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15 June 2023, Volume 44 Issue 06

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Academic Salon Column for New Insight of Textile Science and Technology: Key Technologies of High Quality Aramid and Its Product Application

Research progress in color construction of high-performance fibers and its products

XIA Liangjun, CAO Genyang, LIU Xin, XU Weilin

Journal of Textile Research. 2023, 44(06):  1-9.  doi:10.13475/j.fzxb.20230200602

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Significance High-performance fibers are key materials for the development of national textile industry, which is related to the development of national economic and strategic security. For the purposes of aesthetic enhancement, functional flexibility, and feature identification, demands on color construction of high-performance fiber have become an important driving force for the development of the colorful society. The development of color construction technique ranges from the chemical coloration to structural coloration technology. Additionally, future high-performance fiber will be permeable for long-term multi-field development in the applications of advanced and sophisticated areas, which is indispensable part of social progress, and integrating color construction of high-performance fiber is an ideal way to realize highly flexible and adaptive. To clearly understand the development and applications of high-performance fibers, master the frontiers and development trends of dyeing methods, and break through the technical bottlenecks of the industry, this paper comprehensively reviewed the research progress in color construction of high-performance fibers and its products.
Progress The technical innovation and research status in color construction of the representative aramid fiber, carbon fiber, polyimide fiber, and ultra-high molecular weight polyethylene was focused. According to the structural characteristics, physical, and chemical properties of high-performance fibers, the aspects of fiber raw materials, molding processing, surface modification, and dyeing process are innovated, from which to implement color construction. Based on the development of chemical coloration methods including carrier dyeing, non-aqueous media solvents dyeing, dope dyeing, and structural coloration technology, maintaining the inherent high-performance characteristics is the building blocks of color construction process. The design of coloring method matching to the materials and structure effectively improves the dyeing property and dyeing fastness of high-performance fiber. However, significant limitation of promising coloring methods, which meets the social development concept, was demonstrated in industrial application.
For the aramid fiber, based on the pre-regulation of the molecular structure, the low temperature carrier dyeing has been carried out for bright color and high color fastness. However, the removal of residual carrier, the safe reuse, and reduction of the influence on the mechanical properties should be further investigated. Due to the high crystallinity, high chemical inertness, and strong light absorption characteristics of carbon fiber, the structural color methods have been extensively used to construct colored carbon fibers, while the influence of interface properties to color fastness is an urgent problem to be solved. The golden color of the polyimide fiber will also affect the further color construction. Presently, the color construction methods of polyimide fiber mainly include carrier dyeing and surface modification dyeing. Carrier dyeing of ketone carriers is effective to the color construction, which can significantly improve the color fastness of polyimide fibers. According to the physical and chemical structural properties of ultra-high molecular weight polyethylene fiber, the modification of dyes is a preponderant method for achieving color diversity.
Conclusion and Prospect High performance fiber refers to the chemical fiber with special physical and chemical structure, performance, and special function. As typical representative of high-performance fiber, carbon fiber, aramid fiber, polyimide fiber and ultra-high molecular weight polyethylene fiber are the four most widely used in aerospace, national defense science and technology, military engineering, construction industry, transportation, medical protection, civil industry, and electronic communications. However, the unicity of color limits its application to further expansion. Aiming at the problem of color construction, the methods including carrier dyeing, non-aqueous solvent dyeing, fiber surface modification dyeing, stock solution coloring, as well as physical structure color construction have been improved.
Based on the current color construction technology, the attention of development tendency in the future will be attracted on promoting energy-saving, low-carbon, green and environmental protection dyeing, strengthening clean, and safe production. Meanwhile, theoretical fundamental research on the color construction of high-performance fibers is necessary to further investigate. Combining the macromolecular chain, chemical structure, molding process, surface physical, and chemical properties to achieve theoretical breakthrough in the color construction, theoretical innovation, and theoretical guidance for the preparation of colored high-performance fibers will be promoted.
Additionally, to improve the dyeing depth and color fastness of fibers and reduce the structural damage in the color construction process of high-performance fibers, further attention should be paid to maintain the excellent structural stability. Therefore, in the development of color construction, balance the relationship between the color construction technology and high-performance fiber properties will promote the high-quality development and application expansion of high-performance fiber and its products. This paper summarized in the main the basic principles and research progress of the above-mentioned high-performance fibers, and also pointed out the main challenge and research direction of this research direction.

Research progress of aramid nanofiber aerogels

LÜ Jing, LIU Zengwei, CHENG Qingqing, ZHANG Xuetong

Journal of Textile Research. 2023, 44(06):  10-20.  doi:10.13475/j.fzxb.20230101602

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Significance Aerogels are synthetic solid nanomaterials formed by the replacement of liquid in a gel with gas. The continuous network structure renders aerogels with extraordinary properties, including ultralow density, super-high porosity, high specific surface area, low thermal conductivity, low optical refractive index and low dielectric constant. They have demonstrated tremendous potentials for various applications, such as thermal insulation, environmental protection and separation. However, in the development process of aerogels, there are still questions to be answered on development of new sol-gel transition principles and strategies, effectively control of macro morphology of aerogels, improvement of service performance, and expansion of the application field. As newly emerging aerogels, aramid aerogels utilized aramid nanofibers as building blocks have the potential to provide answers to the above-mentioned questions. In order to accelerate the development of aramid nanofiber aerogels from laboratory investigation to practical application and thus promote the development of the entire aerogel industry, the research status of aramid nanofiber aerogels are comprehensively reviewed in this paper.
Progress The building blocks of aramid nanofiber aerogels need to be obtained. So far, various methods have been developed to prepare aramid nanofibers, which can be classified into "top-down" and "bottom-up" methods. The rheological behavior of aramid nanofiber dispersion shows significant shear thinning behavior. In addition, the dynamic stress scanning test reveals that the aramid nanofiber dispersion shows elastic behavior in a certain stress range. These distinguishing features indicate that the aramid nanofiber dispersion can be processed through wet spinning, blade coating, 3D printing, and so on. Therefore, aramid aerogel fibers have been prepared via wet spinning or relevant spinning method, such as liquid crystal spinning. During the fabrication process, novel dynamic sol-gel transition principles was proposed. The as-prepared aramid aerogel fibers were shown to possess nano-porous network structure and inherit excellent physical and chemical properties of aramid materials, demonstrating ultra-low thermal conductivity and excellent mechanical properties. Besides, the aramid aerogel fibers were further functionalized to render them with unique functions, such as hydrophobicity, absorbability, and electric conductivity. These aramid aerogel fibers demonstrated wide potential applications in the textile field, which can be woven into thermal insulation fabrics and smart thermal regulation fabrics. In terms of aramid aerogel films, the fabrication process includes blade/spin coating, sol-gel transition, and special drying process. The typical aerogel structure was found to bring about aramid aerogel films with high specific surface area and low thermal conductivity. The post-processing and functionalization were shown to further improve their mechanical properties and electric conductivity. These aramid aerogel films have demonstrated great application prospects in separation and filtration, electromagnetic shielding, infrared stealth, thermal management, and so on. In addition, direct-ink-writing 3D printing and microgel-directed suspended 3D printing strategies were developed to fabricate 3D aramid aerogels. These printing technologies enable aramid aerogels with arbitrary shape realized. Thus, the mechanical or thermal insulation performances can be customized through simple structural design.
Conclusion and Prospect In view of the current urgent demand for high-performance aerogel materials, the research on aramid nanofiber aerogels will remain a research focus. By analyzing the research situation about the preparation, performance and application of aramid aerogel fibers, aramid aerogel films and 3D printed aramid aerogels, it can be confirmed that the development stage of aramid nanofiber aerogels is still in the initial exploration stage. On the one hand, the preparation technology of aramid nanofiber aerogel is not yet mature, and it needs to integrate deeply with traditional fiber, film or 3D printing technologies. There are many key points that need to be improved urgently, such as continuous solvent replacement, drying and other processes. The ultimate performances of aramid nanofiber aerogels have not been reached, and there is still room for improvement in mechanical properties. Therefore, it is necessary to further research on aramid nanofiber aerogels, optimize their preparation technologies, improve their performances, and reduce their production costs, so as to widen applications in thermal management, intelligent protection, separation, filtration and other fields.

Advances in design and fabrication of aramid fiber's surface and interface structure based on direct fluorination

LÜ Junwei, LUO Longbo, LIU Xiangyang

Journal of Textile Research. 2023, 44(06):  21-27.  doi:10.13475/j.fzxb.20230100402

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Significance Due to the advantages of low density, high strength, excellent environmental stability and wave-transparent of aramid fiber, it is gradually becoming the most important representative fiber in the high-performance organic fiber family. Among the wide range of applications of aramid fiber, the use as reinforcements in advanced composites might be the most important. However, poor interfacial interaction between aramid fiber and composite matrix has been a key issue to limit further mechanical improvements in composite design. Herein, direct fluorination using elemental fluorine or F₂/N₂ mixture to direct treat aramid fiber surface is efficient strategy to enhance composite interface. Utilizing the ultra-strong oxidation of F₂, direct fluorination could easily dope fluorine content groups with high polarity in a large scale to improve wettability between fiber and matrix, while post-purification is needed due to the characteristic of vapor-solid reaction. Besides, direct fluorination induced C—F bonds also have significant designability in derived grafting reactions for further well-performed composite interface. Therefore, direct fluorination exhibits huge potential in the future composite design and manufacturing.
Progress Advances of direct fluorination in enhancing composite interface could be divided into three stages: ① Direct fluorination induced high-polar fluorine-contained groups and extra oxygen species significantly improves the interfacial wettability between fiber and polymer matrix, where the optimized interfacial wettability would enhance the interfacial combination of the composite; ② C—F bonds not only have high polarity, but also exhibit flexible feasibility in deriving reactions like nucleophilic substitution and atom transfer radical polymerization, thus further grafting reaction could be realized on fluorinated aramid fiber surface to obtain better composite interfacial properties; ③ Direct fluorination with typical radical characteristic induces significant radical species in fluorinated aramid fiber, then the relevant polymerization with high grafting density could be restricted on fluorinated aramid surface and got much better composite interface. Therefore, direct fluorination exhibited flexible ability in designing numerous high-performance interfacial structures of composite product servicing in different environments.
Conclusion and Prospect In previous research work, it has been demonstrated that direct fluorination is a low-cost and industrially applicable fiber surface treatment technique that can significantly improve the surface properties of fibers and their interfacial bonding with the polymer matrix while maintaining the intrinsic excellent mechanical properties of the fibers, thus improving the mechanical properties of the interfacial phase in the composite. In fact, further development and application of direct fluorination technology in the design and construction of interfacial structures for fiber surface modification and its reinforced composites is still needed, which is expected to better solve potential scientific and technical problems in the development of the mechanics of fiber-reinforced composites and provide new methods for the modulation of fiber surface modification and its interfacial properties of composites. Three problems and trends in the research of direct fluorinated aramid surface modification and its composite interface are listed as follows: ① Due to the high chemical reaction activity of fluorine gas, the current principles and methods of its regulation are insufficient, how to more effectively regulate the fluorination reaction rate and the selectivity of fluorination reaction sites, as well as how to more effectively avoid the chain-breaking behavior of macromolecular chains are the focus of further research and development of direct fluorination technology; ② It is necessary to construct continuous gradient changing polar structures and their interfacial properties on the fiber surface through direct fluorination reactions and their derivative grafting reactions, so as to more accurately describe and establish the quantitative constitutive relationship between the physicochemical structure of the fiber surface and the fine mechanics of the composite interface; ③ More efficient methods and corresponding engineering equipment are in high demand for regulating the homogeneity of direct fluorinated fibers.

Preparation and properties of dyeable meta-aramid fiber

GUAN Zhenhong, LI Dan, SONG Jinling, LENG Xiangyang, SONG Xiquan

Journal of Textile Research. 2023, 44(06):  28-32.  doi:10.13475/j.fzxb.20221202201

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Objective The molecular chain structure of meta-aramid fiber is relatively regular, coupled with strong hydrogen bonding between the molecular chains, and it has excellent mechanical properties and comprehensive properties. Its disadvantages lie in its difficulty in dyeing due to its regular molecular structure, high crystallinity, high orientation and high glass transition temperature, which limits its further application. This research was carried out in order to improve the combination of meta-aramid fibers and dyes, improve their dyeing properties, and further expand the application of meta-aramid fibers in the field of post-dyeing.
Method This research uses solution polymerization method to add the form of the third monomer in the polymerization process, introduce easy-dyeing groups into the molecular structure of polyphthaloyl-m-phenylenediamine, adjust the number of easy-dyeing groups, and then adjust the molecular structure of the polymer to achieve the objective of easy dyeing.
Results In this paper, 4,4'-diaminophenyl sulfone (DDS) was selected as the third monomer, and the modified meta-aramid fiber was prepared by adjusting the content of sulfone group in the molecular chain. The results show that the dyeing property of modified meta-aramid fiber was significantly improved with the increased amount of DDS. When the molar ratio of m-phenylenediamine to DDS was set to 7∶3, the modified meta-aramid fiber maintained good mechanical properties, and the prepared modified meta-aramid fiber showed excellent dyeing property (Tab. 1). After that, the dyeing properties of modified meta-aramid fiber, conventional meta-aramid fiber and imported XJ easily dyed meta-aramid fiber products were analyzed. The K/S value of the modified meta-aramid fiber prepared in this research using Cationic Red FBL dye was 3.82, 1.39 higher than that of conventional meta-aramid fiber. The K/S value of Cationic Blue FGGL dye was 5.83, which is 2.74 higher than that of conventional meta-aramid fiber. The K/S value of modified meta-aramid fiber dyed with Disperse Red S-GS dye was 4.61, 2.44 higher than that of conventional meta-aramid fiber, and the K/S value of Disperse Blue S-GL dye dyeing was 1.45, 0.94 higher than that of conventional meta-aramid fiber (Tab. 3). The dyeing effect of modified meta-aramid fiber was significantly improved by using different dyes for dyeing analysis.
In order to further verify the dyeing effect of modified meta-aramid fiber, the modified meta-aramid fiber was spun and woven into a fabric. The mechanical properties, flame retardancy and color fastness after dyeing of the fabric were tested. Compared with conventional meta-aramid fiber, the mechanical properties and flame retardancy of modified meta-aramid fiber did not change significantly. The color fastness to dry and wet grinding and light fastness were improved by 1 level. From this point of view, sulfone group was introduced into the molecular structure of meta-aramid fiber, the combination of the fiber with cationic dyes and disperse dyes has been significantly improved, and thus achieves the objective of easy dyeing. After the fabric is woven, the post-dyeing is carried out. Compared with the imported easy-dyeing meta-aramid fiber products, the dyeing property is equivalent to the imported XJ easy-dyeing meta-aramid fiber, and its mechanical properties, color fastness and other aspects are better.
Conclusion An easy-dyeing meta-aramid fiber product with excellent comprehensive performance was successfully prepared.The research results are expected to be applied in the field of individual protection in the future, to protect people's lives and property. The development objective of easy-to-dye interposition aramid fiber products is to improve the production technology level of high-performance fiber in our country, and speed up the process of substitution of domestic interposition aramid fiber in various fields.

