Table of Content

15 January 2023, Volume 44 Issue 01

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Invited Column: Frontiers of Textile Science and Technology

Research status and development trend of perspective preparation technologies and applications for textiles

WU Jing, JIANG Zhenlin, JI Peng, XIE Ruimin, CHEN Ye, CHEN Xiangling, WANG Huaping

Journal of Textile Research. 2023, 44(01):  1-10.  doi:10.13475/j.fzxb.20220706210

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Significance Chemical fiber is a necessary component of human productivity and daily living. Since the 1970s, China's chemical fiber industry has developed quickly, and China has led the world in production of chemical fiber for almost 20 years. In 2021, China's chemical fiber output has reached 60.25 million tons, or more than 70% of the total amount produced worldwide. Currently, the development of high performance, functional, and intelligent textile products has drawn considerable attention as consumer demand has increased significantly. The production of raw resources, technological advancement, and the application fields of functional products are all significant variables. The future development of the textile industry is undoubtedly very important, and in order to be clear about the future development direction, it is thus crucial to summarize the possible and potential development trend of novel technologies and improved products with higher performance and wider application fields in future textile industry on the basis of the existing technologies and problems.
Progress Currently, significant obstacles still exist to the growth of the textile sector, which are mostly seen in the following four aspects: 1) shortage of resources for fiber raw materials; 2) increase of processing costs; 3) products elevation. Middle and low-grade products no longer have any advantages, the production and processing capability is forced to migrate out of China, and new and high-grade products are being developed and produced; 4) absence of innovative technology. The developed synthetic biological method and genetic engineering technology can successfully prepare bio-based raw materials like 1, 3-propanediol and lactic acid in order to avoid the significant consumption of petroleum-based raw materials and the competition between bio-based raw materials and grain. Fiber material forming technology is moving progressively in the direction of an effective multi-flow, sustainable, green, and intelligent technology introduction. Furthermore, the fiber forming technology is more advanced to achieve the accurate building of multiple fiber structures. A greater range of applications can be met by the expansion and performance improvement of fiber structures. Application of clothing in the direction of development for high performance, minimal loss, light weight, and multifunctional clothing. Additionally, textiles have new uses in the development of biomedical materials, environmental protection filtration materials, and agricultural production materials. The innovation products are multi-functional and more intelligent, and can realize the active adaptation of structure and performance in varied application conditions.
Conclusion and Prospect The development of textile industry and textile technology has played a crucial role in the evolution of human civilization. Today in the 21st century, the textile industry is no longer just a conventional industry to meet the needs of human clothing. Its technological development is more advanced and cutting-edge: 1) the innovation of raw materials. Innovations in feedstock technology such as the development of bio-based feedstocks have made fiber products more environmentally friendly. Pure organic polymers are no longer the only type of fibrous matrix materials; in addition, inorganic, metal, and organic-inorganic hybrid fiber materials are now covered. 2) forming technology. Fiber material forming technology is gradually moving toward an effective multi-flow, environmentally friendly, and sustainable processing process. Infinite creative potential exists for final applications thanks to the advancement of fiber forming technology and the evolution of fiber on a multidimensional scale. 3) intelligent manufacturing. The adoption of intelligent manufacturing, complete process automation, information technology, and digitalization can significantly increase the productivity of the textile sector. 4) more diverse applications. In the future, textiles could be used in apparel, wearable textiles, household textile items, and extremely innovative fields including biomedicine, the environment, energy, agricultural production, building, and transportation, among others, with the focus on intelligence and function. The textile sector has demonstrated multifaceted inventive growth that will open up more room for human civilization and technology advancement.

Review on thermal-drawn multimaterial fiber optoelectronics

ZHANG Jing, HUANG Zhiheng, NIU Guangliang, LIANG Sheng, YANG Lüyun, WEI Lei, ZHOU Shifeng, HOU Chong, TAO Guangming

Journal of Textile Research. 2023, 44(01):  11-20.  doi:10.13475/j.fzxb.20220606310

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Significance With the rapid development of textile engineering and material science, intelligent fibers and related fabrics have become the preferred carriers for wearable electronics with their advantages in softness, lightness, and breathability. A variety of fiber manufacturing technologies has been developed, enabling conventional fibers with new capabilities such as environmental/physical/chemical sensing, logical computing, human-machine interaction, and so on. Among these manufacturing techniques, the thermal drawing process can be adopted to fabricate multimaterial optoelectronic fibers, providing an innovative research for intelligent fibers and fabrics. By enriching fiber structures, materials and post-treatment techniques, thermal-drawn fibers can be integrated with multiple functions such as multi-parameter sensing, temperature regulation, and information interaction, broadening the application scenarios of fibers.
Progress Thermal-drawn multimaterial optoelectronic fibers are generally drawn from fiber preforms with a fiber drawing tower. The external forms, internal structures, and materials of fiber preforms can all be designed with great flexibility according to the applications and functions. The diameters of fibers are typically in the micron range, and the structures of the fibers are consistent with the preform rods. In addition, fiber post-treatment techniques, such as thermal treatment and cold-drawing process, can further enrich and modify the structures, giving more ways to improve the functionalities of fibers.
With these advanced fiber drawing and processing technologies, micro- and nano-structured fibers can be achieved. For example, a low-loss CO₂ laser-propagated photonic bandgap fiber has been achieved with a hollow core surrounded by a solid multilayer structure of high refractive-index contrast. The fiber has a large photonic bandgap and omnidirectional reflectivity. Nanowires, structural micro- and nanospheres, nanorods, and porous fibers have also been produced in a scalable way by the in-fiber fluid instability phenomena, cold-drawing deformation, and salt leaching techniques. Moreover, surface micro-nano imprinting technology has been utilized to construct specific fibers with micro/nano-surface patterns.
The richness of structures and materials gives fibers a variety of advanced functionalities, such as sensing, energy management, neural probing, and information interaction. For sensing, the thermal-drawn fibers have been achieved with acoustic, photoelectric, strain, and chemical sensing. For energy management, fiber-based devices are enabled with the functions of passive temperature regulation and energy generation/storage. Thermal-drawn fibers have also been widely used as neural probes because of their flexibility, small size, and conductive property. In addition, semiconductor diodes and integrated circuits have been integrated into thermal-drawn fibers successfully, which empowers the fibers with the abilities of logical computing and information interaction.
Conclusion and Prospect This work focuses on the research progress and application fields of thermal-drawn multimaterial fiber, reviews the regulation of the micro/nanostructures inside the fibers by thermal drawing, and discusses their applications in sensing, energy, biology and others with recent studies.
However, there are still some limitations to thermal-drawn multimaterial fiber optoelectronics. 1) Only a few of materials and structures are investigated and applied into the system. 2) The mechanical properties and comfort of wearing of thermal-drawn fibers need to be improved. 3) It is still difficult to integrate multiple functions into one fiber. 4) The abilities of logical calculation and data management of the thermal-drawn fibers should be enhanced.
The future research trends of thermal-drawn multimaterial optoelectronic fibers are discussed from five aspects: more material selection, complex fiber structure, textile processing, multi-function integration, and artificial intelligence. It is foreseen that current mono-functional thermal-drawn multimaterial optoelectronic fibers can be improved for higher integrations, better mechanical properties, and more intelligence. These advanced fibers can also be combined with conventional textiles to enable their functionalities, comfort of wearing, and applicability to scenarios.

Research progress in display units fabricated from textiles

SHI Xiang, WANG Zhen, PENG Huisheng

Journal of Textile Research. 2023, 44(01):  21-29.  doi:10.13475/j.fzxb.20220606609

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Significance As the window of human-machine interaction, demands on displays have become an important driving force for the development of the information society. The development of display technology ranges from the early three-dimensional bulky cathode ray tube display to flat-panel liquid crystal display, and now to the two-dimensional thin-film organic light-emitting diode display, and the displays are becoming flexible and lightweight by reducing the thickness of the device. With the rapid development of emerging fields such as wearable devices, smart interactions and the Internet of Things, displays are required to fit the irregular surface of the human body, match the human body in mechanical properties and remain stable under three-dimensional deformation. Additionally, future displays should be permeable for long-term comfort in the applications of human-machine interaction and health monitoring. Textile is an indispensable part of our daily life, and integrating displays into textile is an ideal way to realize new displays that is highly flexible, adaptive to complex deformation, and permeable.
Progress Light-emitting devices are the basic components of displays. Dynamic images in displays are realized by controlling light-emitting devices according to the driving program. Until now, three types of textile light-emitting device structures have been developed. They are textile-based planar light-emitting devices, light-emitting fibers, and warp-weft interwoven light-emitting devices.
Textile-based planar light-emitting devices are prepared by attaching flexible thin-film light-emitting devices to the textile substrate or depositing active materials layer by layer on the textile substrate to obtain light-emitting devices. Owing to the wide investigation on materials and fabrication of planar light-emitting devices, it is easy to achieve high luminance and efficiency in textile-based planar light-emitting devices for better display performance. However, the modulus of film materials is always higher than the modulus of textiles. The mismatch between the mechanical properties leads to reduced flexibility of the textile, and the devices can the easily peeled off from the textile or fade in performance during deformation.
The two-dimensional thin film light-emitting devices are converted into one-dimensional light-emitting fibers, which are the building blocks of textiles. Light-emitting fibers can be woven into textiles without sacrificing the inherent permeability and flexibility of textiles. Through the design of material and device structure, meter-length light-emitting fibers were realized based on AC electroluminescent material. Light-emitting fibers with good mechanical stability and flexibility can be woven into textile to display pre-designed weaving patterns. However, this is a significant limitation because simply based on pre-designed patterns, it is almost impossible for them to satisfy the display applications like computers and cell phones.
For real displays consisting of an array of pixels, the pixels are individually controlled in real time for dynamic change. A strategy is proposed to build micron-scale light-emitting devices at the warp and weft interwoven points. Composite warps that load luminescent materials and transparent conductive wefts were developed, and the textile pixels were formed by contacting two fibers during weaving. This method unifies the textile and the display device in function, structure, and fabrication method. High-resolution display in the textile was achieved by applying digital signals to warps and wefts.
Conclusion and Prospect In the past decade, many efforts are made to design materials, device structures, and fabricate methods for displaying textiles. High stability, flexibility, and permeability of displaying textiles are achieved by developing one-dimensional fiber devices, and pixel displays with high resolution and large-area integration are facilitated by developing warp-weft interwoven devices. However, the following problems remain to be solved to promote the practical application of displaying textile.
1) Luminescent materials are the basis for high display performance. Unique highly curved structures of fibers lead to new requirements for the composition, structure, film forming method and mechanical stability of light-emitting materials.
2) Full-color display is indispensable for human-machine interaction. In planar display, full color is realized by mixing the light emitting from three adjacent light-emitting devices in red, green, and blue. Fiber-shaped light-emitting devices are curved light sources. The space distribution of emitted light from fiber devices is different from that from planar devices, which demands new principles of color mixing.
3) Resolution is a key parameter for display quality. The resolution of displaying textiles is still far below that of the commercial displays. It is challenging to uniformly load the luminescent materials on superfine fiber and reveal the light-emitting mechanism of interwoven light-emitting devices in the size of tens of microns.
4) Systematic integration is the foundation of practical application. In order to integrate displaying textiles with other fiber devices such as battery fibers and sensing fibers, problems should be solved to connect fiber electrodes in high bonding strength and stable electrical conductivity under deformation. Matching of electrical parameters among textile devices should also be investigated for the reliable operation of the textile system.

