enhanced conductivity and antimicrobial properties particularly when the chemical reduction process was applied. Besides they showed improved crystallinity compared with pure PAN nanofibers. While the reduction process made the highest contribution to the ultimate tensile strength, elongation, and conductivity of the nanowebs, f-MWCNT content had negligible effect on conductivity of the nanowebs. Considering all the results obtained in this study, composite nanofiber webs of PAN with 1 w% f-MWCNTs and 1 w%AgNO3 can be suggested for use as antistatic and antibacterial filaments.
This study embodies evaluation of ideal test specimen dimension for the study of tensile characteristics of lapped seam parachute canopy fabric. Due to anisotropic nature of textile fabrics, the mechanical property of unseamed and seamed fabric changes with the change in specimen test direction. Therefore, measurement of tensile property at different bias angle (an acute angle between warp and specimen length/test direction) becomes more important in parachute canopy where joining of its various parts is not only in principle direction but also at different bias angle. The present paper deals with the influence of bias angle of stitching on breaking strength and elongation of unseamed and lapped seam parachute canopy fabric using test specimen dimension based on previous practice. Present study reveals that there is need of re-specification of specimen dimension for evaluation of tensile properties of parachute fabric. With the changes in angle of bias, width and gauge length of test specimen, the number of different category of warp and weft yarns available between the specimen grip lines changes and can be calculated mathematically. This has important role in affecting the ultimate properties of parachute fabric. Based on the study, an optimized dimension of test specimen has been postulated for evaluation of tensile characteristics of parallel/opposite stitched specimen through which reliable test result can be obtained. The proposed dimension can be used for comparative analysis of breaking strength and elongation of unseamed and seamed fabric at different bias angle.
Roller blind fabrics are preferred and commonly used in home and office. In general, these fabrics are produced by coating the acrylic blended material, which is known by their ultraviolet properties, onto polyester woven fabrics. In this study, in order to characterize the sound insulation properties of roller blind fabrics, coating resin having different ratios of acrylic are applied onto different polyester woven structures. Sound absorption properties of these fabrics (front and back sides) are measured through dual microphone impedance tube and investigated by statistical analyses. Regression curves are obtained and optimum fabric properties on sound absorbing property have been suggested. As a result, acrylic content in coating material, fabric type, and viol structures occurred by coating process on the woven fabric are found as effective parameters on sound absorption properties of these fabrics. Increasing acrylic content in the resin up to 40% increases the sound absorbing value but further increasing this ratio yields sound reflection from the structure, in general. Optimum sound absorption and reflection values are provided with 40% acrylic rate in coating mixture.
This paper presents an experimental investigation into the influence of bond characteristics between textile and matrix on the mechanical behavior of textile-reinforced concrete (TRC). Two types of tests were performed, i.e. pullout test and uniaxial tensile test. Self-compacting fine-grain concrete was adopted. Two kinds of hybrid textile, consisting of both carbon and E-glass yarns, were specially prepared for this study. The experimental results show that sticking sands on the textile after epoxy resin impregnation can improve the interfacial property between textile and matrix. The specimens with textile of 10 mm x 10 mm mesh have stronger bond strength than those with textile of 25 mm x 25 mm mesh, and can reach the maximum tensile strength of yarns when the initial bond length is between 30 mm and 35 mm. Moreover, sticking sands on the textile can improve the multiple cracks form and the ultimate bearing capacity of TRC under uniaxial tensile load. Specimens with textile of 10 mm x 10 mm mesh have higher first-crack loads than those with textile of 25 mm x 25 mm mesh whether or not the textile surface treatment was conducted, and also have better crack distribution. Finally, based on the experimental results from TRC under uniaxial tensile load, a double linear constitutive equation of stress–strain relationship of carbon fiber yarn is provided in this paper.
Finite element analysis and experimental studies are presented on in-plane tensile and compressive properties under quasi-static loading for two types of hybrid composites made by using unidirectional T620S carbon and E-glass fabrics in a common matrix, epoxy resin. Results are also generated for plain T620S carbon/epoxy and plain E-glass/epoxy composite laminates. Quantitative data for tensile and compressive properties are presented. It is observed that for hybrid composites, placing carbon and glass fiber parts alternately in every layer (intralayer configuration) gives higher tensile and compressive strengths. Tensile failure strain is higher for intralayer compared to interlayer hybrid configuration.
Meltblown fabrics composed of a thermotropic liquid crystalline polyester were subjected to heat conditioning at various temperatures. Physical effect of the treatment was investigated by tensile testing of the fabrics and the individual fibers. The fabrics exhibited increased tensile strength by more than 100% after the heat conditioning due to inter-fiber bonding in the fabric structure and morphological reorganization of the thermotropic polymer. The calorimetric behavior of the polymer was further investigated to obtain information about the internal structure. Structural change during the annealing was also visually observed under a polarized light microscope.
The influence of bias angle of stitching on tensile characteristics of lapped seam parachute canopy fabric has been studied based on proposed test specimen dimension as reported in Part I of this paper. Test results obtained using the postulated test specimen dimension exhibit reliable tensile properties of canopy fabrics. It is also therefore possible for comparative analysis of tensile strength and elongation of unseamed and seamed fabric at different bias angle. During comparative analysis, the data obtained from the previous test dimension (as mentioned in Part I of this paper) and new test dimension show that there is significantly large difference in absolute values of tensile data obtained by these two methods. The trend of breaking elongation is same in both the cases, but the trend of tensile strength is somewhat different with these two dimensions. Besides these, the absolute values of tensile data obtained through proposed specimen dimension are found to be realistic as compared to the results based on previous test dimension.
A radically new innovation was established for development of electromagnetic interference shielding. The innovation emphasis synthesis of carboxymethyl cellulose (CMC), carboxymethyl cellulose composite containing different metal nanoparticles (CMC-MNPs), and carboxymethyl cellulose nanofiber mat (CMC-NF) and carboxymethyl cellulose containing metal nanofiber mat (CMC-MNPs nanofiber mat) by electrospinning technique. Metal nanoparticles used include copper nanoparticles, iron nanoparticles, zinc nanoparticles, cadmium nanoparticles, and cobalt nanoparticles. Synthesized CMC–MNPs were characterized by using scanning electron microscopy coupled with high-energy dispersive X-ray and UV–visible spectroscopy that was used for confirmation of nanoparticles formation. The scanning electron microscopy images clearly showed regular flat shape with semiporous surface. All metal nanoparticles were well distributed inside the backbone of the cellulose without aggregation. The average particle diameter was 29–39 nm for zinc nanoparticles, 29–33 nm for cadmium nanoparticles, 25–33 nm for cobalt nanoparticles, 23–27 nm for copper nanoparticles, and 22–26 nm for iron nanoparticles. Electrospun carboxymethyl cellulose and CMC–MNPs nanofiber mats were synthesized by electrospinning technique and characterized using scanning electron microscopy, energy dispersive X-ray, and transmission electron microscopy. Scanning electron microscopy images of electrospun carboxymethyl cellulose and CMC–MNPs nanofibers reveal smooth and uniformly distributed nanofibers without bead formation with average fiber diameters in the range of 300–450 nm. Moreover, the diameters of electrospun carboxymethyl cellulose nanofiber mat were not affected by the presence of metal nanoparticles. Metal nanoparticles’ content inside the electrospun CMC–MNPs nanofibers was investigated by using atomic absorption spectroscopy. Electromagnetic interference shielding of electrospun carboxymethyl cellulose and CMC–MNPs nanofiber mats was evaluated. Data showed that the EMI-SE was increased in presence of metal nanoparticles and depending on both the metal nanoparticle contents and the electrical conductivity of metal nanoparticles.
Composites comprising a braided poly(lactic) acid (PLA) filament and calcium phosphate bone cement (CPC) were inferred to maintain space and to pack porous fillers into restorative sites. Composites of alkalized multilayer-PLA braids and CPC (PLA/CPC) were divided into various groups according to a series of heat-treatment periods that lasted for 60, 90, 120, 150, and 180 min at 160℃; subsequently, these composites were characterized. Strength decays of samples were also compared after 24 h immersion in Hanks’s physiological solution. Results showed that the PLA/CPC specimens were toughened after treatment at 160℃ for 120 min. Furthermore, the moduli of PLA/CPC groups increased significantly when the heating time was more than 150 min; this effect was generated by the cold crystallization within the PLA filaments. The reduced stress in the composites after immersion was attributed to the fibers that protruded from the scaffold surface and to hydrolysis. The mechanical test results for the PLA/CPC composites indicated that the toughening effect was strengthened significantly under prolonged heat treatment, especially when the heating time was longer than 150 min. The cold crystallization degree of PLA increased, thereby enhancing the strength and toughness of a specimen before immersion. Thus, PLA/CPC composites can be used to simulate potential bone functions as well as to maintain three-dimensional spaces and pack porous fillers into restorative sites conveniently.
This paper investigated the mechanical properties of GQ-6 subjected to a tremendous amount of uniaxial tests. Such material is a new kind of ultra high molecular weight polyethylene fiber and aimed to be adopted in stratospheric airship. To begin with, mono-uniaxial tensile tests were conducted. The cycling-uniaxial tensile experiments were then carried out on the basis of the mono-uniaxial tensile tests data. Finally, performances of welding seams were thoroughly investigated with forty welding specimens. Results of mono-uniaxial tensile tests revealed that such woven fabric possesses high tensile strength and low elongation ratio at break. Meanwhile, the stress–strain behaviors were fitted by the Ogden model and a good agreement between such model and experimental data was obtained. Influences of the uniaxial loading cycle on such woven stiffness were discussed and the elastic moduli were defined with a standard hysteresis loop. For the welding tests, four types of overlapping welding failures were discovered. Compared with intact specimens, an appropriate welding width of 60 mm and an approximate 15% discount of the ultimate tensile stress on the intact textile were obtained.
The properties of fibers were significantly affected by drawing during the spunbond process. In this paper, the influence of drawing pressure on the properties of spunbonded PET/PA6 hollow pie wedge bicomponent filaments was studied, and their performance was characterized by differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, Beion F6 fiber fineness tester, and single fiber strength tester. The hollow pie wedge bicomponent fiber had a distinct interface between the two polymers due to poor compatibility. With increasing of drawing pressure, diameter of the fibers reduced regularly. When the drawing pressure increased, both the degree of crystallinity and orientation of bicomponent fibers enhanced, and the melting point of polyester component increased as well. Furthermore, with increasing of drawing pressure, the breaking strength of the fibers increased, but the breaking elongation and linear density decreased.
In this study, optimized conditions were established for diatomite grinding, which is a natural inorganic mineral with inherently high oil absorption capacity. Diatomite surface was modified with a fluorocarbon chemical and stearic acid via facile methods for enhancing compatibility between polypropylene and diatomite. Polypropylene/diatomite composites were generated in a twin screw extruder with/without using compatibilizer, and nonwoven structures were produced via meltblown technique. Pore size and void content analyses showed that addition of diatomite led to thicker fibers (1–17 µm (the neat polypropylene) vs. 1–32 µm (2 wt.% diatomite containing polypropylene)). Diatomite incorporation into polypropylene resulted in a rigid and brittle structure and a worsened oil absorption property (rust inhibitor oil absorption capacity: 1184% ± 105% (the neat polypropylene) vs. 718% ± 78% and 1089% ± 136% (2 wt.% diatomite containing polypropylene)). Increasing oil viscosity resulted in increased discrepancy among the oil absorption capacities of the neat polypropylene and diatomite containing polypropylene. Analysis of variance tests showed no changes or statistically insignificant differences in oil absorbency.
In this study, a novel approach and the related equipment of coaxial electrospinning have been developed to fabricate a new ultrafine polysulfone amide/polyurethane coaxial fibers at nanoscale, with the polysulfone amide as the core and the polyurethane as the shell of the blended fibers. As the co-spinneret has effects on the structure and properties of the spun fiber, three types of co-spinnerets with different diameters were designed to investigate its effects on the fabricated fibers in this research. Three series of polysulfone amide/polyurethane coaxial fibers were spun using the self-developed coaxial electrospinning equipment, and these fibers were characterized systematically using scanning electron microscope, transmission electron microscope, X-ray diffraction, differential scanning calorimeter and thermogravimetric. High-speed photography was used to digitalize the image of the tailor cone and jet motion of polymer fluid during the spinning process, which provides a detailed description of the electrospinning for the further theoretical analysis. The three-dimensional electric field simulation was also carried out to model the differences of electric field. Our experimental results show that the mechanical and thermal properties of the core–shell fibers fabricated in this research have been improved in the comparison with the fibers spun using the conventional single-needle electrospinning method. The composite fibers have the core–shell structure, so that it can combine the excellent thermal properties of the polysulfone amide and the excellent mechanical properties of the polyurethane. The newly developed polysulfone amide/polyurethane fiber could be used in the field of industrial textiles; it has the potential applications for the development of high-performance apparels in the future.
Textile products are considered as an acceptable alternative for commonly used composite reinforcement due to their lightweight as well as relatively high specific strength and stiffness. Among the variety of textile structures which could be employed in composite manufacturing, the role of weft-knitted fabrics is almost very limited. This is because employing the weft-knitting technology would provide such structures with inferior mechanical properties due to their highly looped construction as well as low fiber volume fraction. But on other hand, it is important to be noted that some advantages such as high energy absorption, good impact resistance, and formability of knitted structures made the researchers to focus on investigating different methods by which the inferior mechanical properties of ordinary weft-knitted fabrics could be improved. Inserting the reinforcing yarns through the warp and weft direction of the knitted fabrics is considered as one of the effective solution for improving their mechanical behavior which eventually leads to a high potential product called as biaxial weft-knitted fabrics. In this literature, it is aimed to review different aspects of novel designed biaxial weft-knitted fabrics which could be suitable for a broad area of technical application such as composite reinforcements.
For decades, street lighting and electric poles are made of metal and it is vulnerable to corrosion due to the harsh weather and chemicals. To overcome such essential problems, galvanized iron is used although it adds more hard work to increase the manufacturing cost. Therefore, fiber reinforced polymer lighting pole is proposed. Fiber reinforced polymer materials possess many advantages such as corrosion resistance, high specific strength and stiffness, etc. Two-dimensional woven fabrics and three-dimensional woven fabrics preforms are used to produce composite structures. However, complex shapes cannot be manufactured as a one piece preform. Woven fabrics, whether two-dimensional or three-dimensional need to be cut into patterns to finally produce the complex shapes. These processes add more cost and time to the final composite products. In this research, innovative technique to produce a three-dimensional complex shape knitted preform using regular flat-knitting machine will be presented. Production of such shaped three-dimensional preform permits the production of one piece-shaped preform without any connection or further sewing processes. Produced knitted preform can be used for various reinforcement applications such as light and communication poles, scaffold facades, traffic sign, oars, and wind mill blades.
Sandwich structure of non-woven composite is produced by using a compressive hot pressing method. It is ranging from 2500 grams per square meter (gsm) to 3500 gsm. Composite sample is designed using Box and Behnken model. Considering 50–70% weight of jute fibre content with 30–50% weight of hollow conjugated polyester fibre, ideal thickness of the composites is maintained in the range from 4 to 5 mm. Thermal properties such as thermal conductivity, thermal resistance, thermal transmittance and thermal diffusivity were evaluated by considering three factors: weight of jute (A), weight of hollow conjugated polyester (B) and thickness of the composite (C). The thermal conductivity of the composite material is determined by heat flow meter method ASTM C518. Experiment result will help to make a suitable standardized panel composite for thermal insulation. It requires 3600 gsm 51/49 parts of contribution of jute/hollow conjugated polyester fibre with 5.0 mm thickness and 3200 gsm 76.5/23.5 parts of contribution of jute/hollow conjugated polyester fibre with 4.5 mm thickness of the composites. The composite weight of 3280 gsm shown optimized thermal responses, it was predicted from response surface method graph. Contribution of jute/hollow conjugated polyester fibre of 54/46 parts with 5.0 mm thickness would be considered to make standardized composite panel. Mostly air conditioning process reduces the energy cost spent for the thermal stability in indoor climate of dwellings.
Warp-knitted spacer fabrics for cushion products are in contact with different parts of human body. Surface shapes of most contacting parts can be simplified as spherical caps, while there are few reports on relationship between sphere diameter and compression property of spacer fabric. Therefore, the main content dealt with in the paper was to conduct spherical compression and simulation analysis of warp-knitted spacer fabrics. Five spherical indenters were selected and three compression indices were featured. Comparisons of compression indices results of spacer fabrics amongst five spherical indenters exhibited good relations. Moreover, spherical compression behavior was simulated by finite element method to better understand the mechanism of spherical compression deformation of warp-knitted spacer fabrics. The results that relative errors of the compression indices were all small showed a good accordance between theoretical and experimental results; then, stress distribution and displacement evolutions were analyzed to discover deformation mechanism of spacer filaments compressed. It is effective to simulate the spherical compression performance between different parts of human body and spacer fabric.
Because of important potential and application prospect of aligned scaffolds in tissue engineering, it is necessary to prepare aligned scaffolds different from previous methods. We have prepared poly(lactic acid) fiber/polyurethane adhesive composite-aligned scaffolds by 1000 poly(lactic acid) melt parallel arrangement fibers and different polyurethane contents at 5, 10, 20, 25, and 30% separately. It can be found that polyurethane contents have great influence on bonding effect between fiber and adhesive, surface and cross-sectional morphology, thickness, weight, contact angle, stress and strain, pore diameter, porosity, pore interconnectivity, water absorption, and gelatin impregnation. The maximum of pore diameter and porosity of aligned scaffolds can be achieved to 64.24 µm and 66.67% by controlling poly(lactic acid) fiber parallel arrangement and polyurethane adhesive content. Moreover, the ultimate stresses of aligned scaffolds are 3.47 MPa along length direction and 1.02 MPa in width direction. Each composite-aligned scaffold has better fiber parallel arrangement, pore structure, and stress.
This paper proposes lightweight textile acoustic structure, wherein electrospun polyacrylonitrile-based nanofibers enhance sound absorption properties with no weight and thickness penalty. Polyacrylonitrile nanofibers with diameter of 110 ± 7 nm were electrospun on spacer-knitted fabrics by varying deposition amount and surface coating arrangement. Proposed novel approach eliminated additional processing steps such as handling and post-lamination and provided easy scalability of nanofibers at macro-scale. The results showed that the sound absorption of nano-enhanced specimens was improved drastically when deposited amount of nanofibers or its effective surface area increased. Sound propagation paths in different configurations were interpreted from sound absorption and air permeability measurements. The sound absorption coefficient values up to 0.7 are achieved in the low and medium frequency ranges with no weight and thickness penalty by tuning deposition amount and surface coating arrangement.
Nowadays, nanofiber for filtration is drawing attention because of its large surface area and smaller pore size. In this study, aerosol filtration is carried out using nanocomposite filter made of polyacrylonitrile nanofibers with incorporated silver nanoparticles at different weight percentages of 5, 10, and 15 (based on the weight of polyacrylonitrile) sandwiched between polypropylene spun bonded nonwoven. Dimethylformamide acts as both solvent and reducing agent for polyacrylonitrile and the formation of silver nanoparticles, and the silver nanoparticles were characterized using ultraviolet–visible spectroscopy and X-ray diffraction. Further, Box–Behnken method was used to prepare filter media using areal density of nonwoven substrate, electrospinning time, and silver wt.% as process variables. Later, the developed filters were studied for aerosol filtration efficiency at face velocity of 5 cm/s against NaCl aerosol particles ranging from 0.3 to 10 µm, respectively, as well as studied for anti-bactericidal activity against gram-positive Staphylococcus aureus and gram-negative Escherichia coli bacteria. From the study, the developed polyacrylonitrile/silver nanofiber filters possess 99% aerosol filtration efficiency with good anti-bactericidal activity, which potentially improves filter quality.
Braided suture made with different materials and sizes is commonly used in many surgical interventions. Their key properties include tensile strength during tightening, knot security, surface morphology, knot slippage, and behavior during healing period. We have developed different testing procedures to measure these properties, but selection of suture should be brought under simultaneous considerations of all preferred properties related to surgical interventions and surgeon requirement.
In this study, we propose a new approach for appreciation of surgeon satisfaction by using global quality index corresponding to simultaneous satisfaction of several suture properties such as organoleptic and mechanical properties. A global quality index was developed by using desirability functions. A statistical survey based on the evaluation of suture qualities by Tunisian surgeons allowed the determination of surgeon's requirement, weights, and objectives of individual desirability functions corresponding to each suture property. Braided sutures have been submitted to different developed tests for the evaluation of suture properties during healing and tying. The obtained results are converted to individual desirability index in order to evaluate satisfaction degree of each suture property. Finally, geometric and arithmetic mean aggregation are used to determine the global quality by attributing relative weight to each individual satisfaction degree. Global quality index of polyamide-braided sutures fabricated under different braiding conditions was determined. Obtained results allow the identification of optimal suture for specific surgical interventions.
In this study, weft-knitted strain-sensing structures are described, along with the materials and manufacturing techniques required to produce the fabrics on a computerised flat-bed knitting machine. Knitted sensing fabrics with conductive yarns, i.e. silver-plated nylon yarn and polyester-blended stainless steel yarn have been created with different design possibilities. A laboratory test set-up was built to characterise the knitted sensors and the resulting equivalent resistance under the different level of strains. The most successful samples have been realised through a series of single conductive courses within the interlock base fabric structure using silver-plated nylon in terms of responsivity, repeatability and lower electrical signal drift. Deficiencies associated with strain-sensing structures realised through the intermeshing of conductive yarns have also been addressed.
This paper aimed to reveal the low-velocity impact responses characteristics and failure mechanism of 3-D braided composites with experimental and frequency domain analysis method, respectively. The low-velocity impact tests were carried out by Instron® 9250 drop-weight instrument with five different impact velocities from 1 m/s to 6 m/s. The results showed that the peak load and absorbed energy increased with the increase of impact velocity. The load–time curves which were in time domain were transformed into frequency domain with Hilbert–Huang Transform (HHT) method. Combined the failure morphologies of 3-D braided composites with frequency domain analysis results, it could be precisely found out the failure mechanism of 3-D braided composites. At the impact velocity of 1 m/s, the 3-D braided composites only had elastic deformations. With the increase of impact velocity, resin crack was the main failure mode of 3-D braided composites. The frequency of impact stress waves which caused the elastic deformation and resin crack mainly located at 0–10 kHz and 60 kHz. When the impact velocity increased to 6 m/s, fiber tows breakage was the main failure mode, and the frequency of impact stress wave located at 15–20 kHz.
A new solid unit cell model is developed based on the microstructure analysis of three-dimensional (3D) six-directional braided composite (6DBC) produced by four-step 1 x 1 procedures in this research. First, the volume control method is applied to analyze the spatial movement traces of yarns. Then the microstructure configuration and squeezing condition of yarns is analyzed in detail by the mathematical modeling. The relationships between the microstructure parameters of unit cell and the braiding process parameters are derived. The parametrical solid unit cell model for modeling the microstructure of 6DBC is established. Finally, the main microstructure parameters of specimens are calculated to validate the effectiveness of the model. The predicted results agree well with the available experimental data. In addition, the squeezing conditions of the braiding yarns and the axial yarns are analyzed in detail, respectively. The variations of the key microstructure parameters with the braiding angle are discussed. Results indicate that the parametrical unit cell model has provided a better understanding of the relationship between the microstructure and the braiding process parameters for 3D 6DBC.
Novel flame-retardant back coating layer for historic textile fabrics was developed. Silica nanoparticles originated from agriculture waste rice husk were prepared through one pot thermal method. The morphological and structure properties of nanoparticles were studied. The silica nanoparticles were further impregnated with organic borate producing flame-retardant composite. The obtained composite incorporated with the binder by mechanical mixing providing flame-retardant coating paste. The coating paste spread on the back surface of textile fabrics. Varied compositions of nanoparticles, binder and organic borate were studied in the back coating layer. The flammability, thermal stability and mechanical properties of the blank and treated samples of linen fabrics as an inner support to the historical textiles were investigated. Flame retardancy of the back-coated linen samples has improved achieved high class of flame-retardant textile fabrics of zero rate of burning compared to 80.3 mm/min for blank. The synergistic effect of flame retardancy between nanoparticles and organic borate was investigated. The tensile strength of the flame retardant fabrics was enhanced by 27% and elongation was improved. The effect of industrial aging on the flame retardancy and mechanical properties of flame-retardant back coating textiles was studied.