Fiber Materials

Preparation of SnO₂/polyvinylpyrrolidone anti-corrosive membrane and its application in flexible Al-air battery

SHI Haoqin, YU Ying, ZUO Yuxin, LIU Yisheng, ZUO Chuncheng

Journal of Textile Research. 2023, 44(06):  33-40.  doi:10.13475/j.fzxb.20220306901

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Objective With the update and iteration of material science and energy technology, the demand for portable wearable electronics is increasing. Therefore, flexible electronic energy storage equipment is particularly important. Flexible Al-air battery can be used as energy storage devices for wearable electronic products due to their excellent characteristics of flexibility and low cost. However, hydrogen evolution corrosion of metal anode of flexible Al-air battery is serious in alkaline environment, which results in uneven anode consumption and battery bulge, shortening battery life and reducing the corrosion of hydrogen evolution of anode.
Method In order to slow down the hydrogen evolution corrosion in the anode of flexible Al-air batteries, nano tin dioxide (SnO₂) and polyvinylpyrrolidone (PVP) were uniformly dispersed in absolute ethanol as the precursor solution, then the SnO₂/PVP membrane were prepared by electrospinning. The membrane-attached aluminum foils served as the anodes for Al-air batteries. SnO₂/PVP membrane were characterized and tested by X-ray diffraction(XRD), scanning electron microscope(SEM), contact angle, hydrogen evolution test, Tafel, EIS and battery performance test, and the effect of SnO₂content on corrosion inhibition rate and battery performance were also explored.
Results XRD and SEM showed that the SnO₂/PVP thin membrane had clear composition (Fig. 4), and SnO₂ nanoparticles were embedded into PVP fibers (Fig. 5). Through the self-made experimental device test, hydrogen evolution rate and hydrogen evolution amount of aluminum foil with functional membrane decreased significantly (Fig. 7). The hydrogen generation rate ratio of the two groups of experimental data with the largest difference reached 3 times. Then we tested the dynamic polarization curves of the potential of aluminum anodes attached with different membranes in 2 mol/L KOH solution, and obtained the corresponding corrosion current density (Tab. 1). When pure aluminum was used as anode, the corrosion current density was 0.29 mA/cm². With the mass fraction of SnO₂ increased to 40% and 50%, the corrosion current density decreased to 0.14 mA/cm² and 0.11 mA/cm², and the corrosion inhibition rate increased to 51.7% and 62.1%, respectively. The result is in good agreement with that of hydrogen evolution rate experiment. The battery performance test and the discharge curve is shown as follows: the discharge voltages of the three cells with the anti-corrosion membrane decreased slightly, but the discharge times of the cells with the 50% SnO₂/PVP membrane reached 168 min and 127 min respectively at the discharge densities of 3 mA/cm² and 5 mA/cm². Compared with pure aluminum anode aluminum-air battery (70 min and 53 min), the utilization rate of aluminum anode metal was increased by 140.0% and 139.6%, respectively. The specific capacity of the battery was positively correlated with the content of SnO₂ in the membrane. Although the anti-corrosion membrane improves the anti-corrosion performance and specific capacity, it sacrifices a certain power density (as indicated in Fig. 10). However, it can still be applied to low-power flexible electronic devices and expand the application of flexible batteries.
Conclusion SnO₂ nanoparticles are embedded into PVP fiber by electrospinning process, and aluminum foil is used as the receiving base to successfully prepare anti-corrosion membrane suitable for flexible Al-air batteries. A flexible Al-air battery was designed and manufactured, the SnO₂/PVP membrane had an obvious inhibition on the hydrogen evolution corrosion of the anode of Al-air battery, and the discharge time of the fabricated flexible battery increased with the increase of the mass percentage of SnO₂ (within a certain range). Under the action of anti-corrosion membrane, the battery power density decreased slightly, but the prepared flexible Al-air battery was still suitable for small power flexible electronic equipment, expanding the application of flexible batteries.

Design and electrochemical properties of porous and interconnected carbon nanofiber electrode

WANG He, WANG Hongjie, ZHAO Ziyi, ZHANG Xiaowan, SUN Ran, RUAN Fangtao

Journal of Textile Research. 2023, 44(06):  41-49.  doi:10.13475/j.fzxb.20220309901

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Objective Supercapacitors have shown good application potential in the field of energy storage and conversion due to their long span of life, environmental friendliness, higher security, fast charging and discharging capacity, and high power density, which attracted much research attention. As an important electrode material, the physical and chemical properties of carbon nanofibers affect the electrochemical performance of the electrode. However, the low specific surface area and porosity as well as the non-interconnected structure between fibers lead to the poor electrochemical performance of carbon nanofiber electrodes, which limits their development and application in supercapacitors. Therefore, it is imperative to design and develop good carbon nanofiber electrodes.
Method Porous and interconnected carbon nanofibers were prepared by electrospinning polyacrylonitrile (PAN) and high amylose starch (HAS) blends followed by pre-oxidation and carbonization. The cross-linking reaction between glutaraldehyde and starch was used to construct the interconnected structure of carbon nanofibers. Meanwhile, the thermal degradation of starch was used to create pore structures and increase specific surface areas of carbon nanofibers. During electrospinning, the voltage, distance, and extrusion speed were set as 20 kV, 15 cm, and 1.2 mL/h, respectively. The obtained nanofibers were pre-oxidized in a muffle furnace at 240 ℃ with a heating rate of 2 ℃/min for 2 h. The carbon nanofibers were prepared by carbonizing pre-oxidized nanofibers in a tubular furnace at 1 000 ℃ with a heating rate of 5 ℃/min for 2 h.
Results The addition of HAS and glutaraldehyde crosslinking had a great effect on the morphologies of nanofibers and carbon nanofibers. The prepared PAN/HAS nanofibers and carbon nanofibers had smaller diameters of 570 and 370 nm compared to the pure PAN nanofibers (910 nm) and carbon nanofibers (620 nm) (Fig. 1). After glutaraldehyde crosslinking, PAN/HAS-based carbon nanofibers had N and O co-doping with a high C content of 94.8% (Fig. 2). The presence of N and O elements as shown to improve the hydrophily and conductivity, and also to provide more active sites for carbon nanofibers. These characteristics played a positive role in improving the electrochemical performances of prepared carbon nanofiber electrodes. Moreover, the PAN/HAS-based carbon nanofibers with interconnected structures had better graphitized extents than non-interconnected carbon nanofibers (Fig. 3). The addition of HAS successfully increased the specific surface area, total pore volume, mesoporous volume, and microporous volume of carbon nanofibers, while the pore volume of carbon nanofibers crosslinked by glutaraldehyde was further increased. For carbon nanofiber electrodes, micropores were more conducive to the storage of ions, and mesopores were more conducive to the diffusion of ions. Their synergistic effect could improve the electrochemical performances of the electrodes (Fig. 4). The interconnected carbon nanofiber electrode had the best specific capacitances under cyclic voltammetry and galvanostatic charge-discharge measurements in a three-electrode system. At a scan rate of 10 mV/s, the specific capacitance was as high as 260 F/g, retaining 68% at a high scan rate of 200 mV/s (Fig. 5). The specific capacitance was as high as 255 F/g (1 A/g), retaining 71% at a high current density (20 A/g) (Fig. 6). In addition, after 10 000 charge and discharge cycles, the capacitance retention rate was as high as 99.8%, showing excellent cycle durability (Fig. 7).
Conclusion Porous and interconnected carbon nanofibers for supercapacitor electrodes were proposed by carbonizing electrospun PAN/HAS nanofibers. The fiber diameter, specific surface area, porosity, micro-meso pore content, and interconnected structure of PAN/HAS-based carbon nanofibers were tailored by glutaraldehyde crosslinking reaction. The prepared carbon nanofibers had nano-sized fiber diameter (370 nm), high C element content (94.8%), good graphitized extent, and also exhibited large specific surface area (647 m²/g), high total porous volume (0.60 cm³/g), high micropore content (67%), and small pore size (2.6 nm). These excellent physical and chemical properties could provide conditions for high-performance electrodes in supercapacitors. When interconnected PAN/HAS-based carbon nanofibers were used as active materials to prepare into electrodes, the electrode had a high specific capacitance about 255 F/g, a good rate capability about 71%, a low internal resistance about 0.64 Ω, and an excellent cycling stability about 99.8% after 10 000 charging and discharging cycles. The design of novel carbon nanofibers was expected to be widely applicable for the development of high-performance electrodes for energy storage field.

Effect of spinneret rate on structure and properties of nanofiber core-spun yarns prepared by continuous water bath electrospinning

ZHOU Xinru, FAN Mengjing, HU Chengye, HONG Jianhan, LIU Yongkun, HAN Xiao, ZHAO Xiaoman

Journal of Textile Research. 2023, 44(06):  50-56.  doi:10.13475/j.fzxb.20220402201

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Objective The spinneret rate as one of the electrostatic spinning parameters affects the performance of nanofiber core-spun yarns structure. This research aims to optimize the process parameters of electrospinning in order to meet the technical requirements for structure and properties of nanofiber core-spun yarns made from such made nanofibers.
Method A homemade electrostatic spinning device was set up for continuous preparation of nanofiber core-spun yarns. Through continuous double needle bath electrostatic spinning method, a core yarn was created using polyester (PET) as the core yarn, polyamide 6 (PA6) nanofibers as the coating layer, offering properties of the nanofibers and traditional yarn mechanical properties of nanofiber core-spun yarn. The morphology, crystal structure and mechanical properties of PET/PA6 nanofiber core-spun yarns were analyzed and characterized by scanning electron microscopy, differential scanning calorimetry and universal material testing machine. The influence of spinneret rate on the structure and properties of nanofiber core-spun yarns in double-needle water bath electrospinning was investigated.
Results By changing the spinneret rate in electrospinning process, the influence of different spinneret rates on the structure and properties of nanofiber core-spun yarn was analyzed. The results show that nanofibers could be formed on the surface of core yarn in the range of 0.10-0.40 mL/h spinneret rate, but the collection state and diameter of nanofibers were different. When the spinneret rate was greater than 0.10 mL/h, the adhesion phenomenon occurred between nanofibers due to the larger jet solution from the surface of Taylor cone. With the increase of spinneret rate, the diameter of nanofibers increased to a certain extent, and the porosity of PA6 nanofiber coating decreased because of the adhesion between nanofibers. In the range of 0.10-0.40 mL/h of spinneret rate, the crystallinity of nanofibers decreased with the increase of spinneret rate. When the spinneret rate is 0.10 mL/h and 0.15 mL/h, the crystallinity of nanofibers was within the range of conventional PA6 fiber crystallinity. The crystallinity of nanofibers was slightly less than that of conventional PA6 fibers. The reason was that the shape of Taylor cone was broken with higher spinneret rate, and the increasing instability of jet flow leads to the decrease of crystallinity. In the range of 0.10-0.40 mL/h spinneret rate, with the increase of spinneret rate, leading to the increase of breaking force. But the strength and elongation at break show a decreasing trend, which is consistent with the changing trend of crystallinity. The highest breaking strength was (0.66±0.13) cN/dtex at 0.10 mL/h, which was about 1/5 of that of conventional PA6 fiber. The breaking strength and elongation at break of nanofiber core-spun yarns were slightly higher than those of core-spun yarn, while the breaking strength of nanofiber core-spun yarns decreases with the increase of its linear density. Therefore, the combination with conventional fiber yarn is beneficial to improve its mechanical properties, and can give yarn high specific surface area, and expand the use of yarn.
Conclusion The prepared nanofiber cored yarn has a good cored structure according to the scanning electron microscope characterization of cross-section and surface morphology of nanofiber core-spun yarns. And the diameter of the coated nanofiber is 66-80 nm, and the porosity decreases with the increase of the spinneret rate. The crystallinity of nanofibers is in the range of 19%-24.15%, and decreases while spinneret rate increases. The strength and elongation at break of PA6 nanofiber coatings decrease with the increase of spinneret rate, and the strength of PA6 nanofiber coatings is about 1/5 of that of conventional polyamide 6 fibers. The nanofiber core-spun yarn maintains its mechanical properties such as strength and elongation at break. It is of great significance to study the influence of process parameters on the structure and performance of nanofiber core-spun yarns in the process of electrospinning, which can also bring thinking to researchers and provide reference for subsequent research and experiments.

