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The porous structure formed by the interweaving of yarns in textiles is favorable for sound absorption. However, the absorption of sound waves by porous materials conforms to the law of linear response, which leads to poor sound absorption of textiles in the low-frequency range. It is usually necessary to increase the thickness to improve the low-frequency acoustic absorption performance of textiles, which does not meet the performance requirements of lightness, thinness, width and strength. This work proposes a method to increase the acoustic absorption performance based on acoustic-electric conversion and yarn resonance effect. In the form of a woven spacer fabric structure, different parts of the structure were prepared using nylon and PVDF yarns with different triboelectric sequences to realize acoustic-electric conversion between dielectric materials. Control samples woven with the same material were also prepared. Further, the resonance frequency of the yarns was modulated by controlling their tension to change the resonant frequency corresponding to the maximum acoustic-electric conversion efficiency and sound absorption peak. It was found that fabrics composed of two different materials had better sound absorption than fabrics composed of only one material. This is because the larger triboelectric sequence difference between materials results in more charge transfer, which favors acoustic-electric conversion and acoustic energy consumption. A significant acoustic absorption peak at 390 Hz with a peak value of about 0.05 was observed for a fabric with a thickness of about 4 mm after tension adjustment. This study demonstrates that acoustic-electric conversion between dielectric yarns and proper tension control improves the acoustic absorption efficiency and provides a reference for the development of structures based on this novel acoustic absorption mechanism. [ABSTRACT FROM AUTHOR]

(1) Background: It is simpler and more environmentally friendly to use supercritical CO2 fluid technology to process skincare viscose fabrics. Therefore, it is significant to study the release properties of drug-loaded viscose fabrics to choose suitable skincare drugs. In this work, the release kinetics model fittings were investigated in order to clarify the release mechanism and provide a theoretical basis for processing skincare viscose fabrics with supercritical CO2 fluid. (2) Methods: Nine kinds of drugs with different substituent groups, different molecular weights, and different substitution positions were loaded onto viscose fabrics using supercritical CO2 fluid. Then, the drug-loaded viscose fabrics were placed in an ethanol medium, and the release curves were drawn. Finally, the release kinetics were fitted using zero-order release kinetics, the first-order kinetics model, the Higuchi model, and the Korsmeyer–Peppas model. (3) Results: The Korsmeyer–Peppas model was the best-fitting model for all the drugs. Drugs with different substituent groups were released via a non-Fickian diffusion mechanism. On the contrary, other drugs were released via a Fickian diffusion mechanism. (4) Conclusions: In view of the release kinetics, it was found that the viscose fabric can swell when a drug with a higher solubility parameter is loaded onto it using supercritical CO2 fluid, and the release rate is also slower. [ABSTRACT FROM AUTHOR]

(1) Background: Supercritical CO2 fluid (SCF-CO2)-assisted impregnation presents advantages on loading active drugs to polymer substrates, since it enables the realization of a drug-loaded polymer without any solvent residue. Besides, CO2 gas and drugs can be recycled and utilized again. Resveratrol-loaded diacetate fiber by SCF-CO2-assisted impregnation was done to give diacetate fiber biological activity function for enhancing its added value. (2) Methods: The effect of SCF-CO2 temperature, pressure and treatment time on loading ability (LA) of resveratrol onto diacetate fiber was explored by ultraviolet visible spectrophotometer. The variation of structure and property of diacetate fiber was analyzed by characterization instruments. (3) Results: LA had been increasing with SCF-CO2 treatment time, temperature and pressure when SCF-CO2 was above 70 °C, 12 MPa. The inhibiting rate of resveratrol to free radicals was affected positively by SCF-CO2. After resveratrol was impregnated by SCF-CO2 it appeared some small white granular substances on the surface of diacetate fiber. It had a good interaction between resveratrol and molecular chain of diacetate fiber. (4) Conclusions: Resveratrol was well-loaded onto the diacetate fiber by SCF-CO2 assisted impregnation. [ABSTRACT FROM AUTHOR]

To characteristic tensile behavior of woven fabric and identify tensile failure mechanism is still a challenging work. In this paper, a new acoustic emission-based method is applied for the characterization of textile fracture mechanism. A set of acoustic emission signal acquisition devices was used to collect the acoustic emission signals, which is equipped on the electronic fabric strength tester during stretching. The proposed Hilbert-Huang Transform processing method was developed to identify the acoustic characteristics of collected unsteady acoustic emission signals of the woven fabric, which can be used to describe both time and frequency information. The experimental results demonstrate that acoustic emission signal is affected by orthogonal friction between warp and weft yarns rather than the fabric structure. [ABSTRACT FROM AUTHOR]