This article reports on oil sorption behavior of needle-punched nonwoven fabrics made from milkweed, kapok, cotton and polypropylene fibers using air-lay and carding technologies. The effects of fiber and fabric parameters on oil sorption and retention capacities, and oil sorption rate and fabric strength were investigated. Fabrics made using natural fibers such as milkweed and cotton were found to selectively absorb oil over water. Milkweed and kapok nonwovens displayed higher oil sorption and retention capacities as compared to cotton and polypropylene nonwovens. Further, milkweed and kapok nonwovens exhibited higher oil sorption rate as compared to cotton and polypropylene nonwovens. The porosity of nonwoven fabric was found to play a vital role in determining the oil sorption capacity. Although the web-forming technology did not affect the oil sorption and retention capacities and oil sorption rate, it affected the fabric strength significantly. Cotton nonwoven kept on artificial sea water for 10 days displayed very low water sorption capacity, although the nonwovens produced using natural fibers exhibited preferential sorption of oil over water and high oil sorption and retention capacities; which are advantageous in using them as oil sorbents to cleanup oil spills on oceans, but they offered low fabric strength. These findings indicate that further research works are required to improve the strength of natural fiber nonwovens for sustainable oil spill removal.
This paper focuses on using response surface methodology (RSM) and artificial neural network (ANN) to optimize the diameter of Gum tragacanth (GT)/poly(vinyl alcohol) (PVA) nanofibers. However, producing curcumin-loaded GT/PVA nanofibers with using these optimized conditions is another aim. RSM methodology based on four variables (voltage, feed rate, distance between nozzle and collector, and solution concentration) with three levels and ANN technique were compared for modeling the average diameter of nanofibers. In the RSM method, the individual and interaction effects between the parameters on the average diameter of nanofibers were determined using Box-Behnken design (BBD). Data sets of input–output patterns were used for training the multilayer perceptron (MP) neural networks trained with back-propagation algorithm for modeling purpose. Experimental results for both ANN and RSM techniques showed agreement with the predicted fiber diameter. High-regression coefficient between the variables and the response displayed that the performance of RSM for minimizing diameter of nanofibers was better than ANN. Based on response surface model, optimum conditions (polymer concentration of 4.2% (w/v), distance between the capillary and collector 20 cm, applied voltage of 20 kV and flow rate of 0.5 mL/h) were obtained for producing GT/PVA nanofibers with minimized diameter. Then curcumin-loaded GT/PVA nanofibers were produced with acquired optimum condition and the effect of curcumin concentration (3 and 5% (w/v)) on the morphology, diameter and biological properties of nanofibers was investigated.
This paper presents a new region-based image fusion algorithm and its applications for measuring essential parameters of nonwoven structures. The algorithm combines a series of partially focused images of the same sample view captured at different focusing points to form a fully focused image that is fundamental for accurate detections of fiber edges in the structure. It starts with selecting a number of source points based on the maximum gradient matrix, and locating initial fiber boundaries using the pixel-based image fusion algorithm. Within the fiber boundaries, the source points diffuse in the same rate, and the boundaries are formed when their expanding fronts encounter each other. These new boundaries divide the image view into regions of various sizes, each representing a coherent area centered at one source point. Finally, each region is filled with the corresponding region that has the highest average sharpness value among all of the multi-focus images. The paper also presents the experimental results on the fiber diameter, fiber orientation and pore size distributions of nonwovens generated by using this algorithm, in comparison with the results from other methods.
Layer-by-layer self-assembly technology was introduced with adsorption of oppositely charged polycations and polyanions. The composite thin film consisting of quaternized chitosan derivative/poly(2-acrylamide-2-methylpropane sulfonic acid sodium salt) was created on the surface of cotton fabrics by using this method without much damage for breaking strength of swatches. The oxidative chlorine of five bilayers deposited on the swatches could reach 0.25%. The treated cotton fabrics exposure to dilute household bleach possessed excellent antimicrobial property, which could inactivate 100% of Staphylococcus aureus and Escherichia coli O157:H7 bacteria with a contact time of 1 min. The chemical surface modification, surface morphology, washing stability, storage stability, and mechanical property of the modified swatches were characterized and confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, stability measurement, and tensile strength test, respectively.
Textile-based body worn sensors are preferred due to its comfortability for continuous monitoring of the body vital signs and kinematics. This research discusses the development and characterization of elastomeric tape for strain sensor application and is used for the measurement of elbow angle. The stress strain properties of commercially available elastomeric tapes have been analyzed for the selection of suitable specifications of elastomeric tape. The actual sensor has been developed with the help of narrow width tape loom by introducing the silver-coated nylon yarn in the middle of the tape structure. The effect of linear density of conductive yarn and number and strands of conductive threads used on sensitivity of the sensor was studied. The repeatability of the developed sensor was characterized by cyclic testing using Zwick tensile tester.
Based on the results, polyester yarns were used as base threads along with rubber threads for the sensor development. It was found that sensor developed using finer yarn with six conductive threads has higher sensitivity. The developed sensor was integrated on to elbow sleeve and elbow angle measurement was done. The results of the developed tape sensor have been compared with the hospital goniometer for 10 male subjects. The results showed that the developed tape sensor is suitable for measuring the elbow angles up to 150°.
This paper involves a comprehensive evaluation of electromagnetic shielding characteristics of woven fabrics. The conductive fabrics produced by using cotton/copper-wrapped and cotton/stainless steel-wrapped hybrid yarns in plain and twill weaves were tested in single and double layer structures to determine the electromagnetic shielding effectiveness (EMSE), absorption and reflection values over an incident frequency of 0–3000 MHz. In addition, the shielding effectiveness (EMSE) of these conductive fabric layers was tested under pure cotton fabric. The results indicated that fabrics including copper-wrapped hybrid yarns exhibited EMSE values that increase with increasing incident frequency then decline after a peak value is reached. On the other hand, fabrics including stainless steel-wrapped hybrid yarns showed no sharp peak values, instead; slight peaks were observed. The differences between the EMSE values of plain and twill weave fabric samples were found to be statistically insignificant. The use of fabrics including stainless steel-wrapped hybrid yarns in the layered structures resulted in better shielding effectiveness in a wider incident frequency range when compared to the fabrics including copper-wrapped hybrid yarns. Finally, it was found that the use of conductive fabrics under pure cotton fabric did not interrupt the shielding effectiveness of the conductive fabrics, which can lead to consider the use of layered structures for garments requiring special protective capabilities.
A conductive poly(o-anisidine) (POA)/poly(ethylene terephthalate) (PET) nonwoven composite was prepared by chemical oxidative polymerization of o-anisidine in aqueous HCl solution. The effects of the oxidant type, oxidant/monomer mol ratio, and polymerization temperature and time were studied on POA content and surface resistivity of the composite. It was observed that the swelling of PET in 1,4-dioxane decreased the surface resistivity of the POA/PET composite by up to 18.5 k/cm2, when compared to that of the unswollen PET nonwoven. According to the electromagnetic shielding effectiveness (EMSE), and the relative shielding efficiency of the absorbance (Ab) and reflectance (Re) values of the composite in the range 15–1500 MHz, 99.9% of the shielding was obtained with an attenuation of 33 dB at 15 MHz. The durability of the composite was determined by measuring its surface resistivity after domestic washing and commercial laundering.
This study examined the effects of ultrasonic welding parameters on bond strength, seam thickness and seam stiffness, as well as water permeability. For study purpose, two types of four-layered fabrics with same compositions and different areal densities suitable for inner part of sport shoes were used. Two different types of seams, lapped and superimposed, were applied for ultrasonic welding and also compared by traditional seam applied by shoe manufacturer. The morphology of different type of seams was also analyzed to observe the influence of welding parameters on the layers during the ultrasonic welding process. Bonding strength was found to depend on the seam type and composition of the joined fabric layers. It was confirmed by the shoe manufacturer that all the produced welded seams provided the requested minimum bond strength to be suitable for the use of the shoes. The traditional seams applied by the shoe manufacturer were thicker but had lower stiffness in comparison to all welded seams. It was also found out that ultrasonic welding damaged the membrane, which was confirmed by no water resistance of welded seams. Statistical analysis showed that ultrasonic welding parameters, such as welding frequency and velocity, influence the bond strength, thickness, and bending stiffness of welded seams, but the obtained results were statistically insignificant.
The aim of the present work was to develop and evaluate a controlled drug delivery wound dressing based on polymeric porous microspheres, which are also termed as microsponge drug delivery system. For this purpose, turmeric (drug)-based polymeric porous microspheres formulations were developed by quasi-emulsion solvent diffusion method. The production yields, actual drug content, drug entrapment efficiency, particle size, formulation of the material, and in vitro release were studied. On the basis of maximum drug released, a formulation was selected to incorporate into wound dressings with the help of a binder by spraying technique. Finally, the selected formulation and samples of wound dressings containing microsponges were subjected to scanning electron microscopy and drug release analyses. The result of in vitro release shows that microsponge drug delivery system is a versatile tool that has a potential to convert any wound dressing into a controlled drug delivery wound dressing.
Pressure garments are used to heal different medical conditions such as hypertrophic scars, venous problems and orthopaedic disorders. The requirement of therapeutic pressure for different applications is different. So there is a need for engineering pressure garments according to the requirement. Pressure garments are made from elastic knitted fabric. The principle of pressure generation depicts that the tensile property of the elastic knitted fabric is an important factor which can be regulated by varying the property of elastic inlay yarn used in the fabric. Little information is available in this aspect. In the present study, elastic knitted fabric tubes were prepared by varying the linear density of the elastic inlay yarn. Pressure exerted by the fabric tubes was studied on 10 male and 10 female upper arm of left hands. The pressure generation behaviour was then compared in between male and female subjects. The results were also compared with pressure development on rigid body. Results showed that tensile property of elastic knitted fabric can be regulated by varying the linear density of elastic inlay yarn. Pressure exerted by the fabric tubes can be regulated by changing the linear density of elastic inlay yarn. Pressure generation was always higher on rigid body than human body.
The building industry is now evolving in a rapid pace due to the massive need to build and rebuild the cities. While designing the building, the owner appreciates the esthetic aspects, whereas the contractor is more interested in a performance-based approach for its construction. The current study investigates the integration of industrial textiles in buildings. For that, life spawn estimation of textile materials is crucial due to the different existing French regulations that set a minimum durability criterion. The paper presents a methodology for lifetime estimation and an application to two fabrics intended for use as facing materials for buildings. A series of aging tests were carried out and extrapolations were made to reach the research goal. The results of tests that were carried out indicate the feasibility of the textiles’ lifetime estimation methodology used.
Biobased fabrics are now getting widely used as solar shading for managing solar gain and daylight management and reducing building peak load and annual energy consumption of existing buildings. This work proposes to characterize five spunlaced nonwovens made of 65% of flax and 35% of viscose with different grammage. Radiative properties (transmissivity, reflectivity and absorptivity) are evaluated not only over the sun’s spectrum, but also over UV, visible and IR spectra. In addition, hygrothermal properties, such as thermal resistance, specific heat capacity or water vapor resistance, are also evaluated. Results indicate that these nonwovens present low transmittivity, which is interesting in the view of managing solar gain. Furthermore, it was found that radiative properties are mainly influenced by nonwoven’s thickness and porosity, as well the relative humidity. Lastly, hygrothermal properties (thermal resistance, thermal conductivity and water vapor resistance) are impacted mainly by porosity.
To improve the wearing comfort, durability, and antibacterial properties of the electromagnetic (EM) shielding property, a type of multifunction EM shielding woven fabrics which having great liquid transport and drying ability were fabricated in this study. This study aims to investigate theirs liquid transport, drying, and electromagnetic (EM) shielding properties. For this purpose, initially six types of multifunctional crisscross-section polyester (CSP)/antibacterial nylon (AN)/stainless steel wire (SSW) metal hybrid yarns with different wrapping amounts were produced using hollow spindle spinning technique. Conductive woven fabrics were then woven with CSP/AN/SSW metal hybrid yarns as weft yarns, and PET filaments as the warp yarns. The liquid transport and drying ability of the conductive woven fabrics were evaluated in terms of wicking ability and water evaporation rate, which are two vital factors that affect the physiological comfort level of personal protective clothing (PPC). Results indicated that adding CSP yarn in the fabricated EM shielding woven fabric could obviously improve the drying rate of the fabric. The EM shielding behavior of these woven fabrics were analyzed using a vector network analyzer in the frequency range of 300 kHz–3 GHz. Results showed that the wrapping amounts of the metal hybrid yarns significantly affect the wicking and drying abilities of the woven fabrics. In addition, the lamination angles of the fabrics with different amounts of layers remarkably affect their EM shielding characteristics.
A cyclic phosphonate ester flame retardant was applied to improve the flame retardancy of poly(lactic acid) (PLA) nonwoven fabric by a pad-dry-cure technique. The effects of curing temperature and flame retardant dosage on the flammability of PLA fabric were analyzed. The burning behavior, thermal stability and flame-retardant mechanism of the flame-retardant PLA fabric were investigated by limiting oxygen index (LOI), vertical burning test, microscale combustion calorimetry (MCC), thermogravimetric (TG) analysis and scanning electron microscopy (SEM) with energy dispersive spectrum (EDS). The treated PLA fabric exhibited good flame retardancy, and its LOI was about 35%, whereas this value was 26.3% for the untreated fabric. No obvious difference of the MCC test results between the untreated and treated fabrics was found. The results from TG analyses indicated the formation of a very small amount of char during the thermal degradation process of the treated PLA fabric. The SEM-EDS analysis showed an obvious decrease in the phosphorus content of the flame retardant fabric after burning. These indicate that the gas-phase flame-retardant mechanism during combustion is dominant, and results in the good flame retardancy of the treated fabric in the presence of a very small amount of char residue.
The impact response to twill weave carbon fabric/epoxy composite laminate structure has been investigated by employing two types of the stacking sequences of composite laminate structure to low-velocity impact loadings by using a Drop-Weight Machine (CEAST 9350 drop tower). An engine hood is the intended application for the composites. The air-coupled ultrasonic C-scan technique (NAUT21) has been selected in order to characterize impact damage size, delamination, flaw detection, and damage in composite laminate structures. The effect of increasing impact energy was illustrated with both types of the stacking sequences of the composite laminate structures until complete perforation of specimens at 25 J due to degradation of mechanical properties of composite laminates. The failure processes of damaged specimens for different three impact energies (5 J, 15 J, and 25 J) were being evaluated comparing load–displacement curves and images of damaged samples were taken from both impacted and nonimpacted sides through C-scan. The performance index and absorbed energy of the tested structures were investigated. The primary damage modes were found to be fiber fracture, delamination, and matrix cracks.
This paper details about weaving of single-layer 3D ‘T’ profile with fillet for use as insert in composite ‘T’ joints and ‘T’ stiffeners. The ‘T’ insert with fillet was woven using 3 K carbon tows on a narrow width multi-beam automatic loom. Weaving was carried out based on the double-cloth weaving principle. Novelty of the work lied in the approach adopted for designing of the weave architecture in developing 3D ‘T’ profile with fillet portion, arriving at the pick cycle diagram for weave design development which has been detailed in this paper. Test results of composite ‘T’ joints fabricated incorporating the insert showed strength improvement as well as change in crack propagation mode as compared to conventional ‘T’ joint. The continuous insert with fillet acted as a bridging member among the three sections of the ‘T’ joint, thus contributing to performance improvement.
The desire for sport products with enhanced performance and efficiency has been known for many years and nanotechnology has opened new routes for the production of functional sportswear. The objective of this paper is presenting an overview on applications of nanotechnology in different sport sections with the main emphasis on sport flooring, clothing and shoes. Some of the important features imparted into sport apparels by nanotechnology are also thoroughly discussed. Following the current trend sportswear of all types will experience the nanotechnology revolution, in the near future.
In the present study, nanoscaled poly (vinyl alcohol) (PVA) fibers were prepared by electrospinning. An attempt has been made to examine the effects of different process parameters on the mean fiber diameter and tensile strength of poly (vinyl alcohol) nanofibers. Mean fiber diameter and strength of nanofibers were investigated by scanning electron microscopy and universal testing machine, respectively. Response surface methodology was used to establish a quantitative basis for the relationships between the electrospinning parameters such as solution concentration, applied voltage and spinning distance with the diameter of prepared nanofibers and their tensile strength to predict the optimum conditions. The relationships between the responses and the variables were visualized by contour plots. According to the results, solution concentration was found to be the most significant parameters affecting nanofiber diameter. There was no significant difference between the effects of parameters on tensile strength. The fiber diameter increased, but tensile strength decreased by increasing the concentration of the polymer solution. The predicted fiber diameter and strength were in good agreement with the experimental results.
The shear behavior of 3D spacer knitted fabrics was investigated by using a picture frame fixture. Three different methods were used to find the shear angle during loading rate of 10 mm/min. All the tests were recorded by a CCD monochrome camera. The images acquired during loading process were used for analysis in order to obtain the full-field displacement and shear angles at chosen points on the surface of test specimen. An experimental and analytical investigation of picture frame shear fixture was conducted to determine its suitability for measuring intra-ply shear properties of 3D knitted spacer fabrics. In this work, a fixture was designed to analyze the in-plane shear behavior of these fabrics. The nonlinear behavior of shear force versus shear angle and the deformation mechanism were analyzed. The curves for shear force versus shear angle and position of buckling for in-plane shear test are recorded by considering two different frame lengths in order to compare with each other. Load–displacement curves of intra-ply shear tests are also analyzed. In addition to this, a program was developed in MATLAB using Hough transform to analyze the shear angle in the real-time image taken during displacement of specimen at various positions. The results of image analysis were compared with the actual experimental results. These findings are important requirements for further improvements in designing of picture frame fixture and to study the in-plane shear properties of 3D fabrics.
Duck and chicken feather fibers are waste products of the poultry industry, creating a serious solid waste problem around the world. Previous works showed that feather fibers can be reused to adsorb heavy metal ions from water. But the raw feather fiber only exhibits moderate heavy metal ions adsorption capacity, not cost-effective to be reused as adsorbent in a large scale. To improve the adsorption capacity of feather fibers, sodium pyrosulfite (Na2S2O5) was used in this paper to modify the feather fiber in order to improve its Pb2+ adsorption capacity. Scanning electron microscopy and Fourier transform infrared spectroscopy quantified chemical and structural changes of Na2S2O5-modified feather fibers. In addition, Na2S2O5-modified feather fibers were processed into feather/polypropylene melt-blown filter cartridges and their dynamic Pb2+ adsorption properties were investigated by using the test equipment set up in our lab. Finally, the desorption effects of NaOH and sodium sulfide nonahydrate (Na2S·9H2O) aqueous solutions on the feather fiber adsorbed with Pb2+ were studied. It is found that Pb2+ adsorption capacity of the feather fiber increased after being modified by Na2S2O5. Modified feather/polypropylene filter cartridge exhibited higher Pb2+ adsorption capacity than feather/polypropylene filter cartridge and pure polypropylene filter cartridge in the whole dynamic adsorption process.
This paper presents the results of research work carried out to investigate the heating properties of nylon knitted fabric impregnated with a polymerised solution of polypyrrole. The inspection of the molecular polypyrrole electro-conductive pathways responsible for the heating effect of the knitted fabric was investigated using a scanning electron microscope. Further to this, the heat generated by the polypyrrole impregnated fabric was observed under varying power supply terminal separation distances in order to understand the relationship between the length of the polypyrrole electro-conductive fabric and the level of heat generated. The sample with the lowest terminal separation distance i.e. 5 x 1 cm2 produced more localized heat and reached a temperature level of 114℃ in less than three minutes. Additionally a thermo-mechanical characterisation of this knitted heating material was carried out against varying levels of strain and compression. The maximum stress and ultimate strain values of both treated and untreated samples were found to be similar. However, it was observed that the extensibility of the samples affected the generation of heat. The suitability of knitted fabric impregnated with polymerised polypyrrole heating elements for in-car applications where the heating elements may be next to skin was also discussed. The investigation concluded that polypyrrole heating fabric is suitable for next-to-body heating applications which can be engineered by controlling the optimum electrical pathways provided by the network of polypyrrole molecular chains together with the correct power supply levels to work under a defined fabric strain range. The purpose of the current research is to provide a new material that could help to develop heating fabrics with improved textile properties.
In the present study, the effects of different dopants such as camphorsulfonic acid (CSA), dodecylbenzene sulfonic acid (DBSA) (70 wt% in isopropanol), and dodecylbenzene sulfonic acid sodium salt (DBSANa+), and different solvents such as N-methylpyrrolidone (NMP), and N,N-dimethylformamide (DMF) on the structure and properties of polyacrylonitrile (PAN)/polyaniline (PANI) composite nano/microfiber web produced by the electrospinning technique have been investigated and compared to each other. It has been observed that the nano/microfibers produced from NMP solvent generally had larger fiber diameters than the nano/microfibers produced from DMF, while the use of DBSANa+ resulted in the formation of larger diameters in comparison to other dopants. The use of NMP as the solvent resulted in higher breaking stress values for the reference samples and the composite samples, which contained CSA-doped PANI while the samples that contained DBSA(iso) and DBSANa+-doped PANI showed lower breaking stress values when electrospun from NMP. While the solutions prepared using DBSANa+ showed higher solution conductivities, the use of NMP as the solvent resulted in lower solution conductivity values. Higher conductivity values were obtained with CSA in NMP and with DBSA(iso) in DMF. The conductivity values of the composite nano/microfiber webs were around 10–8 and 10–9 S/cm, which is the range for antistatic materials instead of insulator materials as pure PAN.
In this research work, the feasibility of using the needlefelt carpet waste as a lightweight aggregate for producing lightweight polymer concrete was studied. Carpet waste was shredded into small pieces and added to the polymer concrete mixture to reduce the density of the resultant product. Incorporation of a small amount of carpet waste (2.5% in weight of concrete) decreased the density of polymer concrete up to 23%. The results show that the flexural and compressive strength of lightweight polymer concretes decreased by increasing the carpet waste content. Compressive strength of lightweight polymer concrete significantly decreased with increase in the waste content. All lightweight polymer concrete samples under flexural test exhibited the post-cracking response with a remarkable improvement in the toughness and the strain capacity. An increase in the energy-absorption capacity from 53% to 129% was observed for lightweight polymer concrete samples, depending on the waste content.
Aim of this study was to investigate the effects of filament cross section on the performance of automotive upholstery fabrics. Thirty-six yarns were produced by changing the cross section of poly(ethylene terephthalate) fibers (round, octolobal and W-channel) and the air-jet texturing parameters (overfeed and number of core and effect yarns). After heat-setting and dyeing the yarns were woven into fabrics and laminated. Performance tests of both the air-jet textured yarns and the fabrics were carried out. It was observed that W-channel gave the most different air-jet textured yarn structure. It formed a bulky, uneven yarn structure with many open loops. No pronounced difference in the recovery from strain behaviors of the air-jet textured yarns was recorded. For all the cross-section types, increase in the looped structure resulted in higher permanent elongation values. In case of fabrics, all the filament cross sections gave satisfactory results for the light fastness and the abrasion resistance tests. It was concluded that changing filament cross section had the most significant effect on air permeability. W-channel gave the lowest air permeability, while octolobal gave the highest one.