Research progress in smart fabrics for thermal and humidity management

CHEN Jiahui, MEI Tao, ZHAO Qinghua, YOU Haining, WANG Wenwen, WANG Dong

Journal of Textile Research. 2023, 44(01):  30-37.  doi:10.13475/j.fzxb.20220705708

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Significance With rapid development of today's social population and the increasing scarcity of fossil energy, a huge contradiction arose between the surge in energy consumption, e.g., from air conditioning, and the global goals of "carbon peaking" and "carbon neutrality". The large amount of greenhouse gas emissions caused by air-conditioning, refrigeration and heating have also become an urgent problem to be solved. Therefore, it is necessary to seek a new method for effectively adjusting the thermal and moist comfort of the human body so as to reduce the energy consumption caused by air conditioning. Textiles can also play a role in managing human comfort in daily life, but would mainly rely on the thickness of clothing to regulate human body temperature. In order to better meet the modern day requirements for life comfort, the active adjustment of smart textiles has demonstrated the potential for adjusting the human body's thermal and moist comfort, thereby reducing the energy consumption in the process of cooling and heating by air conditioning. Under the premise of the "double carbon" goal, this has could be a promising solution.
Progress This review summarizes the research progress in adjusting the thermal and moist comfort of the human body by using smart fabrics. The principle of regulating the thermal and moist condition of the human body through the fabric is introduced. In addition, the researches and mechanisms of the current study on regulating the thermal and moist comfort of the human body by means of fabric materials or fabric structures have been summarized. Coating or combining high-performance materials was adopted to prepare thermal and moist comfort fabrics aiming to regulating human body temperature. High infrared reflection materials such as silver and titanium dioxide, high thermal conductivity materials such as boron nitride nanosheets (BNNSs), and high infrared transmission materials such as polyethylene (PE) are proposed. All of these high-performance materials can be used for raising or decreasing the body temperature. The review also introduces the thermal and moist comfort adjustment of smart fabrics caused by different fibers and fabric structures, such as thermal fabrics made of porous fibers, moisture-absorbing and quick-drying fabrics caused by asymmetric structures, and intelligent adjustment fabric that can respond to changes in fabric pore size caused by external temperature and humidity. Finally, this review paper analyzed and discussed the current difficulties and challenges in smart fabrics with different fabrication methods.
Conclusion and Prospect The smart fabric that can manage thermal and humid conditions of human body is necessary and the key is energy shortage. However, the performances of the thermal management, humidity management or thermal and humidity management of the recent smart fabric are directly affected and limited by the materials. Few high-performance functional materials can be utilized to fabricate smart fabrics. In addition, the main technical means of preparing thermal and moist comfort smart fabrics are coatings and material composites. However, the stability of coatings, the compatibility of composite materials, and the difficulty of industrial production limit the development of thermal and moist comfort smart fabrics. Therefore, it is necessary to prepare new fibers that can respond to external heat and humidity stimuli, so as to realize the preparation of fabrics that can intelligently regulate human body temperature and humidity. Additionally, the ease of construction, preparation, and large-scale production of fibers can reduce the cost of smart fabric production. Finally, the current preparation methods and functional principles of intelligent thermal-moist comfort fabrics are summarized, and a low-cost and large-scale preparation method for intelligent thermal-moist comfort fabrics is proposed by technological innovation of fibers.

Research progress in compression garments against musculoskeletal deconditioning in microgravity

ZHANG Qian, NIU Wenxin, JIANG Chenghua, GAO Jing, WANG Lu

Journal of Textile Research. 2023, 44(01):  38-46.  doi:10.13475/j.fzxb.20220702009

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Significance The microgravity environment in space causes human musculoskeletal deconditioning to gravity, triggering a number of physiological changes, such as muscle atrophy and bone loss. Such pathologies affect the ability of astronauts to perform their missions and expose them to a higher risk of fracture and disc herniation upon return to earth. There has been widespread interest and concern about how to combat the adverse pathologies caused by the microgravity environment on the human musculoskeletal system. Compression garment is an important medium for generating mechanical interactions on the human body. The desired pressure can be obtained by adjusting the material and structure of the compression garment. In addition, compression garments are lightweight and compact, which have important advantages in space flight. It is significant to explore the current status of research on compression garment against microgravity environments by using a combination of clothing ergonomics and human biomechanical principles. This will help to guard the health of astronauts and promote the development of human spaceflight technology.
Progress This paper specifically analyzes the countermeasure mechanisms and structural efficacy characteristics of existing compression garments for space stations, such as the penguin suit and gravity loading countermeasure skinsuit (GLCS), and related prototype garments reported in the literature. The study concludes that the current compression garments are classified into tension-pressure and gas-pressure countermeasures. The penguin suit selects elastic tension straps to apply axial load on the body. However, the poor comfort limits its cap ability to apply loads to the body. The GLCS applies bi-directional elastic fabric to balance the axial load and circumferential pressure. It can be seen from the performance evaluation of some GLCS versions that GLCS has cut down its mechanical function while continuously improving its comfort. Other prototypes categorized as tension-pressure garments are based on the principle of providing pressure along the vertical axis of the body. Gas-pressure countermeasures, for example, lower body negative pressure (LBNP) garment uses negative pressure to create a ground reaction force on the bottom of the foot. The energy consumption and bulkiness of LBNP is a problem that needs to be solved. Moreover, some harness-type accessories provide resistance to movement and load on the body by combining with other equipment.
Conclusion and Prospect The key technology for compression garments against microgravity environments is to balance loading functionality and wearing comfort. At the same time, the evaluation of human dressing-related indicators should be strengthened. At present, such compression garments have problems such as insufficient gravity loading and incomplete performance testing. This paper proposes the following countermeasures to solve these problems. On the one hand, the consideration of textile process should be enhanced when fabricating garments. For example, the performance of the garment should be improved by introducing different mechanical properties and other functional yarns. Form different functions in each area of the garment by choosing different molding processes. The relationship between the mechanical properties of garments and the load functions required by the human body should be explored in depth, providing a reliable basis for the preparation of garments. On the other hand, the evaluation of compression garments should include three aspects, i.e., loading functionality, wearing comfort and physiological adaptability. The performance assessment of the mechanical interaction between the garment and the human body should be strengthened. The assessment of the human body's physiological adaptation to garment can be reinforced by introducing simulation technology. The future research direction focuses on three aspects: material process, evaluation system and technology transformation. Researchers can focus on developing new materials that are durable, moisture permeable and comfortable, whilst engineers should concentrate on improving the intelligence and accuracy of evaluation methods. Further, efforts can be made to convert this aerospace technology into rehabilitation measures for bedridden patients.

Flower-shaped graphene oxide in-situ unfolding polyamide-6 and functional fibers thereof

CHEN Chen, HAN Yi, SUN Haiyan, YAO Chengkai, GAO Chao

Journal of Textile Research. 2023, 44(01):  47-55.  doi:10.13475/j.fzxb.20220709209

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Objective Graphene has the highest mechanical strength, electrical conductivity and thermal conductivity among all known materials, with unique characteristics in optics, acoustics, electromagnetism, catalysis and so on. Therefore, the combination of conventional materials and graphene would lead to novel composite materials with high performance and multi-functions. Among them, graphene composite fibers have been extensively explored in the last decade. Compared with conventional fibers, graphene composite fibers have demonstrated obvious advantages in mechanical strength, thermal conductivity, electrical conductivity, flame retardancy, antibacterial property, far infrared emission, UV protection, corrosion resistance and other properties. However, blending and surface treatment methods lead to defects in mechanical properties, durability, color diversity and weaving of composite fibers, which needs to be further improved.
Method An in-situ unfolding polymerization strategy was introduced to massively prepare multifunctional polyamide-6/graphene fibers, in which graphene sheets grafted with polyamide-6 (PA6) distribute uniformly. Flower-shaped graphene oxide (fGO), which was obtained by spray-drying of graphene oxide aqueous dispersion, was added into melted caprolactam under stirring. PA6/fGO chips were prepared by polymerization process. The whole reaction took place in a 3 L autoclave, using water as catalyst. The PA6/fGO chips were then melt spun into continuous fibers for characterization.
Results After a process of swelling, expansion and dissociation, fGO was tranformed into GO sheets in melted caprolactam, where strong interactions took place between caprolactam molecules and GO sheets via hydrogen bound (Fig.1, Fig.2). The homogeneous dispersion of GO sheets in melted caprolactam was obtained by dispersing fGO powder for 1.5 h. During the polymerization process, the surface of GO was grafted by PA6 molecules, which improved the interface compatibility between GO and PA6 (Fig.3). PA6/fGO was dispersed steadily in 64% formic acid, and such mechanism was further proved in AFM detection. The PA6/fGO copolymer was shown in the form of flakes with a height of 4-5 nm, higher than that GO (0.8 nm) and that of graphene (0.34 nm). The chips of PA6/fGO show excellent spinnability, and the composite fiber can be woven into fabircs (Fig.4). The polymerization process was not sufficient to fully reduce graphene oxide, while the addition of fGO led to the crystal transformation of PA6, conducive for obtaining higher strength (Fig.5). Low amount of fGO was able to improve the crystallinity of polymer and higher crystallization temperature, but the effect on the relative viscosity and thermal weight loss was not obvious (Fig.6, Fig.7 and Tab.1). The tensile strength of PA6 single fiber was increased by 25.4% and the tensile modulus 49.5% with the addition of 0.1% fGO, whereas increasing the fGO content by 0.6% resulted in decrease in the mechanical properties of the composite fiber (Fig.8). With outstanding functions in antibacterial performance, antiviral behavior, far infrared emission, negative ion generation, and UV protection, the PA6/fGO composite fabric shows broad application prospects (Tab.2).
Conclusion Flower-shaped graphene oxide and PA6 are compounded by in-situ unfolding polymerization. It was found that the flower-shaped graphene oxide microspheres gradually swell, expand and dissociate in melted caprolactam, and that the unfolded graphene oxide sheets are covalently grafted with PA6 molecules, forming a polymer brush structure, which improves the interface compatibility. The chain growth of PA6 will not be affected by low dosage addition of fGO, which would however induce transformation of PA6 crystal into a more stable form. The crystallinity of PA6 demonstrates a peak with the addition of fGO. The low dosage addition of graphene oxide has little effect on the relative viscosity and thermal weight loss of PA6, and the tensile strength and tensile modulus of the fiber increases by 25.4% and 49.5%, respectively. The composite fiber demonstrates multifunctionality in effective antibacterial performance, anti-virus behavior, far infrared emission, ultraviolet protection, and negative ion generation. The applications of PA6/fGO multifunctional fabric in different areas remain to be explored in the near future.

Preparation of green-solvent-based polyamide nanofiber membrane and its air filtration performance

ZHOU Wen, YU Jianyong, ZHANG Shichao, DING Bin

Journal of Textile Research. 2023, 44(01):  56-63.  doi:10.13475/j.fzxb.20220607808

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Objective The epidemic of COVID-19 and its variants is endangering human health. Wearing protective masks can effectively reduce the infection risk by resisting the inhalation of the polluted air containing the coronavirus. Electrospun polyamide nanofibers can be used as the core layer of protective masks and have lately received growing attention because of their high filtration performance and robust mechanical properties. However, existing electrospun polyamide nanofiber filters are usually prepared from toxic solvents which could cause severe environmental pollution and endanger workers' health, hence, their practical application should be restricted. Therefore, it is imperative to seek and develop green-solvent-based polyamide nanofiber filters.
Method Innovative polyamide nanofiber filters were developed by direct electrospinning technique based on green solvents (Fig.1). Ethanol as the solvent and water as the nonsolvent were adopted to prepare the green-solvent-based polyamide (GSPA) nanofibers by designing spinning solutions with different ethanol/water mass ratios (i.e., 10:0, 9:1, 8:2, 7:3, and 6:4). During electrospinning process, the working voltage, tip-to-collector distance, and solution extrusion speed were set as 30 kV, 15 cm and 1 mL/h, respectively. The nanofibers prepared with the different ethanol/water ratios were denoted as GSPA-0, GSPA-1, GSPA-2, GSPA-3, and GSPA-4, respectively.
Results It was found that water content had a great influence on the morphological structures of polyamide nanofibers (Fig.2). After introducing a small amount of water, the obtained GSPA-1 nanofibers featuring thinner diameter of 332 nm were compared to the GSPA-0 nanofibers (499 nm). The enhanced conductivity (10.5 μS/cm) of waterborne spinning solutions (Fig.3) stimulated more charges on spinning jets and led to larger electrostatic force, thus greatly elongating the jets and thinning the fiber diameter. However, with the further increment of water concentrations from 20% to 40%, the obtained fibers exhibited an increased average diameter ranging from 443 to 1 553 nm, which was mainly attributed to the larger viscosity of spinning solutions. Although water cannot dissolve polyamide, homogenous waterborne polyamide/ethanol solutions can still be obtained with different ethanol/water mass ratios within a broad area in the stable region (Fig.3). The average pore size of GSPA-1 membranes decreased by 55% compared with that of GSPA-0 membranes, contributing to high filtration efficiency. Moreover, with different concentrations (10%, 20%, 30%) of water, the fluffy structure of GSPA nanofibers were achieved with a high porosity (>80%), which would offer more passageways to transmit air rapidly. As the water concentration increased, the breaking strength of membranes increased at first and then decreased (Fig.5), and the GSPA-1 membranes exhibited the highest breaking strength of 5.6 MPa, which was believed to be related to the enhanced entanglements and contacts among the adjacent fibers because of the small fiber diameter. The GSPA-1 membranes displayed the highest filtration efficiency (99.02%) for the most penetration particles (PM_0.3) by virtue of the small fiber diameter but suffered from poor permeability with a pressure drop of 158 Pa. Moreover, the GSPA-1 membranes possessed the highest quality factor of 0.029 3 Pa^-1, suggesting the optimal filtration performance among different GSPA membranes. A high PM_0.3 removal efficiency (>95%) was achieved for GSPA-1 filters under various airflow velocities ranging from 10 to 90 L/min (Fig.7). Compared with conventional melt-blown fibers, the GSPA nanofibers featured a smaller diameter and higher Knudsen number (Fig.8), and PM_0.3 were captured mainly on the surfaces of green polyamide nanofibers (Fig.9), demonstrating the higher adsorption ability benefiting from the larger specific surface area.
Conclusion A cleaner production of polyamide nanofibers for air filtration was proposed by direct electrospinning based on green and sustainable binary solvents of water and ethanol. For the first time, the structure including fiber diameter, porosity, and pore size of electrospun polyamide nanofibers were precisely tailored by manipulating water concentration in spinning solutions. The prepared environmentally friendly polyamide nanofiber filters feature the interconnected porous structure with the nanoscale 1D building blocks (332 nm), mean pore size (0.7 μm), and porosity (84%), thus achieving efficient PM_0.3 capture performance with the filtration efficiency of 99.02% and pressure drop of 158 Pa, which could be comparable to previous toxic-solvent-processed nanofibers. Moreover, the GSPA nanofibers exhibit robust mechanical properties with an impressive breaking strength (5.6 MPa) and elongation (163.9%), contributing to withstanding the external forces and deformation in the practical assembly and usage of resultant filters. It is envisaged that the green-solvent-based polyamide nanofibers could be used as promising candidates for next-generation air filters, and the proposed waterborne spinning strategy can provide valuable insights for cleaner production of advanced polyamide textiles.