The configuration method of reasonable flame retardant fabric specification was studied. 26 kinds of flame retardant yarn with different formations were designed and processed.35 kinds of weft double fabrics with the same texture specification and 13 weft triple fabrics with same texture specification were woven. Among them, some were formed with different flame retardant yarn with layered configuration while some were corresponding homogeneous fabric.The breaking strength, tear strength and flame retardant index of each fabric were tested. The test results showed that the mechanical properties of fabric with flame retardant fiber layered configuration was normally lower than those of homogeneous fabric.The flame retardant property was better than that of homogeneous fabric.It was pointed out that part of flame retardant fibers with lower cost or even the common fibers could be used in flame retardant fiber layered configuration.So under the condition of keeping the same flame retardant property,the cost of flame retardant fabrics could be reduced and higher cost performance could be obtained. [ABSTRACT FROM AUTHOR]

via the acoustic emission technology, a method used for investigating the single fiber fracture sequence during tensile fracture process of blended yarn, which is made of different kinds of fiber was presented in this paper. As the fibers aggregate together after spinning process, the tensile strength of the yarn mainly originates from the strength of the fibers inside the yarn, as well as the cohesive force and surface friction between the fibers. In order to collect the acoustic emission signals generated during tensile fracture of the yarn and different single fibers, the acoustic emission technology was adopted. Firstly, the time-frequency matrix of the acoustic emission signal was constructed on the basis of Hilbert-Huang transform; subsequently, the singular value of the signal was obtained by singular value decomposition of the time-frequency matrix of the signal; ultimately, the singular value of the signal was judged by the fuzzy c-means cluster analysis. The results showed that the singular value can be used not only to characterize the fractures of different kinds of fiber in an efficient way, but also to identify the fiber fracture sequence during tensile fracture process of blended yarn, providing an excellent theoretical support for researching into the yarn formation process. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) fabrics were coated with the coupling agent 3-glycidyloxypropyltrimethoxysilane and graphene oxide (GO) by conventional pad-dry-cure processing method. The coated PET fabrics burnt without the melting state and formed the denser and tighter char directly during the combustion. In order to explain the restraining effect of GO, the structure and thermal stability of the coated PET fabrics, the structure of the forming char after vertical burning test were discussed. The morphology images showed that GO formed the uniform film on the entire fabric surface and infrared spectra indicated the successful fabrication of GO on PET fabric by the presence of the peaks at 3420 cm-1 and 1732 cm-1. While the thermal stability changed slightly with coating and XPS analysis illustrated that the ratio of C/O decreased and the function group C = O increased. It can be shown that the addition of GO played the physical role in the dripping resistance of coated PET fabrics. [ABSTRACT FROM AUTHOR]

Energy release usually accompanies the single-fiber tensile fracture, and can be monitored using acoustic emission technology. Generated during the process of molecular structure fracture of various fibers, the acoustic emission signals can be extracted to identify different fracture types of fiber, which is especially important to the yarn formation process. In this study, a low-noise fiber-stretching device was employed to process the weak-intensity signal generated during fiber tensile fracture; in addition, the Hilbert–Huang transform (HHT), principal component analysis (PCA) and least squares support vector machine (LSSVM) algorithms were combined to identify the collected acoustic emission signals of polyester and cotton fibers. At the same time, it was verified that compared with the single-fiber breaking acoustic emission signal obtained by the electronic single-fiber strength tester, the signal acquisition device based on pneumatic components proposed in this paper can significantly improve the signal-to-noise ratio of the signal. According to the algorithm recognition results, the recognition rate of the two fibers increased from 74% to 95%.The experimental results indicate successful measurements of different fractures of two types of fiber. [ABSTRACT FROM AUTHOR]