Fabrication and properties of antibacterial polypropylene melt-blown nonwoven fabrics by reactive extrusion

CHEN Zhuo, DAI Junming, PAN Xiaodi, LI Mufang, LIU Ke, ZHAO Qinghua

Journal of Textile Research. 2023, 44(06):  57-65.  doi:10.13475/j.fzxb.20220103301

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Objective Because of the different biological structure of virus and bacteria, traditional antibacterial polypropylene melt-blown nonwoven fabric is difficult to have good killing effect on virus. Hypochlorite or chlorine-containing disinfectant that can release active chlorine has been reported to have excellent inactivation effect on bacteria and viruses. Therefore, the design of a polypropylene melt-blown nonwoven fabric was carried out to release active chlorine in order to effectively solve the problem of poor inactivity of air filter materials on viruses.
Method Modified polypropylene (PP) grafted methyl acrylamide (MAM) resin was prepared by using reactive extrusion process to graft the halogen amine precursor onto the PP molecular chain through a free radical initiator, before the PP-g-MAM resin was added to the melt-blowing machine. The PP-g-MAM melt-blown nonwoven fabric for chlorination and re-electret was fabricated, in order to obtain polypropylene melt-blown nonwoven fabric with high efficiency filtration and sterilization and antiviral function. Scanning electron microscope was used to characterize the average diameter of PP-g-MAM melt-blown nonwoven fibers and the fiber diameter distribution.
Results The average diameter of PP-g-MAM melt-blown nonwoven fibers is 7.24 μm, and the fiber diameter distribution is concentrated in 1-3 μm (Fig. 7). Compared with the pure PP resin, two new characteristic peaks appeared in the wavelength range of 1 700-1 500 cm^-1 for the purified PP-g-MAM resin, corresponding to the C=O bond stretching vibration peak of 1 668 cm^-1 and the N—H bond bending vibration peak of 1 600 cm^-1 (Fig. 4). The grafting efficiency and grafting rate of MAM was 43.02% and 1.01% by organic element content detection. In the thermal weight loss behavior, the thermogravimetric (TG) curves of PP resin and PP-g-MAM resin almost coincided, and so did the differential thermogravimetric (DTG) curves (Fig. 5), where the initial and termination decomposition temperatures of PP-g-MAM resin were 427.9 and 469.2 ℃, respectively. In terms of mechanical properties, the tensile stress at break of PP-g-MAM melt-blown nonwoven fabric is between 1.14-1.19 MPa, and the elongation at break is about 70% (Fig. 6). The filtration effect of PP-g-MAM melt-blown nonwoven fabric on 0.3 μm particles is 98.6% (Fig. 8). After chlorination, the filtration effect decreases by 4%-14%, and the longer the chlorination time, the more the filtration performance decreases. After chlorination re-electret, the filtration performance of PP-g-MAM melt-blown nonwoven fabric is restored to more than 98%. The pore size of PP-g-MAM melt-blown nonwoven fabric has a certain increase compared with PP melt-blown nonwoven fabric(Fig. 9). In the chlorination process, PP-g-MAM melt-blown nonwoven fabrics chlorinated in acidic environment have more active chlorine content, and the longer the chlorination time, the higher the active chlorine content(Fig. 10). Under the condition of chlorinated solution pH value of 5 and chlorination time of 15 min, the content of active chlorine in chlorinated PP-g-MAM melt-blown nonwoven fabric is 0.038%. The antibacterial rate of chlorinated PP-g-MAM melt-blown nonwoven fabric against Escherichia coli and Staphylococcus aureus was more than 98% (Fig. 12), and the antibacterial rate against Escherichia coli was more than 99% under the contact time of 20 min (Fig. 13).
Conclusion MAM was successfully grafted into the polypropylene molecular chain. However, PP-g-MAM melt-blown materials and PP melt-blown materials have little difference in performance, so the grafting of MAM has little effect on the heat resistance, mechanical properties and fiber morphology of PP melt-blown materials. Due to chlorinated solution immersion reasons, PP-g-MAM electret melt-blown nonwoven fabric electrostatic charge is lost with the solution, which leads to significant decrease in the chlorination of nonwoven fabric filtration performance, and in the electret again, nonwoven fabric filtration performance restored to the level before chlorination. In the chlorination process, the acidic condition of chlorinated solution is more likely to improve the content of active chlorine in PP-g-MAM melt-blown nonwoven fabrics, which may be due to the high content of hypochlorous acid in the acidic environment solution, which is easier to transform the halo amine precursor, and the longer the chlorination time, the more the grafted halo amine precursor is transformed. Chlorinated PP-g-MAM melt-blown nonwoven fabrics can effectively kill Escherichia coli and Staphylococcus aureus.

Textile Engineering

Holding force of non-absorbable barbed sutures and its influencing factors

CHENG Yue, ZUO Han, AN Qi, LI Dawei, ZHANG Wei, FU Yijun

Journal of Textile Research. 2023, 44(06):  66-71.  doi:10.13475/j.fzxb.20210907201

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Objective The holding force of non-absorbable barbed sutures is a very important index, but its influencing factors have not been systematically studied. Therefore, this work was carried out to explore the influence of needle shape and linear structure on the holding force of non-absorbable barbed sutures.
Method Six kinds of barbed sutures with different needle types and linear structures were prepared and tested via bending model on silica gel artificial skin tissue. The micromorphology of different specimens before and after the holding force test was observed by microscope. Besides, chemical composition and tensile performances of different specimens were tested and analyzed.
Results After the holding force test, silica gel residue can be observed at the roots of the two barbed sutures (Fig. 4), indicating that the barb has a certain ability to hold the silica gel artificial skin tissue. Fourier transform infrared spectroscopy (FT-IR) results illustrated that the chemical structures of sutures A1 and B were both non-absorbable polyamide sutures (Fig. 5). Tensile performances of A1 and B sutures were compared, and there is no significant difference in strength between the two, but suture B showed a better breaking elongation (19.42±2.67)% and flexibility (Tab. 3). Finally, the holding force of the six barbed sutures was tested via bending model on silica gel artificial skin tissue and the influence of barb and needle structure on holding force was analyzed (Fig. 7). The external expansion angle of suture A1 and B were (15.13±2.08)° and (16.32±1.01)°, the cut depth of suture A1 and B were (0.091±0.018) mm and (0.114±0.041) mm. The two parameters of suture 6 were greater than that of suture 1, which is beneficial to improve the holding area of barb to surrounding artificial skin tissue. In addition, the cut distance of suture B was (0.865±0.016) mm, less than that of suture A1, which was (0.982±0.018) mm, indicating a higher barb density for suture B. The influence of needle structure on holding force was further divided into needle shape, chord length, radian and curvature. Results show that the holding force of sutures A1 to A5 were (3.86±0.38) N, (3.95±0.50) N, (5.71±0.62) N, (8.00±1.20) N and (4.56±0.34) N, respectively. Under the same conditions, the holding force of round needle barbed suture A2 and A4 was higher than that of triangular needle barbed suture A1 and A3, respectively. The chord length of suture A3 and A4 are longer than that of suture A1 and A2. The larger the chord length of the suture needle, the greater the holding force of the barbed suture. The radian of needle in suture A5 is smaller than that in suture A3, the holding force of barbed suture produced by small needle was lower than that produced by large radian needle. The curvature of needle in suture A5 is smaller than that in suture A1, the smaller the curvature of the needle, the greater the holding force generated by the corresponding barbed suture.
Conclusion Holding force of six kinds of non-absorbable barbed sutures were tested via bending model on silica gel artificial skin tissue. Under the same conditions, appropriately increasing the external expansion angle or cut depth, reducing the cut distance of the suture can improve the holding force of barbed sutures. The specification and structure of needle also have a certain effect on the holding force of barbed sutures. Under the same conditions, the holding force of round needle barbed suture is greater than that of triangular needle barbed suture. With the same radian, the larger the chord length of needle, the greater the holding force of barbed suture. With the same curvature, the larger the radian length, that is, the longer the chord length and needle length, the higher the holding force of barbed suture. With the same needle length, appropriate reduction of the curvature of needle can increase the holding force of barbed suture.

Measurement of yarn tension in axial direction based on transverse vibration frequency

LI Yang, PENG Laihu, LIU Jianting, HU Xudong, ZHENG Qiuyang

Journal of Textile Research. 2023, 44(06):  72-77.  doi:10.13475/j.fzxb.20220203101

Abstract ( 92 )   HTML ( 4 )   PDF (5232KB) ( 17 )   Save

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Objective In the process of textile production, constant yarn tension is essential to ensure product quality, and excessive tension during yarn transmission will cause sudden stress change or even yarn breakage and will affect fabric formation, resulting in inelastic fabric structure and seriously affecting the quality of products. In order to detect yarn tension efficiently and conveniently, a method based on transverse vibration frequency non-contact detection of yarn tension is developed.
Method The transverse vibration characteristics of a moving yarn were studied by combining theoretical modeling, numerical analysis and experimental verification. The equation of yarn transverse vibration was derived based on chord vibration theory, and the yarn vibration frequency was obtained. The yarn tension was further calculated according to the relationship between frequency and tension. A yarn tension measurement method based on transverse vibration frequency measurement was proposed, and an open structure yarn transmission experimental platform was designed and built for experimental verification. The measured values were fitted to the generalized regression neural network model.
Results When the linear density is constant, the yarn vibration frequency increases with the increasing velocity; the greater the linear density, the smaller the yarn vibration frequency. First, the geometric parameters of the moving yarn are determined, and the fitting formula among the yarn motion speed, vibration frequency and tension is established. Then, the yarn vibration frequency and velocity data were obtained experimentally, and the vibration frequency and motion velocity were substituted into the fitting formula to obtain the yarn tension. Finally, the calculated yarn tension was fitted using the GRNN model to obtain the final tension results. The data generalized regression neural network fitting curve using the vibration frequency for measuring the yarn tension is on the same overall trend as the tension trend measured by the tension sensor(Fig. 5 and Fig. 6). In the actual working state, the yarn vibration frequency will be disturbed by other external factors such as machine vibration, and the yarn tension measured by the vibration frequency will also produce large fluctuations, so that the measurement results show a dispersed state is not conducive to the real-time control of the tension. Due to the uncertainty of the geometric parameters of the yarn, the error of the fitting formula, and the accuracy of the vibration frequency obtained by the high-speed camera, there are some errors in measuring the yarn tension based on the vibration. However, the measurement accuracy of the method can also be further improved, such as using a more accurate signal processing technology to process the vibration displacement signal. At the same time, although this method can effectively measure the yarn tension, but still has a certain application range. As the velocity increases, the system vibration frequency gradually decreases and disappears at the critical velocity. Therefore, in order to detect the vibration frequency of the system vibration, the yarn movement speed is less than the critical speed of the instability.
Conclusion The yarn vibration equation of the string vibration theory is established, and then the yarn vibration frequency is calculated by the fitting formula between the yarn tension, motion speed and vibration frequency; then the result is fitted through the generalized regression neural network model. The accuracy and reliability of the measurement of the yarn tension and the fitting algorithm are verified. At the same time, the influence of yarn density and motion speed on vibration frequency is also considered, and it has strong applicability for yarn with different line density and different motion speed.

Design and application of equal float length on full-color weave in triple-weft jacquard fabric structures

ZHOU Jiu, HU Yili

Journal of Textile Research. 2023, 44(06):  78-84.  doi:10.13475/j.fzxb.20220103501

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Objective The triple-weft combined full-color structure fabric is based on the hierarchical combination design mode, and the color rendering effect of the weave on the surface of the jacquard fabric is demonstrated by the structure color rendering mode of three sets of weft juxtaposition. However, in the design process of the combination structure, the technical problem that the warp float length cannot be controlled after the combination will result in unclear outline of the weave patterns, which affects the color rendering effect of the weave of the combination full-display structure. In order to solve the technical problem of the uncontrollable warp float length of the full-color weave in the triple-weft jacquard fabric structure on the basis of satisfying rich colors, this paper proposed the design principle and design method of the full-color weave in the triple-weft jacquard fabric structure with equal floating.
Method The triple-weft combined full-display structure was taken as an example, where the technical characteristics and structural characteristics of the three-weft combined full-display structure were analyzed in depth, and the technical factors affecting the warp floating length of the combined full-display structure were optimized. In the 1∶1∶1 design process of three-weft combination full-display structure, the optimization formula of cycle number of basic weave with equal length of warp float length was formed, and the methods for designing the starting point position, for optimizing of step-number of weaves and their combination were established, and a design method for triple-weft combination full-display structure was put forward, to facilitate the effective control of the longest warp float length in the combination structure. Finally, the combined basic structure with uniform distribution of weave points was selected to construct the combined full-display weave library for design practice to verify the feasibility of the combined full-display structure with equal float length.
Results This optimization design method can not only satisfy the effect of the colorful halo pattern of the combined jacquard fabric, but also effectively control the warp float length of the combined structure. The color transition of the fabric obtained from the sample followed the principle of color rendering weft space collocation mixed color rendering. The fabric surface warp structure was closely interwoven, the yarns are arranged neatly and uniformly, the warp float length was effectively controlled, and the ratio of each float length was made equal in a single cycle, the longest warp float length is R-1(R is number of weave repeat). At the same time, combined full-display structure and equal warp floating length structure had clear junction and did not interfere with each other in the application process. By comparing the full-display structure effect drawing of the combination of long warp and float length with the organization structure drawing, the surface effect of the fabric was rough, float length was messy, and slip was obvious. The results could be used to standardize the digital design technology of jacquard fabric, and provide reference for the optimal design of digital jacquard fabric.
Conclusion Based on the analysis of the technical characteristics of the triple-weft combination full-display structure, a design principle and method of controlling the longest warp float length in the triple-weft combination full-display structure is proposed in this paper, which is the technical scheme for achieving equal warp float length in the triple-weft combination full display structure. ① After the three groups of basic tissues were combined in the latitudinal direction of 1∶1∶1, the ratio of warp float length of the combined basic tissues was equal, the longest warp float length was R-1, and the number of tissue cycles met the requirement of R=3n+1 or R=3n-1, where n was a positive integer, which was the applicable condition for realizing the equal warp float length. ② The design practice verifies that the fabric with three weft equal warp float length combined full-display structure can satisfy the color rendering effect of full-display jacquard fabric and effectively control the warp float length of the combined fabric, so that the fabric is tightly interwoven and the float length is unified. The design principle and method proposed in this paper is aimed at the design optimization of triple-weft combination full-display structure, which can not only meet the technical requirements of mass production of jacquard fabric, but also provide ideas for the intelligent design of digital jacquard fabric.

