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    15 May 2023, Volume 44 Issue 05
    • Invited Column: New Dyeing Technology for Reducing Pollution and Consumption
      Review of new dyeing technologies for reactive dyes and disperse dyes
      WU Wei, JI Bolin, MAO Zhiping
      Journal of Textile Research. 2023, 44(05):  1-12.  doi:10.13475/j.fzxb.20230200802
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      Significance Although dyeing is an important technique to give color to textiles, it also depletes resources and creates a lot of pollution. Reactive and disperse dyes are the most widely used dyes for coloring cellulose and polyester fibers, respectively. The output of two dyes accounts for more than 70% of the total output of dyes. However, reactive dyeing has problems with insufficient dye utilization, excessive use of inorganic salts, and high wastewater discharge. Meanwhile, the reduction cleaning step in the disperse dyeing process uses a lot of water and energy. The dispersants and unfixed dyes which are washed off in the reduction cleaning step will cause more difficulty in treating wastewater. Therefore, innovative dyeing techniques of two dyes that can solve these problems were reviewed in this paper.

      Progress In order to reduce the usage amount of inorganic salts in reactive dyeing technology, researchers developed a series of methods to increase the affinity of dyes and fibers, such as cationic modifications and designing macromolecular dyes. In order to improve the utilization of dyes, the wet pickup of the fabric was controlled at a low level to reduce the hydrolysis of reactive dyes. The low wet pickup dyeing technologies are foam dyeing, vacuum-dewatering aided pad-steam dyeing, spray dyeing and ″moisture fixation″ dyeing. Organic solvent (ethanol, decamethylcyclopentasiloxane, silicone oil) /water mixed solvent, liquid ammonia, and organic mixed solvent (dimethyl sulfoxide/dimethyl carbonate) were used as dyeing media to reduce the wastewater discharge. In order to solve the problem of low dyeing efficiency and high material consumption of rope dyeing, open-width dyeing technology for the cotton knitted fabric was developed. For disperse dyeing techniques, the first advancement is the development of alkali-resistant disperse dyes, which were created to solve the problem of water and energy usage during the reduction cleaning process. Owing to the same alkaline conditions, the pre-treatment and soap-washing procedures can also be combined with alkaline dyeing technology to increase production effectiveness. Secondly, the polymer dispersants with low molecular weights, no matter the synthesized copolymer anions or modified biomass polymers, were designed to make the dyes maintain nanoscales in water by grinding. Thus, the nano-scale liquid disperse dyes were prepared to improve the dyeing uptake and reduce loose color. With the use of microcapsule shells, the non-reduction clearing effect is achieved through the adhesion on the surface of the fabrics. Finally, non-aqueous media such as supercritical carbon dioxide fluid or organic solvents (decamethylcyclopentasiloxane, liquid paraffin) are used for dyeing to save water consumption.

      Conclusion and Prospect To sum up, the development of the two dyeing technologies focused on reducing the use of chemicals and wastewater emission, improving the utilization rate of dyes, and improving the efficiency of dyeing production. The use of reactive dyes with little or no salt has the problem of poor dyeing levelness or color fastness. For the wet pickup dyeing technology, the main direction of future research is to control the uniformity of dyeing and improve the color fixation rate to the highest level. The directions that need to be explored include the adaptability of open-width dyeing technology for knitted cotton textiles to thin fabric and the enhancement of process stability. Alkaline dyeing, nano liquid disperse dyeing and non-reduction clearing dyeing technologies have basically reached the industrial level, but it is still necessary to improve the categories of dyeable fabrics and improve the dyeing quality. It still needs to keep developing the theoretical framework and supporting equipment for less-water or non-aqueous dyeing technologies, whether they use reactive or disperse dyeing systems. In the future, reactive and disperse dyeing technologies continue to advance in a green and consumption-reduction direction, which will encourage the textile dyeing and printing industry to achieve the ″carbon dioxide emissions peak and carbon neutrality″ target as soon as feasible.

      Preparation and inkjet printing smoothness of monodisperse polystyrene and poly (styrene-co-styrene sulfonate) latex particles
      SU Jing, GUAN Yu, FU Shaohai
      Journal of Textile Research. 2023, 44(05):  13-20.  doi:10.13475/j.fzxb.20221205201
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      Objective The smoothness of digital inkjet printing depends on the pigment ink's particle size, but at the moment, research on the relationship between particle size and flow primarily focuses on the suspension system of large particles, and the choice of pigment ink particle size is largely determined by engineering expertise. Consequently, it is crucial to develop a realistic particle size range appropriate for inkjet. However, most convenitional pigments are prepared by grinding or other physical methods, and their size and morphology distribution is relatively random, making quantitative research impossible.

      Method As a new polymer, latex particle size is easy to control and the performance is stable, making it a suitable choice for the study of particle size and inkjet fluidity. Monodisperse spherical polystyrene (PSt) and poly(styrene-co-styrene sulfonate) (P(St-co-SS)) latex particles of different sizes were prepared by mini-emulsion polymerization and soap-free emulsion polymerization, respectively, which were configured into PSt latex particle dispersions and P(St-co-SS) latex particle dispersions. The relationships among latex particle size, storage stability and inkjet fluidity of the dispersions were investigated.

      Results In this research, monodisperse spherical PSt and P(St-co-SS) latex particles with controllable particle size of 50-250 nm were successfully prepared by changing the addition of potassium persulfate (KPS), sodium dodecyl sulfate (SDS) and sodium p-styrene sulfonate (SS) in the reaction components. The prepared latex particles were uniform in size and had a spherical structure (Fig.2). The results of storage stability tests suggested the temperature range of 4-50 ℃ for PSt latex particle dispersion and P(St-co-SS) latex particle dispersion, respectively (Fig.4). It was seen that the storage stability of both PSt and P(St-co-SS) latex particle dispersions was higher than 96% in this temperature range, and that the smaller the particle size of latex particles, the better the storage stability of the dispersions. Subsequently, the dispersion was filtered using a filter membrane with an absolute pore size of 1 μm, and the results of the filtration rate reals that the filtration flow rate of the dispersion became higher as the particle porosity ratio decreased (Fig.5). When the particle porosity of the PSt and P(St-co-SS) systems was smaller than 8.5% and 9.5%, respectively, the filtration flow rate of the dispersion appeared to be higher than 2 mL/s. DFT simulation was carried out using the finite element analysis method. The results from the simulations showed that the increase of the particle porosity ratio led to the decrease of the actual dispersion flow radius (Fig.6), which eventually resulted in blockage of the filter membrane pores. Direct grafting of sulfonic acid groups on the particle surface provided more effective mutual repulsion between particles than adding dispersant, thus better hindering the agglomeration and sinking of particles in high-speed flow and increasing the flow of the dispersion (Fig.7).

      Conclusion In the case of particles dispersed by dispersant alone at a solid content of 8.5%, the dispersion is essentially unable to flow when the particle porosity ratio exceeds 10%, while P(St-co-SS) latex particle has a fixed sulfonic acid group on its surface, that the particle porosity ratio threshold can rise to about 9.5%. Meanwhile, grafting or modifying the surface of the particles with hydrophilic functional groups enables better cold or hot storage stability of the particles as opposed to adding surfactants to the dispersion. Therefore, an appropriate reduction in solid particle size together with an increase in the number of particles with hydrophilic functional groups can improve the dispersion storage and the inkjet printing smoothness.

      Continuous preparation of large-area structurally colored fabric with bionic photonic crystals
      WANG Xiaohui, LI Xinyang, LI Yichen, HU Min'gan, LIU Guojin, ZHOU Lan, SHAO Jianzhong
      Journal of Textile Research. 2023, 44(05):  21-28.  doi:10.13475/j.fzxb.20220801401
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      Objective Photonic crystals (PCs) are composed of different dielectric constant materials in a periodic arrangement possessing a photonic band gap (PBG) that blocks the propagation of electromagnetic waves with certain wavelengths. If the wavelength of the blocked electromagnetic waves is in the visible light range, it forms a structural color. At present, it is difficult to fabricate continuously PCs coated fabrics with structural color in a large area, and it is difficult to balance the structural stability and optical properties of PCs, limiting the practice application of PCs in textile coloring field.

      Method A PCs-coated fabric was designed, achieving the rapid and continuous preparation of PCs with high structural stability and high color saturation on the fabric surface. Structural colored fabric was composed of a fabric substrate, a polymer layer and a PC layer. Liquid photonic crystal (LPC) with precrystallized structure was rapidly prepared by the rotary evaporation method, which was used as the working liquid for assembly. The surface of the fabric was coated with special polymer-L slurry with a scraper, and dried at 80 ℃ for 3 min and 120 ℃ for 1 min to form a flat polymer-L film on the surface of the fabric. The LPC was coated on the surface of the fabric pretreated by polymer-L with 20 μm filament rods, and then assembled at 60 ℃ for 5 min to obtain the PCs-coated fabric. Based on the assembly process and method of PCs, a pilot equipment for continuous fabrication of structural colored fabric is designed accordingly.

      Results LPCs were prepared by means of physical distillation and concentration to increase the volume fraction of nanospheres in colloidal system. By introducing dispersant-3B into the polystyrene (PS) nanospheres system, the problem of microspheres condensation during the process of spin evaporation was effectively solved. With the increase of dispersant-3B, the structural color brightness of LPC increased. When the dosage of dispersant was 1.5%, the structure color of the dispersion solution was not obvious (Fig.3). In addition, the results showed that the prepared LPC with excellent dynamic recovery exhibited bright structural color, and its optical properties were regulated by the volume fraction and particle size of the nanospheres (Fig.4). When subjected to external disturbance, the LPC was disassembled, and the structural color disappeared. After the external force was released, the LPC with precrystallized structure was rapidly reconstructed and restored, and the structural color was reproduced (completed within 10 s) (Fig.5). LPC was applied to the fabric surface with polymer coating by shear induction of external force, and the LPC was reconstructed and colored quickly (within 1 min) (Fig.8). After proper heating post-treatment (60 ℃, 5 min), as the water in the LPC continued to evaporate, the lattice spacing of the PC was decreased, but the structure color blue-shifts and the brightness of LPC showed significant increased. With the complete evaporation of water, the solid PC was formed. The interfacial molecules of the polymer layer migrate to the interior of PC, stabilizing the structure of color layer of the PC on fabric surface (Fig.9 and Fig.10). Using LPC as the assembly intermediate and self-developed pilot equipment, the rapid and continuous preparation of structurally colored fabrics was achieved (Fig.12).