In this study, bisphenol-A-based acrylated epoxy oligomers were prepared and utilized to improve the adhesion strength of polyester cords onto rubber. The structure of the oligomers was characterized by Fourier transform infrared spectroscopy and 1H-NMR spectroscopy. Ultraviolet-curable adhesive formulations were prepared by using acrylated epoxy oligomers and applied onto the polyester cord fabric by a dip-coating method and irradiated. Ultraviolet-cured coatings were characterized by thermal and scanning electron microscope analysis, contact angle measurements. In the second stage of the experiment, ultraviolet-cured polyester cords were adhered onto rubber under heat and pressure. The prepared adhesive formulation was expected to improve the adhesion strength. The adhesion strength of the coated material was evaluated by using peel test as a function of the carboxyl/epoxide ratio. The adhesion strength of 18.0 N/cm was obtained when the carboxyl/epoxide ratio was set as 1. It was observed that peel strength, contact angle, and surface energy values of acrylated epoxies strongly depend on the acrylic acid content of the oligomer.
Fire protective clothing worn by the emergency responders may be exposed to intensive heat condition time and time again during a firefighting work. In this research, the level of thermal protection retained by the fire protective clothing after repeated exposures to flash fire was investigated from bench-scale test to full-scale test. A thermal protective performance tester and an instrumented manikin with a transverse motion system device which was capable of simulating the action of running across the flame were used for the exposure test. Physical properties (mass, thickness, thermal shrinkage, tear strength) and thermal protective property of the test specimens were examined after each exposure. The results showed that repeated heat exposures resulted in continuous decrease of mechanical performance of the fabrics. The thermal protective performance of fabrics with good thermal dimensional stability such as polybenzimidazole/Kevlar and flame resistant cotton decreased after exposure. For the fabrics with severe thermal shrinkage such as Nomex IIIA and polysulfonamide, the thermal protective performance was improved due to the increase of fabric thickness induced by thermal shrinkage. However, this positive effect of thermal shrinkage diminished in the manikin test as it decreased the air gap size between the garment and flame manikin. The thermal protective property of Nomex IIIA garment exhibited continuous decrease after repeated exposures. This study was expected to provide new sights for the performance evaluation and application of fire protective clothing.
Phytochemicals have been used over the centuries in order to cure various diseases and still do to this day. Phytochemicals are herbal extracts that are also named herbal remedies. Curcumin (CUR), which is a natural polyphenolic compound derived from the roots of the plant Curcuma Longa, has many therapeutic properties. CUR has poor water solubility and instability that has confined its further applications, thus there is need for a carrier to deliver the drug consistently. In this research, the feasibility of using polycaprolactone/gelatin nanofibers as carriers for CUR is examined. Nanofibers are obtained by electrospinning method. The morphology of nanofibers was observed by scanning electron microscopy. Fourier Transform Infrared Spectroscopy and differential scanning calorimetry is used to study the thermal behavior of the nanofibers. Antibacterial tests were conducted against methicillin-resistant staphylococcus aureus (MRSA) and extended spectrum β lactamase (ESBL). These pathogens are very dangerous and versatile pathogens emerging rapidly causing nosocomial infections in hospitals. The nanofibers were 99.9% antibacterial against MRSA and 82.56% against ESBL. The results showed that these nanofibers have potent antibacterial activity against both Gram positive and Gram negative bacteria. As a result, these nanofibers are very promising materials for antibacterial applications.
In this study, far-infrared/anion-releasing elastic warp-knitted fabrics were successfully fabricated. Firstly, the composition and twist degree of ring-spun complex yarns that were made by rotor-twisting machine and ring-spinning frame were optimized based on twist contraction, hairiness, and tenacity measurements. The shell materials—1-ply bamboo charcoal (BC) roving, 1-ply phase change material (PCM) or the both (BC/PCM), and the core material—BC/stainless steel (BC/SS) wrap yarn, were formed into different compositions of ring-spun complex yarns. Afterward, elastic warp-knitted fabrics were fabricated using the optimized complex yarns as weft yarns, and rubber threads and polyester (PET) filaments as warp yarns. Air permeability, far-infrared emissivity, and anion amount of resulting warp-knitted fabrics were evaluated. Ring-spun complex yarn result shows that, twist contraction rate ratio increased, but hairiness decreased with increase of twist degree. Tenacity of ring-spun complex yarn made by BC roving (Type A) or PCM roving (Type B) first increased and then decreased with twist degree. However, when 1-ply BC and 1-ply PCM rovings were used as shell materials, the tenacity of resulting ring-spun complex yarn (Type C) decreased with twist degrees. Consequently, 12 twists per inch (T.P.I.) was the optimal twist degree for the following fabrication of warp-knitted fabrics. Air permeability, far-infrared emissivity, and anion amount of elastic warp-knitted fabrics composed of BC/SS wrap yarn and BC roving reached 44.35 cm3/s/cm2, 0.94 and 420 counts/cm3, respectively, indicating excellent breathability and far-infrared/anion-releasing health care functions.
Conducting polyaniline-coated polyester textiles have attracted much attention due to their wide range of surface resistivity. The surface resistivity depends strongly on the polymerization condition. In this work, polyaniline coated on textile by in situ chemical polymerization method. The influence of substrate modification, synthesis condition, and especially redoping procedure on the surface resistivity of polyaniline-coated textile was investigated and an optimum condition specified. The obtained results indicate that polymerization in an ice-water bath and in a monomer:oxidant:HCl molar ratio equal to 1:1:7 for about 4–6 h decreases the surface resistivity significantly. Furthermore, the experimental results show that etching the surface of textile and redoping procedure with concentrated HCl vapor can decrease the surface resistivity, in a short time.
A new acoustic absorbing/cushioning composite is fabricated by thermoplastic polyurethanes honeycomb structure -- thermoplastic polyurethane honeycomb cushion and grid, and composite nonwoven in this study. Composite nonwoven is composed of different layers of polyester/polypropylene nonwoven and polyester nonwoven. Research result shows that layer combination of polyester/polypropylene nonwoven and polypropylene nonwoven affects acoustic absorption and thermal conductivity of resulting composite nonwovens. The thermal conductivity of composite nonwovens decreases to 0.02213 W/(m K), showing excellent thermal-insulating property. Honeycomb structure–thermoplastic polyurethane honeycomb cushion and grid broadens the acoustic absorbed frequency and improves the mid- and high-frequency absorption coefficient and cushioning property of thermoplastic polyurethane/polyester/polypropylene composites. Incorporation of different honeycomb structure into composite nonwovens presents diversified acoustic-absorbing characteristic profiles. The resulting 35-mm-thick thermoplastic polyurethane/polyester/polypropylene composites absorb 85% acoustic waves at 1250 Hz and 94.2% at above 2000 Hz as well as 92.88–96.59% impact energy. Therefore, it becomes an excellent alternative for protective wall in kindergarten and gerocomium and compartment wall in the building.
Reinforcing concrete with fiber is one of the most effective methods to improve the properties of cement-based materials. In this study, the effect of using two different polyamide fibers (i.e. PA6 and PA66) as reinforcement in fine aggregate concretes was investigated. The effects of the fiber length and type of supplementary cementitious materials (SCM) were also studied. Three-point bending test, pullout, and compression tests were carried out on the cementitious composites. The effect of embedment length was also investigated on pullout behavior. Pseudo-strain hardening behavior was obtained in the fiber-reinforced concretes. Although there was no significant difference in the flexural properties of composites containing PA66 and PA6 fibers, the pullout load and energy which were obtained by PA66 fibers were 36% and 45% higher than PA6 fibers, respectively. It was found that an increase in PA66 fiber embedment length up to 10 mm leads to an increase in pullout energy. The compressive strength of more than 90 MPa was obtained using PA66 fibers, which were considerably higher than ordinary concrete and PVA fiber-reinforced concrete.
The flame retardant functionality was imparted in cellulosic textile using banana pseudostem sap, an eco-friendly waste plant product. The extracted sap was applied in three different pH conditions, viz. acidic, neutral and alkaline to the pre-mordanted bleached and mercerized cotton fabrics. Flame retardant characteristics of both the control and the treated fabrics were analysed in terms of limiting oxygen index, vertical flammability and heat release related properties using a cone calorimeter. The thermal degradation and pyrolysis mechanism were studied using thermogravimetric analysis and differential scanning calorimetry. The elemental analysis was carried out with X-ray fluorescence, and the quantification of phosphorus and nitrogen was also done. Besides, the charring mechanism of both the control and the treated fabric was analysed in detail, and a char structure model has been proposed. The treated fabrics were also evaluated in terms of colour and other physical properties.
The natural fibre composites are potential alternative of glass fibre composites for structural applications, automobile and furniture industry, but these are susceptible to the bacterial attack. The current study aims to investigate the bio-functionality of composites using flax woven fabric reinforcement along with ZnO nanoparticles. The ZnO nanoparticles were synthesised by sol–gel method and added in different fractions to unsaturated polyester resin before impregnation of reinforcement. The composites were fabricated by vacuum bag moulding technique, and bioactivity was tested in terms of antibacterial activity (zone of inhibition). The ZnO nanoparticles imparted bioactivity to the composites even in the lowest amount (0.02% by weight). These bioactive composites will help to lower the risk for fibre degradation and enhance the service life of composite, by restricting the growth of bacteria.
Natural flax fibres have been extensively recognized by automotive industries to reduce the weight of vehicles and obtain recyclable composite parts. Most of composite parts are produced by using resin transfer moulding or thermoforming processes. As the first step of these two composite manufacturing processes, the preforming is quite important. Braided and woven fabrics are widely used as textile reinforcements to manufacture the advanced composite parts. But few research works concern the preforming of the reinforcements based on natural fibres and also there is no analysis of dry braided fabrics forming. In the present work, the studies of formability behaviour of braided and woven fabrics made of the same flax/polyamide 12 commingled yarns are performed. Furthermore, an experimental comparison between the preforming behaviour of braided and woven flax/polyamide fabrics is investigated under identical preforming conditions. The different formability behaviour and the defects developed during preforming stage are analysed. First results obtained on hemispherical shape show a higher deformability for the braided reinforcements, which can generate some forming defects, in particular buckles.
Uniaxial tensile and bending properties of lightweight thermally bonded nonwoven layers produced from the blends of Estabragh (milkweed)/polypropylene fibers have been focused in this paper. For this, different material variables such as the blend ratio as well as some parameters of thermal bonding process including the calendering speed and temperature were considered in this study. Eighteen fibrous samples from six Estabragh/polypropylene blend ratios of 10/90, 25/75, 40/60, 55/45, 70/30, and 85/15 at three different layer weights (g/m2) were produced on a laboratory-scale carding machine. During needle-punching operation, different punch densities at low levels of 20, 30, and 40 punches/cm2 were applied to the samples in order to increase the layer strength by increasing the fiber entanglement while the fiber breakage remains in such minimized level. Thermal bonding process was then carried out on the produced nonwoven samples using an apparatus equipped with a pair of heated calendering in which three different levels of temperatures as well as three levels of calendering speed were considered as the process variables. Taguchi’s analyzing method was employed for statistical investigations of the results. The findings showed that the blend ratio of fibers, layer weight, and the applied temperature during the thermal bonding process significantly increased the nonwoven layer resistance against axial tensile forces. On the contrary, variables punch density and calendering speed had no significant effects on the breaking force values of the samples. Considering the samples' bending rigidity, it was fount that all the variables except the calendering speed, have significant effects.
The present work deals with the identification of a new natural fiber from the Phoenix sp. plant and their characteristics were studied for preparing the fiber-reinforced polymer composites. This fiber was extracted by simple manual peeling process. Physico-chemical and mechanical properties are studied according to the standards. The morphology of the fiber was studied by using scanning electron microscopy. X-ray diffraction and Fourier transform infrared spectroscopy are used to identify the crystallinity index and chemical groups present in the fiber, respectively. The fiber has an average diameter of 577 µm and density of 1.2576 g/cc. The cellulose, lignin, wax, ash, and moisture contents present in the fiber are 76.13%, 4.29%, 0.32%, 19.69%, and 10.47%, respectively. The crystallinity index was 57%. The Griffith model was used to obtain the average values of diameter and tensile properties of Phoenix sp. fiber. The maximum tensile strength and Young’s modulus were around 348.95 MPa and 7.62 GPa, respectively. The Phoenix sp. fiber properties were compared with the properties of existing natural fibers.
Cooling garments containing phase change materials are one of the practical techniques used for improving thermal comfort and worker’s performance in hot environments and under protective clothing. Such garments absorb the body's excessive heat and help the body reach thermal comfort situation by reducing the heat content of the body. The amount of heat absorbed by the phase change materials and the efficiency of the cooling garment can be affected by several parameters. This study uses a software modeling to investigate the effect of different factors such as ambient temperature, the use of protective clothing over the cooling garment, and the type of phase change material bags coating on the efficiency of the cooling garment. The results showed that temperature of the environment in which the cooling garment is used could largely affect the cooling efficiency of such garments. Increasing the ambient temperature from 30 to 40℃ can reduce the cooling efficiency of the garment up to 70%. Also, the use of cooling garment under protective clothing was simulated in this paper as a practical way to improve the thermal situation of the body. It was also shown that insulating the outer surfaces of phase change material bags against the surrounding environment could enhance the cooling power of the garment by 20 to 34% depending on the type of the coverings.
In the present study, coating formulations based on carbon nanoparticle (125–150 nm) and two component polyurethane resin [Polyester polyol-8 and hexamethylene diisocyanate [C8H12N2O2 (NCO-(CH2)6–NCO)] have been prepared in concentration of 5,6,7,8, 9 and 10 g of carbon black in 100 ml of polyurethane solution and was applied on cotton fabric adopting knife over roller coating technique. The coated fabrics were evaluated for surface resistivity and relevant microwave properties i.e. permittivity, scattering parameters, reflection, transmission, absorption, reflection loss and electromagnetic interference shielding in HVS free-space microwave measurement system. It is observed that increasing the carbon content increases the permittivity values and decreases the impedance. It is seen that with increase of carbon content up to 7 g, absorption increases due to increase of permittivity while with further increase of carbon content from 8 to 10 g, absorption decreases due to increase of conductivity and thereby increased reflection. The coated fabric at 6.55 wt% carbon and 93.45 wt% PU in thickness of 1.3 mm has shown about 46% absorption, 29.49% transmission and 24.5% reflectance in X (8.2–12.4 GHz) and Ku (12–18 GHz) frequency band. When electrical thickness of coated fabric equals /4, a peak of reflection loss is observed due to Salisbury absorption mechanism. Highest reflection loss of –31.39 dB at 17 GHz, more than 20 dB in bandwidth of 16–18 GHz and more than 10 dB in entire Ku- band is achieved. Coated fabric may be used as apparel for protecting human being from hazardous microwave and for radar absorbing structural materials for defence applications.
The development of electric circuit fabrication on flexible polymer substrates has attracted significant interest as a pathway to low-cost, comfortable movement and large-area electronics among direct printing techniques. The term electronic textiles, or e-textiles, are used to denote the class of fabric structures that integrate electronic elements with textiles and can sense changes in its environment and respond to it. This new class of wearable electronic systems is being designed to meet new and innovative applications in the military, public safety, healthcare, space exploration, sports and consumer fitness fields. In this paper the inkjet printing technique (office thermal inkjet printer) was used as a simple method to chemically deposit silver Nanoparticles (85–300 nm) to the flexible surface. It is done by ejection of silver nitrate and ascorbic acid as a reducing agent to attain nanometals on the surface. Ink concentration and repeating the printing sequence of each ink determines molar ratio ejection of ink and is found to be necessary to be evaluated in order to attain the highest level of conductivity. The main purpose of this work is to gain the highest conductive printed tracks by using statistical design of experiment method on the fabric surface by applying inkjet technique. By optimizing the mentioned parameters, the highest conductivity of printed flexible tracks on the surface of paper is gained 8.0635 x 105 S/m and the result for polyester fabric is obtained 1.2417 x 104 S/m whereas metallic silver wire has a conductivity of 6.173 x 107 S/m.
Achieving whiteness and opaqueness has been an issue in paint, ceramic, paper, and coating industries from the very beginning. In the past two decades, biomimetics, for the construction of bio-inspired functional materials, has attracted much attention. As an application of biomimetic science, various structural colored materials are investigated by many researchers. The white beetle exoskeletal scales is one of those materials that shows a brilliant white color caused by randomly arranged chitin nanofibers. This material is the inspiration for achieving light weight, efficient, and low-cost white coatings by means of a nanostructure. We used this idea in this research to apply nanofibrous polymeric layer on a substrate, paper sheet in here, and witnessed the possible achievements by varying the nanofiber layer characteristics that underpin its optical properties. We coated nylon and PAN nanofiber layers on the surface of a paper using an electrospinning method and for both polymers desirably high whiteness and opaqueness achieved. Moreover, it was observed that end-use application in printing and writing is easily attained on the nanofiber-coated paper using the common methods. Measuring the properties of the nylon nanofiber-coated paper showed that the tensile strength and hydrophilicity slightly increased depending on the nanofiber layer characteristics.
Reinforcement of the thin-wall structures under internal pressure by braiding method has many applications in different industries. In this way, the effective braid angle determination will be important in achieving a stable and resistant structure. The main aim of this work was finite element modeling and experimental validation of these structures under internal pressure. Therefore, a thin silicon pipe as the core was covered with different braid angles in braiding machine and then was subjected to internal pressure. After that, a finite element model was implemented for a repeatable part of the samples as a unit cell using ANSYS software to calculate the pressure–diameter diagram of the samples. Finally, in order to verify the accuracy of the finite element models was recorded the increase in braided pipes diameter up to rupture by camera and prepared pressure–diameter diagram for all samples by image processing method. The comparison of the finite element method results and image processing showed a good agreement with high accuracy. Also was observed in finite element modeling that the relationship between diameter-pressure in 55 degrees was rather linear, generating forces in the pipe surface of thin silicon due to internal pressure along braid strands direction as confirmed by image analysis.
Sonic velocity of knitted fabric samples was measured by Dynamic Modulus Tester, and the relationship between changes in the mechanical properties and their sonic velocity was investigated. Through the measurements, sonic velocity was found to be highly correlated not only with fabric static elastic modulus but also with fabric breaking strength, breaking extension, and work of rupture. Sonic velocity, as found, depends on the direction of measurement, walewise or coursewise, and is a linear function of the number of wales and courses per centimeter and loop-shaped factor. Furthermore, the effect of applying dynamical loading on the fabric leads to changes in fabric mechanical and structural properties, which can be patterned through the measurement of their sonic velocity. The dynamic modulus tester measured the velocity of sonic pulses in materials. This technique will help in prediction of the change in mechanical properties of the fabric tensioned structures during their service life.
Intelligent energy shunting fluid/fabric base structure which utilizes well-processed shear thickening fluid has been developed. The shear thickening fluid has been synthesized by a powerful mechanical stirrer to disperse 12 nm silica particles into polyethylene glycol 200 g/mol at three concentration levels from low to near maximum packing as 15, 25 and 35 wt%. Examining the rheological behavior of the shear thickening fluid indicates that the increase of shear thickening fluid concentration leads to significant increase in the suspension’s initial, critical and ultimate (up to 104 Pa.s) viscosities, reduction of the critical shear rate, increase of viscoelastic modulus and instability of the suspension. The quasi-static puncture test results demonstrate with the increase of shear thickening fluid concentration, the maximum bearable load by the 15, 25 and 35 wt% shear thickening fluids-treated Twaron® composites increases by 132, 315 and 362%, and the energy absorption increases by 143, 159 and 209%, respectively, compared to the neat fabric. Regarding penetrator structure and dimension, by using rounded penetrators, windowing and pull-out mechanisms would be expected at low velocities. However, sharp-nosed penetrators most likely cause yarns to push aside that is not taken into account as a perfect criteria for investigation of puncture resistance performance. Also, larger penetrators have a larger presented area of impact and, as a result, break more number of yarns to penetrate the fabric.
In this study, a new multiunit cell model is proposed based on the microstructure analysis of three-dimensionally full five-directional braided composites produced by four-step 1 x 1 procedures. The new multiunit cell model consists of five kinds of unit cells, namely interior, exterior surface, interior surface, exterior corner, and interior corner unit cells, which are developed by control volume method to characterize the unique microstructure features for different regions of three-dimensionally full five-directional braided composites. The relationships between the microstructure parameters of unit cells and the braiding process parameters are analyzed in detail and the structural parameters of the preform are derived. Especially, the squeezing condition of the yarns in the interior region is studied. Finally, the main microstructure parameters of braided specimens are calculated to validate the effectiveness of the multiunit cell model. Good agreement has been obtained between the predicted values and the available experimental data. In addition, the variation of the volume proportion of five kinds of unit cells to the overall specimen with the number of yarn carriers is discussed, respectively. The effect of braiding angle on the squeezing factor of braiding yarn is analyzed. Results indicate that the presented multiunit cell model can be adopted to effectively predict the microstructure and structural parameters of three-dimensionally full five-directional braided composites.
Polyethylene terephthalate multifilament fabrics used as filtration and operating room textiles possess through-thickness pore channels at the yarn intersections (meso-pores). These pore channels pose a risk for the penetration of contaminated fluids and particles. The size of pore channels may be reduced by high-density weaving. However, this leads to reduced drapability and thus to degraded application properties of the fabric. To satisfy the requirements without impeding the physiological properties of the textile, fluid- and particle-tight fabrics are developed. This was realized by partial immobilization of functionalized micro particles into the meso-pores. A reduction of the pore size without complete pore-closure is achieved by establishing a net-like particle structure in the meso-pores. To match the requirements of intensive use, permanent particle-bonding to the fiber surface is necessary. This can be achieved by suitable polyethylene terephthalate fabric surface-modification, dependent on the particle functionalization. The investigations have shown that functionalized particles establish a very good inter particle bonding as well as to the fiber surface. An increased permanent bonding can be realized by a modification of the fabric surface which is tuned to the functionalization of the particle.
Nerve guides are the bridging devices used to bridge the proximal and the distal ends of the dissected peripheral nerves. Biocompatible nerve guides comprising polycaprolactone/polyvinyl pyrrolidone polymer were developed using centrifugal spinning technique. The developed nerve guides were loaded with triterpenoids isolated from Centella asiatica. Drug-releasing studies were carried out at various drug-loading percentages in the phosphate buffer releasing medium. The release studies confirm that the drug can be released into the medium to the extent of 50%. Cell culture studies also confirm that the triterpenoids-loaded nerve guides are biocompatible, provide an oriented substratum for cell adhesion and proliferation which is necessary for guided tissue regeneration.
In order to model complicated folded fabric, this paper proposed a new reverse modeling method. Two kinds of concrete implementation were investigated, which were based on graphical deformation and nonlinear dynamics, respectively. The first method learned from Free-Form Deformation technology is used to form the regular folds, while the element distortion rises. The second method adopts a fluid structure interaction algorithm to form the irregular folds. Both methods can transform the finite element model from expanded state to initial folded state without changing the mesh topology. Therefore, the mapping relationship between the finite element models of expanded state and folded state can be naturally obtained. Then, the initial stress used to modify the model can be calculated according to the mapping relationship, and the modifying can ensure the accordance of inflated flexible fabric’s geometry and the original design. At last, the finite element model of an inflatable fabric, which cannot be modeled by exiting method, was established by the new reverse modeling method with its feasibility and accuracy verified by comparing the calculation results. The results of this study could provide a reference for modeling complicated folded fabric.
The aim of this research was to establish the optimum processing conditions for producing hydroentangled nonwoven fabrics best suited for application in disposable and protective wear, such as surgical gowns, drapes and laboratory coats. Carded and cross-lapped webs, from greige cotton, viscose and polyester fibres of three basic weights, were hydroentangled, at three different waterjet pressures on a Fleissner’s Aquajet hydroentanglement machine. An antibacterial agent and a fluorochemical water repellent finish were applied in one bath using the pad-dry-cure technique to impart both antibacterial and water repellent properties to the fabrics. The standard spray ratings, tensile strength and extension at break for three treated and untreated fabrics were evaluated. The spray ratings for the treated fabrics ranged from 80% to 90% against zero for the untreated fabrics while the tensile strengths in both the machine and cross-machine directions of treated fabrics were greater than that for the untreated fabrics, the reverse being true for the extension at break. Contact angles for all treated fabrics exceeded 90° which indicate good resistance to wetting. The finishing treatment decreased the mean pore size of all fabrics and increase in waterjet pressure and fabric weight decreased the air and water permeability. In this study, it was observed that low weight fabrics of 80 g/m2 hydroentangled at low waterjet pressure of 60 bars were suitable for use due to their higher air and water vapour permeability as well as higher pore size distribution. These fabrics meet the requirements for surgical gowns, drapes, nurses’ uniforms and laboratory coats.