Design and three-dimensional simulation of multi-color striped fabrics

ZHENG Peixiao, JIANG Gaoming, CONG Honglian, LI Bingxian

Journal of Textile Research. 2023, 44(06):  85-90.  doi:10.13475/j.fzxb.20220100101

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Objective Multi-color striped fabrics are one of the important fashion elements in knitwear design. The development of the knitwear fashion trend reveals that fabrics with a small number of colors can no longer meet the needs of consumers. How to carry out a reasonable and feasible secondary innovative design based on multi-color striped fabrics to replace the original monotonous stripes is the challenge to the majority of designers. In this process, it is also a big problem to predict the feasibility of knitting and the color effect of multi-color striped fabrics.
Method To quickly generate a feasible design scheme and three-dimensional (3-D) simulation for multi-color striped fabrics, the pattern design models were constructed and the colored-yarn knitting sequence model was generated according to the knitting principle and characteristics of the striping circular weft knitting machine. The types of colored yarn knitted by each knitting system were calculated and the yarn guiding model was generated. According to the yarn arrangement principle, the yarn threading model was established. The loop geometry and translation mapping models were constructed, and the 3-D simulation method of multi-color striped fabrics was explored with coordinate translation mapping.
Results The design and simulation of eleven-color gradient striped fabric were taken as an example to verify the knitting feasibility for pattern and threading design on the four-color striping circular machine. The fabric design and 3-D simulation process were used to verify the feasibility of the study method (Fig. 2). The pattern model (P) and knitting model (K) were generated according to the pattern design, and the color sequence was reordered from large to small in proportion to produce colored yarn knitting sequence model (Y) (Fig. 3). According to the parameters of the knitting machine and the above pattern model, guiding instructions of yarns were assigned to the guiding devices in each knitting system to obtain guiding model (G) (Fig. 4). Based on the yarn guiding model, the codes of colored yarns in each knitting system were arranged in the yarn threading model(T). Only the number 1 to 4 thread adjusting fingers were arranged in the yarn threading model, enabling patterns of eleven-color striped fabric to be knitted normally on the four-color striping circular machine (Fig. 5). The results of the design model show that the proposed method can effectively predict the knittability of multi-color striped fabrics on the striping machine. For 3-D simulation, the coordinate model of the loop control point (L) was established. The relative position of each loop in the fabric coordinate system was achieved based on the knitting model, hence obtaining the loop translation model (t). Finally, the new spatial coordinate of each loop control point (L') at different positions was calculated. With the help of the Three.js tool, the 3-D simulation of the multi-color gradient striped fabric was achieved (Fig. 6(b)). The results show that the simulation method can visually and clearly display the color effect of multi-color striped fabrics (Fig. 6(a)), and the simulated color effect is regarded as satisfactory.
Conclusion A scientific and effective method for yarn threading design, knittability test and 3-D simulation of multi-color striped fabrics is explored. It is proved by practice that the pattern and threading design model can effectively verify the pattern knittability, so as to guide the fabric design and production. The proposed translation mapping method can effectively reduce the amount of data calculation and improve the running speed of simulation, so as to establish the 3-D simulation of fabric and predict the beauty of color quickly. This method can be applied to the design and 3-D simulation of four-color, six-color, and other multi-color striped fabrics with jacquard. It not only can automatically generate the design scheme according to the pattern, predict the knittability and aesthetics of the machine, but it can also accurately locate the wrong position in the design scheme and generate optimization suggestions, which helps improve the design production efficiency and reduce the waste of raw materials from the root.

Shape memory alloy composite yarn and its fabric actuation performance

FU Chiyu, XU Ao, QI Shuo, WANG Kai, MIAO Ying, SHANG Lulu, XIA Zhigang

Journal of Textile Research. 2023, 44(06):  91-97.  doi:10.13475/j.fzxb.20220407401

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Objective Artificial muscles have shown great importance in the development of wearable devices, exoskeletons, prosthetics and robotics in recent years. Although many artificial muscles based on the novel actuation technologies have been reported, challenges such as single actuation form, complex processing and limited flexibility remain to be addressed. Textile-based artificial muscles exhibit high flexible and light weight properties, but the actuation performance still needs to be enhanced. In order to investigate and develop textile-based artificial muscles with high-performance, it is highly desirable to combine the active materials with textiles.
Method A thermally driven composite yarn actuator with Ni-Ti alloy as the core and polyimide (PI) fiber as the sheath was designed. Specifically, the Ni-Ti alloy filaments were covered by the PI fiber on a friction machine. Due to the good thermal stability of the PI fibers and excellent thermal actuate performance of Ni-Ti alloy filaments, the fabricated yarns can respond to the heat. In addition, thanks to the good conductivity of the alloy filaments the fabricated yarn and fabric are able to be actuated by the electrothermal.
Results A shape-programmable woven fabric actuator was successfully prepared using the composite yarn, the mechanical properties and thermally driven characteristics of the composite yarn and its fabric were initially explored. The results showed that the composite yarns exhibit a hierarchical structure with PI fiber uniformly covering the shape memory alloy filament, which greatly enhanced the wearability of the fabrics. The phase transition temperature of the shape memory alloy was determined by differential scanning calorimetry (DSC) analysis. The mechanical performance test results showed that as the temperature increases, the shape memory alloy filament transformed from the martensitic phase to the austenitic phase, leading to an increase in the modulus of the filament. The obtained yarns showed excellent electrical and thermal properties with temperature up to 35 ℃ under 2.5 V. In addition, the composite yarn can remain a stable temperature, which demonstrates the potential to be applied at low voltage and ability of regulating the temperature by various applied voltages and currents. The results of electrical and thermal driving tests showed that the yarn exhibits good electrical heating and thermal stability, and the higher the loaded current and voltage, the higher the yarn temperature and the shorter the time to reach the steady state. The thermal induced actuation test results show that the composite yarn and its fabric will recover to the initial linear state after being thermally driven. The yarn can be actuated within 6.2 s under 5 V and the angle returned to 135° in 3.4 s, indicating the fast actuation characteristic of the composite yarn. In addition, the high temperature resistant and shape programmable composite fabric actuator prepared by woven interval weft method enables different shape actuation. Due to the programmable properties of memory alloys, fabrics that have been annealed at high temperatures are able to exhibit different actuation movements.
Conclusion In this work, a shape memory alloy-based composite yarn was designed. The yarn was fabricated by covering the PI fiber on the shape memory alloy filament via a friction spinning machine. A shape programmable fabric actuator was fabricated by weaving technique. The mechanical properties and thermal actuation characteristics of the composite yarn and fabric were systematically investigated. Through the test results, the following conclusions are obtained: ① The higher the temperature, the higher the reversion stress of the shape memory composite yarn. ② The shape memory composite yarn has good electrical heating and thermal stability performance. ③ The prepared composite yarn has good electric heating performance. The actuating action can be completed within 6.2 s at 5 V. ④ The composite fabric actuator with high temperature resistance and shape programmable was prepared by weaving method. The fabric was shape-programmed to achieve different actuation motions. The shape-memory composite yarn and fabric can be applied in the fields of smart wearable devices and medical rehabilitation.

Establishment and realization of technological model for weft-knitted two-side transfer fabrics

ZHANG Jing, CONG Honglian, JIANG Gaoming

Journal of Textile Research. 2023, 44(06):  98-104.  doi:10.13475/j.fzxb.20220105701

Abstract ( 117 )   HTML ( 6 )   PDF (3670KB) ( 29 )   Save

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Objective Weft-knitted two-side transfer fabrics are regarded as complicated in technology and difficult in design. In order to achieve rapid design of weft-knitted two-side transfer fabrics, this paper studies and develops the weft-knitted two-side transfer fabric design system aiming to tackle the complicated design of weft-knitted two-side transfer fabrics.
Method The structure forming principle of weft-knitted two-side transfer fabric was analyzed, and the process design model of weft-knitted two-side transfer fabrics was established. The mathematical relationship between transfer pattern and process structure was described by using mathematical matrix and multi-dimensional process decomposition method. The multi-dimensional technological decomposition of the pattern effect was achieved on a graph, and the three-dimensional mathematical matrix was used to represent the artistic information for pattern grid and knitting pattern grid to assist the structural decomposition and the knit process. The pattern design process was simplified by means of algorithm and primitive mapping.
Results The schematic diagram of the established process design model was shown in the weft-knitted two-side transfer fabric with two jacquard and two loop shifting (Fig. 1). The process design model of the weft-knitted two-side transfer fabric involves multi-dimensional information. The pattern effect picture was divided into the front pattern and the reverse pattern and the two sides of the fabric were divided into the front and the reverse pattern. The three-dimensional matrix was used to describe the information. The color information in the cell was stored as the corresponding three-dimensional data. The fabric pattern was woven by A/B yarn system and two loop shifting systems, and the knitting design of yarn A, yarn B, needle cylinder loop shifting and needle disk loop shifting were established respectively. The corresponding color, position information c_k, t_k, flower width w, flower height h, and process flower height H were obtained. The structural break represented the breakdown information defining the color of the knitting intention diagram corresponding to the knitting action, and converted it into the process knitting diagram, specifically and intuitively expressing the knitting state of the yarn. Based on HTML5, ASP.NET framework, JavaScript and C# language, a process design system for weft-knitted two-side transfer fabrics was developed. The functions of the four modules in this paper were mainly achieved through organization filling and entity mapping. The organization filling process was to obtain the corresponding parameters through the user's drawing of the pattern design and knitting design. In the process knitting diagram, the left vertex was used as the reference point to fill the structure breakdown diagram from left to right and from top to bottom. Canvas's double-buffer technology was applied when drawing the process knitting diagram. The drawn elements were pasted on the canvas one by one based on the left vertex. The schematic diagram was shown in the design and development interface of weft-knitted two-side transfer fabric (Fig. 7).
Conclusion The product design method for weft-knitted two-sided transfer fabric is standardized and the process design process for weft-knitted two-sided transfer fabric is simplified. It has been proven that the design model can accurately describe the pattern and weave information, and can guide the process design of weft-knitted two-sided thansfer fabric. Based on the proposed system module, the design of the weft-knitted two-sided thansfer fabric design system has been completed from the design of the pattern intention to the realisation of the process weaving diagram, and it has been verified that the method can be applied to the process design of weft-knitted two-sided thansfer fabric. The problem of unstable speed and compatibility of the weft-knitted weft-knitted two-sided thansfer fabric design system due to the variability of the existing weft-knitted weft-knitted two-sided thansfer fabric design is solved, and the rapid and efficient development of weft-knitted weft-knitted two-sided thansfer fabric is achieved.

Weaving process modeling and micro-geometry prediction of three-dimensional orthogonal woven fabrics

MA Ying, XIANG Weihong, ZHAO Yang, DENG Congying, LU Sheng, ZENG Xianjun

Journal of Textile Research. 2023, 44(06):  105-113.  doi:10.13475/j.fzxb.20210403501

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Objective Fiber-reinforced polymer composites comprise aligned, random, or woven fibers in polymeric matrix. The commonly used woven fabric-reinforced composites made of high-performance fibers are frequently used in applications that require durability in aggressive environments. To achieve deep-level exploitation for engineering applications, modelling of the fabric's microgeometry and the mechanical response is crucial. However, research to characterize these microstructures highly depends on its microscope images and assumes constant yarn cross-sectional shape, which is not the case for most woven fabric types. Since the fiber architecture of woven fabrics has a profound effect on their mechanical properties, a dynamic simulator capable of modelling fabric weaving process considering textile mechanics is necessary.
Method A dynamic textile weaving simulator was established to link weaving actions to fabric patterns and microstructures. Digital element approach (DEA) was implemented under the framework of the software package digital fabric and mechanics analyzer (DFMA). This method established the geometrical model of the key components of a loom. Yarn interlacing motion was guided by weaving matrix specified by steps. Shedding, weft insertion, beat-up, let-off motion, and take-up actions are modelled. The inter-fiber contact force, fiber forces (tensile, shear, and bending), and boundary conditions in weft direction are considered utilizing the central difference algorithm. The weaving process of four unit-cells in the warp direction of a 10-layer three-dimensional orthogonal woven fabric was explicitly modelled at filament-level to derive for its microgeometry.
Results It took 160 steps in total to complete the process, each cell takes 40 steps to weave. During each step, heddles lift or lower the connected warp or binder yarn to form a space between the fell and heddle. Then, the shuttle moves across the encircled space and layers on weft yarn followed by the beat-up motion. The results show that the micro-geometry of the unit-cell is affected by neighboring cells and subjected to change during the weaving process. Take cell two as an example. In step 80, the right edge of the weft yarns was lined up with the reed at the fell, leaving an empty triangular region encircled by binder yarns. After weaving cell three (step 120), the empty space had disappeared and was filled with filaments, causing a reduction in cell thickness and width. The microstructure of cell two ceases to change at approximately step 160 or beyond. The thickness and length of cell two decrease and its microstructures converge with further weaving steps. During yarn-interlacing and shedding motion, the microstructure of the weft yarns next to the fell changes drastically. When some of the warp yarns are raised and the rest are lowered, the fabric next to the fell rips open between the warp yarns in the up and down positions. A V-shaped passage much larger than the yarn cross-sectional area was formed, causing filaments inside the passage to scatter in random directions in an extremely loose state. These filaments were disrupted again by the beating motion before deforming back into a racetrack cross-sectional shape. When the weft yarns on top were pushed to the fell, the filaments circled by warp yarns and the fell bundled up tightly together to form a triangular cross-sectional shape. It changes into a semi-lenticular shape as the weaving process continues. The microstructure, thickness, crimp angle, and cell width of cell two are measured and compared to the actual specimen. The discrepancies are 1.37%, 0.75% and 0.39%, respectively.
Conclusion A dynamic textile weaving simulator which explicitly models shedding, weft insertion, beat-up, let-off motion, and take-up actions was established. This method fully models loom kinetics and kinematics and is capable of generating multiple cells in consecutive. The weaving process of a 10-layer three-dimensional orthogonal woven fabric was successfully modelled step-by-step at the filament level. Four cells in warp direction were produced. The simulation process reveals the revolution of weft yarn microstructure during shedding and beating motion and therefore concluded that the fabric microgeometry changes during weaving. It takes approximately 80 steps (the number of steps to produce two cells in the lengthwise direction in this case) for the microstructure of a newly woven cell to converge. The stress, as well as the cross-sectional shape of weft yarns are approximately symmetrical from top to bottom. The cross sections of the second cell in the warp direction closely match the microscopy images and accurately capture the main characteristics of the fabric, as regard to the fabric thickness, yarn crimp, yarn path, and cross-sectional shapes. This work provides a reliable method for weaving process study and the findings give valuable insights into fabric design and manufacture instruction.