      Conclusion The proposed preparation method of the PC-coated fabric demonstrated the advantages of simple operation and obvious effect. LPC with pre-crystallized structure and excellent dynamic recovery can be prepared rapidly and macroscopically by spinning evaporation. The special dispersant-3B introduced in the process of spin evaporation plays a synergistic role with SDS anionic surfactant in the system, significantly improves the steric hindrance and charge effect between the nanospheres, illustrating the resistance to the condensation of the microspheres. By pretreating the surface of textile substrate with special polymer, the PC layer is stabilized by utilizing the relaxation, activation, diffusion and recuring properties of interfacial polymer molecule, and the consistency of high structure stability and high color saturation of PCs-coated fabric can be achieved. Using LPC as the assembly working liquid, combined with the external force induced self-assembly method and the corresponding continuous processing equipment, the rapid large-scale continuous preparation of the PC-coated fabric with a fascinating iridescent effect can be achieved.

      Study on disperse dye staining on polyester/cotton blended fabrics in non-aqueous medium dyeing system
      YI Jingyuan, PEI Liujun, ZHU He, ZHANG Hongjuan, WANG Jiping
      Journal of Textile Research. 2023, 44(05):  29-37.  doi:10.13475/j.fzxb.20221005001
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      Objective Fabrics made from blended fibers demonstrate their advantages and enrich textiles diversification, of which polyester/cotton blended fabrics are most widely used in the textile and fashion industry. In order to save energy and reduce emission, non-aqueous media dyeing technology has been applied to the dyeing of polyester/cotton blended fabrics, using non-aqueous media, such as decamethylcyclopentasiloxane (D5), paraffin liquid, cooking oil and so on. Nevertheless, the phenomenon of staining persists during the dyeing process of polyester/cotton blended fabrics, resulting in decreased production efficiency and heightened pollution. This paper aims to investigate the mechanism behind the staining of cotton components in polyester/cotton blended fabric by disperse dyes in non-aqueous dyeing systems, with the objective of mitigating the staining of dyes during the dyeing process.

      Method Based on the determination of azo dyes which have high uptake rate and suitable for polyester dyeing in non-aqueous media, and anthraquinone and heterocyclic dyes commonly used in conventional water bath, this research focused the dyeing and staining of disperse dye for polyester/cotton blended fabric in non-aqueous medium dyeing system. The influence of disperse dye structure, dyeing temperature, accelerant, dyeing time and dispersant NNO on the disperse dye staining, and dyeing effect of polyester/cotton blended fabric in non-aqueous medium dyeing system were investigated. Owing to the structure of polyester/cotton blends, it was difficult to isolate cotton staining for independent study. Therefore, conducting experimental research using 1.3 g of polyester fabric and 0.7 g of cotton fabric to simulate 2 g of polyester/cotton(65/35) blended fabric was necessary to gain a better understanding of the degree of cotton staining, and to demonstrate it more intuitively. One-bath-two-steps method was used for dyeing. In order to investigate the influence of dyeing conditions on dyeing performance, C.I Disperse Red 177 was chosen as disperse dye in the subsequent experiments. The uptake rate and staining rate of disperse dyes were calculated by measuring the amount of dye in the dyeing residue and the stripping solution. The distribution of disperse dye on polyester/cotton fabric was characterized by the relative staining rate of disperse dye.

      Results The uptake rate of anthraquinone disperse dyes on polyester in non-aqueous medium dyeing system was only 12.0%, which was too low for dyeing polyester/cotton blends ( Fig.2 and Fig.3). The uptake rate of azo and heterocyclic disperse dyes on polyester components was above 80%. The complexity of disperse dye structure, the number of molecular substituents, molecular planarity, and relative molecular weight showed great influence on the uptake and staining of disperse dye. C.I. Disperse Red 177 was chosen as a representative azo disperse dye, and the results of the uptake of dye and the color depth of the dyed fabric indicated that the Disperse Red 177 had a higher uptake rate and it was more efficient using in non-aqueous medium. The influence of temperature on dyeing performance of polyester/cotton blended fabrics was investigated in non-aqueous medium with different contents of accelerant X (Fig.4). No matter what content of accelerant, raising the dyeing temperature was found to improve obviously the dyeing performance of disperse dyes on polyester/cotton blended fabric. The accelerant affected the dyeing/staining of polyester and cotton simultaneously (Fig.5) because the swelling degree of polyester and cotton fiber were improved at the same time when a certain amount of dye accelerant was employed during dyeing, and because the resistance of disperse dyes to diffusion into inside of fiber was decreased. It revealed from the research that the swelling degree of polyester fiber was less than that of cotton fiber, and the relative staining rate of disperse dyes was increased with the increasing content of dye accelerant. Polyester/cotton blended fabric dyeing was carried out for different dyeing time periods to investigate the relationship between the dyeing time and the dyeing performance (Fig.6), suggesting that dyeing time had little influence on the staining of of disperse dye but it would increase the uptake of disperse dyes. The addition of dispersant NNO in the dyeing process would not improve the dyeing performance of disperse dyes (Tab.2), but it had an influence on the staining rate of disperse dyes.

      Conclusion Based on the uptake/staining rate and the relative staining rate of disperse dyes, azo dyes are more suitable than anthraquinone and heterocyclic disperse dyes for dyeing polyester/cotton blended fabric in non-aqueous media dyeing system. Polyester/cotton blended fabric dyed with Disperse Red 177 was more effective and efficient in non-aqueous medium dyeing system. The optimum dyeing conditions for disperse dyes were found, which were 140 ℃ of dyeing temperature, 10% (o.w.f) of dyeing accelerant, and 60 min of dyeing time period. If the dye accelerant and dispersant NNO were used in the dyeing bath at the same time, the disperse dyes were easy to aggregate, and the staining of dye on the surface of the dyed fabric becomes seriously, resulting the level dyeing property was poor, indicating that the accelerant and dispersant NNO should not used in a same non-aqueous media dyeing system.

      One-bath process for bleaching and dyeing of polyester-covered cotton fabric using disperse dye with high resistance to alkalis and peroxides
      WANG Xiaoyan, MA Ziting, XU Changhai
      Journal of Textile Research. 2023, 44(05):  38-45.  doi:10.13475/j.fzxb.20221201701
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      Objective The inner cotton component of polyester-covered cotton fabric is soft, comfortable, sweat-permeable and air-permeable, and the outer polyester component is anti-wrinkle and wear-resistant. Polyester-covered cotton fabric is widely used in daily wear, school uniforms, firefighting apparel, sanitation apparel and other fields. However, the conventional processes for bleaching and dyeing polyester-covered cotton fabrics have problems of high consumptions of water and energy, and low production efficiency. This research aims to use a disperse dye with high resistance to alkalis and peroxides to construct a one-bath process for bleaching and dyeing polyester-covered cotton fabrics.

      Method The selected disperse dye was evaluated for its resistance to alkalis and peroxides. Experiments were carried out to investigate the influence of hydrogen peroxide concentration, processing time, and processing temperature on the performances of bleaching and dyeing in one bath. The optimal process was defined by monitoring the whiteness of cotton component and the color depth (K/S) value of the polyester component.

      Results The synthesized disperse dye was shown to be of high alkali-resistant and high peroxide-resistant type, withstanding dyeing with at 2 g/L NaOH alkali regulator concentration and 5 g/L H2O2 (30%) (Tabs.2 and 4). One-bath process for bleaching and dyeing polyester-covered cotton fabrics was designed based on the synthesized disperse dye with high resistance to alkali and peroxide. The influence of H2O2 concentrations and temperature maintaining time on the whiteness and K/S value of polyester-covered cotton fabric treated by one-bath dyeing polyester and bleaching cotton process were tested, respectively. Under the conditions of 2 g/L of H2O2 (30%) and a temperature maintaining time of 0 min at 100 ℃, the whiteness of the cotton component of the polyester-covered cotton fabric reached 80, almost the same as the whiteness obtained by the conventional process. In addition, the concentration of H2O2 (30%) and temperature maintaining time were shown to have no influence on the K/S value of the polyester component (Fig.5). Therefore, the optimal H2O2 (30%) concentration was selected to be 2 g/L and the optimal temperature maintaining time 0 min at 100 ℃. In order to further analyze the bleaching and dyeing effect of polyester-covered cotton fabrics under high temperature and high pressure treatment, the influence of processing time on the whiteness and K/S value of polyester-covered cotton fabrics treated with one-bath dyeing polyester and bleaching cotton process were investigated (Fig.7). It was found that the polyester-covered cotton fabrics could be optimally bleached and dyed in one bath under the conditions of 2 g/L of H2O2 (30%), 130 ℃ and 30 min. The one-bath process treated polyester-covered cotton fabric lead to a 8% bursting strength loss, showing around CIE whiteness 80 of cotton component and good moisture permeability (Tabs.5 and 6). Meanwhile, the color difference of dyed polyester component treated by the one-bath process and conventional process was lower than 1.0. The dyed polyester component provided by one-bath process had rubbing and washing color fastness of grade 4-5 or above, and sublimation color fastness of grade 4 or above.

      Conclusion One-bath process for bleaching cotton component and dyeing polyester component of polyester-covered cotton fabric has been achieved by a disperse dye with high resistances to alkalis and peroxides. The polyester-covered cotton fabrics could be optimally bleached and dyed in one bath under the conditions of 2 g/L of hydrogen peroxide (30%), 130 ℃ and 30 min. Compared with the conventional process, the one-bath process provided a polyester-covered cotton fabric that had less bursting strength loss, a comparable degree of whiteness (around CIE whiteness 80) and an acceptable color difference (ΔECMC< 1.0). The polyester-covered cotton fabric processed in one bath had color fastnesses of grade 4 or above. Therefore, the one-bath process of the polyester-covered cotton fabric for bleaching and dyeing has the advantages in shortening process flow, and saving costs in water and energy.