The use of passive coatings could be a new solution to improve the cleaning potential of interior textiles in hospitals. In these years, the scepticism toward the use of antibacterial textiles in the health care sector is emerging, and in the Nordic countries, the implementation success is confined. From this perspective, the purpose of this paper is therefore to address focus on alternative passive coatings that without actively killing the bacteria provide a hydrophobic and easy-to-clean textile surface. The paper relates to an in-situ study evaluating the effect and cleaning potential of SiO2-coated textiles compared to traditional textiles and a hard plastic surface as a reference material. Through the study, arranged at an outpatient lung department at Hospital Vendsyssel, Denmark, five different surface materials were installed on hospital chair armrests and sampled with microbiological contact plates through a three-week period. By determining the level of contamination on these surfaces, the study illustrates that the SiO2-coated textile is possible to clean to an acceptable level below the critical limit value of 2,5 Colony Forming Units (CFU) per cm2. In comparison, the traditional textiles were only cleaned to the acceptable level in 56% of the microbiological controls, while the regular hard plastic surface only had acceptable levels of contamination in 25% of the samplings.
The objective of this research is to study the thermal comfort of simulated multilayered diaper structures in dry and wet conditions. To that end, a back sheet, breathable films, a superabsorbent core, and top sheets were provided and diaper structures were generated. In order to reveal their possible effects on thermal comfort, five different types of breathable films and two different types of top sheet layers were selected. Relative water vapor permeability, water vapor resistance, thermal conductivity, thermal resistance, and thermal absorptivity characteristics were analyzed and the results were evaluated statistically using analysis of variance tests. The test results indicated that the breathable film type and the top sheet type used showed significant changes on the breathability and thermal comfort of the diaper structures in dry state. Nevertheless, no statistically significant effects were observed in wet state.
This study aims to introduce a novel protocol to characterize the thermal protective performance of fabrics used in firefighters’ clothing under hot-water exposure. For this, new and improved test methods were developed to evaluate the performance of a set of fabrics under exposure to hot-water splash and hot-water immersion with compression. The thermal energy transmission through the fabrics tested was thoroughly investigated, and the physical properties that affect the performance of fabrics were statistically identified. It has been found that mainly mass (hot-water) transfer occurs through fabrics in a hot-water splash; whereas, both conductive heat and mass transfer predominate in a hot-water immersion with compression. The compression applied in the exposure of hot-water immersion changes the physical properties of fabrics, thereby reducing fabrics’ performance. The structural configuration and physical properties (e.g., air permeability, thickness) of fabrics are crucial to their heat and mass transfer and therefore to overall fabric performance. This study’s findings may contribute to developing new fabric testing standards, as well as improved thermal protective clothing to provide better occupational safety and health for firefighters.
A new concept in improving the thermo-oxidative stability of carbon fiber polymer-matrix composites (CFPMCs) by adopting integral reinforced structure was investigated. Specimens of three-dimensional and four-directional braided carbon fiber/epoxy composites (BC) and laminated plain woven carbon fiber/epoxy composites (LC) were subjected to isothermal aging at 90℃, 120℃, and 150℃ in air circulating ovens for various durations up to 13 days. The process resulted in progressive deterioration of the matrix reins and fiber/matrix interfaces, in the form of chain scissions, weight loss, and fiber/matrix debonding, which significantly led to the decrease of the flexural strength. Besides, the flexural properties’ retention rates of BC were higher than those of LC at the same aging conditions due to the difference of the reinforced structures. On the one hand, LC lost more weight than that of BC because the percentage of fiber ends area exposure to air in LC specimen was three times more than that in BC specimen. On the other hand, the BC specimens can resist the flexural load as an integral structure although the resin was damaged and the adhesive force between fiber bundles and resin decreased after thermo-oxidative aging, and no delamination happened like the LC specimens. Therefore, adopting three-dimensional and four-directional braided preform as the reinforcement of CFPMCs is an effective way to improve their thermo-oxidative stability.
This study uses metallic wires, stainless steel (SS) wires, and copper (Cu) wires as the core and 75 denier polyester (PET) fibers as the wrap material to form the metal/PET wrapped yarns. The optimal SS/PET and Cu/PET wrapped yarns are then made into different woven fabrics. The test results of the metallic wrapped yarns show that the optimal tenacity occurs with the wrapping count being 12 turns/cm, while the metal/PET woven fabrics have a low surface resistivity due to the conductive metal/PET wrapped yarns along the weft direction. An increasing number of laminating layers increases the electromagnetic shielding effectiveness (EMSE) while decreasing the air permeability of the woven fabrics. The laminating angle is also proportional to the EMSE of the woven fabrics. In sum, the combination of metal wires and PET fibers provides the resulting woven fabrics with good EMSE.
Cenosphere is a ceramic-rich industrial waste produced during burning of coal in thermal power plants. This study deals with the effect of cenosphere as particulate filler on mechanical behaviour of woven jute-glass hybrid composites. The hybrid composite consists of jute and glass fiber as reinforcement and epoxy as matrix. The conventional hand lay-up technique is used to prepare composite specimens. Cenosphere of different weight percentage (5, 10, 15 and 20 wt%) was added to the hybrid composite. The samples were tested as per ASTM standards for their mechanical and flexural properties to establish the effect of filler content. It is found that the mechanical properties are significantly influenced by addition of waste ceramic filler cenosphere up to 15 wt% and increases the tensile, flexural and interlaminar shear strength by 90.47%, 24.32% and 16.75%, respectively, in comparison to unfilled composite. The morphologies of the composites studied by scanning electron microscope indicate good dispersibility of cenosphere in the matrix, which in turn improves the strengths appreciable.
To enhance the anti-ultraviolent properties of technical jute fabrics, the enzymatic surface coating with the in-situ produced phenolic polymers of polyhydric phenols was investigated in this study. Firstly, the laccase-mediated polymerization of the five polyhydric phenols (catechol, resorcinol, hydroquinone, pyrogallol and phloroglucinol) was analyzed by FT-IR. Catechol and pyrogallol were polymerized together by laccase with ether bonds linked. On the contrary, the units of resorcinol, hydroquinone and phloroglucinol in their enzymatically formed polymers concatenated to each other by C-C bonds. Then, the coated jute fabrics were characterized in terms of X-ray photoelectron spectroscopy and scanning electron microscopy. The increasing of the C/O ratio on the jute fabric surface after the coating treatments supported the achievement of the enzymatic coating on jute fabrics via the in-situ polymerization of phenolic compounds and the grafting reaction of polyphenols with lignins on the surface. The sequence of the coating extent by using various polyhydric phenols was proved to be catechol, pyrogallol, resorcinol, phloroglucinol and hydroquinone in order from rich to poor according to the O-C-O component of cellulose in the C1s spectra of jute fabrics and the scanning electron microscopy photographs of jute surfaces. Lastly, the ultraviolent protection factor and the ultraviolent resistance of the coated jute fabrics were measured. The ultraviolent protective performance of jute fabrics after the coating treatments depended both on the coating amount and the chemical structure of the coated polymers. Among the tested polyhydric phenols, the polymerization of catechol obtained the best coating for ultraviolent protection. Different polyhydric phenols employed for the enzymatic coating showed different trends in ultraviolent protection factor of jute fabrics with the increasing of incubation time. The jute fabrics coated with in-situ-generated polycatechols or polyresorcinols had excellent ultraviolent resistances.
There have been various efforts on frequency selective surface in recent years, and of course, some research progress has been made, especially in numerical calculation and simulation field. However, it seems that less work is done on the processing and forming methods. Soft fabrics are periodic and have advantages over the rigid materials in lightweight, softness, low bending rigidity, which make it possible and meaningful to study their filtering property as the medium in electromagnetic field. In this paper, a kind of electromagnetic functional textile based on frequency selective surface was proposed specifically for 10 GHz, dominant frequency of X-band radar. The full-wave simulation software, HFSS v14, was used for theoretical simulation and optimization, and two complementary cross-shaped unit cells with optimum size were obtained. Then, the frequency selective fabrics were manufactured through silk-screen-printing technology and measured using transmission method. It showed that the measured and simulated results had good consistency, and the fabricated frequency selective fabrics had ideal band-stop or band-pass performance. Finally, according to the analysis of S21 curve and transmission line equivalent circuit modal, the filtering mechanism was explained and the great potential in practical application of frequency selective fabrics was further illustrated.
In this study, the influence of a new surface treatment of the textiles to reinforce concrete materials has been investigated. The short polyvinyl-alcohol fibers were attached to the textile surface to achieve a fluffy textile. The flexural and peel tests were employed to study the effectiveness of the surface treatment on the carbon textile. As a result, the applied treatment considerably improved the bond properties between the textile and cement matrix up to 43%, and enhanced load-bearing capacity of textile-reinforced cementitious composites by up to 56%.
A successful prosthesis has to emulate physiological and biomechanical performances of the native ligament. Today, there is no ideal artificial ligament that simulates the performances of the human anterior cruciate ligament. This work aims to study the impact of the braiding parameters on ligaments mechanical performances. The braiding parameters include yarn count, braid architecture, and machine settings (take-up speed). Two braided architectures were designed: a biaxial quadruple braid and a triaxial quadruple one incorporating elastane. Mechanical properties of these structures were measured and compared to those of the natural ligaments. Elastic recovery under traumatic force was studied in order to compare the elasticity of the manufactured samples. The obtained results showed that the elastic recovery was improved with the incorporation of elastane filaments and prostheses mechanical properties match closely those of the native anterior cruciate ligament. Finally, a response surface methodology was used to predict and optimize the prostheses mechanical properties.
This paper presents a study of heat-setting treatment on tubular polydioxanone stents which can be used as intestinal implants. Two PDO monofilaments with linear densities of 100 ± 2 and 150 ± 2 tex respectively were used for producing a set of weft-knitted tubular stents using a small-diameter, circular weft knitting machine. The heat-setting treatment was used for the stents to restore a tubular shape. The physical, mechanical and thermal properties of the stents were examined before and after the heat-setting treatment. The results of mechanical testing illustrated that the prototype stents in this work could achieve higher radial forces than Wall stents and Z stents on the market. The heat setting with temperature of 80℃ and time of 5 min were found to be more appropriate for the stents. In conclusion, the stents were successfully developed and have potential application for the treatment of intestinal stenosis or obstruction.
Polymer chains were introduced to esterified hydroxyapatite particle surface with methacrylic acid for modification and subsequently modified particles were immobilized onto PET filter fabric via heat fusion method to impart adsorption property. The polymerization process of methyl methacrylate on esterified hydroxyapatite surface was optimized and effects of treating time, temperature, particle size, and concentration on immobilization ratio and pore size of filter fabric were discussed. FTIR were applied to characterize the structure of modified hydroxyapatite and treated PET filter fabric. TG was used to determine average chain length of grafted polymer on particles. The results showed that polymer chain with length of 13.57 (mole ratio to hydroxyapatite) was introduced to particle surface and modified particles were embedded onto PET filter fabric with a hydroxyapatite immobilization ratio of 63.6% and pore size of 102.3 µm under optimum conditions. Cadmium adsorption amount of 118.4 mg/g was achieved at the cadmium concentration of 392.8 mg/L, implying that PET filter fabric has adsorption ability toward heavy metal ions.
Nanotechnology provides the ability to engineer the properties of materials. Nano zinc oxide having particle size ~50 nm was used with different concentrations to coat the following textiles fabrics: cotton, polyester and blend cotton/ polyester (65/35) using the pad-dry-cure method. The main advantages of these treated samples were their light weight, increasing surface area per unit volume with increasing treatment concentration. The treated samples were characterized through the following measurements: wide angle X-ray diffraction, mechanical tests (tensile strength and elongation percentage) and thermal properties, i.e. diffraction scanning calorimeter. The results indicated that the behavior of the change in crystal parameters for treated cotton samples greatly differed as compared for polyester. The highest intensity and d-spacing in case of treated cotton were observed at zinc oxide concentration 0.25% followed by a decrease. The polyester samples showed gradual increase in intensity by increasing the zinc oxide concentration, while the hybrid structure blend samples followed the mixture behavior rule. The order of improvement in crystalline parameters for the three treated samples was cotton > blend > polyester. Also, the order of improvement in mechanical properties was cotton > polyester > blend; these results may be due to the uniform distribution of ZnO nano-particles on the fabric surface thus the elasticity of the coated fabric increases.
Braided and biodegradable polyglycolide suture was antibacterially functionalised with N-halamines via layer-by-layer assembly technique. Multilayers of chitosan (polycation) and poly-sodium-p-styrenesulfonate (polyanion) were successfully coated via electrostatic assembly, followed by top layer of chitosan on polyglycolide suture. Upon chlorination of coated suture with dilute sodium hypochlorite solution, the amino groups of chitosan were transformed into N-halamine structures. The transformation was assessed by iodometric/thiosulfate titration, Fourier transform infrared spectroscopy and differential scanning calorimeter analysis. The surface morphology of coated suture was observed by scanning electron microscope and atomic force microscope. Chlorine loading, antibacterial efficacy and tensile strength of chlorinated sutures treated with two different molecular weights of chitosan were compared and evaluated. A general trend of linear increase in chlorine loadings of sutures with the increase in number of layers and solution concentration was found. The chlorinated suture with high molecular weight chitosan coating completely inactivated both Escherichia coli O157:H7 and Staphylococcus aureus bacteria within 15 min of contact time. The 3T3 mouse fibroblasts in vitro cell cytocompatibility studies demonstrated that antibacterial sutures have fairly good biocompatibility.
Composites with different arrangements of continuous carbon fibers, with the poly(ethylene terephthalate)-spunbond nonwoven fabrics as substrates, were fabricated for optimization of electromagnetic interference shielding performance. Effects of these structural parameters, including array spacing, the number of layers, and overlap angle, were investigated within the frequency band of 30 MHz–1.5 GHz, which includes the major electromagnetic wave frequency from daily electronic device or apparatus. Within 30 MHz–750 MHz, shielding effectiveness was fortified with the decrease of array spacing and the increase of the number of layers owning to the increase of the continuous carbon fiber content. Whereas, within the frequency band of 750 MHz–1.5 GHz, the number of layers presented little effect on the shielding performance reasoning that the impact of continuous carbon fiber orientation was more significant than that of continuous carbon fiber content. While the array spacing was 8 mm and the maximum value of shielding effectiveness for the two-layer composites was 46.8 decibel at frequency of 1000 MHz. For multilayer composites, shielding performance was improved by synergistic effects of overlap angle and array spacing. Hence, composite with three layers, array spacing of 12 mm and overlap angle of 0°–0°–45° achieved the highest electromagnetic interference shielding properties of 60.49 decibel, corresponding frequency of 1.0 GHz. The results of this work demonstrated a potentially efficient and economical way to fabricate the electromagnetic interference shielding composites with less content of continuous carbon fiber and to simultaneously achieve superb shielding performance. This work will be significant for further study in the electromagnetic interference shielding composite industry in the near future.
Effect of stacking sequence of mechanical and tribological properties woven bamboo–glass fabric reinforced polymer hybrid composites has been investigated experimentally. Laminate samples were fabricated by hand layup technique in a mold and cured under light pressure at room temperature for 48 h. All the laminates were made with a total of four plies, by varying the number and position of glass layers so as to obtain five different stacking sequences. One group of all bamboo laminate was also fabricated for comparison purpose. Specimen preparation and testing were carried out as per ASTM standards. The results indicated that the properties of bamboo composite can be significantly improved by incorporation of glass fiber in polymer composite. The layer sequence has greater effect on mechanical and tribological properties of hybrid composite.
This paper presents a study on the bending behavior of rectangular textile patch antennas including analytical modeling, full wave simulations, and experimental measurements. In the proposed analytical model, the textile patch antenna was treated as a laminated composite beam. Therefore, after locating the position of neutral axis considering the tensile modulus and the dimensions of each layer, the classic cylindrical cavity model was modified to predict the relation between resonance frequency and bending curvature, taking into account the patch’s elongation. Since the presented interdisciplinary analytical approach is associated with a set of simplifying assumptions, a full wave model was also utilized to study this effect. All the simulations were performed in two modes; patches with fixed and elongated dimensions. Finally the results of both models were compared with the experimental measurements and the effects of bending on the resonance frequency of textile patch antennas were discussed in more detail. The obtained results showed that some parameters including the direction of bending, substrate thickness, and mechanical properties of antenna’s components can alter the textile patch antenna’s behavior under bent conditions.
Mass production of nanofibers from needleless electrospinning shows great potential in research and development of nanofibers. However, how to improve the electrospinning performance so as to achieve high quality nanofibers is still of great challenge. In this study, airflow has been applied to optimize upward needleless electrospinning from ring spinneret. Effects of airflow speed and the position of airflow on the nanofiber quality and production rate have been investigated. It has been found that thinner and more uniform nanofibers were produced when airflow was applied to needleless electrospinning system. It also improved the collected nonwoven membrane, resulting in better nanofibrous structure of the as-spun nanofibers. Application of airflow on needleless electrospinning would further benefit the development of mass production of nanofibers from needleless electrospinning.
Ultrasonic modification was used as a simply-operated and efficient method for improving the hydrophilicity and cytocompatibility of polyglycolic acid (PGA) and poly lactic-co-glycolic acid (PLGA, lactide:glycolic acid (LA:GA) = 10:90) fibers, and maintaining the tensile property at the same time. The fibers were pre-treated ultrasonically by dipping in the mixed solution composed of absolute ethyl alcohol and polyphosphoric acid (PPA) (volume ratio 1:1) at 250 W ultrasonic power for 6 min. Scanning electron microscopy was used to observe the surface morphology of PGA and PLGA fiber before and after modification. Fourier transform infrared spectroscopy was used to investigate the change of fiber chemical composition. X-ray diffraction and differential scanning calorimetry analysis showed that the crystalline degree of modified PGA and PLGA fibers decreased. The results of tensile test indicated that compared to that before modification, the breaking strength of modified PLGA increased, while the breaking strength of PGA fiber remained unchanged. The water contact angle of modified fiber was lower than that of unmodified fiber, showing higher hydrophilicity. The cell proliferation assay indicated that fibroblast cells attached and proliferated better on the modified fiber, which means the modified fibers possess good cytocompatibility. These results suggested that ultrasonic modification is an easy-operated and efficient method and the modified PGA and PLGA fibers could be useful in the biomedical textiles field.
In this work, poly(acrylic acid) has been grafted onto cotton fibers through the free radical initiated polymerization and the resulting fibers have been characterized by Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy analysis. The grafted fibers have been loaded with copper nanoparticles using in situ approach. The Transmission Electron Microscopy (TEM) analysis of Cu nanoparticles revealed that almost 45% of the particles had a diameter range of 60–80 nm. The copper nanoparticles loaded fibers show slow release of Cu(II) ions, extended over a period of around 50 h. The release of Cu(II) ions followed a second-order kinetic model successfully. The fibers also exhibited an excellent antibacterial action against model bacteria Escherichia coli as tested by zone of inhibition method.
A green and biodegradable hemp/cotton spunlaced nonwoven was developed to research oil flowing property and practical application. The filtration area of nonwoven and flux of experimental oil have great influence on pressure drop. Filtration area, thickness, mean pore diameter, porosity, and fiber diameter of hemp/cotton spunlaced nonwoven, flux, and density of experimental oil are used to verify previous pressure drop theories and permeability coefficients. The results demonstrate that Reynolds number of hemp/cotton spunlaced nonwoven at different fluxes is small (Re <1) at the state of laminar flow. Through 2D simulation of oil flowing through porosities of hemp/cotton spunlaced nonwoven on the basis of uniformly and disorderly arrangement fiber model, the results indicate that streamline of oil is curve in porosities in the case of fiber disorderly arrangement model. This paper mainly focuses on combining with practical application and theoretical simulation for better understanding the streamline shape and pressure drop distribution in the pores of material as clean oil flowing through porous nonwoven.
In this study, an improved free surface electrospinning was applied to large-scale production of polyvinyl alcohol nanofibers by utilizing a stepped pyramid stage. Multiple polymer jets were observed to form on the edges of the stepped pyramid stage. The influences of operating parameters (e.g. polymer solution concentration, applied voltage and collecting distance) on fiber diameter as well as productivity were experimentally investigated. Response surface methodology was utilized to obtain a quantitative relationship between selected electrospinning parameters and the average fiber diameters as well as the productivity, and the analysis of variance has been used to the statistical validation of regression models. Adjusted R-squared was found to be 98.79% and 98.55% for the fiber diameter and productivity, respectively. The results indicated that the solution concentration had a statistically significant effect on the fiber diameter and the applied potential influence, largely on the productivity.
We explore the structure of a textile absorber in terms of its electromagnetic and absorption properties in the microwave region. Its absorption characteristics are similar to those reported for various metamaterial-based absorbers, exhibiting absorption as high as 98% at resonance. In addition, the angular behavior of the absorption properties of the sample reveal incident angle independency, which is the other added value of the study. Also, the suggested textile absorber has a simple configuration, which introduces flexibility to adjust its material properties and easily tune its structure to suit other frequencies. The proposed textile absorber and its variations have myriad potential applications in radar technology, long distance radio telecommunication, and so on. Although in its current state the proposed structure provides almost perfect absorption covering a wide range of microwave C-Band, the developing technology will soon allow manufacturing textiles that can manipulate lights, leading to the design of invisibility cloak and other science fiction devices besides finding important application areas in medical science.
The Taguchi method was adopted to optimize the fabrication condition of solid state polymerized polyamide (SSP PA66) nanofibers with respect to minimizing nanofiber diameter. A novel fabrication system called air-sealed centrifuge electrospinning was used for preparing high-quality nanofibers. In this study, solution concentration, rotational speed, syringe content, and applied voltage were selected as key parameters affecting the diameter of the fabricated nanofibers. The morphology of the electrospun nanofibers was analyzed by using the field-emission scanning electron microscope. Nanofiber diameters ranging from 20 to 250 nm were successfully controlled by the Taguchi method, and the statistical data based on experimental results indicated that the syringe content and rotational speed had greater influences (35.76% and 23.93%, respectively) on nanofiber diameter than did solution concentration and voltage (21.36% and 11.49%, respectively). Lower syringe content as well as higher rotational speed decreased the nanofiber diameter. The minimum concentration and applied voltage decreased the diameter of SSP PA66 nanofibers. Additionally, altering rotational speed and syringe content had no influence on crystalline behavior of nanofibers.
In this article, submicron barium sulfate particles, as the radiation-resistant component, were incorporated into regenerated cellulose spinning solution. Then a series of X-ray radiation-resistant fibers were fabricated via a primarily industrialized wet-spinning trail, and the resultant fibers were knitted into fabrics by knitting loom. The morphology and structure of the fibers were studied with the aid of scanning electron micrography, Fourier-transform infrared spectroscopy, and X-ray diffraction. The composite fibers exhibited reasonably good properties, which met the criteria of mechanical requirements of commercial textiles—dry breaking strength and elongation (>1.5 cN/dtex and 26%) and wet breaking strength and elongation (>1.4 cN/dtex and 22%) and permanent laundry-resistant abilities even after being washed 20 times. An effective and feasible X-ray radiation-resistant method, the medical digital X-ray photography system, was proposed to evaluate the radiation resistance of the composite fiber and its fabric. The X-ray attenuation ratio of the sample tended to increase with increasing barium sulfate content and finally reached a dose of a 0.1 mmPb lead equivalent. Therefore, these fibers and fabrics can be utilized as the base materials for X-ray radiation-resistant lightweight apparel and detective surgical yarn.