Measurement of infrared emissivity and photothermal absorption rate of fabrics with dual photothermal radiation sources

ZHANG Yue, CHEN Yisong, BIAN Yuyao, LIU Yi

Journal of Textile Research. 2023, 44(06):  114-120.  doi:10.13475/j.fzxb.20220104801

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Objective The infrared emissivity and photothermal absorption rate of fabrics are two important indexes related to the thermal comfort and protection performance of clothing. To study these two characteristics of fabrics, this research aims to explore the infrared emissivity and photothermal absorption rate of fabrics under different photothermal radiation sources through the test device designed according to the new measurement principle, which provides a theoretical basis for the selection of photothermal radiation sources.
Method High reflectance KT board was used in the test device and unidirectional insulation was realized, which eliminated the influence of fabric transmission and solved the real temperature measurement of fabric. During the experiment, the surface real temperature and radiant temperature of 20 fabric samples with different composition, color and structure as well as black copper plate were measured by iodine tungsten lamp and xenon lamp with two color temperatures. The convective heat dissipation coefficients of the reference black body and fabric surface were determined, and the average infrared emissivity and average photothermal absorption rate of fabrics were calculated.
Results Under the radiation of iodine tungsten lamp and xenon lamp, the infrared emissivity of fabrics were found to be in ranges of 0.65-0.85 and 0.60-0.95 respectively, and the photothermal absorptivity of fabrics were in 35%-60% and 30%-90% respectively. The infrared emissivity of the same sample under these two radiation conditions had a certain difference, but both standard deviations were 0.06, with CV values of 7.40% and 12.55%, respectively. It might be that the groups in the fabric dyes could respond to the infrared band, so that the results under different light sources were different. On the other hand, the spectrum of the iodine tungsten lamp coincided with the infrared emission spectrum of fabrics at 8-14 μm by 5%, resulting in a certain interference effect fabric reflection on the measurement of radiation temperature in the iodine tungsten lamp spectrum. The xenon lamp spectrum had no overlap with the measuring window of 8-14 μm, and fabrics had no effect on its reflection. As the proportion of visible light in xenon lamp was greatly improved compared with that in iodized tungsten lamp, the data gap between white fabric and black fabric expanded from 15% to about 60%, which fully reflected the absorption and reflection of sunlight by the color of fabrics. In addition, the test results under both light sources showed that the thickness and gram weight of the fabric had no significant correlation with infrared emissivity (P>0.05), while the fabric type had significant correlation with infrared emissivity (P>0.05). The order of infrared emissivity from high to low was wool, cotton, polyester. The gram weight and type of fabric were not significantly correlated with the photothermal absorption rate (P>0.05), while fabric thickness was low correlation with the photothermal absorption rate (P<0.05, |r|=0.50).
Conclusion The infrared emissivity of fabrics has a certain dependence while the photothermal absorption rate of fabrics has a strong dependence on the color temperature of the light source, which is mainly because the color of the fabric has a strong reflection of the visible wavelength. Because the spectrum of the iodine tungsten lamp overlapped with the measuring band of the infrared temperature sensor, the reflection of the fabric interferes to some extent, and there will be errors in the measurement results. However, xenon lamp has no interference of spectral overlap, so its measurement results are more accurate and it is more suitable as the photothermal radiation source for the test.

Numerical simulation for selecting laser parameters in marking process with different fabrics

LIAN Liping, YANG Pengcheng, YU Zijian, LONG Yangzhao, XIAO Yuan

Journal of Textile Research. 2023, 44(06):  121-128.  doi:10.13475/j.fzxb.20211106001

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Objective Laser marking, which has the advantages of being durable, waterproof and non-contact, is an effective method for recording commodity data and decorating textile products. In the marking process, the laser speed and energy density directly affect the marking effect. The laser energy density and movement speed often show different effects on the fabric substrates owing to the optical and thermal properties. This research aim to optimize the laser marking parameters for the best marking result.
Method To solve this issue, three fabric substrates of cotton, polyester and polypropylene are selected in this research, the ablation process of laser marking fabric surface and the selection principles of process parameters were investigated based on both simulation modeling and experimental analysis. First, the phase change heat transfer models between the laser and different fabric substrates were established. Subsequently, changes in temperature field and material removal during marking were numerically simulated. Finally, the effects of marking process parameters on the marking results were analyzed by thermal diffusion theory in simulation experiments and actual experiments.
Results The simulation results show that the required laser energy density of the three fabric substrates had a linear relationship with the average heating rate and marking depth, and the required moving speed was positively related to the average heating rate. Moreover, the average heating rate of fabric substrates decreased with the increase in material thermal conductivity. The marking width and depth were negatively related to the laser moving speed, and negatively related to the laser energy density during transient changes. After the simulation, actual experiments were conducted for three fabric substrates. The actual experimental results of the three fabric substrates verified that the marking width was positively related to the energy density, and negatively related to the movement speed, which was in agreement with the simulation results. The calculation results of the average width error, and the main sources of its generation were related to the fabric substrate color and the surface roughness. Consequently, because of the different colors of the fabric, there were differences in its light transmission ability. Although the simulation experiments had taken into account the transmission loss, the simulated results were still different from that of the actual experiments. In addition, the simulation experiments assumed that three materials of fabric substrate surface was absolutely smooth,which led to the simulation error. Nonetheless, compared to the others, the actual marking effect of polylester fabric substrate was closer to the simulation experiment, due to its smaller surface roughness and that the laser was more easily reflected on the surface, suggesting that the error generated by the marking increases with the surface roughness of the fabric substrate.
Conclusion In fabric marking, the marking depth is proved to be the main factor affecting the clarity of the mark and is the primary indicator that determines the laser parameters, and some principles for the selection of the three fabric laser parameters are given: ① For laser movement speed of 30 mm/s, the energy density of cotton is at least 0.20 J/cm²; polyester is at least 0.20 J/cm²; polypropylene is at least 0.175 J/cm². ② For laser movement speed of 20 mm/s, the energy density of cotton, polyester and polypropylene is at least 0.125, 0.15 and 0.10 J/cm², respectively. ③ For laser moving speed of 10 mm/s, the energy density of cotton is at least 0.075 J/cm²; polyester is at least 0.075 J/cm²; polypropylene is at least 0.05 J/cm². In addition, the surface roughness of the fabric substrate restrains the marking effect, and the subsequent simulation may further give consideration to the roughness. Both the simulation and the actual experiments prove that some relevant laws can provide some reference for the actual fabric marking.

Dyeing and Finshing & Chemicals

Dyeing kinetics of polylactide/poly(3-hydroxybutyrate-co-valerate) blended fibers and their chenille yarns

TANG Qi, CHAI Liqin, XU Tianwei, WANG Chenglong, WANG Zhicheng, ZHENG Jinhuan

Journal of Textile Research. 2023, 44(06):  129-136.  doi:10.13475/j.fzxb.20220503501

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Objective In order to further understand the dyeing performance of biodegradable polylactide/poly (3-hydroxybutyrate-co-valerate) (PLA/PHBV) blended fibers and their chenille yarns, and to improve the controlled dyeing technology of chenille yarn containing biodegradable polyester fiber, dyeing research was carried out.
Method The dyeing properties of PLA/PHBV fiber and PET/(PLA/PHBV) chenille yarn was studied and the parameters of dyeing rate constant, half dyeing time and diffusion coefficient were analyzed. Dyeing kinetics of C. I. Dispersed Red 60 on chenille yarn and its raw materials were explored and the biodegradable properties of each fiber were also studied.
Results The research results show that dyeing rate of C. I. Dispersed Red 60 on PLA/PHBV fiber and PET/(PLA/PHBV) chenille yarn was increased obviously with the increase of temperature, but the dyeing temperature was found not to exceed 110 ℃ in order to achieve the required mechanical properties of the fiber (Tab. 1 and Fig. 2). When the bath ratio was close to infinity, C. I. Dispersed Red 60 could stain the three materials faster at the initial stage of dyeing, after dyeing at 100 ℃ for 50 min, the adsorption capacity of the fibers to dyes basically reached the equilibrium state (Fig. 4(a)). When the dyeing temperature was increased to 110 ℃, the initial dyeing rate and equilibrium dyeing amount of C. I. Dispersed Red 60 on the three materials were significantly increased, and the time to reach the equilibrium state was shortened to about 40 min (Fig. 4(b)). The adsorption of C. I. Dispersed Red 60 on PET, PLA/PHBV and chenille yarn conformed to the quasi-second-order kinetic equation (Fig. 6). Among them, C. I. Dispersed Red 60 had the highest dyeing equilibrium adsorption capacity on PLA/PHBV fiber, and the lowest on PET fiber. With the increase of dyeing temperature, the dyeing rate of C. I. Disperse Red 60 on the three materials was accelerated (Tab. 3), the half staining time was shortened and the diffusion coefficient was increased (Tab. 4). The results of soil burial test showed that the degradation efficiency of all fibers increased with the extension of soil burial time, and PLA/PHBV fiber had the best degradation performance, followed by PLA. Moreover, the existence of PLA or PLA/PHBV biodegradable polyester fibers could accelerate the degradation rate of PET fiber (Fig. 8 and Fig. 9).
Conclusion It can be concluded from the research that with the increase of dyeing temperature, the dyeing rate of C. I. Dispersed Red 60 on PLA/PHBV fiber and chenille yarn increased, but the dyeing temperature should not exceed 110 ℃, otherwise the strength loss of PLA/PHBV fiber and chenille yarn was serious. The adsorption of C. I. Disperse Red 60 on PET, PLA/PHBV fibers and chenille fibers was consistent with the quasi-second-order dyeing kinetics model. By increasing the dyeing temperature to 110 ℃, the equilibrium dyeing amount, diffusion rate and diffusion coefficient of C. I. Dispersed Red 60 on PET, PLA/PHBV fiber and chenille yarn can be significantly improved, and the half-dyeing time can be shortened. C. I. Dispersed Red 60 had the highest equilibrium dye amount, diffusion rate and diffusion coefficient on PLA/PHBV fiber, and the shortest half-dyeing time. The corresponding value was the lowest in PET fiber. The blending of PLA/PHBV fiber is beneficial to improve the balance dyeing amount, diffusion rate and diffusion coefficient of chenille yarn, and shorten the half-dyeing time. The existence of PLA or PLA/PHBV biodegradable polyester fiber is beneficial to accelerate the degradation rate of refractory PET fiber, which provides a useful reference for the development of products containing biodegradable fiber. Biodegradable polyester materials have the dual advantages of protecting fossil resources and reducing carbon dioxide emission. The research, development and application of biodegradable polyester materials in textile field is an important innovative direction of sustainable development.