      Research on supercritical CO2 waterless dyeing property of polyester knitted shoe materials
      SONG Jie, CAI Tao, ZHENG Fuer, ZHENG Huanda, ZHENG Laijiu
      Journal of Textile Research. 2023, 44(05):  46-53.  doi:10.13475/j.fzxb.20221106501
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      Objective Knitted sports shoe materials have the advantages of structural integration, light weight, comfort and low cost, which attractes wide attention from the industry and consumers in recent years. However, with the increasingly prominent environmental pollution caused by conventional aqueous dyeing, how to achieve the eco-friendly dyeing of sports shoe materials has become the key development direction.

      Method In order to solve the problems of serious dyeing pollution and high energy consumption in the conventional dyeing, waterless dyeing of polyester knitted shoe materials was conducted with Disperse Yellow 54 using supercritical CO2 as medium. Influences of dyeing temperature, pressure, time and CO2 flow on the K/S values and levelling property were analyzed. The mechanical properties of polyester knitted shoe materials before and after dyeing were investigated, including bending, shrinkage, friction, tensile and durable properties.

      Results The results showed that supercritical CO2 displayed obvious influence on the dyeing properties of polyester knitted shoe materials. In supercritical CO2 dyeing system, the K/S values of the dyed polyester knitted shoe materials increased significantly with the rising of dyeing pressure, temperature and time. This is mainly because the increasing CO2 temperature and pressure present more and more plasticizing effect on polyester fiber. The dissolved dye molecules were more likely to approach the fiber interface, and would complete the adsorption through self-diffusion. Compared with aqueous dyeing, the dyeing process of polyester knitted shoe materials was able to completed with in 60 min in supercritical CO2 and the change of CO2 flow rate showed no significant influence on the K/S values. The deviation values of K/S data fluctuated around 0.1 at pressure ranging from 18 MPa to 26 MPa, temperature ranging from 105 ℃ to 125 ℃, time ranging from 20 min to 100 min as well as a CO2 flow from 380 kg/h to 460 kg/h, which represents good levelness. After supercritical CO2 dyeing, color fastness to rubbing and soaping of polyester shoe materials reached level 4 or above(Tab.1). The influence of CO2 temperature and pressure on the mechanical properties of shoe materials was different, and temperature had more significant influence on mechanical properties than pressure. When the CO2 temperature rose from 105 ℃ to 125 ℃, the bending rigidity increased from 9.90 mN·cm to 15.30 mN·cm(Fig.8), the maximum bending strength increased from 75.29 cN to 126.30 cN(Fig.8), the longitudinal shrinkage rate increased from 6.72% to 11.21%(Fig.9), the transverse shrinkage rate increased from 3.80% to 6.58%(Fig.9), the breaking strength increased from 1 048.23 N to 1 281.17 N(Fig.11), the elongation at break decreased from 42.05% to 36.6%(Fig.11), and the bursting strength increased from 2 235 N to 2 390 N(Fig.13). However, the test results revealed that the temperature and pressure played no remarkable influence on the tribological properties(Tab.2), and the static friction coefficient and dynamic friction coefficient of the polyester samples were almost constant.

      Conclusion By using supercritical CO2 instead of water as the medium, waterless dyeing of polyester knitted shoe materials can be achieved, and the deviation of K/S values is stable at 0.1±0.05. The optimal dyeing procedure was determined by balancing the dyeing effect and resource consumption. The dyed polyester knitted shoe materials with superior properties after supercritical CO2 dyeing indicate a favorable foreground. The above investigation provides an impurtant support for the clean industrial production of supercritical CO2 dyeing.

      Fiber Materials
      Preparation and characterization of phase change fibers of bimetal ion crosslinked alginate composites
      DI Chunqiu, GUO Jing, GUAN Fucheng, XIANG Yulong, SHAN Jicheng
      Journal of Textile Research. 2023, 44(05):  54-62.  doi:10.13475/j.fzxb.20211204701
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      Objective In order to prepare multifunctional alginate composite fibers, Zn2+- Ca2+, Cu2+- Ca2+, Sr2+- Ca2+ bimetal ion crosslinked alginate composite phase change fibers were prepared from sodium alginate (SA), silk fibroin (SF), lauric acid palmitic acid binary eutectic mixture (LA-PA) by wet spinning technology.

      Method The influence of bimetal ion crosslinking system on hydrogen bonding of composite phase change fibers was studied by infrared spectroscopy and Gaussian fitting, and the influences of different bimetal ion crosslinking systems on the structure, mechanical properties, thermal stability, thermal properties, water resistance and bacteriostasis of composite phase change fibers were investigated by scanning electron microscope, thermogravimetric analysis, differential scanning calorimetry.

      Results The type of double ions was found to have a great influence on the molecular action. In comparison to the single Ca2+ion crosslinking system, the content increase of intramolecular hydrogen bonds in the bimetal ion crosslinking system resulted in content decrease of intermolecular hydrogen bonds, while the content of free hydroxyl groups hardly changed (Fig.2 and Tab.1). In fibers β-the content of folded chains is an important factor affecting the mechanical properties of fibers, and the breaking strength of fibers varies with β-the content of the folded chain structure increases as it increases (Tab.2, Tab.4). Owing to the wet spinning forming mechanism, there are grooves along the fiber axis on the fiber surface. The Zn2+- Ca2+, Sr2+- Ca2+, Cu2+- Ca2+crosslinked composite phase change fiber showed denser grooves than the single Ca2+ crosslinked composite fiber. Metal ions participated in the forming process of the composite phase change fiber (Fig.3 and Tab.2). The thermal stability of Cu2+- Ca2+ion crosslinked composite phase change fiber was found lower than that of the other three composite phase change fibers (Fig.4). The maximum crystallization temperature and melting temperatures of the fibers are 26.19 and 36.71 ℃, respectively, and the maximum phase transition enthalpy is 25.95 J/g; The phase change enthalpy of Ca2+, Zn2+-Ca2+, Sr2+-Ca2+composite phase change fibers is 24-26 J/g, with a small difference, the phase change enthalpy of Cu2+-Ca2+composite phase change fibers is relatively small, ranging from 17 to 18 J/g (Fig.5, Tab.5). After 50 thermal cycles, the crystallization enthaly and melting enthalpy of the composite phase change fiber decreased by 0.15 and 0.50 J/g, respectively, and the crystallization and melting temperatures changed by 0.78 and 0.40 ℃, respectively (Fig.6, Tab.6). Zn2+-Ca2+composite phase change fibers have the highest swelling rate, followed by Ca2+, Sr2+-Ca2+composite phase change fibers, and Cu2+-Ca2+composite phase change fibers have the lowest swelling rate, which is mainly determined by the content of metal ions in the fibers (Fig.7, Tab.2). Owing to the large amount of Zn2+and Cu2+inside the fiber, which can extensively interact with the bacterial cell wall and lead to lysis or inactivation of proteins in the bacteria, thereby killing the bacteria. Therefore, there is no obvious inhibition circle around the Sr2+-Ca2+and Ca2+composite phase change fibers, while there is an obvious inhibition circle around the Cu2+-Ca2+and Zn2+-Ca2+composite phase change fibers(Fig.8).

      Conclusion The type of bimetal ions has a great influence on the molecular interaction, and the combined effect of the metal ion radius and the metal ion content causes the change of hydrogen bond interaction of different bimetallic ion crosslinking systems. The proper bimetal ion crosslinking system is helpful to improve the mechanical properties of the composite phase change fiber β-the content of folded chain is an important factor affecting the mechanical properties of fibers. The bimetal ion crosslinked composite phase change fiber has a phase change temperature of 21-37 ℃ suitable for human body and a high phase change enthalpy of 17-26 J/g, which has broad application prospects in clothing and other fields. The phase change temperature and enthalpy of the composite phase change fiber before and after 50 thermal cycles have little difference, and the bimetal ion crosslinked composite phase change fiber has good heat storage durability. The water resistance of Cu2+- Ca2+composite phase change fiber is obviously superior to the other three composite phase change fibers. Cu2+- Ca2+and Zn2+- Ca2+composite phase-change fibers have good antibacterial properties against these two types of bacteria.

      Synthesis and fiber fabrication of fully biobased polytrimethylene furandicarboxylate
      HE Shuang, SUN Li'na, HU Hongmei, ZHU Ruishu, YU Jianyong, WANG Xueli
      Journal of Textile Research. 2023, 44(05):  63-69.  doi:10.13475/j.fzxb.20211200501
      Abstract ( 181 )   HTML ( 13 )   PDF (2685KB) ( 179 )   Save
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      Objective Polyester industry is an important industry relating to the national economy and the people's livelihood. Most polyesters are prepared from petroleum and other fossil resources as raw materials. The combustion process of polyester will produce a large amount of carbon dioxide and sulfur dioxide, which not only pollute the environment, but also lead to global warming, climate change and other serious problems. In order to further implement the sustainable development and the promote China's ″double carbon″ strategic goal, it is urgent to minimise the dependence on fossil energy. In 2004, the US Department of Energy released 12 platform compounds derived from biomass that can be converted into high value-added biobased materials. Among them, the chemical structure of 2,5-furanedicarboxylic acid (FDCA) is similar to petroleum based terephthalic acid (PTA), which can be used as an ideal biobased substitute for PTA. With the maturity of the synthesis and purification technology of FDCA, furan based polyester has attracted attention in various fields, becoming a key research direction of biobased high molecular materials. This research focus is on the study of furan based homopolymers and copolymers.

      Method In this research, the use conditions of zinc acetate tetrabutyl titanate composite catalyst were optimized using 1,3-PDO and DMFD as raw materials. The full biological PTF with high molecular weight was synthesized by transesterification melt polycondensation. The chemical structure and thermal properties of the PTF were characterized by infrared spectroscopy, nuclear magnetic resonance hydrogen spectroscopy, differential scanning calorimetry and thermogravimetry, the biobased PTF fibers were prepared by two-step spinning process(UDY-DT), and the influences of different drafting ratios on the mechanical properties of the fibers were studied.

      Results In the process of adjusting the reaction process, it was found that only zinc acetate was added in the esterification stage, and tetrabutyl titanate was added in the polycondensation stage. The alcohol ester ratio was increased to 2.6, which would synchronously reduce the transesterification reaction time (Tab. 1). The analysis of the chemical structure of the product showed that the target product PTF (Figs.3 and 4) was successfully synthesized, and the number average molecular weight of the prepared product reached 3.25 × 104 g/mol, the PDI was controlled below 3 (Tab. 4), and the chip color was light yellow. It is believed that the optimal use conditions of the combined catalyst were found. The glass transition temperature of the synthesized product was 60-62 ℃, the melting point was about 171 ℃, and the initial thermal decomposition temperature was higher than 370 ℃ (Tab.5). With the primary fiber drawn to 2.5 times, the elongation at break of PTF fiber was about 34.2%, and the breaking strength was 0.48 cN/dtex (Tab. 6).