The color gamut space of color mixing for dyed cotton fiber was discussed. Cotton fibers were dyed with different dye dosage to obtain magenta, yellow and blue fibers. Their color characteristic value and spectral reflectance curve were tested. By comparing with magenta, yellow and cyan three-primary color ink of full point printing, the optimized magenta, yellow and cyan colored fibers were confirmed. Basic primary color fibers were taken with the optimized colored fibers. The color gamut space of mixed primary color fibers were studied. Then, it was compared with the color gamut space of mixed dyeing with primary color dyes and the color gamut space of primary color fibers used by enterprises. The results showed that certain color gamut space could be formed for both mixed primary color fibers after optimization and dying with the mixture of primary color dyes. However, they were both much smaller than the color gamut space formed with primary color ink. The color gamut space or the color generation of primary color fibers after optimization was smaller than that after dying with the mixture of primary color dyes. It is considered that the color gamut space of primary color fibers after optimization contains most of the color gamut space of primary color fibers used by enterprises. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the effect of char on the flame retardancy of fabrics by a cone calorimeter, which is an important factor to compare the flame retardancy of different fabrics. Design/methodology/approach: Cone calorimeter measurements were carried out in a Fire Testing Technology (UK) apparatus at the heat fluxes of 50 and 75 kW/m2. Fabrics with one and three layers were employed, with the name of cotton1, cotton3, FR cotton1, FR cotton3, PMIA1 and PMIA3. The dimension of the fabric was 100×100 mm2. A cross-steel grid was used to prevent the fabrics from curling during burning. The distance between the bottom of the cone heater and the top of the sample was 25 mm. Findings: This work was generously supported by National Key R&D Program of China (Project No. 2017YFB0309000), Natural Science Foundation of Shandong Province of China (Project No. ZR2019BEM026), Natural Science Foundation of China (Project No. 51803101) and China postdoctoral science foundation funded project (Project No. 2018M632619). Originality/value: The present research provides insight into the effect of the char formation on the flame retardancy of the fabrics, and a method to comprehensively investigate the char influence in the flame retardancy of the fabrics by a cone calorimeter is proposed. [ABSTRACT FROM AUTHOR]

In the present research, the flame retardancy and pyrolysis mechanism of polyimide fibers were investigated by cone calorimeter, scanning electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and pyrolysis–gas chromatography–mass spectrometry. As it turned out, the polyimide fibers possessed excellent thermal stability and flame retardancy. The onset thermal degradation temperature (Tonset 10%) of polyimide was 587℃ and 610℃ at nitrogen and air atmospheres, respectively. The polyimide fibers cannot be ignited at the heat flux of 35 and 50 kW/m2, while they can be ignited at the heat flux of 75 kW/m2 with the time to ignition of 33 s and peak heat release rate of 53.4 kW/m2. Moreover, the flame retardancy of woven and knitted fabrics was also discussed, which demonstrated that knitted fabric was easier to become thermally thick than woven fabric. Scanning electron microscopy analysis of the residual chars of fibers showed that the shape of fiber can be maintained irrespective of heat flux, but the chemical structure of the fiber was destroyed at the heat flux of 75 kW/m2. The pyrolysis combustible volatiles at 700℃ include benzonitrile, aniline, and phenol, which can interpret the ignition of polyimide fibers. The results obtained in the present research revealed the flame retardancy and pyrolysis mechanism of polyimide fibers, which can guide its application and further modification. [ABSTRACT FROM AUTHOR]

In the present work, the fire retardant properties and pyrolysis mechanism of polysulfonamide (PSA) fibers were investigated by cone calorimetry, scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and pyrolysis-gas chromatography-mass spectrometry. The fire retardant behaviors were reflected by the cone calorimeter data under heat fluxes of 35, 50, and 75 kW/m2. This demonstrated that, when exposed to higher heat flux, PSA fibers were ignited easier and burned more completely, indicated by lower time to ignition and higher peak heat release rate. It was further confirmed from the morphology of the residual chars that the original fiber shape can be kept at lower heat flux, but it changed into coherent carbonaceous chars with holes at higher heat flux. In comparison of the FTIR spectra of raw fibers with residual chars, it was noticed that upon heating, the amide linkage was more liable to be broken than that of sulfone groups. Additionally, with elevated heat flux, most of the absorption bands vanished and transformed into the typical feature of carbonaceous material. The pyrolysis products showed that some volatile products with small molecular weight, such as benzene, benzonitrile, and aniline, can be created at high temperature, which can be easily ignited. With this research, the fire retardant properties of PSA fibers are revealed and the corresponding pyrolysis mechanism is proposed, which can guide its application in practice. [ABSTRACT FROM AUTHOR]

In order to obtain a simple and accurate calculation method of shielding effectiveness for woven fabric containing metal fiber yarns, a conductive grid structure model composed of two parallel metal yarn periodic arrays was established. The two periodic arrays were cross-arrangement. The calculation formula of shielding effectiveness for the fabric was deduced through the transfer matrix of the electromagnetic field. The theoretical value of shielding effectiveness of the fabric using the theoretical formula and the measured value tested by the shielding chamber method were compared. Both sets of data were analyzed respectively from the metallic yarn periodic spacing, diameter, electric conductivity, electromagnetic wave polarization direction, and the weaving angle. The result shows that a reasonable agreement between the theoretical value and the measured value has been achieved in a frequency range from 4 to 14 GHz. This shows that the theoretical calculation model is simple, highly precise, and is valuable for the design and development of fabric containing metal fiber yarns. It can be used for estimating the electromagnetic shielding effectiveness of the fabric. [ABSTRACT FROM AUTHOR]