Construction and strain sensing properties of an ionic hydrogel composite fabric

XU Ruidong, LIU Hong, WANG Hang, ZHU Shifeng, QU Lijun, TIAN Mingwei

Journal of Textile Research. 2023, 44(06):  137-143.  doi:10.13475/j.fzxb.20220304201

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Objective Ionic strain sensing devices are the most promising technology for human-computer interaction. However, current strain sensing devices still suffer from poor interface comfort and low durability of ionic hydrogel. Herein, this work proposes a novel strategy to break through the above bottleneck. A composite fabric was fabricated by encapsulating ionic hydrogel into a knitted fabric for wearable comfort and excellent strain sensing properties.
Method The ionic hydrogel composite fabric was a typical sandwich structure, where the ionic hydrogel was encapsulated by two layers of knitted fabric. The ionic hydrogel was polymerized by acrylamide in a thermal environment. Lithium chloride (LiCl) was used as conductive material. The ionic hydrogel composite fabric was found to have good strain sensing capability, stemming from its three-dimensional cross-linked mesh micro-structure. When the fabric was stretched, the mesh micro-structure of the ionic hydrogel was compressed. Consequently, the ions movement was obstructed, causing an increase in the resistance of the ionic hydrogel composite fabric.
Results The ionic hydrogel has a three-dimensional mesh-like porous structure, which can lock in a large amount of water and provide a medium of movement for ions. Meanwhile, its excellent elasticity and soft feel properties can be obtained by the unique loop structure of the knitted fabric substrate. The ionic hydrogel composite fabric had good strain-sensing properties (Fig. 2) indicated by the slope of the current change rate vs applied strain. The gauge factor gauge factor is a critical index to reflect sensitivity of the strain sensors. The gauge factor was 0.94 with strain ranging from 0% to 30%, then the gauge factor slowed down to 0.82 with strain ranging from 30% to 60%, and the gauge factor decreased to 0.37 with high strain ranging from 60% to 100%. Meanwhile, the response and recovery times for the composite fabric were 310 and 346 ms, respectively (Fig. 3). In order to evaluate the hysteresis performance of the composite fabric under high strain stimulus, the changes in relative current (ΔI/I₀, in which ΔI=I-I₀ and I are the currents before and after strain stimulus, respectively) of the composite fabric during loading-unloading cycles at a maximum strain of 100% was recorded (Fig. 4). The hysteresis was shown at low stretching ratio, which was due to the inability of the reticular microstructure of the ionic hydrogel to recover in time. The composite fabric exhibited wide sensing range (up to 100%)(Fig. 5). The ionic hydrogel composite fabric possesses stable electrical property, the current change ratio of the fabric maintained constant after 5 000 cyclic stretchings (Fig. 6). It was also found that the ionic hydrogel composite fabric was environmentally friendly, with the mass change ratio of the composite fabric being only 3.5%, while that for the pure ionic hydrogel being 76.5%.
Conclusion The design of ionic hydrogel composite fabric enables combined high strain-sensing and environment stability properties. Specifically, the composite fabric shows high sensitivity and wide working range, which is due to the three-dimensional mesh-like porous structure of the ionic hydrogel. In addition, the fabric substrates can be used as water-loss shield layer reducing the moisture loss ratio of the hydrogel. As the proof of concept, a wearable human-computer interaction device has been fabricated to monitor the human movement and recognize voice. Therefore, this work opens a new path for flexible strain sensing devices and has great potential in the field of wearable interaction.

Processing optimization of composite fabrics deposited with electrospinning polyamide nano-fibers

WANG Qinghong, WANG Ying, HAO Xinmin, GUO Yafei, WANG Meihui

Journal of Textile Research. 2023, 44(06):  144-151.  doi:10.13475/j.fzxb.20220201101

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Objective In order to improve the inter-facial bonding between the nanomembrane and woven fabric, and reduce the clogging of the nanofiber membrane micropores caused by the use of glue, effects of conductivity, polyamide 56 (PA56) spinning solution and type of receiving substrate on the surface morphology of nanofibers were investigated. The preparation process of electrospinning nanofiber deposition composite woven fabrics was optimized, and the relationship between microporous structure and inter-facial bonding force was established.
Method Using polyamide 56 as spinning solution, a woven fabric as flexible receiving substrate and needle-free electrostatic spinning machine, instead of using adhesive, the adhesion between nanofiber membrane and textile interface was improved by electrostatic spinning film gradient deposition method to prepare nanofiber composite fabric. The effects of the conductivity of receiving substrate fabric, the concentration of spinning solution, the types and properties of receiving substrate on the surface morphology of nanofiber membrane and the adhesion of composite fabric were explored by analyzing the appearance and cross-sectional morphology of nanofiber membrane combined with the current-voltage curve of fabric and the peeling strength of composite fabric.
Results Nanofiber composite woven fabric was prepared by needleless electrospinning, and the inter-facial bonding force between the fabric and nanofiber membrane was improved by depositing electrospun membrane with concentration gradient. It was found that the optimum spinning concentration of PA56 was 12%-18% (Fig. 3), for creating uniform nanofiber membrane with uniform fiber diameter. Fabric types were shown to have great influence on the morphology and adhesion effect of fiber membrane (Fig. 4), where the optimal receiving substrate was found to be the cotton woven fabric. By improving conductivity of the receiving substrate (as shown in Tab. 2), the composite material demonstrated better surface morphology and receiving effect. Anti-static treatment was able to improve the morphology and deposition effect of nanofibers received by polyester fabric (Fig. 5). Using electrostatic spinning film gradient deposition method was found to improve the peeling strength between receiving substrate and fiber film (Fig. 6 and Fig. 7). Cotton fabric was selected as the receiving substrate, and the nanofiber composite fabric was prepared by gradient deposition process of PA56 low concentration nanofiber layer (6%, 10-20 min) and PA56 high concentration nanofiber membrane (15%, 40 min). The three-layer structure showed great improvement in interface bonding effect (Fig. 8), where the interface bonding force was improved by 3.543 times (Fig. 7), and the finally prepared concentration gradient nanofiber composite fabric demonstrated good hydrophilicity similar to that of traditional textiles (Fig. 9). The surface density and thickness of the prepared concentration gradient nanofiber composite fabric remained unchanged virtually after washing, and the micro-morphology of the fiber membrane before and after washing indicated that washing had little effect on the apparent morphology of the fiber membrane.
Conclusion The nanofiber composite fabric is composed of electrospun nanofiber membrane and ordinary fabric. In this design, nano-fiber films are deposited on the surface of the traditional fabric by concentration gradient method, and nano-fiber composite fabric with higher added value are prepared without using hot melt adhesive or other adhesives. The prepared nanofiber composite fabric is simple in manufacturing method and has certain inter-facial bonding force, and at the same time, it has high specific surface area and porosity of the surface nanofiber material, as well as good mechanical properties of the bottom material, and excellent hydrophilicity and washability. This study helps broaden the potential application value of electrospun nanofiber membrane in the field of functional textiles.

Thermal storage and discharge performance of fabrics with phase change material under low-level radiant heat exposure

ZHU Xiaorong, XIANG Youhui, HE Jiazhen, ZHAI Li'na

Journal of Textile Research. 2023, 44(06):  152-160.  doi:10.13475/j.fzxb.20211201501

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Objective Phase change materials (PCM) are a type of energy storage material, and the phase change layer attached to the thermal protective clothing fabric is able release heat when it solidifies. The release of heat under these two mechanisms may increase the potential danger of skin burns as a result of the heat exposure. Therefore, it is necessary to consider its thermal storage protective effect in the heat exposure stage and the hazardous effect in the cooling stage when exploring the comprehensive thermal protective performance of the thermal protective fabric assemblies incorporated with PCM on human skin.
Method Temperature-regulating fabrics with phase-change materials that can absorb or release heat through phase transition were prepared by using a coating method and were then applied to a multilayer thermal protective fabric system. The heat storage protective performance of thermal protective clothing with PCM and the natural heat release performance and the compressed heat release properties in the cooling stage are quantitatively evaluated through parametric design, the parameters including the thickness of the air layer under the clothes, the intensity of the heat source, and whether the fabric is compressed after the heat exposure.
Results In the stage of thermal exposure, the use of the PCM significantly reduced the skin heat gain during the heat exposure stage. At the same time, the phase change fabric systems significantly reduced the temperature inside the fabric system compared to the uncoated fabric system. In addition, the air layer had a more positive effect on reducing skin heat gain when it was incorporated with PCM. The skin heat gain decreased the most when the thickness of the air layer was increased from 0 mm to 6 mm, and the improvement in the thermal protection effect was not significant when the thickness of the air layer was continuously increased to 18 mm. In the process of natural thermal discharge, with the increase in air layer thickness, the CAE value (energy discharge amount or energy absorption during cooling) of the fabric system decreased. On the whole, the CAE value of PCM fabric system was smaller than that of the coated fabric system, but the heat release efficiency was slightly higher. Therefore, although the PCM fabric system could reduce skin heat gain in the natural heat release stage, more attention was paid to the influence of its heat release in the whole heat transfer process. It was noted that the CAE difference between the PCM fabric system and uncoated fabric system tended to decrease with the increase in the air layer thickness, which indicated that when the air layer thickness was larger, it played a leading role in the heat release of the fabric system, leading to the weakening of the positive role of PCM in the natural cooling process. In the process of forced thermal discharge, the skin heat absorption of the fabric systems increased significantly compared with the natural heat release stage. In particular, the application of compress aggravated the heat release in the PCM fabric systems if the fabric systems had an air layer in the heat exposure stage. When the thickness of air layer was 6 mm and 12 mm, the skin heat gain of the PCM fabric system was increased by 129 % compared with that without pressure.
Conclusion In the heat exposure stage, the comprehensive effect of the PCM fabric system and air layer plays a more positive role in reducing the heat reaching the skin surface. However, in the cooling stage, attention should also be paid to the complex effect of the combination of PCM fabric system and air layer on human skin, especially in the practical application of PCM, the air layer under clothing should be avoided squeezing and destroying as much as possible after the heat exposure stage to avoid causing accelerated release of heat storage and causing more serious heat damage to the skin. This significance of the research lies in the development of new clothing materials, the design of scientific thermal protective clothing systems, and the guidance of high-temperature operators to reduce skin burns by conducting basic research on the dual heat storage and release performance of PCM fabrics.

Preparation and properties of flame-retardant viscose fabrics modified with phosphated polyethyleneimine

JIANG Zhiming, ZHANG Chao, ZHANG Chenxi, ZHU Ping

Journal of Textile Research. 2023, 44(06):  161-167.  doi:10.13475/j.fzxb.20220201401

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Objective As one of the most important regenerated cellulose materials, viscose fibers are easily flammable and it has potential threat to human lives and properties. Researches show that viscose textiles can obtain flame retardancy by flame-retardant additives and finishing. Compared with flame-retardant additives, textile finishing is easy to operate. 1,2,3,4-Butane tetracarboxylic acid (BTCA), as a common cross-linker, has been widely applied to prepare functional cellulose textiles. However, its highly acidic condition may cause big strength loss of viscose fabrics. It is necessary to find an efficient way to reduce strength loss of flame-retardant viscose fabrics cross-linked with BTCA.
Method A multi-amino phosphated polyethyleneimine (BPEI-DP) was synthesized through simple Atherton-Todd reaction and applied to prepare flame-retardant viscose fabric crosslinking with BTCA. The design of BPEI-DP can decrease the acidic condition of BTCA and flame-retardant viscose fabric with low strength loss was achieved. Also, the BTCA crosslinking can improved the washing durability of flame-retardant viscose fabric. The flame retardancy, heat release, thermal stability, washing durability and mechanical properties were investigated.
Results The limiting oxygen index (LOI) value of the viscose fabric was found to increase to 28.9% after finishing with BPEI-DP and BTCA, and the treated fabric presented self-extinguishing behavior with no afterflame/aftergrow appearance and damage length of 9.9 cm in the vertical burning test (Fig. 2 and Tab. 1). The viscose fiber becomes rougher after flame-retardant finishing and some additional characteristic absorption peaks were appeared on the treated viscose fabric (Fig. 3 and Fig. 4), which indicates that flame retardancy was successfully deposited onto the viscose fibers. BPEI-DP/BTCA flame-retardant system showed significantly improvement in the carbon-forming ability of viscose fabric. The appearance of flame-retardant fiber was well maintained after combustion (Fig. 6). 40.0% and 14.8% of char residues were maintained at 800 ^oC under N₂and air atmosphere, respectively(Fig. 7 and Tab. 2). From cone calorimetry test (CCT), it is found that the with maximum heat release rate(pHRR) was reduced by 34% from 284 kW/m² to 189 kW/m² (Fig. 8 and Tab. 3). The washing resistance of BPEI-DP/BTCA treated viscose fabric was comparable to that of Pyrovatex CP. LOI value has slight reduction along with the increase of washing cycles. After 20 standard washing cycles, LOI value decreased from 28.9% to 24.9%, which is much higher than control viscose fabric (Fig. 9). This flame-retardant finishing system effectively maintained the strength of flame retardant viscose fabric. The breaking forces in the warp and weft direction reduced from (406±18) N to (284±13) N and (254±6) N to (168±11) N, respectively. Compared with control viscose fabric, the strength retention rate could reach about 70% and the whiteness has a significant reduction from (77.6±0.3)% to (30.1±0.5)% after flame-retardant finishing (Tab. 4).
Conclusion This study provides ideas for the design and preparation of flame-retardant cellulose fabric with low strength loss. BPEI-DP can not only render viscose fabric with good flame retardancy through improving the char-forming capacity, but also reduce the strength loss of viscose fabric crosslinking with BTCA by decreasing its acidic condition. However, the washing durability of BPEI-DP/BTCA treated viscose fabric is unsatisfactory and this finishing system has bad effect on the whiteness of viscose fabric. Therefore, more efficient and friendly flame-retardant system need to be developed to improve the washing durability and inherent properties of flame-retardant fabric.