      Conclusion The whole biological PTF fiber was successfully prepared by UDY-DT two-step method. After 2.5 times of drafting, the elongation at break of the fiber was 34%, and the breaking strength was 0.48 cN/dtex. Owing to wide molecular weight distribution of PTF, relatively low breaking strength of prepared PEF fiber, and yellow color of polymer and fiber, further optimization and improvement of synthesis and spinning process are required in future research work.

      Preparation and properties of colorimetric sensing nanofiber membrane with wound monitoring function
      DU Xun, CHEN Li, HE Jin, LI Xiaona, ZHAO Meiqi
      Journal of Textile Research. 2023, 44(05):  70-76.  doi:10.13475/j.fzxb.20211111601
      Abstract ( 189 )   HTML ( 22 )   PDF (7051KB) ( 117 )   Save
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      Objective The nanofiber membrane structure with high specific surface area and high porosity can be applied in the detection field in response to external stimuli. Recently, the preparation of colorimetric sensors with nanofiber membrane as a carrier has attracted increasing attention. In order to develop nanofiber materials for monitoring wound infection, a colorimetric sensing nanofiber membrane for wound monitoring was prepared from chitosan/fish gum protein as raw material and plant dye hematoxylin as indicator by electrospinning technology.

      Method Colorimetric sensing nanofiber membrane was prepared by electrospinning technology after the spinning solution containing hematoxylin was well mixed by the original solution coloring method with optimized parameters of electrospinning. Scanning electron microscope, differential scanning calorimetry and X-ray diffraction (XRD) were dopted to characterize the microscopic morphology of the nanometer fiber membrane and analysis, and the color change situation under different pH values was also studied. In addition, the hydrophilicity of the nanofiber membrane was proved by the hydrophobic angle test.

      Results In the prepared nanofiber membrane without beading, the fibers with an average diameter of 346.1 nm were found thin and straight when the mass ratio of chitosan (CS) to collagen (Col) is 1:1 (Fig.1). When the voltage was set to 12 kV, the propulsion speed was 1.5 mL/L, and the receiving distance was 20 cm, the fibers without adhesion phenomenon showed straight and smooth, in which the average fiber diameter was about 264 nm, and the diameter CV value was 14.51% (Tab.2 and Fig.3). Based on the optimal parameters of electrospinning, the colorimetric sensing nanofiber membrane was prepared with hematoxylin (Fig.4). The thickness of the nanofiber membrane was 0.01 mm, in which the average diameter of the fiber was 246.2 nm. The colorimetric sensing nanofiber membrane had a peak of 93.8 ℃, which is lower than CS and Col (Fig.5). This believed to be precise because the melting temperature of polyethylene oxide (PEO) in the nanofiber membrane is lower than that of CS and Col. Therefore, the introduction of PEO reduced the melting temperature of the nanofiber membrane, indicating that the three materials successfully integrated into the nanofiber membrane. Furthermore, the stucture test results showed that the nanofiber membrane reveals a peak near 10°, meanwhile, the peak strength is lower than that of chitosan and collagen (Fig.6). It may be because CS and Col were successfully mixed, which destroys the helical structure of collagen and affects the crystal structure of nanofiber membrane. The contact angle test results showed that the contact angle of the prepared nanofiber membrane changed from 80° to 46° within 4 s, which showed good hydrophilicity and suitability for medical applications (Fig.7). Most importantly, the color changes of colorimetric sensing nanofiber membranes at different pH values (Fig.8). With the increase of pH value, colorimetric sensing nanofiber membranes exhibited different colors. When pH value increased from 5 to 7, the color change was more obvious, the fiber membrane changed from yellow to purple, the color difference from 0 to 10.59, and the color change of nanofiber membrane could be observed by naked eye, which was in line with the need of wound monitoring.

      Conclusion When the mass ratio of the CS to Col of 1:1, the spinning voltage is 12 kV, the pushing speed is 1.5 mL/h, and the receiving distance is 20 cm, the nanofiber membrane obtained possess good hydrophilicity. The average fiber diameter is 246.2 nm, and the diameter CV value is 29.54%. More importantly, the color of the colorimetric sensing nanofiber membrane changes from yellow to purple, when the pH value changes from 5 to 7. Moreover, the color change range of the nanofiber membrane is consistent with the pH value of the exudate when the skin is inflamed, which meets the requirements of wound monitoring.

      Study on performance of nanofiber air filter materials
      HU Diefei, WANG Yan, YAO Juming, DAS Ripon, MILITKY Jiri, VENKATARAMAN Mohanapriya, ZHU Guocheng
      Journal of Textile Research. 2023, 44(05):  77-83.  doi:10.13475/j.fzxb.20210905801
      Abstract ( 239 )   HTML ( 31 )   PDF (6112KB) ( 95 )   Save
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      Objective Filtration performance of air filtration membrane in high-end application has always been a main concern, attracting much research. The electrospun nanofiber membrane and polytetrafluoroethylene (PTFE) microporous membrane are the widely used membranes as high-end air filtration membrane. In order to further investigate the filtration mechanism of nanofiber air filter materials, to understand the correlations between structure features and their filtration performance, and to provide useful guidance for development and application of high-end air filter materials, these six types of filter composite materials are made from nanofiber structure, which is usually used for high-end air filter materials.

      Method These six types of filter composite materials were selected. The structure feature is the main factor influencing the filtration performance of air filter materials, and the electrostatic adsorption is also playing an important role in filtration performance. Therefore, the evaluation of air filter materials in structure, electrostatic adsorption and filtration performance were carried out.

      Results PA6/PET filter composite materials was found to have the highest surface potential which reached to 1.414 kV and its filtration efficiency reached to 99.57%. In contrast, the composite materials with wood pulp paper as substrate showed the lowest surface potential which was 0.070 kV, corresponding to a filtration efficiency of 22.28%, due to the lack of electrostatic adsorption. The crystallinities of samples 1#- 6# were 40.7%、39.4%、44.2%、51.7%、47.6% and 43.5%, respectively. The pressure drops of ePTFE/ES hot-air cotton nonwoven filter composite materials, PTFE/ES hot-rolled nonwoven filter composite materials, and PTFE/ES hot-air cotton nonwoven filter composite materials were 59.7 Pa, 45.6 Pa, 58.8 Pa. The fiber diameter and structure of air filtration membrane also showed to have significant influence on the filtration performance of air filter materials. The smaller fiber diameter, smaller pore size, higher thickness, higher specific surface area resulted in a higher pressure drop and higher filtration efficiency.

      Conclusion The surface potential played the most important role in filtration performance of filter composite materials, the higher surface potential led to a higher filtration efficiency. Besides, the fiber diameter and pore structure and its distribution also had significant influence on filtration performance of filter composite materials. PTFE mirco-porous membrane was produced by stretching, which had lower pressure drop comparing with the nanofibrous membrane produced from electrospinning.

      Classification and identification of foreign fibers based on near-infrared spectroscopy and ResNet
      LI Xueliang, DU Yuhong, REN Weijia, ZUO Hengli
      Journal of Textile Research. 2023, 44(05):  84-92.  doi:10.13475/j.fzxb.20211200801
      Abstract ( 186 )   HTML ( 15 )   PDF (6034KB) ( 60 )   Save
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      Objective It has been shown that image processing methods can not clearly acquire image characteristics of foreign fibers in cotton layers. In order to solve the problem associated to conventional image processing methods, this paper proposed a classification and identification method for foreign fibers in cotton layers based on near-infrared (NIR) spectroscopy and residual neural networks (ResNet).

      Method In this study, 500 groups of foreign fibers spectral data were collected by experiments, including five types of foreign fibers. The spectral collection instrument was a UH4150 spectrophotometer. Savitzky-Golay method was adopted to smooth the spectral data, and F-test and LightGBM classification algorithm was adopted to determine the optimal feature wavelength. The optimal spectral data were converted into Garmian angular summation fields (GASF) images by the Garmian angular field (GAF) method, which preserved the temporal sequences between wavelength sequences. Eventually, the ResNet model was constructed. The GASF images were used as training samples to train the ResNet model.

      Results The foreign fibers' spectral data was smoother than the original spectrum by the Savitzky-Golay method. Noisy data at both ends of the spectrum and near the peaks of functional groups were eliminated (Fig.2). After F-test and LightGBM classification algorithm wavelength optimization, 75 optimal wavelengths were selected. When the number of wavelengths was greater than 200, important information was deleted from the foreign fibers' spectral data (Fig.3(a)). When the number of wavelengths was 75, the optimal performance of the optimized model was the best, and the accuracy reached 98.99% (Fig.3(b)). The accuracy of applying the GASF image to the ResNet model is 99.69%(Fig.7(a)). The loss of the training set showed a sharp drop for the first 50 iterations (Figs.7 (b) and (c)). When the number of iterations reached 70, the training set started to converge. When the number of epochs reached 200, the training set tended to be stable. The classification accuracy of gray-scale and time-frequency images was lower than 99.00%, lower than the recognition accuracy of GASF images(Fig.8). The ResNet model improved classification performance compared with machine learning classification models. Compared with the K-nearest-neighbor (KNN) and decision tree (DT), accuracy increased by 6.67% and 7.60%, and recall increased by 6.91% and 7.09%. Compared with the artificial neural network's multi-layer perceptron (MLP), the accuracy and recall increased by 1.22% and 1.36%, respectively. All the classification performances of rope and feather on the ResNet model reached 100%, indicating excellent classification of these two types of foreign fibers. There were no false positives or missed inspections. Only two misjudged cases were found in 640 foreign fibers samples in the test set, the first being the chemical fibers were wrongly judged as PP yarn. Second, the chemical fiber was wrongly identified as plastic bag.