By using the optimal cone calorimeter, the universal method to study the fire retardant properties of fiber mats with different categories was explored. The challenge in obtaining accurate and repeatable cone calorimeter data was overcome from two aspects, employing a specific fixing mode and optimizing the measurement parameters. It was confirmed that the optimal grid covering rate of 25% and sample weight of 6 g favored repeatable and reliable data. With the improved cone calorimeter method, the reactions to fire of the selected fibers, involving the common and the inherent fire retardant fibers, are analyzed under different heat fluxes, in which the variations of time to ignition, the heat release rate and total heat release were compared. The fire retardant properties of various fiber mats were efficiently obtained by the improved cone calorimeter, which in turn verified its universality. In addition, the comparison between fire retardant properties and heat resistance of fibers demonstrated that the heat resistance is not the sole factor determining the fire retardant performance; the released fuel is much more important than the decomposition temperature. In conclusion, the universal evaluation method for combustion performance of fiber mats by the optimal cone calorimeter has been successfully established, which can serve as an efficient way in predicting the fire retardant properties of the corresponding fabrics. [ABSTRACT FROM AUTHOR]

With the progress of science and technology, consumers pay more attention to bring emotional experience and individual character difference of product, consumer behavior is more affected by the emotional and psychological needs. Based on the analysis of the characteristics of kansei engineering and emotional design, the technical route and method of the design of wool textile products are discussed by kansei engineering. According to the current research status of kansei engineering, the developments of wool textile products based on high sensibility fiber are put forward. Wool fabric mixed with high sensitive fibers such as acetate fiber, Tencel, Roka, and so on, which make the wool textiles with a special style and sense of touch to meet the high quality, aesthetic, emotional and personalized of new requirements, leading consumption and creating new economic growth point. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate(PET) is difficult to be irradiation cross-linked at low dose for the aromatic groups. In this paper, trimethylolpropane triacrylate (TMPTA) was incorporated in PET fibers to sensitize the cross-linking. Changes in PET fibers subjected to electron beam irradiation at dose up to 200 kGy and dose rate 12 kGy/s were investigated by gel content, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, thermal gravimetric analysis and X-ray photoelectron spectroscopy. The gel content was 0.14% at dose of 60 kGy and it arrived at the maximum value 0.53% at 100 kGy. Irradiated fibers showed a decrease in the breaking strength and an increase in the elongation at break. The crystal form of PET fibers had not been changed and crystallinity decreased 28% with the increasing dose. The melting temperature shifted from the original 254.28 °C to 253.44 °C. The thermal stability and the amount of non-volatile residue at 800 °C increased at dose of 100 kGy. XPS analysis indicated that the number of C-C band increased to prove the occurring of cross-link. The surface of PET fibers got rougher after irradiation and the anti-dripping property had not been improved effectively for the low degree of cross-linking. [ABSTRACT FROM AUTHOR]

Planar frequency selective fabrics (FSFs) with Jerusalem-shaped units were proposed in this paper. In accordance with the previous work, the design process was specifically for 10 GHz. Through simulation and optimization procedures, the ideal structure parameters were obtained, and the proposed FSFs with optimized parameters showed good stability to differential and integral algorithms, transmission modes and incidence angles of electromagnetic (EM) waves. To further explore the internal EM transmission mechanism of FSFs, the surface currents at 4, 10 and 14 GHz were analyzed comparatively. Based on the simulated results, 10 samples with the polyester fabric substrate were fabricated through the computer-based carving method and the transmission characteristics were tested using the Shielding Room Method. The fabricated FSFs indeed showed good frequency response characteristics, as expected, and the comparison of measured and simulated results verified the validity of the design procedures. The influence rules of structure parameters (p, a, b, c) were further studied in detail by changing their values properly, and the simplified equivalent circuit model was proposed to explore the corresponding physical mechanism, which could provide physical insight into the performance of the FSFs. [ABSTRACT FROM AUTHOR]