Preparation and properties of antibacterial and anti-contamination biological protective materials

XIA Yong, ZHAO Ying, XU Liyun, XU Sijun, YAO Lirong, GAO Qiang

Journal of Textile Research. 2023, 44(01):  64-70.  doi:10.13475/j.fzxb.20220605207

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Objective Virus epidemic takes place frequently worldwide, and the demand for medical protective clothing as an emergency epidemic prevention material is soaring. At present, the use of disposable protective clothing is a common practice, but it is difficult to deal with the medical wastes, which brings great load to the environment. In addition, medical staff are prone to sweltering, dizziness, nausea and other problems when carrying out high-intensity work. Therefore, there is a need for biological protective materials with high protection, high moisture permeability, washing resistance and applicability to the preparation of medical protective clothing.
Method Integrated design of biological protective materials was carried out with properties including high barrier, bacteria resistance, virus resistance, contamination resistance, high moisture permeability and washing resistance. Nano silver (AgNPs) antibacterial agent was prepared by chemical in-situ reduction with silver nitrate (AgNO₃) as silver source and waterborne polyurethane (WPU) as protective agent. It was mixed into thermoplastic polyurethane (TPU) solution and electrospun to prepare silver-loaded TPU nanofiber membrane, which was used as the inner layer of biological protective material. With the help of plasma technology, nano-scale grooves were etched in the surface of polyester fiber, and polydimethylsiloxane (PDMS) was used as hydrophobic finishing agent to treat polyester fabric, and PDMS hydrophobic film was formed on its surface, and this was used as the outer layer of biological protective material. The inner layer and the outer layer were glued together and compounded to obtain a complete biological protective material.
Results The surface of pure TPU nanofiber membrane was smooth, while uniform AgNPs particles were seen on the surface of silver-loaded TPU nanofiber membrane(Fig.1), suggesting that silver nanoparticles were successfully loaded on the TPU nanofiber membrane. The original polyester fiber has a smooth and flat surface. After plasma treatment, obvious grooves appear in the surface. After hydrophobic treatment, PDMS film is formed on the fiber surface (Fig.3). After hydrophobic finishing, the water contact angle of polyester fabric reaches about 140°, and after washing for 50 cycles, there is no downward trend(Fig.5), which indicates that PDMS is firmly combined with polyester matrix after film formation. When the silver content of the bioprotective material is 200 mg/kg, after washing for 50 cycles, the antibacterial rates of the biological protective material to Escherichia coli and Staphylococcus aureus are 99.89% and 99.27%, respectively. When the silver content increased to 300 mg/kg, after washing for 50 cycles, the antibacterial rate to Escherichia coli and Staphylococcus aureus was 99.99%. (Tab.1). The spraying wetting grade of biological protective materials is grade 5, and it drops to grade 4 after 50 cycles of washing (Tab.2). After 50 cycles of washing, the moisture permeability and tensile property of the biological protective material hadn't changed obviously, the water vapor transmission rate kept 2 654.8 g/(m²·24 h), and the breaking strength kept around 450 N (Fig.6). After 50 cycles of washing, the filtration performance of the bioprotective material remained stable, and the waterproof performance declined slightly. The filtration efficiency of solid particles remained above 99%, and the hydrostatic pressure decreased from 73.5 kPa to 53.6 kPa (Fig.7).
Conclusion The biological protective material prepared by the above method can be possibly used for the development of reusable medical protective clothing with active antibacterial and antiviral functions while efficiently blocking, thus achieving the purpose of efficient protection. TPU nano-fiber membrane enables both micro-pore and molecular moisture conductions at the same time, and the subsequent dispensing compound technology ensures the high comfort of medical staff to the maximum extent. In the future, reusable medical protective clothing is expected to popularly used, and lightweight and portable temperature regulating devices can be possibly prepared by 3D printing technology, so as to endure a medical protective clothing with high protection, high moisture permeability, temperature regulation and contamination resistance.

Fiber Materials

Combustion and charring behavior of polyphenylene sulfide/graphene nanocomposite fibers

DAI Lu, HU Zexu, WANG Yan, ZHOU Zhe, ZHANG Fan, ZHU Meifang

Journal of Textile Research. 2023, 44(01):  71-78.  doi:10.13475/j.fzxb.20210908308

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Objective Poplyphenylene sulfide (PPS) fiber has outstanding performance and cost advantage, and can be used for making heat protection fabrics. However, when it burns, the release of heat and smoke is likely to cause damage to human body. The loose charcoal layer of its combustion will lead to high thermal and smoke release, which will cause harm to the human body. This paper is proposed to improve the structure of PPS burning charcoal layer to achieve low release of heat and smoke, and explores the applications of PPS in engineering thermal protection fabrics.
Method Based on the obstruction effect of graphene (G) and its application in the field of flame retardancy, graphene was introduced to the PPS matrix and melting spinning was adopted to prepare PPS/G fiber. In the study, the crystallinity and orientation structures of the fiber were explored by differential scanning calorimeter and an X-ray diffractometer, and the mechanical properties of the fiber were also investigated. The PPS/G fiber was made into fabrics, cone is adopted to study the heat and smoke release of combustion, and the Raman maps and SEM images of the burning charcoal layer were adopted to clarify the changing mechanism of combustion behavior.
Results PPS/G fibers were prepared by introducing graphene into the PPS matrix, and its microstructure and physical images suggested the characteristics of smoothness and uniformity, indicating that graphene can be well dispersed in the PPS matrix and that the fiber forming process is relatively stable. The mechanical properties of PPS/G fibers were positively influenced by graphene, and the breaking strength and elongation at break were both improved prominently (Fig.3). When the content of graphene was 0.5%, the breaking strength of the fiber was increased to 4.63 cN/dtex, while when the content of graphene was 0.3%, the elongation at break was increased to 22.01%. The improvement of mechanical properties is very beneficial for the application of fiber. In the aspect of combustion performance, the addition of graphene has a significant inhibitory effect on smoke release and heat release. The doped of graphene reduced the peak heat release rate (PHRR) of PPS from 67 kW/m² to 28 kW/m², the total heat release (THR) was reduced from 3.38 MJ/m² to 1.28 MJ/m², and the total smoke production was reduced from 1.055 m² to 0.358 7 m² (Fig.5). All these can be attributed to the change of combustion residual carbon. On the one hand, the quality of combustion residual carbon was significantly improved, at 800 ℃, the residual carbon content of PPS/G fiber was significantly higher than that of pure PPS (Fig.4). On the other hand, the change in structure of carbon residue was obvious. The compactness of the residual carbon is significantly increased, and the carbon layer of PPS/G fabric exhibited a non-porous nature (Fig.6). It is found that the graphitization degree of carbon layer was also significantly increased (Fig.7). The conversion of carbon content and structure is beneficial to inhibit the heat and smoke release, which is the key to the change of PPS/G fabric combustion performance.
Conclusion With the addition of graphene, the barrier effect of carbon layer in PPS/G combustion was effectively increased, and the heat release and smoke release of PPS fabric were significantly reduced. However, for the demand of thermal protection fabric, the blending and other processes need to be further explored to achieve higher heat blockage and smoke inhibitory effects. New solutions that meet the advantages of price and heat protection need to be further sought.

Preparation of cellulose/carbon nanotube composite fiber and its functional applications

PU Haihong, HE Pengxin, SONG Baiqing, ZHAO Dingying, LI Xinfeng, ZHANG Tianyi, MA Jianhua

Journal of Textile Research. 2023, 44(01):  79-86.  doi:10.13475/j.fzxb.20211007408

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Objective Although cellulose fiber has advantages in high moisture absorption, good wearing comfort and low cost, its applications are limited due to its singular function and poor mechanical properties. The introduction of functional materials to give cellulose good electrical conductivity is significant to expand its applications. This research worked to disperse carboxyl-modified carbon nanotubes (CNT) evenly in the cellulose spinning dope so as to achieve high strength and good electrical conductivity of the modified cellulose fibers.
Method In the experiment, carboxyl-modified CNT was dispersed well in sodium hydroxide/urea solution, which can dissolve cellulose at a low temperature (-10 ℃). The composite fibers with different CNT contents (mass fractions of 5%, 10%, 15%, and 20%) were prepared by a laboratory wet spinning device. Meanwhile, the microstructure, mechanical properties and electrical properties of the composite fibers were characterized by scanning electron microscope, X-ray diffractometer,infrared spectrometer,mechanical property tests, and multimeter.
Results When the composite fibers were prepared by wet spinning, CNT maintained directional alignment because of the powerful shearing effect, which effectively improved the performance of the fiber. The surface of the cellulose fiber was smooth, while CNT was uniformly distributed along the radial direction of the composite fiber. It can be seen from the cross-sectional structure that the obtained fibers were dense when a large amount of CNT was encapsulated in the cellulose matrix to form a composite structure(Fig.4). In addition, the XRD and FT-IR spectra (Fig.5, Fig.6) indicated that hydrogen bonding interactions formed linkage between the CNT and cellulose molecular chains. The oriented structure of CNT and the hydrogen bonding interaction with the cellulose molecular chains benefited the composite fiber's mechanical properties. The stress-strain curves of the composite fibers with cellulose/CNT (C/CNT) show that the addition of CNT significantly improved the strength and stiffness of the composite fibers(Fig.7). The breaking strength was 165 MPa when the mass fraction of CNT was 20%, representing an improvement compared to the pure cellulose fiber. In addition, the composite fiber demonstrated electrical resistance of 100,3 kΩ when the mass fraction of CNT was 10%, 20%. Based on cellulose's moisture-absorbing and swelling properties, the composite fiber was further applied to the field of humidity sensing. The composite fiber exhibits excellent humidity sensitivity at room temperature, both air blowing and water immersion of the fiber resulted in detectable resistance changes (Fig.8). The electrothermal performance test revealed that the C/CNT composite fiber with a 20% CNT mass fraction exhibited excellent electrical heating performance. The temperature of the specimen rose to 62.3 ℃ within 15 s when the voltage was increased to 30 V (Fig.9).
Conclusion A homogeneous and stable spinning solution was prepared by virtue of the fact that carbon nanotubes can be well dissolved in sodium hydroxide/urea. The C/CNT composite fibers were prepared by wet spinning. Compared with the original cellulose fiber, the good dispersion and the enhanced interface provided the composite fiber with superior mechanical properties. Combined with the scalability of the wet spinning process and the versatility of flexible conductive fibers, the related work reported in this paper provides a reference for the development and design of lightweight and flexible sensing fabrics in wearable electronics.

Preparation and performance of high efficiency and low resistance polypropylene melt-blown fiber based on supercritical carbon dioxide

TAN Linli, QIN Liu, LI Yingru, DENG Lingli, XIE Zhiyin, LI Shidong

Journal of Textile Research. 2023, 44(01):  87-92.  doi:10.13475/j.fzxb.20211006006

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Objective This work was carried out to reduce the diameter of melt-blown polypropylene (PP) fabric and to solve the contradiction between filtration efficiency and filtration resistance of the melt-blown fabric during air filtration.
Method Two types of novel PP superfine melt-blown fiber were prepared. One was prepared by melt-blowing assisted by electrostatic field, and the other was prepared by firstly treating PP with supercritical carbon dioxide and then melt-blowing assisted by electrostatic field.
Results PP melt-blown fiber was prepared by melt-blowing assisted by electrostatic field. The fiber was thinned, the average diameter of the fiber was decreased from 3.22 μm to 2.44 μm by about 24.2%, and the filtration efficiency was increased from 98.78% to 99.01%. After supercritical CO₂ treatment, the viscosity of PP melt decreased, and the average diameter of the fiber was further decreased to 1.73 μm with the minimum diameter of 780 nm under the synergistic effect between electrostatic field and airflow field. With the decrease of the fiber diameter, the fiber diameter distribution became narrower, the bond point between fibers was decreased, the porosity and specific surface area were increased, and the fiber was more likely to capture the charge generated by corona discharge in the electret process, significantly improving the barrier capability and air permeability of micro-nano fiber. In other words, the contradiction between filtration efficiency and filtration resistance was effectively overcome. The filtration efficiency of the prepared melt-blown fiber was 99.25% for 0.3 μm particles, the filtration resistance was only 23 Pa, with a satisfactory quality factor of 0.213 Pa^-1. Compared with ordinary PP melt-blowing fiber, the breaking strength of melt-blown fiber prepared assisted by only electrostatic field or the combination of supercritical CO₂ treatment and electrostatic field decreased from 2.12 MPa of conventional melt-blown fiber to 1.17 and 1.26 MPa, representing decrease rates of about 44.8% and 40.0%, respectively. The elongation at break was significantly improved, and the decrease of the breaking strength was mainly attributed to the decrease of fiber diameter. In addition, the effective bonding points between fibers became fewer, leading to further reduction in fiber strength.
Conclusion Two types of novel PP superfine melt-blown fiber were prepared, by melt-blowing assisted by electrostatic field and by melt-blowing assisted by electrostatic field following the fiber treatment by supercritical carbon dioxide. Thanks to the synergistic effect of supercritical carbon dioxide pre-treatment and the assistance of electrostatic field, the prepared melt-blowing fiber shows good barrier capability as well as good air permeability. The contradiction between filtration efficiency and filtration resistance of melt-blown fiber in the process of air filtration is effectively solved.