      Conclusion The classification and identification model based on GASF and ResNet improved the feature extraction performance of foreign fibers' near infra-red spectra data. This method can effectively identify the foreign fibers in the cotton layer under a complex environment, with a identification accuracy of 99.69%. The classification and identification method of foreign fibers based on spectra combined with the convolution neural network (CNN) provides new research ideas for classifying foreign fibers in a complex environment. In addition, the method provides technical support for developing the sorting device of foreign fibers. Future research will be further extended to cotton quality evaluation fields, such as content detection of foreign fibers.

      Textile Engineering
      Quantitative analysis method of cotton yarn defects based on heterogeneous ensemble learning
      YANG Yun, SUN Tong, LIANG Zhenyu, PENG Guang, BAO Jinsong
      Journal of Textile Research. 2023, 44(05):  93-101.  doi:10.13475/j.fzxb.20220100501
      Abstract ( 138 )   HTML ( 5 )   PDF (5605KB) ( 37 )   Save
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      Objective Yarn defects are an important index to evaluate yarn quality, and it is necessary to classify the common yarn defects such as coarse yarn segment, thin yarn segment and neps in a more detailed way to achieve multilevel management of yarn quality. The key to yarn defect grading is how to quantitatively analyze the appearance geometric dimensions such as yarn defect length and diameter. Aiming at the problems of low accuracy and poor reliability of the current quantitative analysis methods for cotton yarn defects, a quantitative analysis method for cotton yarn defects based on heterogeneous integrated learning is proposed.

      Methods A two-dimensional dynamic simulation model for yarn defect detection based on capacitance sensor was established to analyze the influence law of yarn defect size on its signal. Following that, the time domain analysis method was adopted to extract the time domain parameters of yarn defect signals as the quantitative analysis characteristics for yarn defects. Then, the support vector regression algorithm, radial basis function neural network algorithm and gradient boosting decision tree were used as primary and meta learners 'respectively' to establish a heterogeneous integrated learning algorithm model for quantitative analysis of yarn defects, which was verified by experiments finally.

      Results Based on the capacitive sensor, the dynamic simulation modeling and analysis of yarn defect detection was carried out, and the comprehensive capacitive sensor detection circuit principle and dynamic simulation analysis results showed that the yarn defect length and yarn defect diameter were the key factors affecting the yarn defect signal change, among which the peak change of the yarn defect signal was affected by the superposition coupling of the yarn defect diameter and the yarn defect length, and the duration of the yarn defect signal peak was only affected by the yarn defect length. The results collected by the time domain analysis method showed that the time domain feature parameters of different levels of yarn defects deminstrated obvious differences, proving that the time domain feature parameters could be adopted to estimate the appearance geometry of yarn defects. However, the relationship between the time domain feature parameters and the appearance geometry of the yarn blemishes remained vague and nonlinear. Therefore, a network with strong nonlinear approximation capability was required to map the time domain parameters and the appearance geometry of yarn defects, namely the quantitative analysis algorithm of yarn defects based on heterogeneous integration learning. The root mean square error and mean absolute error of the yarn defect diameter test set were 0.002 1 and 0.001 2, and the root mean square error and mean absolute error of the yarn defect length test set were 0.002 6 and 0.001 4, which represents a greater improvement than other types of single-model algorithms, and the goodness of fit was close to 1.00, which fully demonstrates that the algorithm proposed in this paper has a better fitting effect on the yarn defect diameter and yarn defect length, and the model has stronger reliability.

      Conclusion A quantitative analysis method of yarn defects based on heterogeneous ensemble learning is proposed. The method picked the yarn defects signal by capacitive sensor, combined the time domain characteristic parameter extraction algorithm and multi-model heterogeneous ensemble algorithm, and conducted quantitative analysis of non-stationary and nonlinear yarn defects signal. The experimental results confirmed that the yarn defect quantitative analysis model based on integration of heterogeneous learning can improve the appearance of yarn defects quantitative accuracy of geometry size with the method of optimal fitting R2 close to 1.00. Compared with the conventional single model algorithm, the accuracy is improved by 10%, indicating the new method has good generalization ability and stability. It provides a more effective quantitative analysis scheme for yarn defects detection system based on electrical signal.

      Fabrication and properties of optical fiber sensing fabrics for respiratory monitoring
      ZHANG Meiling, ZHAO Meiling, ZHANG Cheng, LI Zhihui, SUN Zheng, ZHAO Xiaoxue, MIAO Changyun, WANG Rui, WANG Zhan'gang
      Journal of Textile Research. 2023, 44(05):  102-111.  doi:10.13475/j.fzxb.20220102101
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      Objective Respiration offers useful information for diagnosis and treatment of respiratory diseases, such as anesthetic sensitivity, sudden infant death syndrome, and obstructive sleep apnea syndrome. In this research, an optical fiber fabric for respiratory monitoring was designed based on the side luminous and photosensitive mechanism of the optical fibers for convenient, real-time and effective monitoring of respiration.

      Method The 500 μm-diameter optical fibers were woven into the fabric as warp yarns, and laser marking was performed at the designated positions of the optical fibers to form luminous and photosensitive structures. Displacement in the optical fibers took place due to respiratory movement and the light intensity of photosensitive optical fiber was correspondingly altered, monitering the human respiratory state. The influences of optical fibers marking distance, weft elasticity, optical fibers spacing and optical fibers number on optical fiber respiratory sensing were studied.

      Results The effect of photocurrent signal fluctuation was more obvious when the optical fiber marking distance was 1 cm under the same stretching distance (Fig.4(a)). Under the same conditions, the elastic recovery rate decreated from polyester/spandex yarns, nylon-spandex core-spun yarns, high elastic nylon yarns to high elastic polyester yarns, with the elastic recovery rate of polyester/spandex yarns as the highest. When the fabrics were tensile loaded to make the same extension, the light intensity loss (γ) demonstrated an increase in the elastic recovery rate of weft yarns. For optical fiber respiratory sensing fabrics of different elasticities, the spacing between optical fibers for high elastic fabric changed obviously with the same fabric stretching distance, resulting in the largest light intensity attenuation. The nylon-spandex core-spun weft yarn with the highest elastic recovery rate was selected for further study, and its elastic recovery rate was 70%, which facilitated the tensile deformation of the fabric and obained preferable test results.Nylon-spandex core-spun weft yarn with 70% elastic recovery rate was selected for further study. With the increase of optical fiber spacing, the intensity loss increased and then decreased, and the optical fiber spacing of 4 warp yarns was adopted (Fig.4(c)). The intensity loss of fabrics with even optical fibers was lower than that with odd optical fibers (Fig.4(d)). In the former case the light intensity loss (γ) tended to increase with the increase of the number of optical fibers, and in the latter the situation was opposite. The light intensity loss (γ) of 5 optical fibers was as high as 38.61% with a stretch of 2 cm, and the effect was excellent. In summary, optical fiber respiratory sensing fabric was woven with 3 luminous fibers and 2 photosensitive fibers in intervals as warp yarns. The optical fiber spacing adopted 4 warp yarns. The weft yarns employed polyester-spandex core-spun with a high 70% elastic recovery rate, with the fabric warp density of 300 ends/(10 cm). The 4 cm fabric width and 1 cm optical fiber floating was employed with satin weave. The breathing amplitude in the standing was smaller compared to that of the sitting and walking states for the same position, because the human standing caused less body cavity undulation, and the optical fiber spacing change was less obvious (Fig.5).

      Conclusion The result shows that the light intensity loss of the optimized sensing fabrics is improved from 13.14% to 38.61%. Hence, it can be concluded that the such made sensing fabrics can monitor the calm respiratory signals in sitting, standing and walking below the sternum of body, and the accuracy of the sensing fabric is high with the error range within 1.2 r/min, which is comparable to the performance of a mask respiratory monitor. The optical fiber respiratory sensing fabrics offer high sensitivity good comfort and can be achieved using the conventional technology, showing potentials for industrialization.

      Prediction of loom machine status based on binary K-means theory
      PENG Laihu, TANG Qilin, DAI Ning, HU Xudong
      Journal of Textile Research. 2023, 44(05):  112-118.  doi:10.13475/j.fzxb.20220100801
      Abstract ( 136 )   HTML ( 6 )   PDF (4869KB) ( 20 )   Save
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      Objective Each machine used in the weaving workshop production scheduling scheme is closely related to the textile enterprise production efficiency. In order to solve the problem of existing loom machine caused by time depending on human experience and hard to predict production scheduling, this paper, through the study of dynamic loom weaving process of actual production data prediction algorithm, puts forward a kind of loom machine to help production personnel according to the loom machine time, determines the best production scheduling strategy of the whole production line, improves the production efficiency of the production line and increases the profit of the enterprise. This method does not depend on hardware cost, greatly improves enterprise profit, and is easy to be implemented.

      Method This paper proposes a machine prediction algorithm based on K-means theory. Taking each loom in the weaving workshop as the object, the whole production process of air-jet loom is reasonably divided into five production states by establishing the theoretical model of loom machine prediction. In addition, the dynamic data (weaving yield, sampling time point, current shift, remaining yarn length, variety number) and static data (warp axis number, set axis length) of loom machine production process in the workshop were recorded in time sequence, and the 7-dimensional vector matrix X was established as the original data sample set. Finally, the problem was solved by Python built-in mathematical processing module.

      Results The time series data of characteristic samples in a certain period of time in the actual production process of the equipment were input into the dichotomous K-means algorithm with a clustering index of 5. The algorithm divided the production state data into five clusters, and the orange point was the centroid of the corresponding cluster region. According to the production characteristics, the predicted value of the remaining machine time of the loom machine at this time can be calculated. Sample data of 10 loom machines (the time period of complete production of a warp shaft) were randomly selected from 480 loom equipment in the workshop. The sample data were input into the algorithm to calculate the predicted values of 144 h, 96 h, 84 h, 72 h and 24 h from the actual loom machine and compare the calculation errors with the actual machine values. The results showed that with the passage of time and the accumulation of data. The error between the predicted loom machine value and the actual loom machine value calculated by the dichotomous algorithm model gradually decreased, and the average error of the predicted loom machine value was less than 0.9 h within 72 h before the machine.