This paper investigated the hybridization effect of two chemically different fibers on the flexural behavior of cementitious composite. On this basis, polyvinyl alcohol and polypropylene fibers (polyvinyl alcohol/polypropylene fiber ratios: 75/25%, 50/50%, 100/0% and 0/100%) at different fiber volume fraction contents (1.2% and 2%) were considered as the variables. This study is especially focused on the influence of fiber types and their hybridization on composite deformability. The composite samples are subjected to the three-point bending test after 28 days of curing. The results showed that the fibers increased the flexural strength and ductility of cement matrix. It is revealed that the toughening improvement mechanism of polyvinyl alcohol and polypropylene fibers in cementitious composites are extremely different. Hybridization of polyvinyl alcohol and polypropylene fibers caused no significant improvement on flexural strength, but the strain capacity of composite under flexural load was increased. Finally, it was observed that the replacement of polyvinyl alcohol fiber with 25% volume fraction of polypropylene fibers can be considered as an important method for improving ductility of engineered cementitious composites.
Nonwoven fabrics and aerogel have complementary properties required for good thermal insulation. In this work, the polyester/polyethylene nonwoven thermal wraps treated with amorphous silica aerogel are studied and characterized with regard to thermodynamical properties at subzero temperatures. The characterization of physical structure was done by scanning electron microscope. C-Therm TCi thermal conductivity analyzer was used to measure thermal properties like conductivity, resistance, and effusivity at subzero temperatures. Heat transfer caused by convection through the thermal wraps was measured by particle image velocimetry technique, which allows obtaining information about the current distribution of velocities in two-dimensional array in a flowing fluid. Vector and scalar maps of the fluid flow were caused by thermal convection. The samples were studied for different temperature gradients. On scientific evaluation of results, thermal conductivity and thermal effusivity were found to be differing with respect to different temperatures and fabric density. Thermal resistance showed an increase as the fabric thickness increases. It was observed that fabric density and the aerogel present in the structures have a significant effect on thermal properties of aerogel-treated nonwoven fabrics. The findings in this study are significant and can be used for further research in aerogel-treated nonwoven fabrics.
A weaving process simulation of fabrics, used as fibrous reinforcements in composite applications, is presented in this article. The mechanical modelling of textile structures requires an accurate geometric representation of the woven elementary cell including complex interlacements of yarns and compactions. Using an explicit finite element solver, this paper proposes to mimic the kinematics in the weaving process of an industrial dobby loom in order to produce virtual textile samples whose geometry is driven by weaving loom parts. Different assumptions on the yarn geometrical and material law behaviour are initially taken from the literature to fit to the modelling of an E-glass yarn inserted in a 2D woven fabric. After several simulations, yarn parameters have been adapted to reproduce the observed cross-sectional shapes leading to a higher level of geometrical accuracy. The primary focus of the study has been on a 2D plain weave fabric with E-glass yarns. As a result, it can be observed that the geometry of the simulated yarns is quite similar to the coated samples achieved on real dobby loom using the proposed kinematic model.
The role of automotive textile materials is of great importance and therefore this paper analyses the properties of such materials – airbag fabrics and upholstery fabrics. Fundamental characteristics and construction parameters of airbag fabrics and artificial leather with bonded textile fabric on the back side, as well as joining (sewing) and quality of joining places of cut parts are crucial for durability, comfort and aesthetics of the automotive interior design, and therefore were analysed. Airbag fabric specificity and extreme values of several parameters are achieved by manufacturing process, with extremely high densities in the warp and weft direction, resulting in a great strength and air permeability properties of very low level. The most important parameters for upholstery fabrics (artificial leather) durability are breaking force and elongation at break, and they were tested in different circular directions. Tests showed the direction with greater breaking properties, what is of paramount importance.
The goal of this research is to develop a mathematical model of heat transfer in protective garments exposed to routine fire environment (low level of radiant heat flux) in order to establish systematic basis for engineering materials and garments for optimum thermal protective performance and comfort. In the first stage, this paper focuses on the formulation of heat transfer model suitable for predicting temperature and heat flux in firefighter protective clothing, using COMSOL Multiphysics® package based on the finite element method. Computational results show the time variation of the temperature at the inner face of the protective clothing system during the exposure to a low-radiant heat flux as well as during the cooling-down period. Model predictions of the temperature agreed very well with the experimental temperature. In the second stage of this study, in order to predict the first and second-degree burns, the model of heat transfer through multilayer protective system was coupled with the heat transfer model in the skin. The Pennes model was used to model heat transfer in the living tissue. The duration of exposure during which the garment protects the firefighter from getting first and second-degree burns is numerically predicted using Henriques equation. The results demonstrated that even for a low-level thermal radiant heat flux, a typical three-layer thermal protective clothing system is required to protect the wearer from skin burn injury.
Different hemp-based mono-layer and composite nonwovens were prepared to study the oil filtration properties and to select better product for practical application. Hemp/cotton spunlaced nonwoven, hemp/viscose spunlaced nonwoven, hemp/viscose spunlaced nonwoven impregnated polyacrylic adhesives, hemp woven fabric, and PA6 nanofiber collected on the surface of hemp/viscose spunlaced nonwoven were prepared to make a comparison of filtration properties. Then, two-layer/multi-layer composite nonwovens were also prepared to make a comparison of filtration properties and to research the effect of layer number on thickness, weight, mean pore diameter, maximum pore diameter, air permeability, filtration accuracy, and pressure drop. Lastly, the comparison of filtration properties between commonly used oil filtration two-layer/multi-layer composite nonwovens and our new two-layer/multi-layer composite nonwovens was respectively made to choose a better product for application. The results indicated that composite nonwoven which contained a two layer structure of hemp/viscose spunlaced nonwoven layer and PA6 nanofiber layer had better filtration properties for practical application.
Various fibers have been used to reinforce concrete to enhance properties of cement. This review critically analyses the use of different natural and synthetic fibers, the treatments done on some of them to be used in concrete, their strength and weaknesses to be used for such applications. In natural fibers, bamboo coir and jute which have been extensively used have been discussed. Also, the effect of alkali present in cement mixture on the degradation of natural fibers has been detailed. Critical observations such as change in crack pattern, effect of nature of fibers, and the environment in which they are reinforced have been discussed. Effect of use of different sealing materials for the hydrophobic fibers on the ultimate property of the reinforced concrete has been reviewed for various fibers. A comprehensive review of the synthetic fibers predominantly used in such reinforcements—PP, PE, and nylon—has been given along with a critical comparative study of recent developments in the field. The fiber–matrix interface studies have been discussed and further research areas have been suggested.
Randomly distributed fiber-reinforced soils have recently attracted increasing attention in geotechnical engineering for the second time. On the basis of predictive models that have been presented till now, shear strength of fiber-reinforced soil increases with increase in fiber aspect ratio, fiber content, fiber modulus, and soil fiber surface friction. The main aim of this paper is therefore shear modeling of polypropylene-fiber-reinforced soil composite by considering the fiber orientation parameter. Force equilibrium method proposed by Waldron was extended to predict shear behavior of randomly distributed fiber–soil composite. The fiber orientation factor was derived by using electrical conductivity contours as a novel technique. In electrical conductivity contour method, electrical conductivity is measured between different points through the soil composite. After that a visual matrix is drawn that shows the uniformity of fiber distribution within the soil matrix. The experimental shear tests revealed that the shear strength of 19-mm polypropylene-reinforced soil composite is less than that of 6 - and 12-mm reinforced samples. On the other hand, electrical conductivity contour method showed that polypropylene fibers of 19-mm length present the worst fiber distribution compared to 6-mm and 12-mm fibers. Therefore, the theoretical model was modified with an orientation factor.
Nanofibrous filters made of electrospun nanofibers are used in different types of filtration. In this study, nanofibrous filters comprising of electrospun filter media between two nonwoven layers were placed in cigarette filter tip and the performance of the new filter was assessed. Electrospinning conditions were varied to achieve ultrafine cellulose acetate nanofibers for this purpose. Nanofibers of different diameters and different layer thickness (based on unit area weight) were used. Tar removal efficiency increased by increasing the unit area weight of filter media. Nanofibrous filter containing nanofibers with a mean diameter of 280 nm increased efficiency from 47.7 to 71.6% for filter tip and efficiency sharply decreased by increasing the diameter of nanofibers. Double layer electrospun filter media showed higher efficiency and lower pressure drop than those of single one with the same unit area weight. Tar removal efficiency increased significantly by using nanofibrous filters, whereas the pressure drop was not affected severely. On the other hand, tar/nicotine ratio reduced.
This paper reports the three-point bending fatigue behaviors of four-step three-dimensional braided composite T-beam. The fatigue deformation and damage of three-dimensional braided composite T-beam at different stress levels and fatigue cycles have been obtained to explain the fatigue behaviors. The influence of stress levels on fatigue life is analyzed based on experimental S–N curves performed with the stress ratio (R) value of 0.1 at room temperature. Furthermore, the energy absorptions were analyzed by comparing the integral areas among different stress levels to indicate energy absorption mechanisms. In addition, the fatigue damage location distribution is found according to the damage morphologies of three-dimensional braided composite T-beam. The history of the overall stiffness degradation is found to exhibit three stages of fatigue failure: initial stage, steady stage, and final failure crack stages. The results of this investigation provide an insight into fatigue damage behavior and fatigue life of three-dimensional braided composite T-beam, and it shows that the three-dimensional braided composite T-beam is able to be used as connector.
The aim of this study was to understand the warp and weft directional short beam strength properties of the developed two-dimensional multistitched multilayer E-glass/polyester woven nano composites. The warp and weft directional specific short beam strengths of unstitched structures were lower than those of the multistitched/nano structures. When the amount of nano silica material in the unstitched E-glass/polyester composite structure increased, the warp and weft directional specific short beam strengths of the unstitched/nano structures increased. When the stitching direction increased from two to four directions, the warp and weft directional short beam strengths of all hand-stitched structures slightly increased. In addition, the warp and weft directional short beam strengths of high modulus (stitching yarn Kevlar® 129) lightly and densely machine-stitched structures were slightly higher than those of the low modulus (stitching yarn Nylon 6.6) lightly and densely machine-stitched structures. All composite structures had interlaminar shear failure between layers in their cross-sections, but the interlaminar shear failure in machine-stitched and machine-stitched/nano structures did not propagate to the large areas. The stitching direction, stitching density, stitching yarn, stitching type, and amount of nano materials in the composite structures were identified as important parameters.
Cellulosic fibers, which are widely available in Iran, can be used as convenient materials for cement panel matrix reinforcing with respect to adequate mix design. This paper at the first stage presents a simple model for predicting the fiber reinforced cement panel behavior during flexural loads by implementing "Equal Cross-section Theory". At the second stage, experimental study was carried out to validate the proposed theory. In order to do the experiment, different types of cellulosic fibers were used as cement replacement of 1% by weight. In addition, to solve the problem of swelling of cellulosic fibers within cement matrixes, fibers were treated by UV/ozone and coated with sodium silicate. Compressive strength, flexural strength and density of cement composite samples were investigated in terms of different cellulosic fiber types including viscose, Leafiran, milkweed and hemp and the sodium silicate consumption amount. The results revealed that the use of cellulosic fibers diminished the density and compressive strength of the cement panel specimens. Improvement of flexural strength was only achieved by adding the hemp fibers into the cement panels which showed a good agreement with "Equal Cross-section Theory" outputs. Moreover, the reductions in the compressive and flexural strength of cement panels contained sodium silicate were much smaller than the cement panels with uncoated fibers.
The paper introduces a novel clamp adapter with the goal to improve the quality of the tensile test setup for high-modulus multi-filament yarns. Common tensile test machines damage the yarns initially or prematurely due to non-uniform load introduction which causes stress concentrations. As a result, the theoretical yarn strength (perfectly clamped filaments at a unique length and no initial damage) is underestimated. With the new clamp adapter, higher strengths close to the theoretical values can be measured since the adapter largely eliminates the problems with non-uniform load introduction. A test series comparing yarns strengths tested with the clamp adapter and with commonly used test methods has been performed and the results are discussed in this paper. Furthermore, they are compared with theoretical values using the Daniels fibre-bundle model.
Bicomponent spunbond technology is considered to be the most rapid process of ultrafine fiber nonwoven material. The cross-section of 70% PET and 30% PA6 bicomponent hollow-segmented pie filaments with diameter range from 2 D to 4 D was made by the bicomponent spunbond technology, and fibrillated by the high-pressure water jets at the same time bonded to microfiber nonwoven materials with the dense structure. The structure characteristics of materials were tested to study the feasibility for the air filter, including fineness of the fiber and pore size distribution of the webs. The filtration efficiency and filtration resistance of the webs were studied with the dioctyl phthalate particles in range of 0.3–2.7 micron at face velocity in range of 1.8–4.8 m/min.
It was found that the hollow segmented-pie bicomponent fibers are splitted to microfibers and bonded mechanically by subjecting the web to high-pressure water jets, the total high pressure water jets energy was 5610.2 kJ/kg. The microfibers fibers gathered into fiber bundles on the surface of the webs were found from the 3D images. The filtration efficiency and filtration resistance of the webs followed typical behavior for fibrous filtration media, and the filtration efficiency and filtration resistance of the webs is increased with the weight increases.
Warp knitted spacer fabrics (WKSF) are technical textile structures that present special compression-elastic, air permeability, heat resistance and acoustic damping properties and because of that they are winning more application fields every day. In many of these fields, like the application for cushion structures in car seats and mattresses, the thick WKSF are of special interest and the mechanical behaviour of these structures needs to be known in detail but, although direct relationships exist between the textile technical and technological parameters and the mechanical behaviour of the mentioned structures, this characterisation is still being carried out experimentally. Analytical and numerical models have already been developed to study WKSF structures offering interesting contributions to a better knowledge of their behaviour and providing further research directions but there are some phenomena causing the particular and characteristic mechanical behaviour of these structures that have not been described yet. The aim of this paper is to give a better understanding of the mechanical behaviour of a single vertical spacer yarn of a thick WKSF under compression load by studying, with help of the finite elements method, the variations of the bending moment acting on the yarn during the compression process. In this article it has been found that these variations of the mentioned bending moment are the phenomena responsible for the characteristic mechanical behaviour of the WKSF structures.
In this study, the fabrication of nano-silver doped activated coir charcoal particles (ACC@Ag) was proposed using chemical reduction method. Certain amount of ACC@Ag was added into the spinning solution after de-foaming process to fabricate viscose rayon staple fibers using wet spinning method. The 1.25 denier x 38 mm viscose rayon/ACC@Ag staple fibers was then blended with 1.5 denier x 1.5 in. polyester staple fibers to fabricate PET/rayon/ACC@Ag with 50%/50% blending ratio and 30 s and 40 s linear density using ring spinning process. The blended yarns are expected to be used for the fiber products with anti-bacterial, warm retention, odor absorption and anti-static properties. This ring blended yarns were then used as the raw material to fabricate woven fabrics with anti-bacterial and anti-electrostatic properties which comply with JIS and AATCC standards. The influences of woven structures, fabric constitutions on the temperature difference, anti-bacterial, odor absorption and anti-electrostatic properties of woven fabrics were also investigated. Finally, the potential applications of the woven fabrics fabricated will also be proposed and suggested in this study.
The aim of this study was to understand the warp–weft directional bending properties of the developed two-dimensional multistitched multilayer E-glass/polyester woven nano composites. The warp–weft directional specific bending strengths and modulus of unstitched/nano composite structures were higher than those of the unstitched structures. Contrarily, the warp–weft directional specific bending strengths and modulus of unstitched structure were higher than those of the machine stitched and machine stitched/nano structures due to stitching caused filament breakages. When the stitching direction increased, the warp–weft directional bending strengths and modulus of the structures decreased. The warp–weft directional specific damaged areas of unstitched structure were higher than those of the multistitched and multistitched/nano structures. The addition of nano silica to the stitched structures improved their damage resistance slightly. It was generally found that when the number of stitching directions and stitching density in structures increased, the damaged areas of structures decreased. The failure of warp–weft directional multistitched and multistitched/nano woven E-glass/polyester composite structures was matrix breakages, partial and complete filaments, and yarn (tow) breakages in their surfaces. They had a local delamination in their cross-sections and the delamination did not propagate to the large areas due to multiple stitching. The failure was confined at a narrow area due to multistitching and resulted in the catastrophic fiber breakages. This was considered that the damage tolerance performance of the multistitched structures was enhanced due to stitching, in particular, at four directional stitching.
The hemp root bast paper is innovatively prepared to research the oil filtration properties and air filtration properties for practical application. It can be found that beating degree and weight both have great influence on air permeability, pore diameter distribution, oil/air penetration and oil/air filtration efficiency of hemp paper. The oil filtration efficiency of hemp papers for 0.33 µm particles is 99.7%–99.975% and air filtration efficiency for 0.26 µm NaCl aerosol particles is 99.942%–100%. Through comparison of oil filtration properties and air filtration properties with commonly used automobile engine oil/air cotton paper filtration materials, it can be found that hemp paper has the smaller thickness, weight, mean pore diameter, porosity and oil/air penetration, while the better oil/air filtration efficiency and higher pressure drop. Due to the higher filtration efficiency of hemp papers and green, biodegradable, sustainable resources of hemp plants in the case of environmental requirements, the pilot trial hemp paper automobile engine oil filter is successfully manufactured. The results indicate that hemp papers have better oil/air filtration properties than cotton paper in practical application. We hope that such an attempt will be helpful for practical application of hemp paper and meet the needs of domestic market for filtration materials. Furthermore, it can enlarge the application field and increase the added value of hemp.
Experimental investigations were carried out to determine the flexural behaviour of reinforced concrete beams strengthened with basalt textile-reinforced concrete under monotonic and low-cycle fatigue load. Reinforced concrete beams strengthened with basalt textile-reinforced concrete were tested under four-point bending. The behaviour of the strengthened beam was compared with that of un-strengthened reinforced concrete beam. It is observed that there is an enhancement in energy absorption for reinforced concrete beams strengthened with basalt reinforced concrete even though there is no considerable increase in load carrying capacity. It is observed that when the strengthened beams are subjected to monotonic loading, the increase in ultimate load carrying capacity is marginal but the increase in ductility is 84.5% and the increase in energy absorption is 162% compared with un-strengthened beam. Reinforced concrete beams strengthened with basalt reinforced concrete were also tested under low-cycle fatigue load. It is observed that there is about 20% reduction in ultimate load carrying capacity and 27% reduction in ductility compared to monotonic case. But the cracking and failure patterns are similar in both the cases.
The relationships of mechanical performance with the short-range and long-range structure of 500–900°C carbonized fibers were studied by the combination of radial distribution function (RDF), Fourier transform infrared spectroscopy (FT-IR) and high-resolution transmission electron microscopy (HRTEM), etc. In the range of 500–900°C, there were different laws of change for tensile strength and elastic modulus during different temperature stages. The tensile strength was more nearly directly proportional to temperature, especially at higher than 600°C. The elastic modulus increased slowly from 500 to 700°C, and then elastic modulus increased rapidly after 700°C. The short-range structures had no effects on the mechanical performance. The uniform increasing rate of tensile strength was closely related to the crystallinity degree and crystal size. The outstanding increase of orientation degree was closely related to the change of elastic modulus.
In this study, we evaluated the thermal resistance of various combinations of commercially available, metallised and conventional, mid- and shell-layer materials, and additionally investigated the effect of plasma metallisation of the non-metallised materials. The evaporative resistance of the shell layers was measured, and did not increase due to plasma metallisation. Metallised mid- and shell-layers increased the thermal resistance of fabric assemblies, and this increase was greatest when the thickness and optical porosity of the mid-layer were suitably high.
Polyester fabric was functionalized with ZnO nanorods grown by hydrothermal method. The ZnO seeds were deposited on fabric which provided the sites for growth of nanorods. The functionalized fabric showed self-cleaning by degrading color stains and solution discoloration under the effect of ultraviolet (UV) light which was studied using two azo and one triphenylemethylene dye. The stained fabric was exposed to UV light and K/S (K = absorption coefficient, S = scattering coefficient) values were measured by spectrophotometer. Most of the stains were degraded in first 300 min and they disappeared completely after 24 h. The solution discoloration was studied by using different concentrations of dyes and was characterized by measuring absorbance. The rubbing and washing durabilities of the functionalized fabric were also investigated.
Specific surface and surface porosity are governing factors in the penetration rate and the amount of liquid rise into the yarn. In this work, porous and non-porous fiber yarns of poly (l-lactic acid) (PLLA) were fabricated via electrospinning and twist insertion. The surface of PLLA electrospun fibers became porous after evaporation of highly volatile solvent in controlled humidity and temperature and changing the concentration of PLLA solution, resulted in the fibers with different surface porosity. Smooth PLLA nanofibers were obtained using non-volatile solvent. Consequently, capillary rise was investigated in both the porous fiber yarns and smooth nanofiber yarn. Experimental evidences revealed that two morphological characteristics of fibers, i.e. surface porosity and fineness of fibers in the electrospun yarn have a governing effect on the capillary rise phenomenon. Liquid penetration in electrospun yarn was increased by increasing the fiber fineness and/or decreasing the surface porosity. The results of this work suggest that finer fiber and smooth surface would be more beneficial for wicking.
Bismuth vanadate-coated cotton fabric was synthesized by a chemical bath deposition method at low temperature (≤100°C) and characterized by using scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and UV-V is diffuse reflectance spectroscopy. Its photocatalytic activities were evaluated by decomposition of C.I. reactive blue 19 in aqueous solution under visible light irradiation. The as-prepared composite possesses excellent photocatalytic activity for the degradation of liquid contamination especially in static system due to its large specific surface area. The reduction of total organic carbon (about 48.0% after 4 h of irradiation) showed that the mineralization of C.I. Reactive Blue 19 over the bismuth vanadate-coated cotton fabric is realizable. Moreover, the preparation of the composites is convenient for potential practical application. The formation mechanism of bismuth vanadate on the fabric was also discussed preliminarily.
A soy protein-based water-soluble binder composition for natural fiber nonwoven fabric is discussed in this paper. Before applying to viscose fibers, foam decay studies of soy protein and acrylic binders are carried out and results are compared. The bio-binder (soy protein and sodium dodecyl sulphate modified soy protein) composition effectively binds natural fibers in a nonwoven fabric by foam application method. Such fabrics are widely used for industrial wipes and non-reusable products such as diapers, sanitary napkins, bandages, etc. The mechanical and thermal properties of viscose fabric bonded with soy protein bio-binder are compared with the same fabric produced with commercially applied acrylic binder. Scanning electron microscope was used to confirm the bonding of the viscose fiber with the bio-binders.
The carbon weft-knitted biaxial fabrics stitched by polyester fibers and preoxidized polyacrylonitrile fibers were prepared respectively. Tensile and tearing tests of two types of carbon biaxial weft-knitted fabrics stitched by different fibers were carried out. Stress–strain and load–displacement curves were obtained according to the testing data. The high-speed camera was employed to observe the whole testing process and series of still images were picked up according to the time nodes to analyze the meso-scale mechanism of the extension and displacement of tows on oriented layers and stitching yarns. The properties of the two fabrics were compared based on the research of the stitching yarns mechanical performance. The researching results indicated that preoxidized polyacrylonitrile fiber exhibit higher mechanical behaviors, and its fabric bond displays excellent performance.
Water repellency was conferred to cotton and polyester fabrics by an hybrid organic–inorganic finishing obtained by hydrolysis and subsequent condensation of octyltriethoxysilane (OTES) under acidic conditions, in combination with melamine based crosslinking agent N,N,N',N',N'',N''-hexakis(methoxymethyl)-1,3,5-triazine-2,4,6-triamine (MF). The application on textile samples was carried out by padding followed by drying and thermal treatment. Water-resistance properties were determined in terms of the contact angle, water uptake and drop adsorption times, whereas the surface composition of treated fabrics was characterized by attenuated total reflectance Fourier transform infrared analyses. Textile fabrics treated with the hybrid OTES–MF sol exhibited the best water-repellent properties, when compared to those treated with OTES or MF finishing alone. In particular, cotton and polyester samples, treated with a 60 g/L MF solution in a 1:4 MF:OTES molar ratio, showed a water contact angle of 130° and 150°, respectively. The high hydrophobicity of the treated fabrics is supposed to be due to the structural and stereochemical properties of the finishing. The presence of the MF triazine ring seems to favour both the improvement of the outward orientation of the OTES alkyl chains, and the crosslinking of N-methylol groups to form a three-dimensional film around the fibres which increases the surface roughness. The contact angle values and the characteristic IR peaks confirmed the presence of the hybrid coating on cotton fabrics even after multiple washing cycles.