Simulation and analysis of fiber motion in airflow field of melt blowing

HAN Wanli, XIE Sheng, WANG Xinhou, WANG Yudong

Journal of Textile Research. 2023, 44(01):  93-99.  doi:10.13475/j.fzxb.20211003707

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Objective In the melt blowing process, the polymer melt is attenuated and formed into microfiber in the high velocity airflow field, the fiber motion together with the airflow field play an important role in the fiber formation. The complex interplay between air velocity and polymer motion can affect the final fiber quality, and the velocity and distribution of the airflow requires study and analysis. The information of fiber motion is sought to reveal the mechanism of the formation of microfibers during melt blowing process. It is essential to understand and optimize the melt blowing process.
Method The airflow field was simulated with the computational fluid dynamic approach for the melt blowing process. The characteristics of distribution for airflow field were investigated, with attentions paying to the airflow alone zone, airflow confluence zone and airflow merge zone. The fiber was modeled using mixed Euler-Lagrange approach, and the motion was predicted in the melt blowing process. The standard linear solid (SLS) models in the bead-viscoelastic fiber element were proposed for melt blown fiber formation simulation. The simulated fiber motion was compared with the fiber motion in experiment, which was captured with a high-speed camera.
Results The simulation results show that there are two airflow recirculation zones between the converging jets for the melt blowing slot-die. The recirculation zones are in a subtriangular area near the die face and are filled with hot air (Fig.3). It is important for not only rapid fiber attenuation but also energy conservation. The melt blowing airflow field is divided into the airflow alone, the airflow contact fusion zone and the airflow merge zone. The distribution of the airflow field causes the airflow velocity to vary at different positions. At x=0 mm and z<1 mm, the airflow velocity fluctuates because there is a recirculation area of the airflow under the melt blowing die. When z>1 mm, the airflow velocity increases first and then decreases. The maximum air velocity is 165.88 m/s at z=5 mm, indicating that the two airflows merge together (Fig.4). For the melt blowing fiber motion simulation, it is found that the airflow turbulent fluctuations are related to the fiber motion in the melt blowing process. The fiber path shows a small perturbation developing into the whipping in the airflow zone alone. As the fibers continue to move, there is fiber crossing and loop formation in the airflow merging zone. In the airflow contact fusion zone, the fiber whipping increases and the drawing ratio is the largest (Fig.5, Fig.6), and this is the main zone of fiber refinement. The fiber motion is also recorded and observed using high-speed camera. In the beginning, the fiber is a straight segment and fluctuates, and then the trajectory forms the fiber loop in the move path. The fiber loops are drawn and elongated in the airflow field. The elongation of the fiber loop results in the attenuation on fiber diameter (Fig.7). The whipping, folding into loops and trajectories of fiber motion are consistent with the simulation results.
Conclusion The airflow field for the melt blown slot-die is simulated. There are three airflow distribution zones: the airflow alone, the airflow contact fusion zone and the airflow merge zone. The distribution of the airflow field has an important influence on the fiber motion. The motion process of the fiber in the melt blowing airflow field is simulated and analyzed using the Euler-Lagrange method. It is pointed out that the melt blowing fiber was divided into three stages in the drawing process. The polymer jet appears with the whipping motion in the airflow alone and the whipping of fiber increases in the airflow contact fusion zone. The fiber movement appears to cross and fold into loops in the airflow merge zone. The motion of the melt blowing fibers is also captured by high-speed camera experiments. It is found that the continuous semi-annular loops appear during the fiber forming process, and the whipping of fiber has an important effect on fiber attenuation. Using airflow simulation and fiber model, fiber attenuation is known to be strongly dependent on airflow field and fiber motion. This work provides an insight that the melt blowing airflow field and the fiber attenuation which gives a useful understanding for the melt blowing fiber formation.

Textile Engineering

Influence of yarn twist on properties of cotton/spandex/silver wire core spun yarns

LI Long, WU Lei, LIN Siling

Journal of Textile Research. 2023, 44(01):  100-105.  doi:10.13475/j.fzxb.20211100606

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Objective The application of conductive yarns in flexible and wearable smart devices has attracted extensive attention from many researchers. The key objectives of this research included preparing elastic and conductive yarns with excellent textile properties such as color attributes, wearing comfort, and environmental friendliness.
Method In order to prepare a conductive yarn with favorable textile properties, cotton roving, silver wire and spandex were selected as the raw materials. By designing the feeding of raw materials and attaching a positioning device between the front roller and the yarn guide in the ring spinning machine, an elastic conductive core yarn with spandex as the core, silver yarn and cotton fibers as the sheath with cotton fibers on the surface of the yarn was produced to investigate the influence of yarn twist on the elasticity, conductivity, abrasion resistance and breaking strength of the core spun yarn. Using the model of silver wire tightly wrapped around the spandex surface (Fig.2), the theoretical value of the length of silver wire wrapped around the spandex surface in the core spun yarn with different yarn twist was calculated.
Results The experimental results showed that the elasticity of core spun yarn varied with yarn twist, and the elasticity of core spun yarn at constant elongation and at constant load was larger at a yarn twist of 70 twist/(10 cm) than yarns with other yarn twists (Fig.4). In the unstretched straight state of the core spun yarn, the measured resistance of the yarn increased with the increase of yarn twist (Tab. 2), because increasing the yarn twist causes the pitch of the wrapping silver wire to decrease and the length of the silver wire in the unit length of core spun yarn to increase. At 10% elongation of the core spun yarn, the measured resistance of the yarn was smaller than that of the same length of core spun yarn in the unstretched state, and the difference between the measured resistance of the same length of core yarn in the elongated state and in the unstretched state was smaller at a twist of 75 twist/(10 cm) (Tab. 3). At 10% elongation of the core spun yarn, the measured resistance of the core yarn per unit length was greater than the theoretical resistance of the straight silver wire, indicating that when the core spun yarn elongation is at 10%, the silver wire in the yarn was not at the completely straightened state, and the yarn elongation caused the pitch of the silver wire over the spandex became larger and the actual length of the silver wire in the core spun yarn per unit length became smaller. At 75 twist/(10 cm), the core spun yarn showed higher wear resistance. Because when the twist is too high, the torque of cotton fibers in the yarn is high, the fiber stress increases, causing the cotton fibers to be easily worn off and the wear resistance of the core spun yarn is reduced.
Conclusion The elasticity and conductivity of core spun yarn are closely related to the yarn twist level. For the actual core spun yarns, the silver wire is not tightly wrapped around the surface of the spandex core, and there are cotton fibers between the spandex and the silver wire, causing the theoretical resistance value per unit length to be smaller than the measured resistance value. Since cotton fibers can be dyed in different colors and the cotton fibers are distributed on the surface of the core spun yarn, this work can be used to further develop elastic and conductive yarns in different colors and comfortable to wear for the transmission of electrical signals in smart wearable textiles, powering electronic textiles, and electrical heating devices. The preparation process of this core spun yarn is environmental friendly. In the application of flexible and wearable smart devices, such elastic and conductive core spun yarsn have a good development prospect.

Influence of twist on quality indexes of polyamide/cotton blended yarns

YU Xuezhi, ZHANG Mingguang, CAO Jipeng, ZHANG Yue, WANG Xiaoyan

Journal of Textile Research. 2023, 44(01):  106-111.  doi:10.13475/j.fzxb.20211104206

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Objective Polyamide /cotton blended yarns not only possess outstanding wear resistance, elasticity, fatigue resistance and impact properties of polyamide fiber, but also moisture absorption and permeability, soft and warm characteristics of cotton fiber. In order to further improve its quality, the relationship between twist and each quality index of a polyamide/cotton blended yarn was analyzed to predict the blended yarn quality based on the yarn twist. The study provides theoretical basis for twist design and rapid adjustment in spinning production.
Method The polyamide/cotton blended yarns with linear density of 27.9 tex and blending ratio of 50:50 was spun from polyamide 66 with linear density of 1.67 dtex and length of 38 mm and Xinjiang cotton fiber 229 with a linear density of 1.64 dtex by conventional ring spinning. 16 polyamide/cotton blended yarns were spun on FA506 spinning frame by changing the twist gear and setting 16 twist levels. In the spinning process, the sliver blending was adopted, where polyamide sliver and cotton sliver were produced by blowing-carding process respectively, three blending, roving and spinning.
Results The relationship between twist and quality indexes of polyamide /cotton blended yarns was analyzed by the SPSS software. Twist was significantly correlated with 6 quality indexes, i.e., breaking strength, breaking strength CV, breaking elongation, thick places, thin places and hairiness. However, it has little correlation with elongation CV, evenness and neps index of blended yarn (Tab.2). By using the SPSS software, the scatter plot of twist and the above-mentioned six quality indexes was drawn, and the regression curve was plotted. The regression curve shows that the six quality indexes of polyamide/cotton blended yarn do not show linear distribution against twist variation trend (Fig.1, Fig.2). Therefore, the best fitting equation between twist and these six quality indexes was obtained by the curve estimation and fitting analysis method provided by the SPSS software (Tab.3).
The breaking strength of polyamide /cotton blended yarns increases first and then decreases with the increase of twist (Fig.1, Fig.2 and Tab.3). The fitted model judgment coefficient is 0.919, the critical twist is 1 228 twist/m, and the corresponding maximum breaking strength is 8.1 cN/tex. The fitting curve of the breaking strength CV of the blended yarn shows a trend of rising first and then falling, the fitted model judgment coefficient is 0.653, and at the twist of 1 307 twist/m the curve demonstrates a maximum value. The breaking elongation of blended yarns increases with the increase of twist, and the fitted model judgment coefficient of regression equation is 0.627.
The thick places and thin places of polyamide /cotton blended yarn decrease with the increase of twist, and increase with the increase of twist when it decreases to a certain extent. The judging coefficients of the cubic fitting curve are 0.790 and 0.748, when the minimum value of fitting curve appears, the twist is 1 259 and 1 407 twist/m, respectively. The hairiness of blended yarn decreases with the increase of twist, and then tends to level off. The judging coefficient of the cubic fitting curve is 0.971. In order to further verify the validity of the fitting equation model, the residuals between the test data and the predicted values of 6 quality indexes of blended yarn are calculated, the absolute value of the residual value between the test group data and the predicted value was within 3 standard deviations of the residual value, and there is no abnormal point (Tab.4).
Conclusion In this paper, a regression model presenting the relationship between breaking strength and elongation, thick places, thin places, hairiness and twist of polyamide /cotton blended yarn was established using SPSS software, and the validity of the model was verified by the residual error between the test group data and the predicted value with good forecasting capability. It shows that twist can reasonably reflect the tensile properties, thick places, thin places and hairiness of polyamide/cotton blended yarn.
The significance of this model is that it can predict and control the tensile properties, thick places,thin places and hairiness of polyamide/cotton blended yarn based on the twist of process parameters during spinning. The twist of the yarn could be designed and adjusted according to customer requirements to reduce the test cost and to achieve high efficiency and energy saving.