This study introduced trimethylolpropane trimethacrylate into ultra-high molecular weight polyethylene fibers through supercritical CO2 pretreatment before the fibers were irradiated under an electron beam. Significant differences, emerging in the ultra-high molecular weight polyethylene fibers’ gel content, mechanical properties, and creep property according to their different irradiation doses, were studied through one-way analysis of variance. Regression equations were established between the irradiation dose and the gel content, breaking strength, elongation at break, and creep rate by regression analysis. A reasonable irradiation dosage range was determined after a verification experiment and the impact trends were analyzed; additionally, the sensitized irradiation crosslinking mechanism of ultra-high molecular weight polyethylene fibers was preliminarily examined. Then the surface morphology, chemical structures, thermal properties, and crystal properties of treated ultra-high molecular weight polyethylene fibers were measured. The results showed that as the irradiation dose increased, the gel content first rose and then declined; the breaking strength decreased continuously; the elongation at break increased at first and then decreased; and the creep rate originally fell and then rose before finally declining slowly. Electron beam irradiation had a significant etching effect on the fibers’ surface, and both the melting point and crystallinity decreased slightly. [ABSTRACT FROM AUTHOR]

Thermal degradation behaviors and fire retardant properties of poly(1,3,4-oxadiazole)s (POD) and poly(m-phenylene isophthalamide) (PMIA) fibers were investigated. The thermal gravimetric analysis (TGA) demonstrated that POD exhibited higher onset thermal degradation temperature (T) than PMIA, exceeding nearly 80 °C. The thermal degradation kinetics, evaluated by the modified Coats-Redfern method, displayed that the apparent activation energy (E) of POD and PMIA fibers was similar when the conversion rate ( α) ranges from 0.2 to 0.5, while with the α from 0.6 to 0.8, the E of POD was significantly lower than that of PMIA. The fire retardant performance of POD and PMIA fibers were evaluated by cone calorimeter under heat fluxes of 35, 50 and 75 kW/m, during which the temperature of the fibers were monitored by a thermocouple. Surprisingly, POD fibers showed inferior fire retardant performance in comparison with PMIA, with lower time to ignition (TTI) and higher peak heat release rate (PHRR). The origin of the different fire retardant properties of both fibers was revealed by analyzing the residual chars and gaseous products during thermal pyrolysis. The morphology confirmed that stable and compact chars can be formed in PMIA. In addition, the Fourier Transform Infrared Spectroscopy (FTIR) characterization of the residual char revealed that POD can form carbonaceous chars at the heat flux of 50 kW/m, while the heat flux of PMIA was 75 kW/m. The pyrolysis products characterized by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) indicated that POD can be pyrolyzed completely at 600 °C, while the temperature of PMIA was 700 °C. [ABSTRACT FROM AUTHOR]

Based on traditional frequency selective surfaces (FSSs), the research ideas of novel frequency selective fabrics (FSFs) are proposed. In this paper, the specific square-loop patch FSF was chosen as an example to illustrate the design procedures, including ANSYS (HFSS) simulation and numerical calculation methods, and then a computer-based experiment was conducted to develop prototypes. Although the simulation, calculation, and experiment results have minor differences, especially the resonance frequency, they show good consistency overall, which demonstrates that traditional design methods could also apply to 2D FSFs. The experiment transmission curve shows obvious band-stop response, peaking at -37.12 dB at the resonance frequency 11.65 GHz, and the narrow bandwidth of -10 dB is predicted from 10.85 GHz to 12.55 GHz. To further verify the validity of design procedures, two complementary cross-shaped FSFs were fabricated through a computer embroidery process, and the experimental transmission curves are complementary as expected, peaking at -26.05 dB and 0 dB at the same resonance frequency 9.65 GHz, and the narrow bandwidths of -10 dB and -0.5 dB are 1.07 GHz and 0.41 GHz, respectively. Although many problems need to be solved in further research, this convenient fabrication method and theoretical basis could make relevant work feasible in later study. [ABSTRACT FROM AUTHOR]