Preparation of flame-retardant and waterproof multifunctional polyester tarpaulin

YANG Haifu, LUO Lijuan, SHI Jianjun, MA Xiaoguang, ZHENG Zhenrong

Journal of Textile Research. 2023, 44(06):  168-174.  doi:10.13475/j.fzxb.20220502701

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Objective Tarpaulin textiles have a wide range of applications in military field, and multifunctional tarpaulin textiles have attracted extensive attentions of researchers. The main purpose of this study is to develop a type of tarpaulin with both flame-retardancy and waterproofness, which are contradictive to each other and are difficult to achieve. The tarpaulin prepared in this study is expected to be used for covering automobile, aircraft, tank and for field tent cloth.
Method The effect of the concentration of flame-retardant TF-11 and the method of dipping the flame retardant on the flame-retardant performance was investigated. In order to improve the flame-retardant and waterproof performance of canvas, DBDPO and Sb₂O₃ were added to PA-822 resin solution and coated on the polyester canvas based on the bromine antimony flame-retardant synergy theory. The flame-retardant and anti-melt-drip mechanism of the multifunctional tarpaulins was analyzed by testing the after-glow time, the after-flame time, the damage length, hydrostatic pressure resistance and breaking strength of the finished tarpaulins, and by testing the carbon residue of the original polyester canvas and the finished tarpaulins with the aid of TG and SEM.
Results The polyester canvas was dipped and rolled twice in 150 g/L of the nitrogen-phosphorus flame retardant TF-11, and after dipping and rolling the fabric had the after-glow time and the after-flame time of 0 s and a damage length of 7.5 cm(Tab. 1). TG analysis showed that the phosphoric acid produced by the flame retardant during combustion was a strong dehydrating agent, which promoted the charring of the polyester canvas and prevented the decomposition of the fabric. The fabric was coated after dipping and rolling with the nitrogen and phosphorus flame retardant TF-11. When the mass ratio of decabromodiphenyl ether (DBDPO) to antimony trioxide was 2∶1 and 30% of the total amount of polyacrylic resin PA-822, the after-glow time and the after-flame time of the coated fabric was 0 s. Compared with the unfinished polyester canvas, the damage length was shortened to 5.5 cm (Fig. 3), and there was no melt drip, and the tarp had a high flame-retardant performance. The SEM images of the residual carbon profile of the finished tarpaulin showed a significant increase in the charring of the coated fabric (Fig. 4) and a significant reduction in the length of damage. This may be due to the synergistic effect of the bromine and antimony added to the coating agent, which promote the charring of the fabric. The char layer inhibits the diffusion of combustible gases and the transfer of heat to achieve the flame-retardant effect, and the bromine and antimony produced the incombustible gas SbBr₃, which reduced the oxygen concentration. Compared with uncoated polyester canvas, the hydrostatic pressure resistance value of the coated polyester canvas increased from 0 to 5.1 kPa (Tab. 2), with excellent waterproof performance. Compared with commercially available tarpaulins, the warp and weft breaking strength of prepared tarpaulins was above 2 000 N (Tab. 4). The flame-retardant effect can reach the degree of self-extinguishing from fire, and the length of damage after burning was obviously reduced, with good waterproof ability.
Conclusion Using polyester canvas as the tarp base fabric, the flame-retardant properties of the polyester canvas were significantly improved by dipping and rolling with the nitrogen and phosphorus flame-retardant TF-11. In order to further improve the flame-retardant and waterproof performance of the polyester canvas, a moisture permeable polyacrylic resin containing bromine antimony flame-retardant was used to coat the fabric after dipping and rolling the nitrogen phosphorus flame-retardant, so that the tarp had good flame-retardant and waterproof performance at the same time, which better solves the contradiction problem between the flame-retardant and waterproof performance of polyester canvas. The multifunctional tarpaulin can reach the degree of self-extinguishing from fire, with hydrostatic performance, can resist the rainstorm soaking, meeting the tarpaulin standard for flame retardant and waterproof performance requirements. In addition to high flame-retardant and waterproof performances, tarpaulin in practical application should also have high strength and corrosion resistance, low weight and fastness to the sun, to cope with different environmental conditions. In protective textiles, the tarpaulin with flame-retardant and waterproof performance has a good prospect for development and application.

Iron ion removal from seed hemp pulp based on synergistic effect of chitosan and polyvinyl alcohol

DI Youbo, CHEN Xieyang, YAN Zhifeng, YIN Xuan, QIU Chunli, MA Weiliang, ZHANG Xiangbing

Journal of Textile Research. 2023, 44(06):  175-182.  doi:10.13475/j.fzxb.20220505801

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Objective The strong adsorption ability of seed hemp on metal ions makes it impossible for seed hemp pulp to spin due to the high iron content, which leads to serious waste of resources restricting the effective utilization of bioresources and the achievement of China's carbon peak and neutrality goals. To address this problem, the adsorption solution (AS) including chitosan (CS) and polyvinyl alcohol (PVA) was designed to adsorb iron ions and therefore reduce iron content followed by study on the removal mechanism, which aim to provide basis theoretical support for the innovation and industrialization of iron ion removal technology of seed hemp.
Method Based on the metal chelation of CS and the emulsification and stabilization effects of PVA, AS was firstly prepared and used to deal with seed hemp pulp in this study, in which the removal effect, optimal removal conditions were explored by evaluating the spinnability of seed hemp pulp and the physical properties of the resulting fiber. In addition, the chelation mechanism of CS on iron ions was analyzed by density functional theory (DFT) employing the DMol³ module in Materials Studio software.
Results AS exhibited effective adsorption on iron ions where CS played a major role and PVA an assisted role. The adsorption effect of AS on iron ions was excellent under the condition of pH = 6.5 but the effect decreased obviously when pH value increased to 8 (Fig. 2), indicating the powerful influence of pH value on adsorption effect. It is observed that temperature has little effect on the adsorption effect of iron ions in the range between 30 and 50 ℃ (Fig. 3). Furthermore, adsorption time showed little effect on the adsorption effect of iron ions and the adsorption equilibrium was achieved with adsorption time of 30 min (Fig. 4).After the treatment with AS on the seed hemp pulp, the required aging rate during the glue making process was decreased and the properties containing polymerization degree, maturity, nickel mesh value and viscosity of the obtained spinning solution were enhanced (Tab. 4). In addition, the spinnability of the spinning solution was significantly improved showing the similar spinnability performance to that of the spinning solution prepared from wood pulp (Tab. 5). Through wet spinning, both the dry and wet breaking strengths of the obtained fibers were enhanced while the number of fiber defects were also significantly reduced (Tab. 6).DFT Calculation results show that all the binding configurations between citric acid (CA), ethylene diamine tetra acetic acid (EDTA), CS and FeCl₂, FeCl₃ were exothermic and form stable chelate. It is worth noting that CS represents stronger chelating ability to iron ions than CA and EDTA, especially the chelating ability to Fe²⁺ was stronger than that to Fe³⁺ (Fig. 5). The reason for the strong chelating ability for CS was contributed to the long distance between coordination atoms and the ease to rotate for coordination atoms leading to the formation of regular octahedron by the coordination of chitosan with metal ions (Fig. 6).
Conclusion Both the spinnability of the seed hemp pulp and the physical properties of the seed hemp viscose fiber are improved after AS treatment. The results show that AS with the mass ratio 1∶2 of CS and PVA, the mass fraction 3.6% adsorbent and pH =6.5 will provide the best removal effect for iron ions at 45 ℃ for 30 min, which can decrease the concentration of iron ions from 52 mg/kg to 35 mg/kg and the obtained seed hemp pulp has favorable spinnability. The adsorption and removal of iron ions in seed hemp pulp is achieved by the chelation of CS with iron ions to form complex in which PVA plays an auxiliary role in emulsification and stability, enhancing the chelation effect of CS and preventing the secondary deposition of iron ions.

Apparel Engineering

Application of virtual garment transfer in garment customization

YE Qinwen, WANG Zhaohui, HUANG Rong, LIU Huanhuan, WAN Sibang

Journal of Textile Research. 2023, 44(06):  183-190.  doi:10.13475/j.fzxb.20220408001

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Objective Design-preserving virtual garment transfer can transfer a garment from one body to another, which is significant for garment customization. However, most current research on virtual garment transfer only focuses on generating personalized 3-D garments rather than 2-D patterns and cannot be used for 3-D scanned human bodies. To address this issue, we propose a garment customization solution for 3-D scans based on design-preserving virtual garment transfer. Given a source garment worn on a source body, this research aims to obtain the target garments and patterns for a 3-D scan and show the final virtual fitting result of the target garment.
Method Firstly, the principle of virtual garment transfer of CLO 3-D and Marvelous Designer software is clarified in detail. Secondly, a method for generating personalized 3D garments and 2-D patterns for the 3-D scanned human bodies is proposed in combination with virtual garment transfer and the "Auto-convert-to-avatar" of CLO 3-D. Finally, the feasibility of this method in actual garment customization is verified by performing virtual garment transfer experiments with scanned human bodies.
Results In order to explore the difference in results between the two virtual garment transfer methods, two experiments were conducted and the results demonstrated that the method of using the default virtual avatar in CLO 3D or Marvelous Designer worked better than "Create fitting suit" when performing virtual garment transfer (Fig. 4). For the 3-D scanned human body, we proposed a personalized garment customization solution (Fig. 6). The virtual garment transfer for the 3-D scan was divided into three main steps. First, we used the CLO 3D default avatar to fit the scan and obtained the converted avatar based on the "Auto-convert-to-avatar " function of CLO 3D. Second, we obtained the transferred garment by transforming the source garment from the source body to the converted avatar. Finally, we fitted the transferred garment onto the scan and obtained the final virtual fitting effect. To verify the effectiveness of our proposed personalized garment customization solution, we scanned four young males with 3-D scanning and then obtained the corresponding converted avatars. For convenience, we denoted the scans as S_A, S_B, S_C, S_D and the converted avatars as C_A, C_B, C_C, C_D, respectively. According to our solution, we quickly obtained the transferred 3-D garment and corresponding 2-D patterns. The experimental results showed that the garments obtained by virtual garment transfer could meet the personalized requirements for different body shapes and sizes of the 3-D scanned human body (Fig. 10). In addition, the transferred patterns can satisfy the needs of actual garment production (Fig. 11).
Conclusion In this paper, we have proposed a personalized garment customization solution for a 3-D scanned human body based on design-preserving virtual garment transfer. For the 3-D scanned human body, our method was available for generating personalized 3-D garments and the corresponding 2-D patterns while also showing the final wearing effect of the transferred garment on the scan. The scheme's feasibility for actual garment customization was verified by conducting virtual garment transfer experiments with 3-D scans. The transferred 3-D garments can fit the scans well, and the transferred 2-D pattern can satisfy the needs of actual garment production. The method described in this paper was quick and effective for creating personalized 3-D garments and 2-D patterns. As a result, it can significantly improve the efficiency of customized garment development and facilitate garment customization in the apparel industry. In practical applications, creating a new style of 3-D garment is only necessary. Our proposed method allows personalized 3-D garments and corresponding 2-D patterns to be quickly obtained for 3-D scanned bodies of different sizes and shapes. In future work, how to optimize the existing personalized garment customization solutions is a topic worthy of in-depth study.

Application of Julia fractal set on design of Adras dress pattern

XU Han, SHEN Lei, CHEN Han

Journal of Textile Research. 2023, 44(06):  191-199.  doi:10.13475/j.fzxb.20220308901

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Objective The emerging culture of ethnic fashion has changed the consumption behaviour of modern people, and clothing products with a sense of fashion and ethnic are attracting attention from consumers. However, traditional design methods are unable to meet the high demand for the development of ethnic fashion patterns. In order to deal with the mismatch between the high demand for the development of ethnic fashion patterns and traditional design methods, a pattern innovation design method was proposed in this research, taking the Uyghur Adras pattern as an example.
Method Through fieldwork and literature research, the historical and cultural connotations behind the Adras patterns were collected and classified. The first step was to refine the line drawings according to the different categories. The classic elements were dismantled and reorganised using shape grammar to obtain new pattern units. Following this, the K-means analysis method was used to create clusters and to extract colours, and to summarise the typical colours of the Adras. Finally, Julia fractal theory and computer algorithms are used to construct models to aid pattern creation.
Results The Adras dresses are divided into skirts and dresses in terms of style. The patterns of the skirt and dress are categorised into two types of pattern composition, the "川" pattern and the "米" pattern. The "米" structure is centred on the collar or waist and spreads out around the plate, while the "川" pattern is arranged in a diagonal pattern along the longitudinal or diagonal direction (Fig. 8). The paper focuses on the composition of the "米" pattern in the skirt, combining it with the highly similar structure of the Julia fractal theory. The best symmetry order index ranges from 8 to 40. When the index is less than 8, it does not constitute a "米" structure yet. When the index is between 8 and 40, the complexity and exquisiteness of the pattern varies with the value. When the index is greater than 40, the details of the pattern decrease with the increase of the index (Fig. 10). A scientific and systematic pattern design system was proposed in this paper aiming to establish the Adras dress fractal pattern design model (Fig. 11). The model includes steps such as creating a new collection, adjusting the symmetry order index, substituting the formula, superimposing the algorithm, adding representative colours and patterns, and fractal rendering. The J-set model with symmetry order indices of 8, 22 and 40 was selected for further design in the new set. Exponential smoothing mappings, inverse mappings, Newton's formulae and superimposing various algorithms were substituted to obtain nine sub-models with completely different forms and effects. Adding Adras innovative pattern units and typical colours, the final rendering resulted in 9 sets of pattern designs.
Conclusion In order to transform the qualitative evaluation into a quantitative one, a fuzzy comprehensive evaluation of the designed pattern was carried out using a five-level scale criterion in four dimensions, i.e. color features, elemental features, structural features and cultural connotations. The modeling of the Adras dress was also carried out on the Style 3D software platform to verify its feasibility. The results show that the design model of the Adras pattern based on Julia fractal theory has good practical application value and helps the inheritance, innovation and development of the Uyghur culture in the digital era. At the same time, it can also provide research ideas and methodological references for the inheritance and innovation of other ethnic patterns. The Adras dress pattern created by this method can combine both fashionable artistic characteristics and ethnic cultural heritage.