Structural design and forming method for one-piece sports knee pads

FENG Yingjie, JIANG Gaoming, WU Guangjun, JIN Shuai

Journal of Textile Research. 2023, 44(01):  112-118.  doi:10.13475/j.fzxb.20210906207

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Objective In order to explore possibilities of developing whole garment knitted products with computerized flat knitting machines, different design methods and forming processes of whole garment products were explored. Taking the knitted sports knee pads as the research object, the design method of the one-piece local multi-layer structure was established by local structure manipulation, leading to the development of various fully formed products with required functionalities.
Method The knee data was obtained by the three-dimensional scanning system, the two-dimensional paper sample size of the knee pads was determined, and the dimensions of the process parameters were substituted into the two-dimensional paper sample to obtain the knitting process parameters for the one-piece knee pads. Local change stitch for knee pads was experimented and designed, and the one-piece partial multi-layer structure was developed by the double needle bed computerized flat knitting machine and the SDS-ONE APEX3 software system. Different loop structures were designed in the patella part and sides of the knee pads to achieve the required protection.
Results With the cooperation of the special yarn self-propelling mouth of the double needle bed computerized flat knitting machine, density triangle and elastic yarn feeder, a three-layer loop structure was knitted at the knee patella (Fig.6), to knit a section of knitted fabric with certain thickness and good elasticity to replace the conventional protective materials.High elastic rubber band and camel hair (Fig.10) were used to increase the elasticity of the overall and local multi-layer structures of the whole garment motion knee pad. Through orthogonal test, the best knitting scheme was determined, and the knee pads with the highest elastic recovery rate (Tab.2) was obtained.
Using the double needle bed computerized flat knitting machine, a section of plain/ring/plain local multi-layer structure was knitted in the knee pad to replace the silicone protective sheet of the conventional sports knee pad. On both sides of the knee pad, and the lower end of this section of air layer was closed and the upper end was open. A section of air layer structure with two ends connected and the middle separated was knitted to fix the spring strip (Fig.12).
The three-layer patella protective layer knitted by the whole garment method was found 68.2% lighter than the conventional silicone patella protective sheet (Fig.13). In addition, the whole garment method eliminated the necessity for cutting and sewing after knitting, and avoided the loss of raw materials in the cutting process, resulting in benefits in saving labor costs, shortening production process, and reducing the loss of raw materials.
Conclusion This paper explores a local multi-layer knitting method of a double needle bed computerized flat knitting machine. By structural design and technological practice, three layers of three-dimensional spacer tissue are used as the patella protective layer at the front of the knee instead of the conventional sports knee pad. A double-layer air layer structure is knitted at the side to fix the spring strip, changing the conventional fixation method of hot-melt adhesive bonded cloth. Sports knee pads knitted with whole garment technology have greatly improved the comfort, shortened the processing flow in production, reduced the consumption of raw materials, and met the requirements of current green development.The development of one-piece sports knee pads expands the application direction of whole garment technology. The experimented knitting method of one-piece partial multi-layer structure can be applied for more applications, with required functionality and high added value.

Influence of interfacial layers on fracture toughness of three-dimensional woven angle interlock SiC_f/SiC composites

DUAN Yadi, XIE Weijie, QIU Haipeng, WANG Xiaomeng, WANG Ling, ZHANG Diantang, QIAN Kun

Journal of Textile Research. 2023, 44(01):  119-128.  doi:10.13475/j.fzxb.20211203910

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Objective Three-dimensional woven angle interlock SiC_f/SiC composites have the advantages of high temperature resistance, low density and long service life, and are an ideal candidate material for thermal aviation terminal components. At present, the research of SiC_f/SiC composites mainly focuses on the first- and second-generation SiC fibers, but few studies on the mechanical properties of the third generation SiC fibers and their three-dimensional woven angle interlocking composites were reported.
Method In order to explore the influence of interfacial layer on fracture toughness of SiC_f/SiC composites, the third generation SiC fibers made in China was selected. Three-dimensional woven angle interlock SiC_f/SiC composites with four interface phases including pyrolytic carbon (PyC), pyrolytic carbon/silicon carbide (PyC/SiC), boron nitride (BN) and boron nitride/silicon carbide (BN/SiC) were prepared by the precursor infiltration pyrolysis processes, chemical vapor deposition process and chemical vapor infiltration process. On this basis, combined with acoustic emission technology, the normal temperature fracture toughness test was carried out, and the microscopic damage mode was evaluated by scanning electron microscopy.
Results All samples showed the characteristic of "pseudo-plastic fracture" (Fig.8). The fracture strengths of P-SiC_f/SiC, P/S-SiC_f/SiC,B-SiC_f/SiC and B/S-SiC_f/SiC are 193.36, 233.97, 89.43 and 218.49 MPa, respectively, and the modulus thereof are 33.86, 33.36, 32.03 GPa and 31.37 GPa, respectively (Fig.9). It was found that the samples with PyC as the main interfacial layer offer good fracture toughness, and the fracture toughness of P-SiC_f/SiC and P/S-SiC_f/SiC are 13.99 and 16.93 MPa·m^1/2, respectively (Fig.10). On the other hand, the B-SiC_f/SiC samples show strong interfacial bonding, with the lowest fracture toughness of 6.47 MPa·m^1/2. However, the fracture toughness of B/S-SiC_f/SiC samples is significantly increased to 15.81 MPa·m^1/2 when the SiC layer is introduced into the interface. The results show that the interfacial layer in the SiC_f/SiC composites has a strong influence on the fracture strength and fracture toughness, but has no great influence on their initial modulus, which mainly depends on the fiber structure and the stiffness of the matrix. In the microscopic damage morphology of SiC_f/SiC composites, the meso-damage of the four samples all involve the matrix fracture, the interface damage, the debonding between fiber and matrix, the fiber fracture and the fiber pulling-out (Fig.11, Fig.12). However, the types of main body damage are obviously different, the sample with composite interface layer produces more AE events before the fiber failure due to the blocking effect of SiC layer on the crack (Fig.13).
Conclusion It can be concluded from the research that the introduction of SiC layer enhances the energy dissipation mechanism of the interface and prevents the crack propagation in the matrix, the cracks in PyC layer and BN layer can be deflected effectively, and the mechanical properties of SiC_f/SiC composite are improved. In addition, acoustic emission (AE) event energy values and numbers of impact can completely describe the real-time damage process of SiC_f/SiC composites. Several problems should be further investigated in the study of the properties of three-dimensional woven angle interlock SiC_f/SiC composites. Firstly, it is difficult to distinguish SiC_f/SiC composites due to their relatively complex microscopic composition and the close density of fiber and matrix. How to monitor the more detailed real-time damage process of materials in the bearing process by means of advanced characterization techniques is a focus of future research. In addition to the experimental testing, it is necessary to develop a high-fidelity numerical simulation method for three-dimensional woven angle interlock SiC_f/SiC composites, establish a more accurate meso-structural model to achieve progressive damage analysis and reveal the failure mechanism.

Compression after impact performance of three-dimensional orthogonal woven composites

YING Zhiping, WANG Weiqing, WU Zhenyu, HU Xudong

Journal of Textile Research. 2023, 44(01):  129-135.  doi:10.13475/j.fzxb.20211003507

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Objective Fiber reinforced composites are widely used in automotive, petroleum, aerospace, and wind energy fields attributed on their high specific strength and modulus. In order to overcome the out-of-plane delamination defects of laminated composites, three-dimensional (3-D) woven preforms are adopted to add reinforcing fibers along thickness direction which effectively prevents delamination cracks. Fabric reinforcement plays an important role in enhancing impact resistance especially under low-velocity impact load. Previous studies have shown that the weaving process can significantly affect the fiber structure. More studies on compression after impact (CAI) of fiber reinforced composites had been carried out, but few studies referred to the influence of weaving tension on the impact resistance of 3-D woven composites. The goal of this research is to investigate the influence of tow tension during weaving on the impact and compression after impact (CAI) performance of 3-D orthogonal woven composite.
Method 3-D woven fabrics were fabricated using self-made loom. Toray T700-24K and T700-12K carbon fibers were used as warp and weft tows, respectively. Aramid yarn from DuPont was used as the z-binding yarn. Warp density and weft density were 50 ends/(10 cm) and 33 picks/(10 cm), respectively. Three tow tension levels (25, 50, 100 cN) were adopted based on the multi-rapier weaving process to obtain 3-D orthogonal woven fabric samples 1-3, respectively. Vacuum-assisted resin transfer technology was employed to fabricate the composite samples. Low-velocity impact test and post-impact compression test were carried out according to ASTM D7136/D7136M-2005 and ASTM D7137 /D7137M-2012.
Results Under the impact energy of 30 J, the 3-D orthogonal woven composites with different weaving tension levels showed different bending stiffnesses and impact strengths, which were specifically notable for the impact force increase rate and impact peak force at the initial stage. The impact resistance of 3-D orthogonal woven composites was expressed as flexural stiffness. Sample 1 had a larger flexural stiffness, and its maximum impact reaction force was 6.3% higher than that of sample 3. The rising stage of the impact force-deformation curves showed different slopes indicating different flexural stiffnesses of the samples. The recovery displacement of sample 3 was the smallest suggesting that a large amount of impact kinetic energy was rebounded. Conversely, the large recovery displacement of sample 1 implying that the impact kinetic energy was absorbed in various forms of damage.
The force-displacement response curves of the composite samples were significantly different, especially in the peak values of the compression load. When the peak values were reached, samples 1 and 2 underwent instantaneous fracture failure, and the bearing capacity decreased rapidly. In contrast, sample 3 had a plateau curve after the peak, which could still bear a certain compression load. The front and back of impact face showed different damage morphologies, including resin fracture and fiber fracture. The z-binding yarns tension caused weft yarn crimping and resin-rich pocket. The samples with high tow tension had a large resin crack and delamination area resulting in the exposure of the weft reinforced tows. In addition, the weft crimping created by high tension of z-binding yarns resulted in buckling failure under compression loading in weft direction. The CAI performance suffered almost 50% decreases with high z-binding yarns tension. Therefore, the increase of z-binding yarns tension reduces the bending stiffness and post-impact compression performance of 3-D orthogonal woven composites.
Conclusion 3-D orthogonal woven fabrics were woven with three tow tension levels. The compression properties of the composite samples were evaluated after impacting on the samples. It was found that when the tension of the z-binding yarns is increased, the crimp of the surface weft tow is increased. The composite material with high z-binding yarns tension formed a large area of delamination on the impact front face, which resulted in the surface weft exposed. The crimping weft tows caused the post-impact compression failure behavior to change from fiber breakage to local buckling, which reduced the compression resistance capacity of the composite. Therefore, the bending stiffness and post-impact compression properties of the 3-D orthogonal woven composites decrease with the increase of the z-binding yarns tension applied during weaving.

Dyeing and Finishing & Chemicals

Replenishment modeling in pad dyeing process with mixed dyes

DAI Yamin, LIU Hongchen, MAO Zhiping, LU Hui, XU Hong, ZHONG Yi, ZHOU Peiwen

Journal of Textile Research. 2023, 44(01):  136-141.  doi:10.13475/j.fzxb.20220100706

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Objective The color matching of dyes is prone to fail in obtaining the desired color in practical production. In the process of continuous pad dyeing, it is necessary to adjust constantly the liquid replenishment to ensure stable dye concentration in the dye bath to avoid color difference between the head and tail in the dyeing process. However, the goal of precise control of the dyeing process cannot be achieved by relying on the experience of dyeing and finishing masters, and replenishment modelling in pad dyeing becomes necessary.
Method In order to explore the digital control method of the replenishment system of mixed dye in the pad dyeing process, the replenishment model was established based on the real-time monitoring of the dyeing process with mixed dyes using Raman spectroscopy. Firstly, the quantitative analysis model of mixed dye concentration with C.I. Reactive Red 195 (RR195) and C.I. Reactive Blue 194 (RB194) was established based on Raman spectroscopy monitoring and partial least square method (PLS). Then, the initial dye uptake rate of RR195 and RB194 were obtained under different dyeing processing conditions. Finally, the replenishment model of the combination pad dyeing was established to calculate the amount of each dye to be added in real-time according to the conservation of mass with dye solution and dyes before and after replenishment, and compared with the replenishment system through the concentration of the original dye solution.
Results The results showed that the correlation coefficients of RR195 and RB194 dyes in the correction set and prediction set in the quantitative analysis model were greater than 0.990 0 (Fig.4), and the root mean square error of cross validation (RMSECV) and the root mean squared errors of prediction (RMSEP) were 0.279 0 and 0.129 0, 0.115 0 and 0.054 5, respectively. The fitting curves of the correction set and prediction set of the two dyes demonstrated a high coincidence. This suggested that the established quantitative analysis model had a high prediction capability. The real-time monitoring of the dyeing process of RR195 and RB194 were achieved by using the quantitative analysis model, according to which the color matching dyeing process of RR195 and RB194 (at a mass ratio 1:1) were obtained in real time. It is assumed that the soaking time of the fabric in the pad dye solution is 6 s, and the initial dye-uptake rate of RR195 and RB194 were calculated as 28.10 and 36.63 mg/(g·min) respectively according to the dye-uptake curves. By using the formula of the replenishment model, it was found that the volume of dye solution to be replenished after dyeing each fabric (3.0 g) was 2.15 mL, and the mass of RR195 and RB194 dyes to be replenished were 13.80 and 16.36 mg, respectively. The color difference of 25 fabrics after the pad dyeing through the replenishment system is maintained at 0.5, and the concentration of RR195 and RB194 in the dye solution remains unchanged. However, the color difference of 25 fabrics after the pad dyeing with original replenishment model is about 7, and the dye concentration of RR195 and RB194 was reduced by more than 50%, which verifies the accuracy of the replenishment model.
Conclusion The experimental results of RR195 and RB194 with color matching dyeing verifies the accuracy of the quantitative analysis model and replenishment model. The developed replenishment model helps control the replenishment system digitally without relying on the human experience, and it minimizes the color difference between the head and tail in the pad dyeing process of color matching. The quantitative analysis model of mixed dye concentration established by Raman spectroscopy and PLS can be used for mixing most dyes without decomposition spectrum. This approach is applicable to further explorations on the influencing factors and mechanism of color matching dyes, and on studying the quantitative evaluation method of color matching dyes.