In this paper, a computer-based carving experiment was conducted to make frequency selective fabrics (FSFs) with cross-shaped units. Different samples with varying frequency selective fabric types, structure parameters, conductive layers, base fabrics and unit shapes were prepared and the transmission characteristics were tested using the Shielding Room Method. The reflection characteristics under different electromagnetic (EM) wave incidence angles were also tested to study the angle stability. Experimental results showed that in the given frequency range of 4–14 GHz, two types of frequency selective fabrics had good complementary transmission characteristics, with ideal bandwidths and resonance peaks, and the aperture frequency selective fabrics showed certain stability to small electromagnetic wave incidence angles. Structure parameters played a very important role in determining frequency response characteristics and base fabrics with different effective dielectric constant could also exert a great influence. However, the change of electrical conductivity within a certain extent would not affect the transmission characteristics and related work should be continued to explore the effect rule. Through rational control of the unit shape to increase or decrease the conductive material mass, broad-spectrum shielding or passing-through properties could be obtained. In the paper, the experimental results were discussed and analyzed in detail aiming at different parameters, and internal causes were further investigated, which could provide reference values for the relevant design and product development process. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Frequency selective surfaces (FSSs) based on textile or textile composite materials are increasingly becoming popular due to their textile nature of high flexibility, softness, low-cost, easy fabrication, and other textile characteristics compared to the traditional metal FSS, especially the two-dimensional FSS fabrics. In this study, a three-dimensional (3D) fabric periodic structure with conductive textile fabricated vertically on the common textile substrate, forming a U-shaped array, is proposed. An experimental validation has been conducted to verify whether the 3D frequency selective structure fabric has good frequency response characteristics and great design ability. The model samples of 3D periodic structure based on velvet fabric with different structure or material parameters were fabricated by hand. Through testing and analysis of transmission and reflection coefficients at 2–18 GHz using the shielding chamber method, the results show that the velvet height of the fabric model periodic structure has an obvious effect on the resonant frequency. With an increase in velvet height, the resonant peak will move towards lower frequency. With an increase of vertical velvet spacing, the resonant frequency will also move towards lower frequency. Velvet material has a slight influence on the frequency response characteristics. The frequency response characteristics of this structure are stable under different incident angles. The 3D periodic structure offers more design freedom and possibilities. Significant effects of wave absorption or selective filtering by the periodic structure can be achieved by regulating the structural parameters and material parameters together. [ABSTRACT FROM AUTHOR]

Having good visual shielding property is a basic requirement for conventional clothing, especially for those with light weight and color used in summer. To date, the focuses of many researches have been concentrated on examining fabric characteristics (such as fabric thickness, weight, structure and fiber type) on the visual shielding property or the development of opaque fiber and such kind of fabrics. Clothing, worn in single or multiple-layer arrangements, is subjected to conditions such as extension and wetting from perspiration or water in the surroundings (such as swimsuit). At the same time, fuzzing and pilling are also the common phenomena to fabric after worn. In this paper, transparency was chosen as the parameter to express the visual shielding property, effects of layers, wetness, fuzzing and pilling conditions and extension on the shielding property of fabrics with different colors were investigated in details. The transparency of the fabrics decreases with the increase of the layers and fuzzing and pilling conditions, but the influences of wetness and extension are adverse. [ABSTRACT FROM AUTHOR]

With the increasing city size, high-power electromagnetic radiation devices such as high-power medium-wave (MW) and short-wave (SW) antennas have been inevitably getting closer and closer to buildings, which resulted in the pollution of indoor electromagnetic radiation becoming worsened. To avoid such radiation exceeding the exposure limits by national standards, it is necessary to predict and survey the electromagnetic radiation by MW and SW antennas before constructing the buildings. In this paper, a modified prediction method for the far-field electromagnetic radiation is proposed and successfully applied to predict the electromagnetic environment of an area close to a group of typical high-power MW and SW wave antennas. Different from currently used simplified prediction method defined in the Radiation Protection Management Guidelines (H J/T 10. 3–1996), the new method in this article makes use of more information such as antennas' patterns to predict the electromagnetic environment. Therefore, it improves the prediction accuracy significantly by the new feature of resolution at different directions. At the end of this article, a comparison between the prediction data and the measured results is given to demonstrate the effectiveness of the proposed new method. [ABSTRACT FROM AUTHOR]

47 kinds of woven fabrics were prepared with different fibers, thicknesses, weights per square meter and percentage covers. Statistical analysis method was employed to study the influence of the material and structure parameters on near-infrared transmission of these fabrics. Firstly, the effect of materials on near-infrared transmittance was determined through the contingency table analysis. Then the parameters significantly influencing near-infrared transmittance were found out and correlations among them were discussed by direct correlation and partial correlation analysis. Finally, regression equation of the near-infrared transmittance was established using factor analysis and principal component extraction. Results show that materials have little influence on near-infrared transmittance of woven fabrics. However, thickness, weight per square meter and percentage cover of the fabrics are closely related to near-infrared transmittance. Because there are correlations among thickness, weight per square meter and percentage cover, two new factors are extracted to establish the regression equation. The equation has an error rate of less than 5 % and thus can predict near-infrared transmittance precisely. [ABSTRACT FROM AUTHOR]