      Conclusion The data results show that the error between the predicted loom machine time and the actual loom machine time is small, which proves the correctness of the theoretical model of loom machine prediction, and the maximum absolute error is not more than 0.9 h (far less than the 2 h error required for production scheduling), which meets the timeliness and accuracy required for production scheduling in the weaving workshop. In addition, the weaving machine prediction algorithm based on bisection K-means theory established in this paper needs to be built on the accuracy and integrity of the data collected by the equipment. Therefore, in the future, we should start to ensure the full coverage of the weaving workshop network and stable and efficient data collection and transmission mode. Although theoretical model of the machine does not support the prediction of warping and sizing equipment, it is also applicable to the spinning machine equipment with similar processes, such as water spraying and rapier type, and has important engineering application value.

      Wearability of knitted fabrics produced from cotton/bio-based elastic polyester fiber
      SU Xuzhong, LIANG Qiaomin, WANG Huifeng, ZHANG Di, CUI Yihuai
      Journal of Textile Research. 2023, 44(05):  119-124.  doi:10.13475/j.fzxb.20211202501
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      Objective Bio-based elastic polyester (PTT) fiber is the only biomass elastic staple fiber that can be commercially produced at present in line with the promotion of environmental protection. PTT fiber has a good development prospect, but is unable to spin yarns from pure PTT fibers at this stage. This paper reports a new spinning scheme for producing cotton/PTT fiber blended yarns and reports on the analysis and comparison of the properties of knitted fabrics from this blended yarn.

      Method Three different forms of cotton fibers were adopted to assist PTT fibers in the blowing process to form cotton rolls and slivers. Cotton/PTT fiber (60/40) blended yarn with a linear density of 14.7 tex was produced by siro spinning, which was used for producing a weft knitted fabric. The properties of bursting, pilling, abrasion resistance, air permeability, moisture permeability and drape of the fabric were measured and analyzed. Then the fabric properties were comprehensively evaluated by using fuzzy evaluation method. The forms of cotton fibers blended with the PTT fiber were carded sliver, carded net and combed sliver respectively, and the corresponding yarns were named as a, b and c.

      Results The longitudinal shape of the PTT fiber is similar to the curl of a spring (Fig.1). The performance parameters of the selected fiber materials were shown that the linear density of cotton fiber was smaller and the average length was shorter than that of the PTT fiber, but the breaking strength and moisture regain are larger (Tab.1). Elongation at break of PTT fiber was high. According to the performance test results of three sets of 14.7 tex cotton/PTT fiber (60/40) blended siro yarns, blended yarns with combed sliver assisted with PTT showed smaller evenness coefficient, less hairiness, and larger breaking strength and elongation(Tab.2). The basic parameters of the Rnitted fabric can be seen that the course and wale densities showed little difference from the uniform set value (Tab.3). By comparing the test data of the Rnitted fabrics, it was concluded that fabric C had higher bursting strength, better anti-pilling effect and better air permeability, and fabric B had good wear resistance, and fabric A illustrated good moisture permeability. The fuzzy comprehensive evaluation model was established to evaluate the fabric comprehensively, and the evaluation function of fabric C was greater than that of fabrics A and B. Fabric C showed high bursting strength and high anti-pilling grade, indicating good durability and breathability of the fabric. The static drape coefficient was found small, suggesting that the fabric had good softness and was suitable for casual wear.

      Conclusion The cotton fiber in the blended yarn has a highly straightened, which can increase the friction between the cotton and PTT fibers to improve the bursting property, anti-pilling and air permeability of blended yarn knitted fabric. It is also revealed that the amount of PTT fiber on the surface in the fabric leads to better wear resistance, however the moisture permeability and drapability of the fabrics have little influence on cotton fiber morphology. Based on the fuzzy evaluation model, the combed sliver of cotton fiber is effective to assist the PTT fiber to form a cotton roll, and the comprehensive wearing performance of its blended yarn fabric is better.

      Preparation and performance evaluation of weft knitted ironing-free shirt fabric based on cotton/shape memory spandex
      WANG Yaqian, WAN Ailan, ZENG Deng
      Journal of Textile Research. 2023, 44(05):  125-131.  doi:10.13475/j.fzxb.20211202701
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      Objective Although the existing cotton shirt fabrics offer good comfort and breathability, it is difficult to meet the dimensional stability requirements for shirt end-use. It is often necessary to finish the cotton shirt fabrics for shape retention without the need of ironing. Such finishing technique often uses chemical reagents for treatment, which will not only affect the comfort and softness of cotton shirt fabrics, but also remain some chemical substances in the fabric. This paper aims to improve the wrinkle recovery performance of weft knitted cotton shirt fabrics by incorporating shape memory spandes fibers.

      Method In order to improve the wrinkle recovery performance of weft knitted cotton shirt fabrics, plain, single bead and double bead fabrics were knitted by using a cotton yarn incorporating temperature-sensitive shape memory spandex. Three different predetermined temperature treatments were carried out on the fabrics. The transition temperature and shape memory performance of shape memory spandex yarn were characterized, and the wrinkle recovery, shape memory performance, elastic recovery performance and shrinkage performance of the fabrics were evaluated.

      Results The results showed that when the temperature reached 32.45 ℃ and above, the shape memory function of shape memory spandex could be triggered by the body temperature. The deformation fixation rate of shape memory spandex was 93.5%, and the shape recovery rate was 91.0%, indicating good shape memory performance of the spandex fiber and the effectiveness of the shape memory spandex in improving wrinkle recovery angle and elastic recovery rate of weft knitted shirt fabric. When the content of shape memory spandex was 8.4%, the wrinkle recovery angle and elastic recovery rate were increased by 20.5% and 14.35%, respectively. The properties of fabrics with different pre-determined temperatures were also found different, and the fabrics at pre-determined temperature of 195 ℃ demonstrated the best dimensional stability.

      Conclusion The human body temperature is used as the triggering temperature of shape memory spandex to trigger the characteristics of shape memory spandex, so that the weft knitted cotton shirt can be automatically smoothed after wearing, achieving the iron-free effect and providing a reference for the development of shirt fabric.

      Full forming process design for three-dimensional knitted products
      LI Yuxian, CONG Honglian, WU Guangjun
      Journal of Textile Research. 2023, 44(05):  132-138.  doi:10.13475/j.fzxb.20211202601
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      Objective From the manufacturing of single component to one-piece products, the full forming computerized flat knitting machines are now capable of rapidly producing knitted products. However, the structure of knitted three-dimensional products is complex, and the forming process needs to be further improved. On the basis of the existing process design methods, the full forming process design of knitted three-dimensional products with more complex structure was carried out, and the process algorithm in the forming process was discussed, so as to facilitate the full formation of three-dimensional knitted fabrics.

      Method According to different appearance contours, three-dimensional knitted products was classified and the cylindrical structure, cubic structure and spherical structure were analyzed based on the full forming process, before selecting truncated cone, frustum of a pyramid and sphere with general characteristics for algorithm model construction. After transforming into the full forming paper pattern, the mathematical relationship between the number of knitting rows, the number of narrowing and widening needles and the inclination angle was explored. Finally, the curved lamp shade was knitted on the four-needle-bed flat knitting machine to verify the feasibility.

      Results From the perspective of appearance and contour modeling, knitted three-dimensional products can be divided into cylinder structure, cubic structure, spherical structure and special-shaped structure, which were utilized to produce clothing, bags, lighting, seats and other categories of knitted products. The truncated cone obtained a full forming paper pattern by cutting and expanding, and a trigonometric function relationship was formed between the number of knitting rows, the number of narrowing and widening needles and the inclination angle, and hence the trigonometric transformation method was proposed. The side shape of the truncated cone was achieved by entering the number of knitting rows and the number of narrowing and widening needles (Fig.6). The frustum of a pyramid was converted into a two-dimensional paper pattern after flattening along the diagonal line of the bottom face, and the upper and lower cover surfaces were converted into parallelograms corresponding to the sides, so as to propose a parallelogram transformation method to simplify the connection process between the sides and the upper and lower bottom surfaces. Similarly, there was a trigonometric relationship between the number of knitting rows, the number of hanging needles and the tilt angle, and the three-dimensional shape was achieved with the help of parallelogram transformation method and triangular transformation method (Fig.8). The sphere was cut and stretched to obtain the full forming paper pattern, and the arc profile was converted into several successively connected moment blocks, so as to propose the inverse fitting method. The edge moment block was adopted to create the arc shape (Fig.10). The example of the arc lamp shade was knitted with obvious arc contour of the lamp shade using the reverse fitting method, and the size parameters met the design requirements (Fig.14).

      Conclusion In the transformation process form a three-dimensional structure to the two-dimensional paper pattern and then to the full forming paper pattern, a corresponding mathematical transformation relationship was established, based on which triangular conversion method is adopted to construct the edge straight contour for the cylindrical products, the parallelogram transformation method is employed to facilitate the three-dimensional structure of the upper and lower cover surfaces for the cube products, and the inverse fitting method is applied to achieve arc appearance modeling for the spherical configurations. The knitted three-dimensional products after structural transformation are knitted on the computerized flat knitting machine, forming one-piece fabrics by the transformation of the full forming process, supported by the process models and algorithms.

      Robustness algorithm for online yarn breakage detection in warp knitting machines
      YANG Hongmai, ZHANG Xiaodong, YAN Ning, ZHU Linlin, LI Na'na
      Journal of Textile Research. 2023, 44(05):  139-146.  doi:10.13475/j.fzxb.20210603501
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      Objective For warp knitting machines, yarn breakage is inevitable in the working process. When a yarn breakage occurs, the warp knitting machine should be stopped immediately for yarn repair so as to avoid causing fabric defects. However, because the yarn diameter is only tens of microns, and tens of thousands of yarns are knitted at high speed at the same time in the knitting process, it brings great difficulties to the online detection of yarns in warp knitting machines.

      Method Aiming at the above problem, this paper proposes a composite detection algorithm. Firstly, the defect feature enhancement method based on dimension transformation was adopted to enhance the stability of the algorithm by data processing. Secondly, on the basis of dimensional transformation data, a yarn breakage detection algorithm based on wavelet transformation was proposed, and the gray level transformation rule of the image was analyzed from the perspective of time domain to realize defect detection. Finally, deep learning was adopted to further improve the robustness of the algorithm.