The need of eco-friendly, sustainable, and biodegradable material for structural and non-structural application increases day by day. Jute fiber is one of the largely produced natural fibers and has properties comparable to synthetic fibers. Currently, abrasive wear of the agricultural and engineering machine components is one of the major industrial problems. An attempt has been made in this paper to study the abrasive wear behavior of bidirectional jute fiber–epoxy composites. Composites of five different compositions with fiber loading ranging from 0 to 48 wt.% were prepared using hand lay-up technique. Observations has been made under steady state condition to understand the effect of sliding velocity and normal load on the specific wear rate and coefficient of friction of the composites. It further outlines a methodology based on Taguchi's experimental design approach to make a parametric analysis of wear behavior. It has been found that the composites with 36 wt.% fiber loading exhibits minimum specific wear rate at different sliding velocity and normal load. The parametric combination of factors, such as sliding velocity of 144 cm/s, fiber loading of 48 wt.%, normal load of 40 N, sliding distance of 70 m, and abrasive size of 200 µm shows an optimum condition for minimum specific wear rate, whereas sliding velocity of 144 cm/s, fiber loading of 12 wt.%, normal load of 10 N, sliding distance of 80 m, and abrasive size of 300 µm show an optimum condition for minimum coefficient of friction. Finally, the worn surfaces were examined using a scanning electron microscope.
Precise characterization of nonwoven fabrics such as their transport properties are of paramount importance in development of advanced filtration processes. Currently majority of available knowledge on transport behavior of fibrous materials is based on macro-scale empirically researched phenomena. Thus, evaluation of transport behavior of nonwovens based on fundamental scientific principles at micro-scale still remains a challenge that has to be tackled by scientists. In this paper, an integrated approach employing high-resolution X-ray micro-computed tomography and finite volume method are presented to predict permeability of needled nonwoven fabrics. In order to achieve the objectives of this research, dimensionless permeability of needled nonwoven fabrics with various porosities was computed using CFD tools. Comparisons of simulated results with experimentally obtained data and the published empirical and analytical models were made. Considering solid volume fraction of the samples, acceptable agreement between the results and previously published findings was observed. It was also established that experimental samples ideally can be represented as a three-dimensional random structure.
The aim of this research is to improve the dyeability and antibacterial activity of silk fabric using natural fungal extract. The natural fungal pigment is extracted from the thermophilic fungi-basedspecies, namely Thermomyces, purified and characterized using Fourier transform infrared spectra, and subjected for the dyeing process. An experiment using Box and Behnken is designed with three levels and three variables using pH, temperature, and time as independent variables and with wash fastness, rubbing fastness, light fastness, and bacterial reduction (%) as dependent variables, and the conditions are optimized. Regression equations are obtained to analyze the fastness properties and bacterial reduction (%), and the optimum process parameters are identified. The result shows that the optimum conditions for dyeing the silk fabric by fungal pigmentation is 2% owm at 60°C for 30 min, maintaining a pH of 3.
In this study, a novel way for modification of wool fabrics by extracted feather protein is introduced. The present investigation aims to establish an environmental friendly approach with feather waste to achieve shrink-resistant wool. For this purpose, chicken feathers were hydrolyzed with a commercial proteolytic enzyme accompanied by a reducing agent. This process was optimized to achieve maximum extraction yield. The extracted feather protein was then applied to modify the wool fibre surface in the presence or absence of a cross-linking agent, glycerol diglycidyl ether. The obtained results showed that treatment of wool fabric with feather protein led to a considerable improvement in anti-felting properties, and application of the cross-linking agent enhanced the shrink-resistant properties of wool further. Besides, the bending length of wool fabrics increased and their tensile strength was apparently unaffected in comparison with the untreated one. The scanning electron micrographs indicated that wool fibers were still intact and were not severely damaged by the applied treatment. The Fourier transform infrared spectra also approved the formation of cross-linked protein on wool fabric.
In this study, production of multilayer surfaces for acoustic and thermal insulation was investigated. After the optimum textile materials had been chosen to provide acoustic and thermal insulation, surfaces were created using different relative methods in this field. Sublayer nonwoven produced from slotted polyester fiber was combined with two different top layers of fabrics, one of which was the top layer of fabric woven from plain weave obtained from texture yarns, which, in turn, was produced from hollow polypropylene, and the other was plain weave obtained from texture weft yarn, which was produced from conventional polypropylene fibers separately. Subsequently, these two different surfaces were combined with polyurethane-based material. Pumice stone powder in three different concentrations and two different sizes was added to enhance acoustic and thermal insulation, after which the sublayer had been coated with an adhesive material to produce multilayer adhesive force and adherence to the wall. Consequently, air permeability, sound absorption, and thermal conductivity coefficients of multilayer surfaces were researched with regard to the type of top layer of fabrics, concentration, and particle size of pumice stone powder. The results demonstrate that the properties of multilayer surfaces concerning acoustic and thermal insulation increase with the increasing concentration of pumice stone powder and with the decreasing sizes of pumice stone particles. In addition, air permeability of multilayer surfaces was ensued to decrease with the increasing concentration as well as particle size of pumice stone powder.
For fiber-reinforced plastic composites, fiber-matrix adhesion is a significant aspect of composite properties. While conventional lightweight structures are always aiming for high fiber-matrix adhesion, innovative and unconventional functional constructions require different concepts. The research work treating adaptive fiber-reinforced plastic composites with shape memory alloy wires presented here uses the approach of actuators freely movable within the composite. This is supposed to prevent mechanical tensions in the interfaces of actuator and composite structure, which would otherwise cause damages of the composite. This work examines hybrid yarns based on friction spinning technology, with shape memory alloy wires as their core component as well as glass fibers, and partly polypropylene, as their sheath component. Additionally, the surface properties of the shape memory alloy wires being used are modified by sanding and coating. The results of a characterization by pull-out testing clearly show that a coating of the shape memory alloy wires with an abherent causes considerable decrease in adhesion and friction in the interface and leads to the mobility of the shape memory alloy wires in the later composite. An even greater effect is attained by sheathing the hybrid yarns in an additional layer of polypropylene, compacting the yarn cross-section. Thus, the pull-out force could be reduced to 35–40% of the reference structure.
This paper describes the measurement of packing density and radial packing density of newly developed three-layered, wool structure yarn for pile carpets. Three different varieties of Indian wool, in terms of fibre diameter, medullation and bending rigidity, were strategically positioned in the (ring spun) yarn cross-section. The measurements of all the researched yarns have shown that radial packing density is neither uniform across the yarn cross-section nor maximum at yarn core. The maximum packing density of these yarns occurs at some different distances from the yarn axis and it sharply decreases from that point towards yarn surface. In general, all the yarns are seen to have slight hollowness near their axis. The possible mechanism of the fibre density distribution in the yarn cross-section is also discussed.
The intimately mixed natural protein fiber hybrid composites in three different fiber concentrations (70:30, 50:50 and 30:70) and two different fiber orientations (parallel laid and cross laid) are produced using silk and wool fibers with polypropylene fibers as matrix material. The composites are fabricated using compression molding technique with optimized process conditions. The effects of fiber content and fiber orientation on mechanical, thermal conductivity and water absorption property are studied. Scanning electron microscope is used to examine the fracture morphology of the composites. The study reveals that the fiber content strongly influences the mechanical, thermal conductivity and water absorption property of the resultant composite. But the fiber orientation shows significant effect only on water absorption property of the composites. It does not show any significant difference in mechanical and thermal conductivity properties of intimately mixed silk/wool hybrid fiber composites.
In the present study, highly aligned poly(-caprolactone) fibrous network produced by centrifugal spinning method was used as base substrate for electrophoretic deposition of chitosan. Two major parameters, namely the material and process parameters were varied to study its effect on add on % of chitosan in the matrices. It was found that the molecular weight and pH of the acidic chitosan solution widely influence the amount of deposition and pattern of deposition. The use of ultrasonic radiation in the electrophoretic deposition cell led to matrices with rough topography. In electrophoretic deposition process, the inherent gas bubbles formation results in formation of porous chitosan structure on the surface of centrifugal spun matrices making it suitable for biomedical applications.
Thermal-resistant coatings, based on polysilazane and polysiloxane polymers, were applied onto the glass fiber rovings with the dip-coating method. The coated glass fibers were characterized by performing different experiments to evaluate the effect of coatings on thermomechanical and topographical properties of glass fiber. The effect of temperature on the mechanical properties of the coated rovings were studied and compared with the uncoated rovings. Thermogravimetric analysis was carried out to investigate the thermal stability of coated samples. Scanning electron microscopy and energy-dispersive X-ray analyses were performed to evaluate the surface topographical characteristics of the glass fiber rovings. These analyses showed the changes in surface morphological properties due to modification of glass fiber by coating treatment. The results of tensile testing indicated that thermal-resistant coatings enhanced up to 60% tensile strength and 20% stiffness of uncoated glass fiber roving. Thermomechanical study up to 500°C revealed that polysiloxane coating on glass fiber showed better performance than polysilazane polymeric coating.
Silver-containing wound dressings are now commonly available with much publicised claims of antimicrobial activities against all kinds of pathogens including methicillin-resistant Staphylococcus aureus (MRSA). However, there are little or no credible reports on the control release agents for the minimum potent quantities of silver needed in dressings for antimicrobial purposes over time. This paper introduces a new biomaterial fibre made from natural polymers with an inbuilt ability to gel and absorb large quantities of pseudo exudates. Furthermore, the new fibre carries up to six times less silver than it is conventionally used in silver dressings and displays a very slow rate of release whilst maintaining full potency over time against known microorganisms including methicillin-resistant S. aureus. The paper concludes that the developed fibre has long-lasting antimicrobial and gelling properties comparable, if not better, than Acticoat AA and Aquacel Ag, two commercially available silver dressings.
In this research, loop-formed fiber is introduced as a novel reinforcement method of soil composites instead of using ordinary fibers. In order to investigate the materials' mechanical properties, the shear behavior of both fiber and looped-fiber-reinforced soil composites was analyzed by micromechanical method (finite element method) and a set of direct shear tests. The results indicate that the looped-fiber soil composite exhibits greater failure strain energy compared with fiber-reinforced soil composite at the same fiber orientation in the substrate. Furthermore, the proposed model demonstrated two major reinforcing components: "the fiber effect" and "the loop effect." The latter effect is the key benefit and the main advantage of using looped fibers over ordinary fibers in soil reinforcement. Altogether, there is a close agreement between finite element method outputs and experimental results, suggestive of a novel technical textile material that could potentially be used in geotechnical engineering.
This paper investigates the flame retardant and mechanical properties of a flax woven fabric that can be used to prepare biocomposites. The flame retardant properties of the fabric are first considered using different ammonium phosphate salts and intumescent systems. It is demonstrated that satisfactory performances can be achieved using this approach. Better performances were obtained with pure phosphate salts in comparison to intumescent systems. This was attributed first, to the carbonization effect of the flax that could thus react with the phosphate and/or its degradation products leading to a stabilisation of the system and second to the lower phosphorus content when the full intumescent system is considered. On the other hand, despite a loss of biaxial tensile properties, the ability of the fire retardant treated fabric to form complex shape such as a tetrahedron was successfully demonstrated. Finally, the flame retardant properties of one-ply composites, using a bio-based matrix (Bioplast from Biotec), was evaluated. It was shown that good fire retardancy performances could be achieved considering only the flame retardancy of the reinforcement phase. This approach has potential for developing future flame retarded biocomposites.
Invariably different fibres are mixed homogeneously at yarn stage to obtain the desired carpet characteristics such as resiliency, lustre, reduced shedding and cost reduction. In order to fully exploit the individual fibre characteristics, i.e. fibre diameter, medullation and bending rigidity, an attempt has been made to engineer the carpet yarns to strategically position different characteristics of fibre across the yarn cross-section. Accordingly three layered engineered yarns of 4 Nm linear density of different fibre components as in control yarns, i.e. Malpura Magra and Chokla wools to 1:4:5 in inner, middle and outermost layer, respectively, were produced by using modified SIRO spinning method on worsted spinning system. The recovery property of yarns was found to be better for all engineered yarns as compared to control yarns. Carpet made from considered yarns were subjected to compression, dynamic loading and abrasion for assessing their performance. Higher bending rigidity and recovery properties of control and engineered yarns have improved the carpet performance. Carpet resiliency was found to be better for carpet made from engineered yarns. The engineered yarn carpets give lower abrasion loss and carpet thickness loss under dynamic loading. Among all the control and engineered yarns, carpets made from two layered roving to obtain three-layered yarn have yielded best results.
Steel-slag asphalt concrete (SSAC) is a type of asphalt mixture that uses slag particles instead of conventional aggregates. It has been proven that replacement of course aggregates by steel-slag particles is the best composition of SSAC mixtures. Despite benefits derived from SSAC, like higher resistance to rutting, the mixture has some disadvantages. Higher optimized asphalt content is the major disadvantage of SSAC compared to ordinary AC mixtures. In order to solve this problem, it is necessary to decrease the bitumen absorption of slag aggregates. One approach that can be taken to increase the viscosity of the bitumen and/or to decrease the effective surface of slag aggregates is reinforcement of asphalt mixtures by using polypropylene (PP) fibers. The main aim of this paper is, therefore, to introduce a novel AC mixture, i.e. PP fiber-reinforced steel-slag asphalt concrete. In this respect, the optimized asphalt content was identified by using Marshall method. Analysis of results shows that the treatment reinforced with 2% of 19 mm PP fibers experiences a decrease in optimized asphalt content about 15% in comparison with the neat mixture, i.e. SSAC sample. Moreover, indirect tensile strength and resilient modulus (MR) have increased.
This paper deals with physical properties and compression behavior of new insole structure. This insole is developed based on a new 3D fibrous structure made of recycled polyester nonwoven (110 g/cm2) laminated with different textile materials by the use of a patented vertical-lapping process (VERTILAP®). To characterize physical and mechanical properties of the 3D structures, a methodology has been set up and new testing methods have been developed. The results of this study have shown interesting properties in terms of comfort and compression behavior (under static and dynamic loading). It has been observed that the 3D structure laminated with hemp woven fabric has the highest water absorbency, the highest thermal conductivity and the coolest touch effect compared to nonwoven made of a blend of polyester and viscose fibers. The compression behavior of the insole has been influenced by the physical properties of the 3D structure. The insoles developed in this work have a viscoelastic behavior with cushioning properties and can resist up to 218 kPa at 50% of deformation under static compression conditions and dissipate sufficient energy (higher than 180 N.mm) which allows the relieve of the foot pressure and distributes loads more evenly on the soft parts of the feet in use case.
The three-dimensional textile composites have excellent advantages of impact resistance, owing to their more integral microstructure and higher interlaminar shear strength than those of laminated composites. The composites are frequently used under impact loading in the practical application. Researches on the impact behaviors can help in the development and optimization of design for textile structural composites. In this review, the development and features of three types of textile structures, including weaving, knitting, and braiding have been introduced respectively, and the current and future potential applications of these kinds of textile structural composites have been described. The impact tension behaviors and the damage mechanisms of textile structural composites have been introduced. The finite element analysis and frequency domain analysis which to reveal the tensile damage mechanisms of textile structural composites under high strain rates also have been investigated. Furthermore, the future development of impact tension behaviors of textile structural composites is also introduced in this review.
Following technological advancements, there is a growing population of cellular phone and computer users. However, these electronic instruments cause electromagnetic waves, negatively influencing users’ health or precision instruments’ malfunction. Therefore, shielding electromagnetic wave becomes an important matter. In this study, stainless steel wires and bamboo charcoal roving are made into conductive yarn with 6 turns/cm by ring spinning machine. On a 14-gauge automatic horizontal knitting machine, the resulting yarn is then knitted into stainless steel/bamboo charcoal conductive fabrics and then evaluated for the electrical property and functions. According to experimental testing, electromagnetic shielding effectiveness (EMSE) of the fabrics increases with an increase in stainless steel content and number of lamination layers. In particular, when laminated at an angle of 0°/45°/90°/–45°/0°/45°, the fabrics have an EMSE of above 30 dB at an incident frequency between 2010 and 2445 MHz. The far infrared emissivity increases with bamboo charcoal content, reaching the maximum of 0.9 , when the fabric was made by one-cycle polyethylene terephthalate (PET)/stainless steel/bamboo charcoal plied yarn in the first feeder and four-cycle PET/bamboo charcoal plied yarn in the second feeder.
As one of the promising adsorbents, activated carbon fibers were modified in order to enhance their sulfur dioxide removal efficiency by depositing strong oxidants. Potassium permanganate (KMnO4) was found to be an effective promoter for activated carbon fibers. The optimum content of KMnO4 on activated carbon fibers was 43.34 wt% prepared from 6 wt% KMnO4 solution. The composition of the challenge gas was found to affect the SO2 adsorption capacity of KMnO4 modified activated carbon fibers. The presence of water in the mainstream improved the desulfurization properties. Prehumidification of the challenge gas increased the breakthrough capacity. KMnO4 modified activated carbon fibers were durable in desulfurization properties during the wet-laying process and was made into activated carbon fiber papers with copolyester as the binder. KMnO4-ACFP was found to be able to maintain the SO2 capacity of KMnO4 modified activated carbon fibers with a breakthrough capacity of 76 mg SO2/g modified activated carbon fiber and 90% saturation capacity of 186.75 mg SO2/g modified activated carbon fiber. Sulfur content on KMnO4 modified activated carbon fibers was increased to 9.47 wt% from 0.045 wt% during the adsorption process which proves the adsorption of sulfur on fiber adsorbents.
This study investigates the thermal and viscoelastic properties of flax preform reinforced epoxy composites. Plain woven flax fabric and 1 x 1 weft rib knitted structures were used as reinforcements and flax preforms reinforced epoxy composites were produced using hand lay-up method. Thermogravimetric analysis (TGA) indicates a decrease in thermal stability of the matrix polymer with the incorporation of flax woven and knitted preforms. The dynamic mechanical analysis revealed a higher storage modulus for woven preform reinforced composite compared to knitted preform reinforced composites. The storage modulus was found to decrease with temperature in all cases. Loss modulus showed shifts in the (Tg) compared to virgin epoxy, with the addition of flax preforms as reinforcing phase, which indicate that preforms plays an important role with respect to Tg. Single tan peaks were observed for all the composite samples tested. The tan peak height was maximum for virgin epoxy matrix, indicating that there is a large degree of mobility, thus good damping behaviours. However, lower peaks were observed for both woven and knitted preform reinforced composites. With respect to the viscoelastic properties the rigidity and endurance of the fibres are highly affected by thermal treatment at temperatures above 70°C and up to 100°C.
Various ratios (30/70%, 70/30%, 50/50% with and without nanosilver) of chitosan (CS; 60–120.000 g/mol) and polyethylene oxide (PEO; 600.000 g/mol) blended nanofibers in the nanofibrous scaffolds were obtained by using electrospinning at ambient atmosphere. Homogenous CS solutions were prepared in 90% aqeous acetic acid. PEO was dissolved in deionized water. Nanosilver dispersion was prepared and added to the 50/50% blend of CS/PEO solution. Properties of all blended solutions were determined by measuring viscosity and conductivity. Differential scanning calorimeter, Fourier transform infrared spectroscopy, scanning electron microscopy analysis and tensile tests were conducted to investigate the characteristics of the final nanofibrous composite structures. Beadless and uniform nanofibers were obtained and the average diameter of the fibers ranged from 63 ± 23 nm to 108 ± 51 nm. The antimicrobial effectiveness of the nanofibrous scaffolds was investigated against Escherichia coli and Candida albicans, and satisfactory results were obtained.
The relative rate of degradation of poly(ethylene terephthalate) geotextiles in various monovalent alkali hydroxides was studied in both aqueous and alcoholic systems. In an aqueous system, the reaction of all three alkalis on poly(ethylene terephthalate) geotextiles is restricted to the surface since tenacity loss was insignificant and no surface cracks was noticed, whereas in an alcoholic system, significant loss in tenacity occurred due to the formation of surface crack. Furthermore, the relative rate of reactivity of metal hydroxides in aqueous and alkaline media was temperature dependent. However, in equimolar concentration, at 80°C, the relative rate in an aqueous system is of the following order: LiOH > NaOH > KOH in the ratio of 1.65:1.1:1.0. Above 80°C, the reaction is reversed, as aqueous KOH reacts faster than aqueous NaOH. Two different activation energies were found for aqueous KOH at a threshold temperature of 80°C. Furthermore, in heterogeneous systems using dimethyl terephthalate, aqueous KOH was slightly faster than aqueous NaOH in the temperature range of 70–80°C. In an alcoholic system, KOH is almost 1.5 times faster than NaOH at 20°C and at 60°C.
A novel braiding–weaving system (BWS) is developed offering broad design and manufacturing possibilities based on hybridisation of weaving and braiding. In order to understand and optimize this machine and to be able to explore all the possibilities regarding complex 3-dimensional (3D) structures design, a new modelling strategy has been developed to generate geometrical skeleton of those structures. This strategy is based on the collision detection and kinematic aspects of the machine itself. Hypothesis given by kinematics allows to simply change the structure type (i.e. braiding or weaving) by changing the yarns paths. Those hypotheses are introduced in the article followed by the model that has been used and the collision detection method. Modelled 3D textile preforms are compared with manufactured samples in order to evaluate the accuracy of the modelling and simulation approaches.
In this article, the effect of various yarn and fabric parameters on the electromagnetic shielding of metalized fabrics coated with polyaniline has been investigated. Copper wires with diameters of 0.06, 0.08 and 0.1 mm were chosen as conductive fillers for producing the metalized core-spun yarn. To investigate the effect of sheath material, cotton, viscose and polyester fibers supplied in a roving form were used to produce different core-spun yarn on a ring spinning frame. From the produced core yarn, woven fabrics were produced in three different pick densities: 12, 16 and 20 picks per cm. Polyaniline was synthesized in two chemical polymerization methods to achieve different surface conductivity. Taguchi’s experimental design was used to estimate the optimum process conditions and to examine the individual effects of each of the controllable factors on a particular response. The fabric parameters considered in this article were: copper wire thickness, sheath material type, fabric pick density and the coating compound chemical polymerization method. The electromagnetic effectiveness was measured at the frequency range of 1.7–2.7 GHz, using a waveguide. According to the level average analysis, fabric density factor shows the strongest effect on electromagnetic shielding, factor thickness of copper wire is the second and is followed by the factor coating compound chemical polymerization method and the sheath material type. The findings revealed that the samples at the frequency range 2.4–2.45 GHz show the highest shielding.
Cellulose acetate nanofiber mats containing tetracycline hydrochloride were prepared by electrospinning. Incorporation of tetracycline hydrochloride (20 wt% based on the weight of cellulose acetate) in the cellulose acetate solution (17% wt/vol in 2:1 vol/vol ethanol-dimethyl sulfoxide) did not affect the morphology of the obtained fibers, as tetracycline hydrochloride-loaded cellulose acetate fibers were smooth. The average diameters of these fibers ranged between 50 and 90 nm. Determination of the release characteristics of tetracycline hydrochloride from the cellulose acetate nanofiber mats was carried out by total immersion in phosphate buffer solution, that is, in the total immersion method, the maximum amounts of the tetracycline hydrochloride released from the cellulose acetate nanofiber into the medium were 10 and 25% µg/100 ml. Antibacterial activity of prepared tetracycline hydrochloride-loaded as-spun cellulose acetate fiber mate was achieved using Escherichia coli and Staphylococcus aureus as a representative each of Gram-negative and Gram-positive bacteria, respectively. Antibacterial activity of tetracycline hydrochloride-loaded as-spun cellulose acetate fiber mat showed effectiveness with 77–88% bacteria reduction after 10 min–1 h for Escherichia coli and approximately 83–85% reduction after 10 min–1 h for Staphylococcus aureus.