Dyeing and Finishing & Chemicals

Preparation and performance of disperse dye printed fabrics with characteristics of vegetation-like Vis-NIR reflectance spectrum

ZHANG Diandian, LI Min, GUAN Yu, WANG Sixiang, HU Huanchuan, FU Shaohai

Journal of Textile Research. 2023, 44(01):  142-148.  doi:10.13475/j.fzxb.20211003407

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Objective With the development of hyperspectral remote sensing detection technology, conventional vegetation-like camouflage fabrics are easily detected due to the phenomenon of "metamerism" based on differences in near-infrared bands, which pose a serious threat to the target's battlefield survival. The use of dyes to prepare vegetation-like camouflage fabrics still faces the problems in complex printing and dyeing processes and low efficiency. Therefore, simple and rapid preparation of camouflage fabrics with a high degree of fit with the vegetation background by the direct printing method of disperse dyes is of great significance for the development of military textiles.
Method Based on the principle of subtractive color mixing, the disperse dyes that meet the requirements of vegetation-like camouflage were screened by disperse dye direct printing, then the vegetation-like Vis-NIR reflection spectrum characteristics of the printed fabrics were prepared. The influence of the types and contents of disperse dyes, the types and proportions of dye combinations, fabric specifications and water content on the characteristics of the Vis-NIR reflection spectrum of polyester printed fabrics were studied. The vegetation-like Vis-NIR camouflage performance was analyzed by calculating the Euclidean distance, the spectral angle, and the spectral correlation coefficient between the printed fabric and the leaf reflection spectrum, and the color fastness performance were evaluated.
Results Different species of green leaves have similar spectral characteristics of Vis-NIR reflectance. Selecting suitable disperse dyes to directly print polyester fabrics can provide them with good vegetation-like Vis-NIR camouflage properties. The type and content of blue disperse dyes were found to be the keys to affect the starting position and slope of the "red edge". For Disperse Blue NP-SBG, Disperse Blue S-GL and Disperse Blue RD-GL dyes, the starting position of "red edge" was not influenced by the change of dye content, but the slope of "red edge" decreased when increasing dye content. For Disperse Dark Blue HGL, Disperse Navy Blue S-2G, Disperse Dark Blue S-3BG, Disperse Brilliant Blue 2BLN, Disperse Blue LF-B and Disperse Blue ACE dyes, as the dye content increases, the starting position of the "red edge" red shifted with a slope increase. The decrease of fabric thickness and the increase of water content both caused reduction in the reflectivity of "near-infrared plateau" of the fabric. The water content of the fabric was identified as the fundamental cause for the formation of the "water absorption valley" in the spectral curve. With the increase of water content, the position of the absorption valley remained unchanged and the reflectance decreased. With the 240 g/m² woven natural white polyester fabric as the base fabric, the printed fabric was prepared under the condition that the mass ratio of Disperse Blue NP-SBG, Disperse Orange 30 and Disperse Dark Blue HGL was set to 2.5:2.0:1.1. When the moisture content was 120.9% (Fig.5), its spectral reflectance curve was found similar to the Vis-NIR reflection spectrum of green vegetation. The Euclidean distance to the spectral curve of Everyreen leaves was 0.346, the spectral angle was 0.169° at 400-780 nm, 0.009° at 780-1 350 nm, 0.094° at 1 450-1 780 nm, and 0.107° at 2 000-2 350 nm, with the spectral correlation coefficient of 0.997 (Tab.3), which meets the first-level hyperspectral camouflage requirements. In addition, the fastness of the printed fabric against fading, staining, dry rubbing and wet rubbing all reached grade 5.
Conclusion The disperse dye-printed fabrics with vegetation-like Vis-NIR reflection spectrum characteristics have good field visible light camouflage performance and Vis-NIR spectral camouflage performance, and the overall color fastness performance is excellent. In the actual application process, a soft and high-strength colorless transparent plastic film was adopted to encapsulate the wet camouflage fabric to keep its moisture content unchanged, which can be used as military tents, camouflage nets, material covers and various weapons and equipment smocks.

Short-process flow preparation and performance of antibacterial down

WAN Yingping, WANG Zongqian, WANG Yingfeng, YANG Haiwei, WU Kaiming, XIE Wei

Journal of Textile Research. 2023, 44(01):  149-155.  doi:10.13475/j.fzxb.20211202007

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Objective Down has the characteristics of lightweight, high fluffiness and low thermal conductivity, resulting in excellent thermal insulation performance, and is widely used in cold-resistant textiles. However, it is eroded by exogenous contaminants, especially after absorbing sweat vapor emitted by the human body, causing the adhered bacteria to proliferate rapidly and develop odor which adversely affect the life quality and health. Research and treatment of down with antibacterial functions will greatly alleviate the bacterial breeding and associated problems of down products, and meet the market demand which is of great significance.
Method In order to reduce the loss of down during down processing for antibacterial performance, antibacterial finishing agents were added in the final rinsing bath. After shocking, soaking, centrifuging and drying, the antibacterial down was obtained. The original and finished down were characterized with scanning electron microscopy (SEM), X-ray energy spectrometry (EDS), and Fourier-transform infrared spectrometry (FT-IR). The antibacterial properties of each sample were tested with the plate colony counting method, and the effect of quick antibacterial processing of down was evaluated simultaneously.
Results In the experiment, the chemical structure of down before and after the antibacterial agent finishing were analyzed by FT-IR (Fig.2). The new characteristic absorption signal peak of the antibacterial down appeared at 1 468 and 1 086 cm^-1, which was attributed the characteristic absorption of C-N⁺ groups in the molecular structure of the cationic quaternary ammonium salt antibacterial agent, indicating the antibacterial agent had been successfully attached to down after finishing. The micromorphologies of the down before and after antibacterial finishing were tested and characterized by SEM (Fig.1). The morphology and fluffiness of the antibacterial down were not affected by the quick processing, and the antibacterial agent was filled in and attached to the grooves and angles of the velvet fiber surface. The antibacterial performance test of down was carried out by the plate colony counting method (Fig.4). No strain appeared in the test surface dishes, and the bacteriostatic rate (BR) reached 100.00%, indicating that the antibacterial down had excellent antibacterial properties against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). These results indicate sufficient amount of antibacterial agent were adhered to the down surface, showing a broad spectrum of antibacterial performance, which can efficiently sanitize gram-positive bacteria and negative bacteria (Tab.1). After 3 cycles of washing, the BR values of finished down against S. aureus and E. coli remained at 90.00% and 66.18% (Fig.5), respectively, suggesting high water resistance. The basic performance indicators before and after down antibacterial finishing were compared and analyzed, and the impact of the quick antibacterial processing on the fluffy quality of down was slight, and the cleanness, residual fat rate, oxygen consumption and odor of antibacterial down were not affected significantly (Fig.6, Tab.2).
Conclusion The antibacterial finishing of down and the bath treatment of water washing have the advantage of quick process, and the new technology overcomes the shortcomings of dryness and fluffy, which hinders the applications in infiltration and functional finishing. The finishing process is quick, convenient and easy to operate, reducing the loss of raw lint during the preparation of antibacterial down. The antibacterial agent used in this research is an environmentally friendly functional finishing agent, and the down fiber after the antibacterial agent finishing has excellent antibacterial properties, which does not affect the quality of the down.

Dyeing and Finishing & Chemicals

Preparation and sensing response characterization of polydopamine modified reduced graphene oxide/polypyrrole conductive fabrics

WAN Ailan, SHEN Xinyan, WANG Xiaoxiao, ZHAO Shuqiang

Journal of Textile Research. 2023, 44(01):  156-163.  doi:10.13475/j.fzxb.20210601908

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Objective Conductive fabric can be easily fabricated into smart clothes comfortable to wear. However, a common problem is that a large mismatch in mechanical properties between the conductive layer and the fabric substrate affects the performance of the flexible sensors. In order to improve the interfacial adhesion between the conductive layer and fabric, and construct an effective contact conductive network to obtain excellent sensing response characteristics, a reduced graphene oxide (RGO) and polypyrrole (PPy) flexible sensor was prepared by surface modification of polyester-spandex knitted fabric with polydopamine (PDA).
Method A knitted fabric substrate was modified by PDA, a PDA-RGO fabric was prepared by impregnation-drying and chemical reduction, and PPy was self-assembled on the PDA-RGO fabric via in-situ polymerization. The PDA modified RGO/PPy conductive fabric sensor was characterized and analyzed by Fourier infrared spectrometry (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), a self-made KTC sensor box, a four-probe square resistance tester, a Martindale abrasion and pilling tester and a universal tensile testing machine.
Results The PDA fabric, PDA-RGO fabric, PDA-RGO/PPy fabric and RGO/PPy fabric were prepared. A comparative study of the influence of PDA modification on the electrical conductivity and sensing properties of knitted fabrics was then carried out. The results indicated that the PDA filled the gaps among the yarns of the knitted fabric and improved the continuity of the conductive layer. The square resistance of the conductive fabrics showed that PDA enhanced the conductivity of the conductive fabric. The square resistance of the PDA-RGO/PPy fabric was about 0.08 kΩ/□. The PDA-modified knitted fabric had a strong adsorption to the conductive layer. RGO and PPy had a synergistic effect on the electrical properties, and the conductive fabrics containing RGO/PPY had better conductivity than fabrics with a single conductive component. The conductive layer of the PDA-modified RGO/PPY fabric had increased interfacial bonding by virtue of the bonding of the PDA. The change in resistance after rubbing was smaller for the PDA-RGO/PPy fabric than for the RGO/PPy fabric (Fig.5). The study of fabric sensing characteristics showed that PDA-RGO/PPy fabric had better sensing properties than RGO/PPy fabric. The stretching range of the PDA-RGO/PPy fabric flexible sensor was 0%~130%, the sensitivity was increased to 39.1, and the response time was 0.06 s. Moreover, the peak value of the relative change of resistance of PDA-RGO/PPy fabric was essentially the same for different stretching rate (Fig.6), proving the accuracy of this flexible sensor. This phenomenon can be explained by the fact that PDA deformed the conductive layer synchronously with the fabric substrate. The PDA-RGO/PPy fabric flexible sensor can be worn on joints such as fingers, wrists and knees to monitor motions. The fabric flexible sensor captures the motions steadily and outputs the relative change of resistance (Fig.11).
Conclusion The results of above characterizations indicate that the interfacial adhesion between the PDA-modified fabric and RGO/PPy is significantly improved, and the conductive network is constructed more continuous. Compared with unmodified fabrics, the modified fabrics has improved durability and rubbing resistance. The experimental results show that the sensing mechanism of the fabric sensor is mainly the disconnection mechanism and crack propagation. Monitoring of different joint motions can be achieved according to the resistance change curve and the data can be used for building human joint motion sensing systems. In the future, the conductive properties of the PDA-RGO/PPy fabric flexible sensor can be optimized by controlling the combination options and shape of the conductive materials for further adjusting the surface morphology of the conductive layer.