      Results To verify the effectiveness of the proposed algorithm, the detection system was built in KARL MAYER RD7/2-12 warp knitting machine (Fig.8). Ten cameras were adopted to shoot at a distance of 1 m. Five groups of experiments were carried out to verify the feasibility of the algorithm under different processing conditings (Tab.1). The first group of data was taken as an example and the detection processes (Fig.10). Five sets of yarn breakage experiments were conducted on three different warp knitting machines, and the methods proposed in this paper can effectively identify yarn breakage. It is shown that the algorithm proposed in this paper can effectively detect yarn breakage. The algorithm proposed in this paper was comared with STL (time series decomposition algorithm) and wavelet decomposition algorithm (Tab.2). The timeliness of different algorithms was analysed, indicating that the conventional STL decomposition algorithm had the worst timeliness (Tab.2). The proposed method and wavelet decomposition showed better timeliness, and it also proved that the introduction of deep learning had no impact on the timeliness of the algorithm. About 120 h of continuous experiment was set to verify the stability of the algorithm proposed in this paper, compared with other algorithms, the missed detection rate and the false detection rate were both decreased (Fig.11).

      Conclusion Aiming at the problem of online detection of broken yarn defects in warp knitting machines, this paper proposes a robustness detection algorithm, which is proven to be feasible by a large number of experiments. An innovative method of weak defect feature enhancement based on dimension transformation is proposed to overcome the degradation of detection stability caused by various weaving processes and serious external noise interference.The problem of restricting the accuracy and timeliness of broken yarn detection on warp knitting machines has been solved. The proposed algorithm has important implications for textile defect detection. At the same time, the proposed algorithm is expected to promote the further development of textile industry towards automation and intelligence.

      Preparation and properties of nonwoven flame retardant sound-absorbing material from Hu sheep wool
      TAN Qifei, CHEN Mengying, MA Shengsheng, SUN Mingxiang, DAI Chunpeng, LUO Lunting, CHEN Yiren
      Journal of Textile Research. 2023, 44(05):  147-154.  doi:10.13475/j.fzxb.20211201201
      Abstract ( 119 )   HTML ( 11 )   PDF (6092KB) ( 66 )   Save
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      Objective The scale of Hu sheep breeding continues to grow, but due to the low quality of fiber, Hu sheep wool is not suitable for preparing medium and high-grade wool yarns, resulting in the low price and low industrial demand. Based on the performance and structural characteristics of Hu sheep wool, this paper explores the development of sound-absorbing material by needle punching Hu sheep wool, which represents an effort to best use natural resources.

      Method Hu sheep wool sound-absorbing materials were prepared by needling, milled finishing and flame retardant finishing. The processing process involves scouring → weighing → opening → carding → lapping→ fleece formation → pre-needling → needling → rolling → milled-finishing → drying → flame retardant finishing → drying → finished product. The effects of structural parameters, milled process and flame retardant process on sound absorption performance were explored.

      Results Hu sheep wool has a distinct medullary cavity, which is a loose porous structure (Fig.2). The Hu sheep wool scales are covered with craze, and the scales are wide and cocked up obviously (Fig.3). The fibers of Hu sheep wool were entangled with each other to form a three-dimensional fiber network (Figs.4-6). The fibers winding of Hu sheep wool needled fabric after milled finishing was more compact than that before milled finishing. After flame retardant finishing, the flame retardant was attached to the fiber surface of the Hu sheep wool needle fabric. When the sound wave range was in the middle and high frequency range, the sound absorption effect of the Hu sheep wool sound absorption material was good (Fig.7). The structural parameters (thickness, surface density and average pore size) of needled sound absorbing materials had influence on sound absorption performance (Tab.3). The horizontal burning performance of the Hu sheep wool needled fabric before flame retardant finishing reached the flame retardant standard requirements, but the vertical burning speed was 276 mm/min, failing meeting the standard requirements(Fig.8). After flame retardant finishing, the horizontal burning performance exceeded the standard requirements, and the vertical burning speed became 0 mm/min, meeting the standard requirements.

      Conclusion Hu sheep wool has an obvious medullary layer, and the porous structure of its medullary cavity makes Hu sheep wool have good sound absorption performance. The Hu sheep wool scales are covered with craze, and the scales were very wide and cocked up obviously. This scale structure makes the Hu sheep wool have good milling power. For Hu sheep wool needled fabric, thickness and surface density are the main factors affecting its sound absorption performance. On the premise of not affecting the lightweight of the vehicle and meeting the requirements of sound absorption performance, the Hu sheep wool needled fabric with a thickness of 3.5-5 mm and a surface density of 350-450 g/m2 can be selected as the sound absorption material for the interior of the vehicle to meet the requirements of noise reduction.

      Dyeing and Finishing & Chemicals
      Photodegradation mechanism and pathway of visible light-response mesoporous TiO2 for Rhodamine B
      WANG Guoqin, FU Xiaohang, ZHU Yuke, WU Liguang, WANG Ting, JIANG Xiaojia, CHEN Huali
      Journal of Textile Research. 2023, 44(05):  155-163.  doi:10.13475/j.fzxb.20220503201
      Abstract ( 203 )   HTML ( 11 )   PDF (7475KB) ( 121 )   Save
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      Objective In order to promote the practical application of deep treatment of organic pollutants in slightly polluted water bodies using heterogeneous photocatalysis, mesoporous TiO2 photocatalyst as a novel photocatalyst with a pore size of 2-50 nm has a particle size of larger than 200 nm, so it was very easy to recycle, thus avoiding the potential nano-toxicity of the nano photocatalyst.

      Method In order to obtain a visible-light-responsive mesoporous TiO2 photocatalyst, chiral mesoporous TiO2 with spirally-stacked structure was prepared by a soft template method constructed with chiral surfactants. By means of various characterization methods such as X-ray spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, surface area and pore size analysis, and circular dichroism (CD), the differences in structure and visible light response of chiral mesoporous TiO2 and achiral mesoporous TiO2 were compared and analyzed. The photodegradation experiment for Rhodamine B (RhB) under visible light excitation was adopted to evaluate their catalytic performance, thus exploring the mechanism and pathway for degrading RhB by chiral mesoporous TiO2.

      Results The average pore diameters of the two mesoporous TiO2 were 6.4 nm and 8.6 nm. The specific surface area, pore volume and pore size of chiral mesoporous TiO2 prepared by chiral surfactants were slightly smaller than those of achiral mesoporous TiO2. The particle size of the chiral mesoporous TiO2 particles was about 200 nm, and it presented an obvious helical packing structure, which also showed a significant chiral correspondence effect. On the other hand, the morphology of achiral mesoporous TiO2 did not show the structure of helical stacking, but only showed the aggregation structure of some particles. Both chiral mesoporous TiO2and achiral mesoporous TiO2had two mixed crystal forms of anatase and rutile (Fig.4). The helical stacking structure of chiral mesoporous TiO2 introduced more defects into the catalyst, so that the contents of Ti3+ and oxygen holes were higher than those of mesoporous TiO2 (Fig.5). Owing to its large specific surface area and excellent visible light response performance, chiral mesoporous TiO2 had a high degradation activity for RhB (the removal rate reached 78% within 5 h), and the degradation process conformed to first-order kinetics (Fig.6). The photocatalytic performance of achiral mesoporous TiO2 (the removal rate was only 16% within 5 h) was much lower than that of chiral mesoporous TiO2(Fig.6). Although the adsorption performance of the two catalysts for RhB was similar, the removal rate of RhB by chiral mesoporous TiO2 was more than 4 times that of achiral mesoporous TiO2(Fig.6). Radical trapping experiments and electron spin resonance (ESR) spectroscopy showed that the active species of chiral mesoporous TiO2 to degrade organic pollutant molecules under the excitation of visible light are ·O2-, ·OH and photogenerated h+ (Fig.7 and 8). When capturing ·O2-, ·OH and h+ during the photodegradation, the removal rates for RhB by the chiral mesoporous TiO2 decreased by 19.2%, 39.7% and 60.2%, respectively, compared with the photodegradation process without adding capture agent (Fig.7). It showed that ·O2-, ·OH and h+ all participated in the degradation of RhB as active species in the photodegradation process. And h+ was the main active species for degrading organic pollutants, followed by ·OH, and ·O2- was the least involved in the photodegradation (Fig.8). The calculation of the Fukui index (f-) of each atom in the RhB molecule proved that the atomic sites that were more likely to give electrons were easily attacked by photogenerated holes for degradation (Fig.9). By analyzing the intermediate products generated during the degradation process (Tab.2), the main pathway of the RhB degradation by chiral mesoporous TiO2 under irradiation of visible light was further obtained (Fig.10).

      Conclusion From the results of our work, the degradation pathway of RhB pollutants was obtained. The first step was that h+ attacked on the C—N bond of the RhB molecules to remove the ethyl group. Then, multiple demethylation and deethylation reactions, and deamination processes were carried out. Until the vulnerable C—N bond site disappears, the h+ would attack the carboxyl group with high electron density and the benzene ring to enable the ring-opening reaction to be continued, and finally RhB was mineralized into CO2, H2O and other inorganic substances.

      Preparation and properties of fast response thermochromic textiles doped with boron nitride nanosheets
      HU Anzhong, WANG Chengcheng, ZHONG Ziheng, ZHANG Liping, FU Shaohai
      Journal of Textile Research. 2023, 44(05):  164-170.  doi:10.13475/j.fzxb.20220400501
      Abstract ( 143 )   HTML ( 12 )   PDF (5586KB) ( 68 )   Save
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      Objective Thermochromic textiles based on fluorane dye microcapsules have many advantages, which are widely used in military camouflage, thermochromic clothing and smart windows, and so on. However, its application in the field of high sensitivity is limited because of its long discoloration time, wide discoloration range and hysteresis. Adhesives were necessary component in preparing the thermochromic textiles because of the lack of adhesion between the microcapsule and the surface of the fabric. However, most of the adhesives are polymer with poor thermal conductivity, which further reduced the thermochromic sensitivity of the fabric. Therefore, it is necessary to improve the color change sensitivity of thermochromic fabrics to broaden its application.

      Method In this paper, fast response thermochromic fabrics were prepared by screen printing technology with a thermochromic slurry including Boron nitride nano sheets (BNNS), yellow thermochromic microcapsule, deionized water, adhesive and thickener. BNNS was adopted to improve the thermal conductivity of the thermochromic fabric, improving the temperature perception of the color chang core material.