A temperature sensing fabric is described, along with the manufacturing techniques required to produce the fabric on a computerised flat-bed knitting machine. Knitted sensing fabrics with copper, nickel and tungsten wire elements have been produced with resistances ranging from 3 to 130 . The most successful samples have been created using textile-wrapped, enamelled wire and not only the textile character of the sensing element was enhanced, but also its tensile strength. A mathematical relationship has been derived between the temperature and resistance of the knitted sensors and this can be used to optimise its dimensions to achieve a targeted reference resistance. The temperature-resistance curves demonstrate a linear trend with a coefficient of determination in the range of 0.99–0.999 and can be integrated into garments to monitor skin temperatures.
Concentrated electric field is crucial in generation of needleless electrospinning, the electric field profile together with electric field strength of the spinneret affect the needleless electrospinning performance directly. Understanding the electric field of spinneret would definitely benefit the designing and optimization of needleless electrospinning. Based on the software COMSOL Multiphysics 3.5a, 3D finite element analysis has been used to analyze the electric field profile and electric field strength of a ring spinneret for needleless electrospinning. The electric field profile shows that strong electric field concentrates on the top of the ring with intensity higher than 70 kV/cm. The electric field of ring spinneret is greatly affected by the geometry of the ring and other experimental parameters such as applied voltage and collecting distance. The electric field analysis introduced in this study will be helpful in selecting proper spinneret and scaling up the production rate of nanofibers in needleless electrospinning.
Functional textiles of far infrared emissivity and electromagnetic shielding are attracting increasing attention, thus in this research we fabricated the bamboo charcoal/metal complex yarns with stainless steel wires or copper wires as the core yarn and bamboo charcoal polyester textured yarn as the wrapped yarn, using a rotor twister machine. The two manufacture parameters were rotor speed (7000–11,000 r/min) and wrapped number (2–7 turns/cm), and the bamboo charcoal/metal complex yarns which had optimum breaking strength and elongation became the weft yarns of the bamboo charcoal/metal complex woven fabrics. After the complex woven fabrics were tested in tensile strength and tensile strain, they were changed with different lamination numbers for the tests of the far infrared emissivity, anion density and air permeability. When the core yarn was 80 ìm stainless steel wires, the complex woven fabrics had the optimum tensile strength and air permeability of 364.8 N and 174.8 cm3/s/cm2. When the lamination number was 2, the complex woven fabrics had the optimum far infrared ray emissivity of 0.94.
An effective defect detection scheme for textile fabrics is designed in this article. Interestingly, this approach is particularly useful for patterned fabric. In the proposed method, firstly, Gabor filter is adjusted to match with the texture information of non-defective fabric image via genetic algorithm. Secondly, adjusted optimal Gabor filter is used for detecting defects on defective fabric images and defective fabric images to be detected have the same texture background with corresponding defect-free fabric images. The significance of the proposed approach lies in selecting Gabor filter parameters with an abundance of choices to build the optimal Gabor filter by means of genetic algorithm and achieving accurate defect detection on patterned fabric. High success rate and accuracy with little computational time online are obtained in the defect detection on fabrics, which indicate that the suggested method can be put to use in practice.
The dispersion property of modified nano-TiO2 particles and its antibacterial properties on cotton fabrics were studied. The nano-TiO2 particles were modified with reactive groups (such as hydroxyl groups, amino groups and silica groups). The modified nano-TiO2 particles were characterized by particle size analyzer, Fourier transform-infrared spectroscopy and transmission electron microscopy. Besides, the chemical load technology of optimizing the nano-TiO2 on the textile fiber combined with fiber by grafting and cross-linking was studied. The results showed that the stability of nano-TiO2 sol was related to the concentration of the modifier and the pH values of the system. The washing fastness and the antibacterial property of the fabric treated by modified nano-TiO2 had been increased and the antibacterial property of treated fabric was also related to the concentration of the modifier. By determining the fiber’s crystallinity, as well as the fabric’s breaking strength and tear strength, the influence of the modified nano-TiO2 photocatalyst on the structural properties of cotton fiber was discussed.
In this review, a summary of documented research on immersion suits (i.e. constant wear, abandonment suit and diving suit) is presented. Particular emphasis was placed on research regarding the performance and analysis of these protective suits. Heat loss from the human body is critical for the protection of the wearer of the suit during cold water immersion, while thermal stress can be experienced by the pilots or helicopter rescuers when wearing immersion suits under normal or hot environmental conditions. In addition, the knowledge gaps have been identified in the aspects of environmental hazards, development of novel textile materials, garment design features and test methods. The key factors that are fundamental to thermal insulation of immersion suits have been summarized. Efforts for improving thermal insulation have been presented. Three-dimensional body scanning, as a new approach being used to understand and improve fit and sizing of garment, may contribute to a better understanding of thermal protection and thermal comfort of immersion suits. The simulation of real open sea scenario to test thermal performance of textiles poses a big challenge for researchers. This article reviews what is known about immersion suits, describes future development trends and identifies domains for improving performance of immersion suits and testing methods.
Hybrid laminates consisting of C-glass woven fabric/epoxy composite plies and 3k-carbon woven fabric/epoxy composite plies are studied for fatigue damage and residual strength. Tension–tension fatigue tests were conducted on notched composite laminates at two load ratios of 0.1 and 0.25. The laminates were fabricated with the hand lay-up process for a symmetrical stacking sequence [0/90]3s made of three 3k-carbon/epoxy composite plies at both top and bottom sections and six C-glass/epoxy composite plies in the middle. Fatigue damage was generated on notched specimens with 4 x 104 load cycles to damage for residual strength tests. The hybridization was found to be beneficial for relative damage sensitivity under one of four different fatigue conditions although its effect was marginal while three other conditions were not in favor. A relative damage sensitivity factor expression (or a criterion) was developed for quantitative comparisons between non-hybrid and hybrid composites and was theoretically demonstrated to be valid for any possible cases where various combinations are possible due to differences in strength reduction rate between two different composite systems. A theoretical framework with the relative damage sensitivity factor is proposed as a guide to deal with the complexity involving uncertainties and a large number of variables in the hybrid composite system. New damage mechanisms of the hybrid system due to dissimilarity between two sub-composite systems (i.e. glass/epoxy and carbon/epoxy) were hypothesized and tested to be valid with evidence based on microscopic and macroscopic examinations. The difference between static and fatigue damage is discussed.
Chitosan is a natural polymer that is well known for its inherent antimicrobial ability and natural healing properties and hence it has been developed into fibres that are used for wound dressing applications. To increase its antimicrobial potency, these fibres are treated with copper sulphate. In a wound environment, copper ions have potent antimicrobial abilities due to their propensity to bind with proteins and ability to produce hydrogen peroxides. In this article, copper-treated chitosan fibres of different concentrations have been tested and analysed to determine the most effective antimicrobial dose for potential wound care dressings. Selected common skin microflora, i.e. Staphylococcus aureus, Staphylococcus epidermidis and Micrococcus luteus, have been used to test the chitosan–copper combinations. The analysis, based on the test methods of zone of inhibition, spectrophotometry and plating technique, has shown that copper concentration of 0.3 gm/ml was highly effective against the three bacteria and could potentially be most suitable formulation for wound dressing applications.
Nanomaterials have created massive opening on textile functionalization such as antimicrobial and sun protection activities of fabrics. The focal point of this paper is to impart antimicrobial and UV protection activities of textile substrates using a nanocomposite hybrid material chitosan with α-iron oxide. α-Fe2O3 nanoparticles were synthesized by self-assembly method and characterized. The average particle size was found to be 27–30 nm by X-ray diffractogram and atomic force microscopic analyses. The α-Fe2O3 nanoparticles were dispersed into the prepared chitosan solution to form the hybrid material. The chitosan-α-Fe2O3 nanocomposite thus formed was subjected to characterizations such as X-ray diffractogram, FTIR and SEM with EDX. The chitosan-α-Fe2O3 nanocomposite was dip-coated on cotton and silk fabrics and antibacterial activity was checked by zone of inhibition method (AATCC 147) against Staphylococcus aureus and Escherichia coli bacteria and the UV protection activity was analyzed using UV-DRS spectroscopy. Results revealed that the hybrid CH-α-Fe2O3 nanocomposite possess improved antibacterial as well as UV absorbing efficiency.
The analysis of the air gap between fire-protective clothing and the skin plays a crucial role in evaluating the protective performance of the clothing. However, the more accurate the analysis of the air gap, the more complex the air-gap model. This article introduces a novel air-gap model that stands halfway in terms of accuracy and complexity between other two models that already exist in the literature. A comparison between the performances of fire-protective clothing predicted by using the three air-gap models is discussed in this article. Different parameters that affect heat transfer within the air gap and hence the protective performance of the clothing were studied to assess the novel air-gap model compared with the other two models. Despite its simplicity, the novel air-gap model predicted the performance of fire-protective clothing as accurately as the most realistic model.
This article investigates the effects of selected finishing methods on wrinkle resistance of laminated and non-laminated car seat cover fabrics. This study was carried out on five types of fabrics that have different properties. Apart from the reference fabric that is commonly manufactured in the automobile industry, four fabrics were produced using four different methods. All sample fabrics were knitted with a three-bar tricot machine at a conventional mill under the same conditions. As seat cover fabrics are generally laminated, sample fabrics were tested as laminated and non-laminated in order to investigate the effect of lamination. Samples were laminated with polyurethane and another warp knitted fabric that was knitted with a two-bar tricot machine and served as a lining. During the study, the wrinkle resistances of 10 laminated and non-laminated fabrics were measured at regular intervals. When the findings of the study were analyzed graphically and statistically, the method of using softening agent at foulard was found to be the most convenient one to produce high wrinkle resistant seat cover fabrics.
Polysulfonamide (PSA) is one of the functional materials with excellent heat and flame resistance properties, which can be potentially utilized in aerospace field and other civil fields. This work presents a feasible method for the preparation and characterization of the electrospun polysulfonamide fibers at nanoscale. The micro-surface morphology and micro-structure of the manufactured polysulfonamide fibers were characterized using the scanning electron microscope. The effects of electrospinning parameters on fibers’ micro-surface morphology and properties were investigated accordingly. It was found that high solution concentration favors the formation of smooth fibers and the low solution concentration leads to the formation of beaded fibers or beads. Small diameter fibers can be spun by increasing applied voltage. A considerable number of thin fibers with diameters <100 nm can be spun with the setting of 12 wt% concentration, 28 kV applied voltage and 15 cm tip–target distance. The crystallinity of the polysulfonamide fibers was measured by X-ray diffraction and its thermal property was investigated based on the thermogravimetric analysis. The experimental data show that the crystallinity and thermal behavior of polysulfonamide fibers can be influenced by the electrospinning parameters, including the solution concentration, applied voltage and tip–target distance, while the applied voltage has no significant effects on the crystallinity of fibers.
The dynamic sweat transfer tester for analyzing the sweat transfer behavior of multi-weave structure fabrics (single fabric contains different weave structures) has been designed and developed. This instrument has been developed to evaluate the sweat transfer rate in 16 different directions and 48 different regions for a test specimen of 7 cm diameter. The concept of the sweat measurement is to measure the sweat transport time required to reach the unit area of the fabric. The instrument works under the principle of electrical conductivity, that is, wetted cotton fabric acts as an electrical conductor between the power connected (5 V) copper pins and ground connected copper pins. The unique feature of this instrument is that the sweat transfer rate can be measured in fabrics which have irregular spreading behavior (single fabric that has different weave structures) at one step. Twelve different woven fabrics have been analyzed for the sweat transfer behavior using the instrument, and the results were well correlated (R2 = 0.925) with manual test method.
Novel nanoencapsulated phase change materials containing polyethylene glycol as the core material and urea formaldehyde as the shell material were prepared with an in situ polymerization method. The prepared nanocapsules were coated onto the cotton fabric using the pad-dry-cure method, and different ratios of nanocapsules to binder agent were evaluated. The morphology and characteristics of the polyethylene glycol and nanoencapsulated phase change materials were measured using scanning electron microscope, transmission electron microscope and Fourier transform infrared spectroscopy. The nanocapsules were found to have a regular spherical shape with a size of 141 nm. The thermal behavior of the textile fabrics was investigated by differential scanning calorimetry and thermal gravimetry analysis. The tensile strength, water absorption and abrasion resistance of the treated and untreated fabrics were also studied. The differential scanning calorimetry results found that the treated fabrics had latent heat storage energy of 0.198, 0.213 and 0.219 J/g, where the measurement was related to the nanocapsules/binder ratio. The thermal gravimetry analysis results showed that the treated fabric with a nanocapsules/binder agent ratio of 3:3 had good thermal stability.
The efficiency of chemical biocides as anti-bacterial agents is well documented and there are various methods to incorporate these bactericidal agents onto commonly used substrates, such as textile materials. Silver is known for its excellent inhibitory properties due to its direct action on the morphology of the cellular membrane of the bacteria. The use of silver is, however, limited due to its cost and challenges to incorporate silver into relevant products and materials with minimal loss of efficiency. In this article, we present an ‘in situ’ (one-pot) process for the formation of silver nanoparticles onto cotton fabrics in an aqueous media. Silver nanoparticles are bonded onto the cotton fibers via a surface modification that involves the use of 3-aminopropyltriethoxysilane. This enables the improved bonding of silver nanoparticles onto the textiles, thus mitigating the challenges associated with the leaching of silver into eluents and wash-offs. Anti-bacterial efficiency testing was also carried out on the textiles with more than 99% reduction of bacterial growth within 1 h of contact. Additionally, the textiles have also demonstrated continued anti-bacterial efficiency after prolonged period of washing. Thus, our method can potentially be applied to large-scale manufacturing of anti-bacterial textiles with potential uses in biomedical and consumer clothing industries.
This paper presents the results of a numerical simulation of the ultimate flax fibre (Linum usitatissimum) tensile mechanical behaviour using finite element analysis. Experimental data were used to develop a numerical multilayer model of the flax fibre. Thus, the influence of some parameters, such as cell wall thicknesses, microfibrils angles (MFAs), biochemical composition and mechanical properties of the biochemical components, on the flax fibre tensile mechanical behaviour has been investigated. Results show that the typical stress–strain curve profile of the flax fibre could be due to the mechanical properties of hydrophilic components (hemicelluloses) and thus to the environmental conditions. A parameter sensitivity study reveals that ultrastructural parameters (hemicelluloses and cellulose Young’s modulus) strongly influence the flax fibre mechanical behaviour and structural parameters (S2 cell wall layer MFA and thickness) significantly influence the fibre longitudinal Young’s modulus. Thus, the knowledge of the fibre ultrastructure seems to be the key of the understanding of the flax fibre mechanical behaviour.
High thermal resistance of thermal insulating fabrics is a major factor in the decision to use them in protective apparel applications, sleeping bags and other functional textiles. New standards and new applications of fibre layers in industrial textiles require more accurate methods of testing of their thermal resistance and conductivity, which minimise the dependence of the measured parameters on the testing conditions, such as the temperature drop between the plates of testing instrument and infrared radiation properties of these plates. In this article, the use of a testing method based on two different temperature drops between the plates of the ALAMBETA testing instrument revealed that the portion of heat transferred by radiation through the tested woven fabrics reached 12–17%. From the second series of measurements it follows that decrease in surface emissivity of the plates of the mentioned testing instrument influences the level of heat transfer by radiation between the plates of the ALAMBETA testing instrument and may cause the changes in the experimentally determined thermal conductivity and thermal resistance of certain porous fabrics. These changes presented up to 8% for the studied non-woven fabrics with low density.
In this study, the application of carbon filament yarn (CFY)-based conductive hybrid yarn as the heating element in a textile-reinforced concrete structure is reported. For this purpose, a hybrid yarn having a core-sheath structure (the core is made of carbon filament yarn and the sheath consists of a mixture of short glass and polypropylene fibres) is manufactured by DREF-2000 spinning technique and integrated into textile structure by tailored fibre placement method. Heat can be generated in the concrete structure by passing electric current through the conductive carbon filament yarn core of the hybrid yarn using the principle of resistive heating, where the sheath acts as the protection and isolation layer. From the initial investigations made on a small concrete specimen, important information is gathered and a large concrete slab with integrated conductive hybrid yarn is manufactured. The heat ability and the comfort level of the manufactured concrete slab are measured. The investigations have revealed the potential of using such hybrid yarn for a pointwise heating of the concrete surface for possible appliance in outdoor furniture.
Electrospinning generates nanofibres at speeds that often surpass those of conventional man-made fibre production. This makes control and manipulation of these nanofibres that much more difficult and challenging. However, to take full advantage of the superior properties of electrospun nanofibres, their production process must be clearly understood and all possible means of fibre formation and hence fibre control explored. This article attempts to explain electrospun fibre production from first principles and uses schematics to follow the electrospinning process from inception, i.e. in the nozzle, to collection with respect to electrostatic behaviours. The complex interrelationship between the charged species in the moving solution and their subsequent polarization and the induced internal field by the applied external electric field are systematically explored and explained.
Cellulose acetate (CA) membranes and films were fabricated, respectively, by electrospinning and solvent casting. A systematic analysis of structure and properties was made to compare the differences between nanotexture and casting texture. Scanning electron microscopy, X-ray diffraction and thermal analysis were used to characterize the morphology, inner structure and thermal behavior of electrospun CA membrane, casted CA film as well as original CA powder. In addition, the pore size distribution and surface hydrophilicity of electrospun membrane and casted film were tested. It was found that the nanotexture produced by electrospinning process had a significant effect on the structure and properties of CA materials. The pore size distribution of electrospun membrane was more uniform, although the mean pore size was larger. In addition, the electrospun CA membrane possessed higher crystallinity and better thermal stability, compared with casted CA film. The results also showed that the electrospun membrane gave a contact angle of 127.2° and was observably more hydrophobic than the casted film, reporting a contact angle of approximately 74.4°.
Drape simulation of textiles is a field of research, which is known in the clothing sector for a long time. The ongoing development of high-performance composites made of textile reinforcements and matrix materials focus the interests on a serial production in many industrial sectors, such as aviation and automotive industries. Challenges occur mainly in the serial production technologies and in supplying concepts for the preform architecture and shape. Research aims on the acceleration of preform manufacturing and the reduction of expensive pretests. Numerical simulation models can help to improve the composite development chain with structure and process simulation. A special challenge in drape modeling is the bending behavior of textiles. This study introduces a novel approach for modeling single textile layers as laminates to gain a correct mechanical behavior, where all deformation mechanisms are uncoupled. The implementation in the finite element software LS-DYNA® is described. An algorithm is introduced which provides the membrane stiffness for each layer of a laminate to fit the measured cantilever bending stiffness of textiles in every bending direction and bending side. The calculated parameters for the laminate formulation result in the requested bending stiffness for the textile layer. The cantilever bending stiffness can be used directly for dimensioning the model.
A layer of TiO2 nanoparticles was deposited on the surface of cenosphere by using tetrabutyl titanate or titanium sulfate as the precursor under hydrothermal conditions. The morphology, chemical composition, crystal structure and optical properties of cenosphere before and after treatments were determined by scanning electron microscope, energy dispersive spectroscopy, X-ray diffraction and diffuse reflectance spectrum. The photocatalytic activity of methylene blue degradation was evaluated by using ultraviolet irradiation. The results showed that compared with tetrabutyl titanate, a thicker layer of TiO2 nanoparticles in anatase structure was deposited on the surface of cenosphere treated with titanium sulfate. The crystal size of TiO2 nanoparticle by using titanium sulfate as precursor was larger than that by using tetrabutyl titanate as precursor. The photocatalytic activity of TiO2-coated cenosphere by using titanium sulfate as precursor was slightly enhanced mainly because of the higher crystallinity of anatase TiO2. The formation mechanisms of TiO2 coating on cenosphere surface and photocatalytic degradation of methylene blue with ultraviolet irradiation were also discussed.
This article studies the relation between fabric tightness and shielding effectiveness (SE) of blended electromagnetic shielding fabric (BESF). The SE of different tightness BESFs is tested using a waveguide testing method. Experimental analyses show that the SE of BESF associates to the tightness linearly, the SEs of same tightness fabrics are consistent under same metal fiber contents, same weave types and different yarn linear densities condition, and the SEs of different type fabrics are inconsistent under same tightness, same metal fiber contents and same yarn densities condition. Moreover, a theory about the relation between the SE and the tightness determined by adjacent yarns states is proposed according to the electromagnetic theory. A number of computation equations about tightness boundary determination are given, which would provide reference for the BESF design, manufacture and testing.
Compression stockings are one of the best known therapies for venous disorders. This treatment is efficient as long as the stockings are worn by the patient. In order for them to be worn, they will have to fit the patient, in terms of comfort and appearance. The aim of this work is to develop a measurement technique adapted to stretchable textile items to evaluate stockings transparency. Our approach is to measure some of the colorimetric parameters of the stocking. Five commercial compression stockings claimed by the suppliers as supposed to present special transparency characteristics have been analyzed and compared. In order to compare stockings of different colours, a "transparency value" has been set. The developed method can help designing more transparent stockings which may be better "accepted" by patients.
The cotton fabrics with the character of anti-crease were obtained by introducing foam technology. It is observed from experimental results that cross-linking agent, curing temperature and curing time all have significant effects on the wrinkle recovery angle and the mechanical property of fabrics. In addition, foam ratio plays an important role in the process of one-side finished fabric. We found that in the case of same weight gain of cross-linking agent, wrinkle recovery angle of foam technology is bigger than that of conventional finish, while the strength loss of foam finish is smaller as compared to conventional finish.
Cotton fabric with improved antibacterial properties is always invited for effective use in wound dressing and healing applications. In this study, poly(N-isopropyl acrylamide) network has been produced in situ in porous cotton cellulose fabric by photo polymerization using UV-radiation. The thermoresponsiveness of the resulting fabric has been used to entrap silver nanoparticles with the fabric. The presence of silver nanoparticles in the fabric has been characterized by X-ray diffraction, transmission electron microscopy, and dynamic light scattering analysis. The fabrics have been found to possess fair mechanical properties. The individual and aggregation particle size of the silver nanoparticles was found to be in the range 13–20 nm and 140–220 nm. This aggregation phenomenon was also confirmed by dynamic light scattering measurement, i.e. 256 nm. The silver nanoparticles exhibits polydispersity index 0.18 and zeta potential -2.86 mV. The fabric exhibited fair biocidal action against Escherichia coli and Staphylococcus aureus, thus indicating its possible utility in medicinal application.
Fiber diameter and its distribution are the fundamental parameters affecting the performance of melt-blown nonwoven materials. This paper proposes a new method to measure diameters of microfiber in nonwoven based on image processing techniques. The one-pixel-wide boundaries of potential fibers were extracted first. The real fiber profiles were then separated from incorrect rectangles by a recognition procedure. Finally, the fiber diameters and diameter distribution were calculated. The experimental results show that the new method is consistent with the manual methods in measuring the main fiber diameter and fiber diameter distribution of melt-blown nonwoven material and has many advantages including efficiency, reproducibility, and objectivity.
This study reports on the development of a sound-absorbing/thermal-insulating nonwoven composite board and its relevant manufacturing process. The developed nonwoven composite board is used to reduce airborne noise and achieve thermal insulation through its irregular, three-dimensional porous structure. The nonwoven composite board is made of recycled polypropylene nonwoven selvages, two types of polyester fiber, and thermoplastic polyurethane. The experimental results reveal the excellent thermal insulating properties of both the polyester fiber/polypropylene and polyester fiber/polypropylene/thermoplastic polyurethane composite boards. In addition, the sound absorption of the polyester fiber/polypropylene /thermoplastic polyurethane composite board performs well in low and medium frequency ranges. For frequencies below 1000 Hz, the best sound absorption coefficient of polyester fiber/polypropylene/thermoplastic polyurethane composite board can reach a value of up to 0.698.