Machinery & Accessories

Nozzle structure optimization based on Flow Simulation for air-jet weaving

FAN Bailin, ZHANG Changrui, GUO Jiahua, HUANG Ganghan, WEI Guoliang

Journal of Textile Research. 2023, 44(06):  200-206.  doi:10.13475/j.fzxb.20210601601

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Objective The key technology to improve the quality and reduce the cost of air-jet loom was to increase the flying speed of weft yarn, improve the quality of air-flow synthesis and reduce the air consumption. In order to improve the comprehensive performance of the auxiliary nozzle for weft insertion of air-jet weaving machines, the optimal model structure of the auxiliary nozzle orifice was simulated and optimized, so as to achieve the optimal weft insertion performance.
Method The Flow Simulation plug-in module in Solidworks software was used in the research, which is a CFD numerical simulation plug-in based on the finite volume method. Flow Simulation is a fully integrated software in Solidworks. The proven computational fluid dynamics (CFD) technology was used to calculate the fluid (gas or liquid) flow inside and outside the Solidworks model. At the same time, the heat transitive model (from models, between models and inside models) caused by convective radiation and conduction will also have an impact. The structural optimization method of Solidworks software was employed to simulate the fluid performance of the auxiliary nozzle orifice. Three dimensional models of the flow field of the auxiliary nozzle orifice with single round hole, double round hole and rectangular hole was constructed to evaluate, the velocity distribution at the section 40 mm away from the nozzle, maximum flow rate of auxiliary nozzle and the mass flow at the inlet of the auxiliary nozzle under the working environment pressure of 0.4 MPa.
Results For a single circular hole auxiliary nozzle, when the cone angle was set to 4°in the positive direction, better results were obtained, and the weft insertion stability was good. A high airflow speed and minimum mass flow rate could increase the weft insertion speed while ensuring the stability of the weft insertion without increasing gas consumption. Compared to the unoptimized model with a cone angle of 0°, when the cone angle was set to 4 ° in the positive direction, the stability of the weft insertion slightly increased, and the maximum flow velocity of the airflow field increased by 3.03%, with the same gas consumption as at 0°.For the double circular hole auxiliary nozzle, group D achieved relatively good results, with good weft insertion stability and slight airflow velocity and mass flow rate increase, which could increase the weft insertion speed while ensuring the stability of the weft insertion, but slightly increased the gas consumption. Compared to the group C before optimization, the stability of group D slightly increased, with a maximum flow rate increase of 0.908%, increased gas consumption by 6.25%. For the rectangular auxiliary nozzle, group B achieved relatively good results. At this time, the stability of weft insertion was good, the airflow speed was slightly increased, and the mass flow rate remained unchanged. On the basis of ensuring the stability of weft insertion, the weft insertion speed could be increased without increasing gas consumption. Compared to group A before optimization, the stability of group B was slightly increased and its maximum flow rate was 2.8%.
Conclusion Flow Simulation plug-in module in Solidworks software is used to analyze the velocity distribution of the section of the auxiliary nozzle with single circular hole, double circular hole and rectangular circular hole at the distance of 40 mm from the nozzle, maximum flow rate of auxiliary nozzle and the mass flow at the inlet of the auxiliary nozzle under the working environment pressure of 0.4 MPa, and then optimize the structure of the auxiliary nozzle to obtain the optimal results. ①For the single round hole auxiliary nozzle, when the cone angle is 4° in the positive direction, the better results are obtained. At this time, the weft insertion stability is good, and the high air velocity and the minimum mass flow rate are obtained. On the basis of ensuring the weft insertion stability, the weft insertion speed can be increased without increasing the gas consumption. ②For the auxiliary nozzle with double round holes, the center distance between the two holes is 2.2 mm, and the cross section air velocity at 40 mm from the nozzle is higher than 90 m/s. The symmetry and the stability of weft insertion is good, which can meet the different requirements of actual weft insertion.③ For the auxiliary nozzles with rectangular shapes, when the length of the jet shapes is 2.034 mm and the width of the jet shapes is 0.885 mm, the air flow velocity at the section 40 mm from the jet shapes is higher than 90 m/s, with good symmetry and stability of weft insertion. The air flow speed is slightly improved, and the mass flow remains unchanged, which can increase the weft insertion speed without increasing the gas consumption on the basis of ensuring the stability of weft insertion.

Trajectory tracking control method of cloth grabbing manipulator based on dynamic modeling

HUANG Chenjing, ZHANG Lei, SUN Xun, WANG Xiaohua

Journal of Textile Research. 2023, 44(06):  207-214.  doi:10.13475/j.fzxb.20211107501

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Objective With the development and popularization of advanced manufacturing technology, the fabric grabbing and transferring work in the textile and garment industry has been preliminarily realized by the use of manipulator. However, in practical applications, the parameters of the manipulator model cannot be accurately measured, and the tracking accuracy would decrease when using the traditional control method. Therefore, it is of great significance to study the trajectory tracking control problem of manipulator with consideration of the uncertain model parameter.
Method Aiming at the dynamic model of the manipulator with parameter uncertainty, a trajectory tracking control method was designed by using backstepping method under the framework of I&I adaptive theory. The dynamic model of flexible joint manipulator with unknown parameters was established before, the adaptive joint moment of inertia was designed using Immersion and Invariance(I&I) adaptive control method, and the invariance and attraction characteristics of error manifold were facilitated through designing a smooth function to ensure that the parameter estimation error converge to zero. Finally, the designed adaptive law is introduced into the recursive process of control law designing to make it adaptive to the uncertain parameter.
Results The adaptive law designed by the I&I adaptive control method has adaptiveness for the uncertain parameter, and the parameter estimation error response curve quickly converges to 0 after a short running time(Fig. 9). Compared with the FPBC(fixed parameter model based backstepping control method), the proposed IABC(I&I adaptive based backstepping control method)was found not only to achieve the desired trajectory tracking effect faster and more stably, but also to stabilize the input torque of the motor faster. The manipulator using FPBC did not track the expected trajectory and has periodic tracking errors(Fig. 5), and the manipulator using proposed IABC tracked the desired trajectory for the first time after about 0.12 s of joint position, and demonstrated good tracking performance, with the tracking error of desired trajectory within ± 0.002 rad. The motor input torque under FPBC entered a stable state around 0.14 s, while under the IABC proposed in this paper, the motor input torque tended to stabilize around 0.07 s(Fig. 6 and Fig. 7). It is obvious that the FPBC made the motor input torque enter a stable state at about 0.14 s, while the IABC proposed in this research made the motor input torque enter a stable state at about 0.07 seconds(Fig. 6 and Fig. 7). In order to verify the trajectory tracking of manipulator end in cloth grabbing and placing, the desired trajectory tracking experiment of manipulator end was simulated using MatLab. The proposed IABC was shown to be effective in achieving accurate trajectory tracking control of the cloth grabbing manipulator(Fig. 10).
Conclusion The proposed IABC can effectively improve the tracking performance of the manipulator joint position and improve the tracking accuracy of the cloth grabbing manipulator. This method takes into account the uncertainty of the moment of inertia of the manipulator dynamic model. I&I adaptive control method is used to design the parameter adaptive law to avoid the over-parameterization problem of the adaptive method based on the Certainty Equivalence principle, while retaining the nonlinear characteristics of the system.

Comprehensive Review

Research progress in electrospinning functional nanofibers with metal-organic framework

JIA Jiao, ZHENG Zuobao, WU Hao, XU Le, LIU Xi, DONG Fengchun, JIA Yongtang

Journal of Textile Research. 2023, 44(06):  215-224.  doi:10.13475/j.fzxb.20211103402

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Significance Nanofiber membrane made by electrostatic spinning has the advantages of small fiber diameter, rich pores in the membrane, small porosity, large specific fiber surface area, and easy functional modification. In recent years, nanofiber membrane has shown broad application prospects in the fields of water treatment, new energy, biomedicine and so on. The molecular structure of metal-organic framework (MOF) has the advantages of high specific surface area, uniform pore size and adjustable structure. It is difficult to give full plays to its performance advantages in the fields of flexible functional film and large-area device. Therefore, it is necessary to make full use of the material properties of electrostatic spinning nanofibers with intrinsic flexibility and easy to achieve large-area preparation. The research and development of polymer composite metal-organic frame functional nanofiber membrane materials based on electrostatic spinning is of great significance to broaden the application field of MOF materials.
Progress In this paper, the feasibility of combining metal-organic skeleton with electrospinning membrane is introduced, and the preparation, development and latest research progress of polymer composite metal-organic skeleton functional nanofiber membrane are reviewed. In addition, the applications of electrospun polymer composite metal-organic skeleton functional nanofiber membranes in water treatment, lithium battery separator, drug delivery, gas separation and other fields are systematically classified and discussed. At present, there are many reports on the research of MOF and polymer blending silk, and the preparation methods can be summarized into three types, i.e. (i) polymer solution spinning mixed with MOF particle, (ii) polymer nanofiber membrane modification with MOF and (iii) one-step blending spinning method. For the first methord, MOF particle mixed polymer solution spinning firstly synthesized MOF powder by traditional method, then dried MOF powder was mixed into the spinning solution by ultrasonic dispersion or high temperature dissolution method to prepare polymer mixed metal organic frame powder functional nanofiber membrane. In the second method, the polymer nanofiber membrane was modified by MOF. In this process, ordinary nanofiber membrane was prepared by traditional method, and then the prepared nanofiber membrane was placed in MOF stock solution, and MOF particles were grown on the surface of the nanofiber membrane. In the one-step blending spinning method, MOF and spinning stock are mixed in a specific ratio before electrospinning. The formation of MOF powder occurs simultaneously with the formation of fiber. One-step blending not only simplifies the preparation process, but also disperses MOF uniformly on the polymer fiber. By simplifying the synthesis of conventional MOF composite nanofibers into one step, it has better applicability to more polymers. At the same time, the problems of phase separation between MOF and polymer and aggregation of MOF in the preparation process are avoided, causing change in material properties. The electrospun polymer composite metal-organic frame functional nanofiber membrane has better characteristics than the pure polymer membrane, such as higher porosity and higher specific surface area, and has application potential in medical treatment, new energy and environmental treatment, which is of great significance for the realization of environmental sustainable development.
Conclusion and Prospect The development potential and existing problems of polymer composite metal-organic framework functional nanofiber membranes in recent years were summarized, and the future development trend of this research field was prospected. Although advances have been made in many areas of electrospun polymer/MOF functional nanofiber membranes, some challenges remain. ① The compatibility between MOF and polymer should be considered in the synthesis process. ② The high temperatures required for most functional nanofiber synthesis processes limit the use of heat-sensitive fibers. ③ During the use of functional nanofibers, the degradation of MOF may hinder its function. ④ Durability and functional regeneration. ⑤ We need to consider the actual situation. For example, some functional nanofiber membranes can only work under certain conditions, such as photoinduced antibacterial MOF/fibers requiring sunlight. Therefore, functional nanofibers with more functions are more likely to become a viable technology. In order for electrospun polymer/MOF functional nanofibers to be widely used, it is necessary to develop low-cost, sustainable synthesis methods and further study the key properties of functional nanofibers such as mass load, BET, coverage and uniformity. The open grid structure of MOF material makes it easy to be chemically modified and can conform to reasonable expectations.

Research progress in fabric comfort based on event-related potential technique

YUAN Jie, ZHAI Shu'na, LOU Lin, WANG Qicai, LEI Yutian

Journal of Textile Research. 2023, 44(06):  225-231.  doi:10.13475/j.fzxb.20220304802

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Significance A large number of experimental studies had been conducted on the relationship between the changes of various physiological indicators of the human body and the perception of human comfort under the tactile, visual and other perceptual stimulation of fabrics. Comfort evaluation based on physiological representations had made great progress and development. However, many methods still have defects in exploring the immediacy of fabric comfort characterization. With the continuous development of biological electroencephal technology, the relatively mature event-related potentials (ERPs) technique has shown the advantage of ultra-high time resolution in the brain perception study of fabric comfort. It was of great scientific significance to improve the temporal resolution of the detection technology to realize the instantaneous capture of dynamic information of brain sensory nerve and explore the in-situ sensing mechanism of fabric comfort.
Progress From the perspective of the perceived process of fabric comfort, the perceived process of fabric comfort could be summarized as the process of physical, physiological and psychological interaction of the system of human body-fabric-environment. Although physical, physiological and psychological methods could all reflect the changes in the comfort level of the human body when it was stimulated by the fabric, it could be seen from the perceptual process that the formation of the comfort level originates from the cerebral cortex. Therefore, physiological representation technology based on brain perception obviously has more representational mechanism advantages for the study of human comfort level. From the perspective of the characterization principle of ERPs technology, ERPs potential signals were obtained by filtering, averaging and stacking electroencephalogram signals stimulated by the same event, and noise potential activities independent of stimulus would cancel each other out in the stacking process, so there was no nonlinear problem in ERPs signals. In addition, the technology also had the advantages of low equipment price, easy to carry, ultra-high time resolution, accurate results, small error, little subjective interference and so on. Therefore, ERPs technology offers certain technical advantages in the physiological characterization of brain perception.
Conclusion and Prospect Therefore, the evoked potentials related to the comfort of fabrics are summarized through the review of relevant research progress at home and abroad. It is concluded that the evoked potentials related to the tactile perception of fabrics are mainly positive components in the middle and late stages and negative components at the stimulation of 450 ms. The late positive component is mainly related to the surface roughness and the perception of contact pressure. The intermediate positive component is related to itching sensation, cold and warm feeling and sticky feeling. The negative potential components at 450 ms of stimulation correlates with the brain's perceived ability to resist interference. The evoked potentials related to the perception of visual comfort of fabrics are mainly positive components, early and middle negative components. Strong visual stimulation can increase the amplitudes of the early positive component, the middle positive component and the early negative component, but the increase of the number of color combinations can prolong the latency of the middle positive component and the middle negative component and slow the recognition speed. Finally, the late positive component is the final decision component of visual comfort perception. The above studies not only proved the feasibility of using evoked potentials to characterize fabric comfort, but also opened up a new method of comfort characterization based on brain perception. In the future, it is expected to construct a prediction model based on brain perception by exploring the quantitative relationship between evoked potentials and various physical factors of fabric, so as to guide the design development of various fabric materials towards comfort and health.