Apparel Engineering

Influence of base clothing on firefighters' physiological and perceptual responses

WANG Shitan, JIANG Shu, WANG Yunyi

Journal of Textile Research. 2023, 44(01):  164-170.  doi:10.13475/j.fzxb.20211201907

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Objective The entire firefighters' protective ensemble includes the turnout gear and base clothing worn. The base clothing is always worn contacting the firefighters' skin and would influence the temperature and relative humidity within the clothing microenvironment as well as the heat and moisture transfer through the garment. This study aimed to investigate the influence of the base clothing on firefighters' physiological and perceptual responses. The outcomes of this study were expected to reveal strategies for combining the optimum clothing style and fabric type of base clothing to improve firefighters' thermal responses and efficiency.
Method A survey was conducted and 203 firefighters' data were collected about the fabric types and configuration styles of the clothing that they wore under their turnout gear. Four base clothing combinations were obtained. Physiological experiments were conducted to detect eight subjects' skin temperature (T_sk), heart rate (HR), galvanic skin response (GSR), overall discomfort sensation, heat sensation, wetness sensation, and adhesion sensation when wearing four types of test samples. Repeated measure analysis of variance was used for the main effects (P<0.05). A four-scale analytic hierarchy process (AHP) model was adopted to determine the comprehensive score of the four base clothing combinations.
Results In the stage of the exercise, S1 presented the lowest T_sk (36.78±0.57) ℃ and was significantly 0.5 ℃ lower than S3 (P=0.00). It was interesting to observe that S2 presented the lowest growth rate of T_sk at the end 10 min of exercise and was 1.8% lower than S3. During the recovery, subjects had the lowest T_sk when wearing S2, which was 0.30 ℃ lower than S3 (P=0.01). The variation of HR was consistent with the result of the T_sk (Fig.6). In comparisons among four test samples, a lower HR in S2 was detected throughout the test. Especially, HR in S2 was 4.31 bpm lower than in S3 (P=0.02) in the exercise. During the recovery stage, HR in S2 continued to be lowest, even where no significant differences were noted (P>0.05). The minimum GSR was reported for S1 among four test samples (Fig.7), which were 1.75 μS lower than S3 (P=0.04). During the last 5 min of exercise, the growth rate was the smallest when wearing S2, which was consistent with the T_sk. The wetness rating in S2 was significantly lower than that of the S3 by 20.37% (P=0.01) during the exercise (Tab.2), which was consistent with the lower GSR in S2. It was also found that the sensation was different in varied body parts. The torso and thighs had the strongest feeling of heat and moisture, and the forearms, knees, and calves have the strongest contact discomfort, such as adhesion and roughness. The AHP model showed the cotton/polyester short-sleeved combined with camouflage trousers had the highest overall score (Tab.3), which facilitates the evaporation of sweat from fully clothed individuals working in high-intensity, thereby reducing the risk of firefighters' thermal strain.
Conclusion Base clothing had impacts on firefighters' physiological or perceptual responses during the exercise and recovery periods. Fabric properties of base clothing, especially sweat evaporation, were observed to have a primary contribution to subjects' thermal responses, no matter what the clothing style was. A cotton/polyester fabric with long pants would be a favorable solution for firefighters to alleviate thermal strain which did not compromise the protection. The optimization of firefighters' base clothing should consider the design of functional zones, such as splicing moisture-permeable and breathable fabrics on the chest and back and splicing flexible fabrics on the calves.

Cross-domain generation for transferring hand-drawn sketches to garment images

CHEN Jia, YANG Congcong, LIU Junping, HE Ruhan, LIANG Jinxing

Journal of Textile Research. 2023, 44(01):  171-178.  doi:10.13475/j.fzxb.20211104908

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Objective Garment image synthesis is an important part of the garment design and manufacturing process, which uses artificial intelligence technology to automatically generate realistic garment images. Garment design relies heavily on the subjective will of the designer, which often needs to be manually achieved by designers. However, this process is time-consuming and quite inefficient. In the context of artificial intelligence, garment image synthesis can significantly improve efficiency by automatically generating garment images. In addition, it has a wide range of applications in virtual try-on, fashion image manipulation and fashion presentation. Therefore, garment image synthesis has received a lot of attention.
Method The garment sketch was guided to automatically generate the corresponding garment image by entering the garment attributes. A garment image generation method based on hand-drawn sketches was proposed, namely AGGAN. Generative adversarial networks with attention mechanism was adopted to learn garment sketches and garment image data to obtain AdaIN parameters after One-hot encoding of garment attributes through the attribute incorporation module, which are incorporated into the model, and the model was trained to learn the correspondence between garment images and their visual attributes, thus can generate corresponding garment images under the guidance of given garment attributes.
Results AGGAN was qualitatively compared with some existing image generation methods (Fig.2). By comparing with all baselines, the AGGAN proposed not only generates garment images with multiple colors, but also generates images closer to the real situation in terms of visual effects. In addition, IS (inception score), FID (fréchet inception distance), and MOS (mean opinion score) was useds for further quantitatively evaluating the model. The IS value of the garment images generated by the method prosposed is 1.253 (Tab.1), which is 13.8% higher than CycleGAN (cycle-consistent generative adversarial networks ) value, and higher than the values from using other methods. The FID value is 139.634, which is 26.2% lower than CycleGAN, and lower than other methods. In addition to the above two evaluation methods, MOS was adopted to evaluate the quality of garment images generated by each method, the MOS score obtained by the method prosposed is 4.352, which is higher than other image generation methods. In order to control the generation of garment images more flexibly, experiments was conducted on attribute-guided garment image synthesis. The garment sketch was controlled by garment attributes to synthesize the corresponding garment image, and the generated garment image has obvious changes in the sleeve length part, which does not seem to be particularly incongruous (Fig.3). The effect of the color attribute on the generated garment images was also explored. Several common color attributes was chosen in the experiments, and it can be seen that AGGAN can generated almost any corresponding color and high-fidelity garment images under the control of color attributes (Fig.4). Texture is also the most intuitive and the main visual feature of the garment image, and several texture attributes was selected in the experiments (Fig.5). From the figure it can be seen that the generation results are more obvious, basically the required texture can be generated, although further improvement is necessary in terms of realism.
Conclusion The research constructed a garment image generation model based on hand-drawn sketches through the attribute incorporation module, attention mechanism and CycleGAN. Combining the advantages of generative adversarial networks and conditional image generation methods, it took garment attributes as conditions to improve the controllability of the garment image generation process, which helps garment designers to achieve automated garment image synthesis. After a series of experiments, the feasibility and effectiveness of the text method were proved. The method proposed provides new ideas for computer-aided garment design. Some improvements should to be made, for example, the generated garment images cannot generate texture attributes effectively, and there are fewer garment attributes studied.

Machinery & Accessories

Cotton impurity image detection based on improved RFB-MobileNetV3

XU Jian, HU Daojie, LIU Xiuping, HAN Lin, YAN Huanying

Journal of Textile Research. 2023, 44(01):  179-187.  doi:10.13475/j.fzxb.20210911809

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Objective The complexity of deep convolutional neural network models makes it difficult for embedded devices to meet real-time online detection, and this research works on an improved RFB-MobileNetV3(RFB-MNV3) method for cotton impurity detection.
Method Firstly, the MNV3 redundant network structure was reduced according to the construction of high-precision lightweight network model and the premise of ensuring high detection accuracy. Secondly, the 3×3 convolutional layer replaced the 5×5 convolutional layer and the 1×3+3×1 convolutional layer was folded to replace the 3×3 convolutional layer as the improved RFB module deployed to the pooling layer of the improved MNV3 to enhance the online detection speed and accuracy of cotton hash. Finally, the algorithm before and after the improvement and other detection algorithms were compared.
Results The influence of training times, different lighting changes and different camera shift poses on the model was investigated using the test set. The improved RFB-MNV3 network model was iteratively trained to improve the average accuracy of cotton impurity classification. The specific classification detection effect under the improved RFB-MNV3 model showed that the detection accuracy was 83%-96% as suggested by the average AP values of the detection results for each category, among which the best effect was achieved in identifying cotton seeds with 96% accuracy (Fig.11). The value of the improved RFB-MNV3 algorithm reached 88.15%, indicating that the accuracy and score (the score of impurity detection under the optimized algorithm) have reasonably high stability, i.e. the model can better classify cotton impurity detection and can basically meet the actual industrial production needs. The detection results were compared with those of the MNV3, YOLOv3, VGG16 and ResNet34 network models (Tab.2). The detection time of the improved RFB-MNV3 model reached 0.02 s, and the online detection accuracy of the improved RFB-MNV3 model reached 89.05%, which is 6.83% higher than MNV3 and 8.48%-17.32% higher than other network models. The average accuracy mean combined with the accuracy and recall rates can be utilized to evaluate the comprehensive performance of image classification. It can be seen that the improved RFB-MNV3 model has a mean accuracy value that is 6.31% higher than MNV3 and 8.76%-17.72% higher than other networks.
Conclusion The new network is improved on the basis of the MNV3 detection network, while the improved RFB-MNV3 module is combined to achieve the purpose of reducing the model parameters without basically losing the model accuracy, solving the problem that the complexity of the deep convolutional neural network model makes it difficult for the embedded device to meet the real-time online detection. The model proposed can effectively achieve the detection of lint images, while the model detection efficiency is high and the storage occupied is small, which can provide the necessary technical support for the development of embedded devices for lint image detection.

Machinery & Accessories

Influence of groove shape on flow field and yarn properties of compact spinning

LÜ Jindan, CHENG Longdi

Journal of Textile Research. 2023, 44(01):  188-193.  doi:10.13475/j.fzxb.20211006906

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Objective Ring spinning produces a wide range of yarn varieties and yarn fineness with great variety of raw materials, and with simple and easy maintenance of spinning machine. These advantages determine its popular use in producing yarns. However, because of the existence of the twisting triangle area associated to ring spinning, it is difficult to further improve the yarn quality. Also the fact that it integrates twisting and winding together, resulting in the incapability of greatly improving the spinning speed and the reduction in production efficiency. Especially in long fiber spinning, harmful hairiness is an important factor affecting yarn quality. How to reduce harmful hairiness and improve yarn quality is a problem to be solved in spinning. This research was devoted to the reduction of harmful hairiness of long fibers to improve the spinning performance for long fibers.
Method In this research, a three-dimensional model of the agglomeration area was established, and the fluid flow in the agglomeration area was simulated by using the Fluent module of ANSYS software. Computational fluid dynamics (CFD) was adopted to simulate the flow field in the gathering area with different groove structures of compact spinning to analyze and compare the characteristics of different groove shapes of the compact spinning device. Finite element method (FEM) was adopted to simulate the CFD models and mathematical statistics methods were employed in processing the experimental data.
Results 27.78 tex ramie yarn was spun and yarn properties were tested to verify the gathering performance of asymmetric grooves and the influence of gathering airflow on yarn formation. Comparing the final yarn results of asymmetric groove, symmetric groove and ring spinning, the yarn hairiness (77.58%) spun by asymmetric groove gathering device was lower than that of ring spinning, and the yarn strength was 14.32% higher than that of ring spinning. Yarn evenness analysis revealed that the evenness CV values of the two compact spinning devices were not greatly improved compared to ring spinning. The results of this experimental hairiness tests were consistent with the aforementioned theoretical results. The asymmetric groove air flow groove gathering device combine airflow and mechanical action for better fiber gathering and can effectively utilize the gathering air flow. Under the action of the higher gathering air flow, the gathering effect of the fiber whiskers was better and the yarn strength became higher, significantly improving the yarn forming performance.
Conclusion Under the same negative pressure condition, different groove shapes affect the transmission effect of negative pressure. Among the two different groove gathering devices used in this research, the asymmetric gathering device showed the highest speed in the gathering direction of the gathering area. It can gather fibers to a greater extent, hence reduce yarn hairiness and improve yarn strength. The experimental results show that the yarn hairiness of the yarn with different air flow grooves is greatly reduced compared with that of the ring spun yarn, and in the final yarn of the asymmetric groove gathering device, the hairiness above 3 mm decreases the most, and the strength increases, which improves the yarn quality and performance. For the air-flow groove with the groove shape used in the asymmetric condensing device, it needs to be further improved theoretically and experimentally, facilitating the industrialization of the ramie spinning device in the future.

Detection of cheese yarn bobbin varieties based on support vector machine

MA Chuanxu, ZHANG Ning, PAN Ruru

Journal of Textile Research. 2023, 44(01):  194-200.  doi:10.13475/j.fzxb.20211204607

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Objective Aiming at variety detection of cheese yarn on the transport guide rail in practical situations, this paper proposed an automatic solution based on image processing. Based on the characteristics of bobbin, a yarn variety detection method based on bobbin image classification was proposed to replace subjective judgment. The method proposed in this paper is aimed to reduce error rate of manual detection and labor costs, and to improve the production efficiency of spinning.
Method In order to facilitate feature extraction, the original image of cheese yarn was processed by the image segmentation method to obtain the bobbin area. Then, the segmented image of the annular bobbin was expanded into a square image by polar coordinate transformation. Color and texture features were extracted from the expanded image and optimized based on feature classification experiments and the elapsed time to jointly characterize the bobbin image.
Results The Otsu threshold method was adopted to find the gray threshold of the bobbin foreground and background, and a binary image was obtained based on the determined threshold. The image contour was used to filter non-target regions in the binary image by setting the area and perimeter threshold of the bobbin region. The binary image containing only the region of the bobbin was adopted as a mask to segment the yarn tube from the original cheese yarn image. For the segmented annular yarn tube, the polar coordinate transformation was applied to transform it into a rectangular image with the circumference of the outer circle and the width of the outer circle. Bobbin image expanded after threshold segmentation provided data support for subsequent research. The non-uniform quantized color histogram features with H:S:V=8:3:3 were optimized by the classification accuracy and the elapsed time of feature extraction (Tab.1). The features obtained by the preferred color quantization method demonstrated satisfactory classification effect on different types of bobbin images with the acceptable calculation time. The performance of different local binary pattern operators was optimized by the bobbin classification experiments. The operator of rotation invariant equivalent LBP_16,2 with the sampling point of 16 and the sampling radius of 2 was optimized to extract the texture features of the bobbin image (Tab.2). The experiments using the fusion feature were performed on bobbin with the same color, the same pattern, different colors and patterns and the results proved that the fusion feature is able to adapt to the bobbin classification detection task in the three cases (Tab.3). The classification results of different feature combinations under the same classification model and the performance of fusion features on different classifiers proved that the method of combining color and texture and support vector machine classification model is effective for bobbin detection (Tab.4, Tab.5).
Conclusion The combination of Otsu threshold method and image contour is successfully used to segment the bobbin from the original image, and it is shown that the bobbin image expanded by polar coordinate transformation can facilitate feature extraction. The optimal technique to characterize the color information of the bobbin image is proven to be the non-uniform quantization color histogram feature of H:S:V= 8:3:3. The preferred way to characterize the texture features of the bobbin image is the histogram feature of the rotation invariant equivalent LBP_16,2. The fusion of the two features can deal with the classification detection tasks of the bobbin in the same color, the same pattern, and different colors and patterns. Different classifiers were compared by the experiments and support vector machine was selected as the optimal classification model because of the best performance. The classification accuracy of this method is 100% in the same pattern of star pattern bobbin, black pattern bobbin and mixed pattern bobbin, which is the highest among different methods. The proposed method has practical value for variety detection of bobbin on the transport guide rail.