Silk fibroin (SF), a naturally occurring protein polymer, has several unique properties such as biocompatibility, biodegradability, minimal inflammatory reaction, and endowed with excellent mechanical properties and process ability. The existing scaffolds used in medical industry lack the degradation and/or slow in healing practice, so clinically there is a need for the development of efficient and reliable biomaterial scaffolds for wound healing. Silk fibroin has shown greater potential for tissue engineering applications. This work is focused on designing biomaterial with silk as raw material and wound healing effect of SF scaffolds were also tested. The silk blended scaffolds were prepared by using SF as a vehicle with dextrin, other healing agent of cactus and epidermal growth factor (rhEGF) are used as the drug releasing model. Scanning electronic microscope (SEM) was used to observe the morphology of prepared scaffolds for process versatility and the highly specific surface area. The structure was studied by Fourier transform infrared. The SF was treated at different concentrations of cactus and rhEGF, to investigate the growth inhibition effect of bacterial growth. The SF scaffolds show favorable stability by their structural integrity, morphology, mechanical properties, and powerful antibacterial efficacy up to 100% to Escherichia coli and Staphylococcus epidermidis significantly intended to provide improved environments for the zone of incubation when compared with normal scaffolds without rhEGF. Therefore, the results give the evidence for the application of SF blended scaffolds in the treatment of wound.
In this study, efforts were taken to identify the most suitable cotton fabric with commonly used structure to be used as protective fabric by the pesticide applicators in the tropical regions, specifically at the time of spraying in the field. As the situation demanded the generation and use of pesticide-borne air for the evaluation of cotton fabrics considered in the study, a test equipment with appropriate features was developed and used. The study revealed that twill fabrics of medium weight construction provide better protection than plain fabrics, especially when they are produced with coarser yarns to achieve the required fabric weight. They are found to give enhanced protection when they are subjected to raising operation. Fabric raised on both the sides performs better than the face side raised fabric. On the contrary, these fabrics in raised or unraised state are found to slightly go down in their performance when they are wet and their performance decreases with increase in wetness. Hence, it is suggested that use of raised fabrics may be avoided for the preparation of pesticide protective clothing as the pesticide applicators are bound to sweat at the time of spraying. As the unraised fabrics give comparatively lower performance reduction on wetting, it can be recommended for the pesticide applicators with the instruction to change the clothing when it become wet to ensure protection.
Energy absorption capacity is of great importance in engineering applications such as bumpers, helmets and packaging. Textile-made composites have attracted world's attention due to their high energy absorption and lightweight. This study aims at evaluating energy absorption capability of composites reinforced by three-dimensional-weft knitted fabrics. To achieve this purpose, weft knitted fabrics with different structures and surface densities were prepared from nylon yarns. Having washed the fabrics, their shapes have changed to three-dimensional ones using a thermoforming process and specific casting. Three-dimensional fabrics were first covered by epoxy resin and then laid in a bed of poly vinyl chloride foam in order to improve their energy absorption capacities. Quasi-static pressure and dynamic pendulum impact tests were carried out for samples. The results were analyzed by the Minitab software and optimal sample was determined.
Nowadays, the advantages of staple fibers applied as reinforcement in cementitious composites are well known. The fiber to cement interfacial interactions influences mechanical properties of composites. Engineered cementitious composites are cement-based composites which are made of cement binder, small size sands, fillers, high modulus fibers, and supplementary cementing materials. They have improved tensile and flexural properties in comparison to normal concretes. To achieve these properties, high modulus fibers such as carbon, steel, and polyvinyl alcohol fibers have been used in engineered cementitious composites. In this research, low modulus polymeric fibers such as nylon 66, acrylic, and polypropylene were used as substitute of high modulus reinforcing fibers in engineered cementitious composite. The low modulus fibers were characterized carefully for physical–mechanical properties. The flexural behavior (flexural strength and flexural toughness) of the engineered cementitious composite specimens from this article was studied using a three-point bending test method. The results were compared to engineered cementitious composite containing polyvinyl alcohol. It was found that low modulus fibers caused considerable improvement in flexural behavior but results were lower than composites containing polyvinyl alcohol fiber. It was also found that these fibers are suitable choices for producing low price, acceptable performance engineered cementitious composites for usual applications in construction industry.
This paper reports a fast, accurate, and non-destructive three-dimensional imaging approach based on using quantum dots and confocal laser scanning microscopy to get three-dimensional images of internal pore structure of the nanofibrous materials. A practical method of making the fiber fluorescent using quantum dots was applied before three-dimensional imaging by confocal laser scanning microscopy. Fibrous scaffolds with different porosity parameters produced by electrospinning and their three-dimensional pore structure was evaluated by this approach. Furthermore, the introduced approach can be used to measure the pore interconnectivity of the scaffold.
Average number of fiber-to-fiber contacts in a fibrous structure is a prerequisite to investigate the mechanical, optical and transport properties of stochastic nano-microfibrous networks. In this research work, based on theoretical analysis presented for the estimation of the number of contacts between fibers in electrospun random multilayer nanofibrous assembles, experimental verification for theoretical dependence of fiber diameter and network porosity on the fiber to fiber contacts has been provided. The analytical model formulated is compared with the existing theories to predict the average number of fiber contacts of nanofiber structures. The effect of fiber diameters and network porosities on average number of fiber contacts of nano-microfiber mats has been investigated. A comparison is also made between the experimental and theoretical number of inter-fiber contacts of multilayer electrospun random nano-microfibrous networks. It has been found that both the fiber diameter and the network porosity have significant effects on the properties of fiber-to-fiber contacts.
In view of the single structure of soft stab-resistant body armor at home and abroad and the difficulty in balancing the stab resistance and the portability, low-twist ultra high molecular weight polyethylene fibers and polyester monofilaments were chosen to produce stab-resistant warp-knitted spacer fabrics. In this paper, quasi-static stab tests were conducted to study the relationships among the stab resistance and fabric density, thickness and the spacer structure. The stab-resistant characteristic of warp-knitted spacer fabric was analyzed by the curve of penetration force versus penetration depth. The experimental results showed that the thickness and the density of warp-knitted spacer fabric and the compressive property of the spacer layer structure were the main influencing factors on the stab resistance. Three-layer composite structure of the warp-knitted spacer fabric could resist the penetration by stages during the penetration process and attained the purpose of multiple protection through the knife self-locking, energy dissipation and friction damping.
In the present work, the effect of fabric mat loading at different impingement angle and impact velocity were reported through solid particle erosion test rig on viscose fiber based needle-punched nonwoven fabric mat reinforced polymer composites. Three types of viscose fiber based fabric mats (VS200, VS400 and VS600 g/m2) were used as reinforcing material. The solid particle erosion wear behavior of viscose fiber based needle-punched nonwoven reinforced composites were evaluated using irregular shape silica sand particles of the size of 250, 350 and 450 µm with a varying stand-off distance (65, 75 and 85 mm), impingement angle (30°, 45°, 60°, 75° and 90°) and impact velocity (45, 54 and 65 m/s). Taguchi analysis was also carried out on the basis of design of experiments approach to establish the inter-dependence of operating parameters on erosion rate of the composites. Analysis of variance and signal-to-noise ratio have been performed on the measured data. The eroded surfaces of these composite samples were examined by scanning electron microscopy to examine the wear modes of the composites. However, Part I discussed the physical, mechanical and thermo-mechanical characterization of the same series of composites and concluded that all the mechanical properties were improving with the increase in fabric mat weight percentages. Furthermore in thermo-mechanical analysis, in the temperature range of 50–60°C the damping factor (tan ) values was found to increase and the peak values of tan was observed in the temperature range of 70–90°C for all the composites.
Since composite structures with soft-material matrix do not have adequate pullout resistance with flat-type reinforcements such as fibers, there are increasing cases where reinforcements with passive resistance are used in conjunction. So, loop-formed polyethylene fibers were used to reinforce soil against shear loading. Afterward, shear behavior of both fiber and loop-formed fiber-reinforced soil composite samples was modeled by using "force-equilibrium method" and "slippage theory" of short fiber composites. The proposed model indicated that both fiber parameters and ambient conditions determine shear strength of a fiber-soil composite. In the next step, a set of laboratory direct shear tests was performed on different samples including neat soil, loop-formed fiber and fiber-reinforced treatments. Thus, it was found that the performance of polyethylene looped fibers in shear strength improvement of soil composite is more than that of the ordinary polyethylene fibers. In addition, a novel apparatus based on fiber pullout test was designed to determine the interfacial shear stress between fiber and soil. Finally, an artificial neural network technique and least square method were used to calculate "fiber reinforcing amplitude" and "slippage ratio", as input parameters required for the model. Consequently, both the proposed models and established artificial neural network adequately predicted shear behavior of loop-formed fiber and fiber reinforced soil composite.
The adhesion strength enhancement of oxygen plasma pre-treated laminated polypropylene nonwoven fabrics using two different types of adhesives was investigated in this study. Fabric surface modification was performed using low-pressure, radio-frequency oxygen plasma treatment. Effect of plasma treatment on fabric surface wettability was determined by vertical wicking measurements. Wettability of highly hydrophobic polypropylene nonwoven samples dramatically increased with increasing plasma power and exposure time. Plasma-treated polypropylene fibers showed rougher surfaces with increased plasma power and treatment times. X-ray photoelectron spectroscopy (XPS) analysis showed that oxygen plasma treatment of polypropylene fiber surface led to a significant increase in atomic percentage of oxygen compound responsible for hydrophilic surface. Peel strength enhancement of produced laminated fabrics was observed for plasma-treated samples compared to untreated samples. PU-based adhesive attached on the surface of both plasma-treated and untreated polypropylene nonwoven, filling the spaces between the fibers due to the penetration of the adhesive agent. The improvement in surface wettability of polypropylene nonwoven and the introduced sites through oxygen plasma treatment resulted in good adhesive bonding. For both adhesives, peel strength improvement of produced laminated fabrics was observed for plasma-treated samples compared to untreated ones. After lamination with polyurethane-based adhesive and 20 wash cycles, decrease in peel bond strength was between 22% and 25% for plasma-treated samples, while it was 36% for untreated fabrics. Laminated samples using acrylic-based adhesives showed much lower peel strength values and washing resistance than samples laminated with polyurethane-based adhesives.
Composites were fabricated using viscose fiber-based needlepunched nonwoven fabric mat as a reinforcement material, with varying mass per unit area of fabric mat (VS200 gsm, VS400 gsm and VS600 gsm) and varying fabric mat weight percentage. The effect of varying mass per unit area of fabric mat and weight percentage loading of these different fabric mats were reported on mechanical, physical and visco-elastic properties of needlepunched nonwoven reinforced epoxy composites. The mechanical and physical characterization was analyzed experimentally, and thermo-mechanical stability studied via the dynamic mechanical analysis, to measure the storage modulus (E'), loss modulus (E'') and damping factor (tan ) of nonwoven fabric mat-reinforced composites over a temperature range of 20°C to 200°C at 1 Hz frequency. The storage modulus (E') diminish with increase in temperature, with a significant fall in the temperature range 50–80°C for all the composites. Loss modulus (E'') shows the variation from 60 MPa to 150 MPa, whereas glass transient temperature (Tg) from the tan peaks, varies from 70°C to 85°C. The comparative analysis shows that with the incorporation of nonwoven fabric mat weight percentage in composites, all mechanical and physical properties of composites improve significantly. These mechanical and physical properties are also improving with raise in mass per unit area of fabric mats from VS200 gsm to VS600 gsm.
In this article, three test methods are described to measure the water spreading behaviour of textiles such as rate of absorbency and total absorbent capacity. The methods described are manual method, commercial image analysis method using Photoshop and embedded image analysis method using digital signal processor through MATLAB software (EIAS). With these methods the rate of absorbency and total water absorbent capacity were analysed in 12 different knitted/woven fabrics. In order to compare the three test methods, the correlation among the methods were analysed. A very good correlation (more than 0.9) was found between the manual water spreading tests and commercial image analysis method using Photoshop when compared to manual versus EIAS method. Also Photoshop versus EIAS method correlation was found better than manual versus EIAS method.
This study investigates the effect of hybridization on tensile strength of woven fabric glass/epoxy composite laminates with two different notch sizes of 5 mm and 10 mm. Tensile tests are performed on notched [0°/90°]3s specimens of woven fabric C-glass/epoxy composite laminates and their hybrid reinforced with woven fabric 3K-carbon layers in order to measure tensile strength and characterize damage mechanisms. The results suggest that hybridization has a considerable effect on the improvement of the tensile strength of C-glass/epoxy composite laminates but also has reduced the rupture strain of the composites. Microscopic observation of specimens after tensile loading reveals the existence of transverse and longitudinal cracks, delamination and transverse fiber damage in hybrid composite laminates.
A needle-punched cotton nonwoven was produced as a precursor for making activated carbon material. Carbonization and activation of the cotton nonwoven was carried out in a high temperature clean room oven. Microporous properties of the nonwoven in terms of surface area, micropore volume, micropore size, and adsorption isotherms were characterized using a micropore physisorption analyzer. Influence of carbonization temperature and difference between the N2 and CO2 adsorptions was analyzed. Tensile strength of the cotton nonwoven before and after the carbonization and activation was evaluated. Microporous structure of the carbonized and activated cotton nonwoven was examined using an scanning electron microscopy technique. The study exhibited that the carbonized and activated cotton nonwoven was a special type of renewable and biodegradable material featuring lightweight, high microporosity, and high performance of chemical adsorption and separation.
Fabric stiffness is one of the most important parameters in estimating the wear and comfort properties of multilayered textile materials. The characteristics of bending stiffness may be determined using different test methods. The aim of this work was to apply the compress hanging loop method for the evaluation of stiffness of coated and laminated fabrics. In order to achieve this purpose an extension machine appropriately equipped with a special device for specimen fixing has been used in this work. The initial and ultimate geometrical characteristics of the loop, and also the forces that were necessary to compress the loops to a certain degree were determined in this work. The investigation reveals that the force, which is necessary to compress the loop to a stated degree, is different not only for specimens cut in various directions but also for those specimens that are of different size. Therefore, the deformation properties are dependent on the material structure and testing conditions. The results indicate that coated and laminated fabrics with larger surface weight were more resistant to compression force. Also for these fabrics the larger difference of compressing force values was determined when the polymer film had been in different loop sides. It should be noted that analysis of geometrical compressed loop characteristics showed that for all tested specimens the upper and lower ratios of formed semicircles were not equal. The investigation reveals that the hanging compressed loop method allows extending the range of tested materials, which include rigid and less rigid fabrics.
Nonwovens have been increasingly used in car interiors for noise reduction. Most of these nonwovens are subjected to thermal treatments to give the nonwovens their final three-dimensional forms. Therefore, it became crucial to investigate the effects of thermal treatment on sound absorption characteristics of nonwovens. In this study, the effects of the material and treatment parameters on airflow resistivity and normal-incidence sound absorption coefficient of thermally treated three-layered nonwoven composites have been studied. The material parameters included fiber size and porosity. The treatment factors included the temperature and duration. The thermally treated three-layered nonwoven composites are classified into three types based on the material content and fiber blend. Sandwich structures consisting of polylactide/hemp/polylactide and polypropylene/glassfiber/polypropylene layers were called LHL and PGP, respectively. The sample which consisted of three layers of an intimate blend of polypropylene-glassfiber was named as PGI. Both temperature and duration of thermal treatment have been found to affect air flow resistivity and sound absorption. An increase in air flow resistivity and a decrease in sound absorption have been detected with heat treatment. A similarity has been observed between the thermal behaviors of PGP and PGI, which included the same thermoplastic polymer fiber. Variation in air flow resistivity of sandwich structure nonwoven composites increased with the increase in temperature, which was not observed in the intimate blend ones. The air flow resistivity of heat-treated nonwovens followed a steeper trend compared to unheated nonwovens per change in material parameters. In terms of treatment parameters, the difference between the thermal treatment and the melting point of the thermoplastics constituent of the nonwoven composite was found to be a significant factor on sound absorption. This effect of treatment temperature on sound absorption changed with treatment duration. The sound absorptive characteristic of the nonwoven composites in terms of sound frequency underwent a change with thermal treatment due to the structural changes with exposure to high temperature.
S band region of electromagnetic spectra is used in versatile applications as in multimedia and communication. Electromagnetic interference makes several electrical, economic, and biological adverse effects. Flexible electromagnetic interference shield from polyaniline-TiO2 hybrid coated cotton fabric was developed and shielding efficiency of coated fabric was calculated in S band region using cavity perturbation technique. The polyaniline-TiO2 hybrid coating was done by one-pot method involving in-situ polymerization. The shielding effectiveness due to reflection, absorption, and multiple reflections were estimated and compared for coated fabrics with different polyaniline: TiO2 ratios. The hybrid coated cotton fabrics had durable electrical conductivity and strength, with good electromagnetic interference shielding in S band region.
In this study, a system was designed and constructed in order to measure the drag force acting on the swimmer simulator. This system must be able to obtain the drag force for a range of swimsuit fabrics to characterize the hydrodynamic properties of swimsuit fabric. In this system, a DC motor was used as the propelling unit; also a voltmeter and an ammeter were applied to measure the input power of motor. To find the relationship between input powers and drag force, calibration was done. The simulator was made from wood in two different sizes. The samples of fabrics were prepared from three kinds of weft knitted fabrics, which are common in production of swimsuits, and were knitted from polyamide6 (nylon), polyamide6-elastan (nylon-lycra) and polyester. The statistical analysis of results show the importance of fabric surface properties and swimsuit design on swimmer’s performance, so clothing engineering and technical clothing design can play a key role in sport engineering.
Recycled high-modulus Kevlar fibers were blended with Nylon 6 staple fibers and biocomponent low-Tm/high-Tm polyester fibers to form high-modulus puncture-resistance nonwoven fabrics via opening, mixing, carding, lapping, needle-punching, as well as hot-pressing processes. In this paper, biocomponent low-Tm/high-Tm polyester fiber content, needle-punching density, and hot-pressing temperature were changed to evaluate the tensile strength, bursting strength and static puncture resistance of resulting nonwoven fabrics as related to aforementioned three parameters based on response surface methodology. The result shows that the tensile strength is highly related to needle-punching density and hot-pressing temperature; but the bursting strength and static puncture resistance are significantly involved with the aforementioned three parameters. The tensile strength, bursting strength, and static puncture resistance all present increasing and then decreasing trend with increase of its respective concerning parameters. Moreover, the static puncture resistance strength has linear dependence on bursting strength.
Polypropylene spunbond, spunbond/meltblown/spunbond, and spunlace fabrics of 35 and 50 g/m2 weight are tested for barrier properties against microorganisms and liquid or body fluids to estimate their suitability for surgical gowns. The fabrics are also treated with different levels of antibacterial and fluorochemical finishes in a single bath using pad-dry-cure method. Liquid barrier properties of samples are analyzed by water impact penetration, hydrostatic pressure test, and blood repellency test. Parallel streak method is used to measure the antibacterial activity on the fabric samples with Staphylococcus aureus. The fabric samples are also analyzed for air permeability and stiffness. It is observed that spunbond/meltblown/spunbond fabric of 35 and 50 g/m2 weight offer sufficient liquid barrier properties for level 2 protection as per the Association for the Advancement of Medical Instrumentation barrier protection classification. Spunlace and spunbond fabrics of 35 and 50 g/m2 weight offer only level 1 protection. Spunbond/meltblown/spunbond fabrics are poorest in terms of comfort, because of their higher stiffness and lower air permeability values; spunlace fabric offers the highest air permeability and lowest stiffness force. Spunbond/meltblown/spunbond fabric samples with 4% and 7% fluorochemical finish and 1.5% antibacterial finish can provide level 4 protection. Spunbond fabrics require 4% and spunbond/meltblown/spunbond fabrics require 1% fluorochemical finish to achieve level 2 protection.
The practice of covering the roof of a building with a layer of living vegetation has many benefits. However, soil is heavy and most soil substitutes present special problems such as a tendency to block drains. Previous studies utilized a lightweight, soil-free growing medium that replaced actual soil to lessen the mechanical load on the roof. This study used a lightweight nonwoven fabric as a growing medium for living roofs. Two types of polyester fibers were blended at various ratios and then thermally dried into various densities. A desirable growing medium must resist moisture deformation and encourage root implantation. The results indicated that 0.030 g/cm3 was the optimum density and that the weight of low-melting-point polyester fibers had to be in excess of 20 wt%. It was anticipated that the manufacturer who adjusts factory parameters to benefit from this research will reduce the production cost.
The cattail fiber assembly used as a sorbent for the sorption of engine and vegetable oils was investigated. The internal factors governing the oil sorption of cattail fibers were discussed. The analysis for the adsorption mechanism of cattail fiber assembly indicated that the tuft of cattail fibers has a down-like structure and, thus, its surface area and retaining space are large. The high surface waxiness and small surface free energy enabled the cattail fiber to have excellent oleophilic–hydrophobic property. The experimental results indicated that the oil-sorption rates of cattail fiber assemblies to engine oil and vegetable oil were 13.4 g/g and 14.6 g/g, respectively, and the oil retention capability to both engine oil and vegetable oil after 24 hours was over 95%. The cattail fibers have similar oil sorption capability with those of nonwoven wool materials, however, nature sorbents such as kapok fibers are superior to the cattail fibers.
Nylon 6, one of the major engineering plastic and synthesized fibers, has the following features: good mechanical property, impact resistance, melt flow, and workability. Thus, it is widely used for auto parts, electronic parts, packing films, textiles, etc.; however, plastic waste from processing nylon 6 has also garnered negative attention. This research plans to simulate recycling and reclamation by multiple melt-blending cycles. Only nylon 6, both nylon 6 and carbon fibers, and both nylon 6 and glass fibers are separately melt-blended for 1–10 times with a screw extractor and an injection molding machine, after which the resulting boards—the nylon 6 boards, the nylon 6/carbon fiber boards, and the nylon 6/glass fiber boards—are evaluated for their mechanical properties. According to the experimental results, the nylon 6/carbon fiber boards exhibit an electromagnetic shielding effectiveness above 20 dB; namely it is able to block 90% of electromagnetic waves. Finally, in terms of the mechanical property analysis, the addition of reinforced fibers contributes greater flexibility and impact resistance to the resulting composite boards.
The performance of ultraviolet protection, antimicrobial activity, soil release action and self-cleaning characteristics of nano zinc oxide (ZnO) with acrylic binder were assessed on the cotton fabric using pad-dry-cure method. Different precursors such as zinc chloride and zinc nitrate were used to synthesize nanoparticles by wet chemical technique. The synthesized nanoparticles were then characterized using Fourier transform infrared spectroscopy, particle size analyser, powder X-ray diffractometry and scanning electron microscopy. The nano ZnO finished cotton fabrics were tested for ultraviolet protection factor, antimicrobial activity, soil release action and self-cleaning action. The wash fastness of nano zinc oxide (ZnO) finished cotton fabrics after 5th, 10th, 15th and 20th washes were assessed. Also the ultraviolet protection factor values, percentage reduction in bacteria and soil release percentage in each washing stage are reported. The self-cleaning activity was assessed for 12, 24and 48 h duration by exposing 6% of coffee stain on the specimen fabrics to sunlight. The zinc oxide nanoparticle size of 24 nm was obtained from synthesis of zinc chloride as a precursor, and another nanoparticle size of 38 nm were obtained from synthesis of zinc nitrate as a precursor. The smaller nanoparticles (24 nm) show better results in terms of antimicrobial activity, soil release and self-cleaning action. In case of ultraviolet protection function, it was found that the fabrics treated with 38 nm nanoparticles exhibit higher ultraviolet protection factor values than the fabric treated with 24 nm nanoparticles. The durability of the imparted functions was in the range 25–38 washes for antimicrobial activity, soil release action and ultraviolet protection, respectively.