ABSTRACT Vinyl acetate was grafted onto poly(ethylene terephthalate) (PET) fibers under electron-beam co-irradiation. Then, the grafted products were hydrolyzed under HCl solution to obtain PET- g-poly(vinyl alcohol) (PVA) fibers. Afterward, to impart superior hydrophilicity and skin care, collagen was immobilized onto PET- g-PVA fibers with glutaraldehyde. The modified fabric was characterized in terms of moisture regain, wettability, and evaporation rate [Ev (%/h)]. The degree of alcoholysis of the grafting product was more than 90% in a 10% HCl solution at 100°C for 4 h, and its moisture regain was 1.4%. The modified PET fabric with collagen showed a shorter drip diffusion time and a higher wicking height than the unmodified PET and PET- g-PVA fabric before and after multiple washings. The evaporation ratio and Ev of the collagen-immobilized PET fibers were far below those of the virgin PET fibers. The chemical structure, surface morphology, and element content of the product were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. This further certified that the collagen-immobilized PET- g-PVA fiber was successfully prepared by the previous procedure. Furthermore, the PET-PVA-collagen fabric was capable of withstanding multiple washing cycles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40597. [ABSTRACT FROM AUTHOR]

Monodispersed LiFePO4 nanocrystals with diverse morphologies were successfully synthesized via a mild and controllable solvothermal approach with a mixture of ethylene glycol and oleic acid as the solvent. Morphology evolution of LiFePO4 nanoparticles from nanoplates to nanorods can be simply realized by varying the volume ratio of oleic acid to ethylene glycol. Moreover, the mechanism of competitive adsorption between ethylene glycol and oleic acid was proposed for the formation of different morphologies. Electrochemical measurements show that the LiFePO4/C nanorods have an initial discharge capacity of 155 mA h g−1 at 0.5 C with a capacity retention of 80% at a high rate of 5 C, which confirms that LiFePO4/C nanorods exhibit excellent rate capability and cycling stability. [ABSTRACT FROM AUTHOR]

Inspired by many strong, toughness, and stiffness materials in nature, we first present bio-inspired structure hybrid films fabricated by layer-by-layer assembly technique based on low-surface-energy graphite micro-sheets and styrenic block copolymers. Compared with pure polymer films, the mechanical properties of the hybrid films have been greatly modified in failure stress, elastic modulus, and failure energy due to the rigid bio-inspired structure. After graphite micro-sheets surface modified by dopamine, a better enhancement in mechanical properties was achieved with the assistance of dopamine surface modification in the almost same content of inorganic component. The layer-by-layer assembly method was improved by introducing the wet-coating techniques that has been widely applied in industry. This improved method is more easily to fabricate large-area hybrid films without destroying the bio-inspired structure of the hybrid films. This improved method and bio-inspired structure were first applied to reinforce elastomer in this work, while this bio-inspired structure has shown great success when applied in the area of plastic. POLYM. COMPOS. 34:1261-1268, 2013. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Irradiation cross-linking of polyamide 6 (PA6) fibers in the presence of polyfunctional monomer was studied. The combination of trimethallyl isocyanurate (TMAIC) and trimethylolpropane trimethacrylate (TMPTMA) was found to enhance the irradiation cross-linking of PA6 fibers efficiently. The effect of dose rate on the irradiation cross-linking was also investigated. The highest gel content was achieved when the fibers were irradiated at a high dose rate of 10 kGy/h. In this case, the breaking strength changed slightly and the elongation at break decreased. At a low dose rate of 1 kGy/h, the breaking strength fell drastically and the elongation at break increased at first and then decreased. The onset temperature of degradation fell and the amount of non-volatile residue at 600℃ increased as the irradiation dosage and dose rate increased. A high gel fraction largely improved the melt-drip performance of PA6 fibers. Irradiation cross-linking did not change the α-phase crystal form of PA6 fibers, and crystallinity decreased as the dose increased. [ABSTRACT FROM PUBLISHER]

Irradiation crosslinking of PA6 fibers with and without the presence of triallyl cyanurate (TAC) was investigated. The dose for incipient gel formation was 500 kGy for pristine PA6 fibers and it decreased to 12 kGy when 5 % TAC was incorporated. Changes in structure and properties of irradiated PA6 fibers were analyzed by X-ray diffraction, infrared spectroscopy and thermal gravimetric analysis. Irradiation crosslinking improved the anti-dripping properties of PA6 fibers effectively. Irradiated samples showed an increase of the breaking strength and then a decrease at further doses due to radiolysis effect, the elongation at break decreased during the irradiation process. Irradiation crosslinking had not changed the crystal form and crystallinity decreased first and then increased to some extent. DSC measurement reported that the melting temperature decreased with increasing the dose. The thermal stability decreased after irradiation whereas the amount of nonvolatile residue at 600 °C increased as the irradiation dosage increased. The infrared spectra of irradiated samples were identical with the unirradiated, no new bands were observed.XPS analysis showed that the number of C-C band increased after irradiation which proves that branching and crosslinking has occurred. [ABSTRACT FROM AUTHOR]