Online measurement of moisture regains of sized yarns based on arc capacitance sensor

LU Haojie, LI Manli, JIN Enqi, ZHANG Hongwei, ZHOU Jiu

Journal of Textile Research. 2023, 44(01):  201-208.  doi:10.13475/j.fzxb.20211004708

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Objective In order to fulfill the online detection of the moisture regain of the sized yarn in the sizing process, to improve the sizing quality, to reduce the carbon emission caused by sizing, and to solve the problem that the use of a contact type resistive measuring instrument may damage the sizing film, a measurement system for sizing moisture regain was developed.
Method According to the electric field model in the arc capacitor and the measurement principle of capacitive method, the model relating the capacitance difference and moisture regain was established. The sized yarn passed through the arc capacitor, and the LCR (inductance, capacitance, resistance) bridge tester captured the capacitance signal and transmitted it to the computer. The moisture regain of the sized yarn was calculated according to the model. The influences of the structure of the arc capacitor, the test parameters of the LCR bridge tester, the test environment, and the solid content of the slurry on the capacitance readings were discussed.
Results The experimental results show that the parameters of voltage, acquisition frequency, and internal resistance of the LCR bridge tester have little effect on capacitance value, while it is greatly affected by the testing frequency (Fig.3). At the frequency of 4 000 Hz, the capacitor was found to have the most significant response to water content (Fig.4), and hence 4 000 Hz was selected as the testing frequency of LCR bridge tester. It was revealed that as the curvature radius of the arc capacitor’s electrode plates increases, the capacitance value decreases, and that when the length of the electrode plate increases, the capacitance value increases. With the wrap angle of the electrode plate was increased, the capacitance value also increased (Fig.5). The capacitance simulated by the finite element technology were consistent with the measured results. The differences between the measured and the simulated values are caused by additional capacitance and environmental interference. Temperature and humidity were found to have a complex impact on the capacitance value (Fig.6), indicating that the system should be deployed under constant temperature and humidity conditions. The moisture regain of sized yarn demonstrated a significant effect on the capacitance, while the influence of fineness and size solid content were not obvious (Fig.7), where it can be seen that moisture regain is nonlinearly related to the capacitance difference. When moisture regain was increased, condensed water on and inside the yarn increased and a strong polarization reaction occurred at the frequency of 4 000 Hz with the capacitance value increasing. An exponential regression model of capacitance difference-sizing moisture regain is established. On the sizing machine, the capacitive sizing moisture regain online detection system developed by the research was adopted to measure the sizing moisture regain. Compared with the results of the oven method, the average error sizing moisture regain measurement was less than 5% (Tab.1).
Conclusion The capacitance value is greatly affected by the test frequency of the LCR bridge tester. The structure of the arc capacitor also influences the test capacitance value. The ambient temperature and humidity have complex effects on capacitance values. The influences of sized yarn moisture regain on capacitance are significant, while fineness and size solid content are not so obvious. The core components of a capacitive sizing moisture regain measurement system designed include an arc-capacitor sensor, an LCR bridge tester and a computer. The arc capacitor has a small and simple structure with low cost. It can measure sized yarns in a non-contact manner. Therefore, this system can be used in engineering practical situations.

Comprehensive Review

Research progress of preparation of nanofiber-supported catalysts and application thereof in environmental protection

CHEN Mingxing, ZHANG Wei, WANG Xinya, XIAO Changfa

Journal of Textile Research. 2023, 44(01):  209-218.  doi:10.13475/j.fzxb.20220102010

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Significance Nano-sized catalysts show higher catalytic activity than bulk analogues by virue of their larger specific surface area. Therefore, nano-sized catalysts have been widely used in the field of catalysis research. However, nano-sized catalysts tend to agglomerate during the application, which leads to the formation of large particles and a huge reduction in catalytic activity. Meanwhile, the recycling of nano-sized catalysts is difficult. These challenges all restrict the application of nano-sized catalysts. In order to solve these problems, some efforts have been made, such as surface modification, and immobilization of the nano-sized catalysts on supports. Among the various supports employed, the nanofibers have attracted much attention by virue of their larger specific surface area and nanoscale diameter. The larger specific surface area of nanofibers leads to an increase in the catalytic activity of nanofiber-supported catalysts as more active sites are available and accessible by reactants in the catalysis process. Moreover, the recovery and reuse of nanofiber-supported catalysts are simple. Hence, the nanofiber-supported catalysts show potential applications in the field of catalysis.
Progress The recent studies about the preparation of nanofiber-supported catalysts and their application in environmental remediation are reviewed. As a general method for preparing nanofibers, electrospinning technology has been known to be able to prepare nanofibers with various compositions and structures. The methods involving electrospinning technology for preparing the nanofiber-supported catalysts could be divided into two ways. One method is coated by an electrospinning process, in which the nano-sized catalysts or catalyst precursors are dispersed into an electrospinning solution followed by the electrospinning process. If the catalyst precursors are added to the electrospinning solution, a post treatment is necessary after the electrospinning process to convert catalyst precursors into nano-sized catalysts. The other method is to deposit the nano-sized catalysts on the surface of nanofiber after electrospinning process. Though the coating method is simple, it is difficult to achieve a homogeneous dispersion of nano-sized catalysts in nanofibers. While the precursor electrospinning deposition method shows more advantages for preparing nanofiber-supported catalysts with quite uniform distribution of the nano-sized catalysts on nanofiber surface. The simplicity of recovery and the higher catalytic activity of nanofiber-supported catalysts makes them economical and environmentally friendly in the application of dye degradation, organic matter degradation, and heavy metal ion reduction, etc.
Conclusion and Prospect According to the reported research, nanofiber-supported catalysts have the advantages of high catalytic activity and recyclability. Thus, nanofiber-supported catalysts have great potential in catalytic applications. However, they still has the disadvantages of poor mechanical properties and low preparation efficiency, which cannot meet the requirement of practical applications. Therefore, some efforts can be made from the following aspects in future research. 1) In view of practical applications, nanofiber-supported catalysts with fine mechanical properties have huge advantages. Some efforts should be made to improve the mechanical properties, such as tailoring the structure by regulating the electrospinning process and using the substrates with excellent mechanical properties as the nanofiber receiver. 2) The large-scale fabrication and commercial application of nanofiber-supported catalysts are still a huge challenge. Therefore, it is necessary to explore the electrospinning process using green solvent and have low cost and high efficiency for fabricating nanofiber-supported catalysts. 3) The catalytic activity of nanofiber-supported catalysts should be improved by optimizing the structure and surface composition of nanofibers as it is highly dependent on the active sites of nanofiber-supported catalysts. Except for the metal-based catalysts, other catalysts should be combined with nanofibers to expand the applications of nanofiber-supported catalysts.

Research progress in fabric defect detection based on deep learning

WANG Bin, LI Min, LEI Chenglin, HE Ruhan

Journal of Textile Research. 2023, 44(01):  219-227.  doi:10.13475/j.fzxb.20211105509

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Significance With the development of science and technology, the improvement of product quality is highly demanded. Although the technologies used in producing textile products have undergone revolutionary advancement which contributes to the textile quality dramatically, defects in textile products such as fabrics remain to be a reality. Fabric defect detection plays an important role in textile industry, and fabric defect detection technology based on deep learning has been paid more and more attention. This paper reports a research and development progress in fabric defect detection based on deep learning.
Progress Deep learning is mainly composed of four steps, i.e., defining model and loss function, training the model, finding optimization method and loop iteration. The research focus for fabric defect detection method based on deep learning mainly includes deep learning models such as convolution neural network (CNN) and automatic encoder (AE). The stack denoising automatic encoder based on Fisher criterion introduces deep learning into this field for the first time, which provides a new idea for the application of deep learning to the field of defect detection. Convolution neural network has achieved good results in the field of image recognition because of its strong nonlinear fitting ability. More precision-based detection algorithms based on candidate regions and more speed-based algorithms based on regression analysis are present. While the advantages of convolution neural network is exploited, other methods are used for exploring the possibility of combined use of models, and provide new ways for defect detection.
Conclusion and Prospect Fabric defect detection methods based on deep learning in recent years are reviewed and summarized, and the effects of different models are compared in detail. Advantages, disadvantages and applicable scope of each model are analyzed, and future development of fabric defect detection method based on deep learning model is prospected. Deep learning models can improve the detection efficiency, but still have some deficiencies. In order to optimize the accuracy of fabric image defect detection, breakthrough should be made from the following aspects in the future. 1) High quality data sets should be established. 2) Specific evaluation criteria need to be established. 3) The applicability should be extended. A single detection method often has limitations, but when different defect detection methods are utilized to deal with different detection needs, the detection results are often different, therefore hybrid methods would have better applicability.

Research progress in dual performance in heat-storage protection and heat-release hazard of thermal protective clothing

ZHU Xiaorong, HE Jiazhen, XIANG Youhui, WANG Min

Journal of Textile Research. 2023, 44(01):  228-237.  doi:10.13475/j.fzxb.20210702510

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Significance When protective clothing effectively insulates heat transfer during the heat exposure stage in either a high or low heat radiation environment, the protective clothing tends to store a lot of heat due to temperature increase in the fabric system, and heat accumulation is an important cause for skin burns. The workers' movement or external pressure makes the clothing contact with the workers' skin more likely which intensifies heat release. Hence, thermal protective clothing has dual performance of heat-storage protection during thermal exposure and heat-release hazard to human body during the cooling stage. Therefore, in order to evaluate comprehensively the dual performance of thermal protective clothing, which is conducive to promoting the design and development of thermal protective clothing and better protecting high temperature workers from burns, this paper summarizes the research on the dual performance of thermal protective clothing at home and abroad.
Progress The relevant evaluation methods of thermal storage in protective clothing include experimental evaluation and numerical simulation. In this paper, the experimental evaluation and numerical simulation research status of heat storage of protective clothing are compared and clarified. The experimental evaluation method comprehensively evaluates the whole heat transfer stage of the fabric system. The considered factors in using numerical simulation method are more comprehensive, and the calculation is becoming faster and more accurate. This review provides analysis of the relevant influencing factors of the dual performance of protective clothing from the aspects of heat-storage protection and heat-release hazard. The influencing factors of heat storage characteristics during thermal exposure are summarized from the clothing factors, environmental factors, and human factors. Clothing factors include the basic physical properties of clothing, air layer, reflective tape and reinforcement materials, environmental factors include heat source form, heat source intensity and heat exposure time, human factors include movement and sweating of the human body. These factors significantly affect the heat storage performance of clothing. In addition, different states and conditions of the fabric when releasing heat cause different degrees of heat damage to the human body. The influences of fabric physical properties, configuration of air layer, fiber moisture, fabric compression on the hazardous performance of protective fabrics caused by heat-discharge in the cooling stage are discussed.
Conclusion and Prospect Thermal protective clothing has both the positive effect of thermal protection and the negative effect of thermal harm to human skin. Thermal protective clothing worn for a certain period of time will produce clothing heat storage and heat release process in all heat environments, and different cooling environments will affect the release amount and release rate of heat storage. Moreover, when taking the dual characteristics of thermal protective clothing into comprehensive consideration, the heat storage performance of the fabric is not proportional to its heat release performance. Hence, starting from the dual performance of heat storage and release of thermal protective clothing, it is of great significance to comprehensively and accurately evaluate the thermal protection performance of protective clothing. As researchers pay more and more attention to the dual performance of heat-storage protection and heat-release hazard of fabrics or clothing, it is suggested that for future research, diversified heat exposure environment and cooling environment should be established for the actual application scenarios of thermal protective clothing, and researchers can establish a sound thermal protection performance evaluation system, and explore its optimal compatibility design based on the dual effect of thermal protective clothing's heat storage and release. The heat-storage and heat-release characteristics of the heat protection fabric system with new materials and the correlation between the heat-storage volume and heat-release volume also need to be explored.