Mie scattering theory has been widely used to solve the problem of light scattering by single spherical particles in many fields. In this article, it was applied for the development of opaque fiber for the first time. Firstly, the spheroid particles were simplified as equivalent spherical particles. Then, the extinction coefficient was calculated using the Matlab program and the influences of the size parameter, refractive index and the wavelength of the incident light on the extinction coefficient were discussed in detail. Finally, the results indicated that the extinction coefficient depended greatly on the dimension and the refractive index of the particles, and also the wavelength of the incident light. For the development of the opaque fiber, it would be better to choose particles that had the higher refractive index and a certain diameter distribution to achieve the most effective light scattering. [ABSTRACT FROM PUBLISHER]

Hydrophobic poly(ethylene terephthalate) (PET) was prepared by reactive blending of PET with double epoxy groups modified polysiloxane (diepsi) or multiepoxy groups modified polysiloxane (multiepsi). The structure of the modified PET was characterized by 1H NMR and intrinsic viscosity. The grafted ratio of diepsi and multiepsi was 1.3 and 0.03 wt%, respectively. With the introduction of diepsi and multiepsi to PET, the water contact angle of modified PET increased from 73° to a maximum of 106°, showing the good hydrophobicity of the modified PET. The samples of modified PET were washed with different solvents and their water contact angles did not significantly decrease, indicating good durability of the hydrophobicity. Moreover, the films of modified PET prepared by solution casting (phenol and 1, 1, 2, 2-tetrachloroethane mixed solution) showed excellent hydrophobicity with the contact angle 151°. Scanning electron microscopy images showed the surface of the modified PET films to be rougher than those of unmodified PET because the introduction of polysiloxane to PET resulted in phase separation during the solvent evaporation process. [ABSTRACT FROM AUTHOR]

In order to obtain poly(ether ether ketone)s having enhanced solubility and processability without extreme loss of other properties, a series of copoly(ether ether ketone)s (Co-PEEKs) with pendant phenyl groups were synthesized from 1,1-bi(4-hydroxyphenyl)-1-phenylethane (ph-BPA), hydroquinone and 4,4′-difluorobenzophenone via aromatic nucleophilic substitution reaction. The structures and properties of the Co-PEEKs were characterized using Fourier transform infrared and 1H NMR spectroscopies, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction and solubility testing. These Co-PEEKs have inherent viscosities in the range 0.14-1.09 dL g−1, and their number-average and weight-average molecular weights reach 72 659 and 163 400 g mol−1, respectively. The Co-PEEK with the lowest content of ph-BPA has a semi-crystalline nature and is only soluble in 98% sulfuric acid. However, with an increase of ph-BPA in the Co-PEEKs, they become amorphous and readily soluble in a wide range of organic solvents and can afford tough films. These Co-PEEKs have glass transition temperatures of 137-180 °C depending on the content of ph-BPA. All the Co-PEEKs have initial degradation temperatures above 480 °C in nitrogen atmosphere. Thus, these Co-PEEKs with excellent thermal stability, good solubility and processability have potential for use in high-performance films, coatings, hollow fiber membranes, etc. Copyright © 2011 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The fine structure of kapok fiber was investigated by transmission electron microscopy. The walls of the fibers contained five layers, observable both in lateral and in longitudinal cross-sections: the cuticle, S; primary wall, W1; secondary wall, W2; tertiary wall, W3; and inner skin, IS. W1, with a thickness of about 200 nm, was characterized by an interlaced fibril-like network. The fine structure of kapok fiber showed that there was an obvious fibril structure. The fibrils of W2 were arranged at a certain angle to the fiber axis; and those of W3 were closely packed and aligned parallel to the fiber axis. The thicknesses of W2 and W3 were the same, about 500 nm. The highest packing density lay in the cuticle, which is the protective layer of the fiber, while the structures of W1 and W3 were more compact than that of W2. Fibrils were easily separated from the relatively loose IS, and dispersed in the lumen. Moreover, there was a transition layer of low-packing density between adjacent layers. The interactions between the fibrils in the transitional layers were weaker than those in the individual layers. The sizes of the smallest visible structural units were not the same for the different walls and the geometric scales were in the range between that of protofibrils and fibrils. The smallest fibril size was 3.2-5.0 nm, which is near the dimensions of the protofibrils of the cotton fiber. Some larger fibrils of different sizes were also observed in the different walls. [ABSTRACT FROM AUTHOR]