      Results BNNS were prepared by high-temperature oxidation and ultrasonic cell pulverization, whose properties were characterized by infrared spectroscopy, raman spectroscopy, X-ray spectroscopy and transmission electron microscope. The results showed that BNNS had a few layers structure with a mean particle size of 100-200 nm (Figs.1-3). A thermochromic printed fabric was prepared by screen printing technology with a thermochromic slurry including BNNS, deionized water, yellow thermochromic microcapsule (15%), adhesive (30%) and thickener (5%). The properties such as color performance and color change performance of thermochromic printed fabric were tested by colorimeter, digital camera and Adobe Photoshop CS software, and the influence of BNNS on these properties were investigated. The increase of BNNS content led to gradually decrease of the K/S value, reduction in the color change time, and narrowing of the color change range. When the content of BNNS was 2%, the performance of color performance and color change performance were generally the best, with the K/S value of 1.8 (Fig.5), the color change time of 8 s, the recoloration time of 13 s (Fig.7), the color change range of 31.4-37.2 ℃, and the recovery color range of 28.8-25.4 ℃ (Fig.8). Compared with the thermochromic fabric without BNNS, the color change time was shortened by 20%, the recoloration time shortened by 10.3%, the color change range reduced by 1.6 ℃, and the recoloration range reduced by 0.4 ℃ (Fig.8). In addition, BNNS content demonstrated little influence on the color fastness of thermochromic textiles. The color fastness to dry and wet rubbing and washing of the fast response color change fabric prepared are above grade 4 (Tab.1).

      Conclusion The thermochromic printed fabric with fast response was prepared by screen printing technology with a thermochromic slurry including BNNS, yellow thermochromic microcapsule, adhesive and thickener. The relationship between the content of thermal conductive BNNS and the color property, color change property and fastness of thermochromic fabric were discussed. The results showed that when the content of BNNS is 2%, compared with the original thermochromic fabric, the fabric has shorter color change time (8 s), recoloration time (13 s), narrower color change range (5.8 ℃) and recoloration range (3.4 ℃). In addition, the doping of BNNS has little influence on the stability and color fastness of the thermochromic fabric, and the thermochromic fabric remains to have excellent color changeability after 200 cycles. However, BNNS is in a form of white powder, and its light scattering makes the fabric pale. Therefore, it is necessary to balance the relationship between discoloration performance and recoloration performance. In general, thermal conductive BNNS can effectively improve the color change sensitivity of thermochromic fabrics, and it also provides a new method of improving the color change sensitivity for other thermochromic materials.

      Preparation and properties of photocatalytic self-cleaning aramid fabrics
      WEI Yuhui, ZHENG Chen, CHENG Erxiao, ZHAO Shuhan, SU Zhaowei
      Journal of Textile Research. 2023, 44(05):  171-176.  doi:10.13475/j.fzxb.20220508001
      Abstract ( 243 )   HTML ( 17 )   PDF (5383KB) ( 89 )   Save
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      Objective Fire-fighting clothing worn by fire-fighters is easy to absorb stains, in fire-fighting action, caused by the burning of rubber, textiles and other inflammable substances and other reasons. Researches on fire-fighting clothing mainly focus on the development of highly-flame-retardant fibers, fabrics and clothing, whilst the self-cleaning performance of fire-fighting fabrics is basically ignored. In addition, improper or excessive washing could easily deteriorate the protective performance. Therefore, development of self-cleaning aramid fabric is important to reduce the deterioration of protective performance caused by washing and to prolong the service life of the fire-fighting clothing.

      Method In order to improve the self-cleaning properties of aramid fabric, TiO2 with stable and good photocatalytic effect, SiO2 aerogel (super-hydrophobic interface) with high porosity and easily form three-dimensional micro-structure, metal ion (Fe), tetraethoxysilane, butyl titanate, polydimethylsiloxane, butyl ferrate, and N-hexane were selected to treat the fabric. One-step spraying method was applied to prepare the photocatalytic self-cleaning aramid fabric. In order to enhance the firmness, the mixed solution of N,N-dimethyl hexamide (DMAC) and water was adopted to dissolve the aramid fabric surface. The differences in surface morphology, chemical structure, hydrophobicity, self-cleaning, photocatalysis, gas permeability and flame retardancy before and after treatment were systematically investigated.

      Results The differences in the properties of aramid fabric before and after the treatment by SiO2-TiO2-Fe composite aerogel was found to be significant. In the aspect of morphology, the surface of the untreated aramid fabric was smooth without obvious attachment. On the contrary, the surface of aramid fabric treated with PDMS/SiO2-TiO2-Fe composite aerogel demonstrated increased roughness, with a layer of granular material uniformly attached to the surface. This shows the effectiveness of PDMS/SiO2-TiO2-Fe treatment to the aramid fabric surface. In the aspect of micromorphology, compared with the infrared spectra of untreated aramid fabric and treated aramid fabric (Fig.2), treated aramid fabric contained Si indicated the successful grafting of SiO2-TiO2-Fe composite aerogel onto the surface of aramid fabric. Static contact angle of the treated aramid fabric was increased to 150.9° suggesting super-hydrophobic critical range (Fig.3). Compared with untreated aramid fabric, carbon black pow der and clay on the surface of aramid fabric after treatment were both washed to the bottom of glass slide, and the surface of the fabric was clean, indicating that aramid fabric after the treatment by SiO2-TiO2-Fe composite aerogel has excellent anti-fouling performance (Fig.4). The photocatalysis degradation rate of methylene blue oil solution increased to 90.7% with the help of being treated by ultraviolet light for 6 h (Fig.5), indicating that the self-cleaning and anti-fouling properties of the treated aramid fabric were improved obviously. Compared with the flame retardancy of aramid fabric before and after the treatment by SiO2-TiO2-Fe composite aerogel, it was found that the flame retardancy decreased slightly, but remained within the standard requirement of B1 grade. It also found that washing has little effect on the flame retardance of fabric, indicating that the combination fastness was strong, and thus it was feasible to use one-step spraying method to treat aramid fabric with SiO2-TiO2-Fe composite aerogel.

      Conclusion Compared with untreated aramid fabric, the static contact angle of SiO2-TiO2-Fe composite aerogel and low surface energy aramid fabric prepared by water-based sol-gel method was increased to 150.9°, the photocatalysis degradation rate of methylene blue oil solution was increased to 90.7% with the help of being treated by ultraviolet light for 6 h, and the self-cleaning and anti-fouling properties of the treated aramid fabric were improved obviously. The results provides a theoretical basis for development of self-cleaning fire-fighting fabrics, and was beneficial to prolong the service life of fire protection clothing.

      Apparel Engineering
      High-precision intelligent algorithm for virtual fitting based on texture feature learning
      LIU Yuye, WANG Ping
      Journal of Textile Research. 2023, 44(05):  177-183.  doi:10.13475/j.fzxb.20220403101
      Abstract ( 167 )   HTML ( 13 )   PDF (9782KB) ( 168 )   Save
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      Objective Virtual fitting provides users with a digital and interactive fashion fitting experience and meets the requirements for garment customization in the fashion industry by using machine vision, artificial intelligence and other technologies. It has attracted keen attention from international brands and researchers. However, due to the influence of various posture, occlusion and interruption in non-fitting area, the existing virtual fitting methods still have problems, such as distortion, blurring and low accuracy. In order to overcome these problems, this paper proposed a high-precision virtual fitting model named as C-CGAN based on texture feature learning.

      Method A garment reconstruction network based on the idea of CGAN was proposed, which used the garment mask positioning and garment texture constraints to learn intelligently the garment reconstruction model under various postures. The encoder-decoder network was utilized to fuse the reconstructed garment and character features. In addition, a variety of comprehensive loss functions were employed to optimize the network performance. A rich texture dataset was eventually constructed based on the international virtual fitting dataset, followed by the development of a garment fitting system in PyTorch environment and its performance evaluation.

      Results The results of C-CGAN showed more significant FID (Fréchet distance) and IS (initial score) optimization effect than that of the newly reported VITON and CP-VTON statistical metrics (Tab.2). However, the PSNR (peak signal to noise ratio) accuracy of CP-VTON was still low, which means it had a lot of distortion. Compared with CP-VTON, in the case of comparable IS, the FID of C-CGAN was reduced by about 11%, the SSIM (structural similarity) is increased by about 25%, and the PSNR was increased by about 78%. Therefore, the performance metrics of this network had significant advantages. In order to compare the visual fitting effect, CP-VTON and C-CGAN were both adopted to synthesize the texture of the model's original tops on the test dataset for comparison of the subjective visual similarity between the virtual fitting results and the real sample in dataset. The comparison results of the virtual fitting (Fig.7) in 9 difficult scenes (Tab.1) showed that CP-VTON was prone to large deformation distortion for some complex textures, such as stripes and wave points, and the model's arm was distorted when occluded. In contrast, C-CGAN was shown to be able to suppress effectively the interference of occlusion and garment texture, truly and exquisitely preserve the details of characters and texture, and had a higher similarity with real samples. Furthermore, in order to verify the applicability of this method in practical applications, a model in test dataset was selected whose original top's texture is light pinstripe. There were ups and downs and pleats at the model's front and waist, respectively, relating to her posture. The virtual garment replacement preview results of seven textures (Fig.8) showed that textured details and features varied on the model's chest and waist corresponding to the posture, such as the fold changes of pure color, the density changes of the wave point and the waveform variation of the stripe. In addition, C-CGAN was shown to preserve well the model characteristics of models and clothing characteristics of other areas.

      Conclusion This paper presented extensive qualitative and quantitative evaluations on the C-CGAN method. The statistical metrics on the test dataset show that the similarity between the C-CGAN virtual fitting results and the real samples is higher, the accuracy is higher, and the distortion is smaller. The subjective visual comparison results of virtual fitting show that C-CGAN has better adaptability to difficult fitting scenes such as stripes, wave points and occlusion, and the reconstructed texture is more natural and delicate, with high matching sense of human posture and good adaptability. The virtual garment replacement preview test results show that C-CGAN can generate texture deformation adapted to human posture for color, stripe and wave point, and the generated image is clear. C-CGAN can provide a realistic virtual fitting experience, which can be widely used in digital fashion application scenarios such as interactive texture reloading and garment assisted design.

      Online recognition system for typical traditional costume images
      YAN Bingyi, HOU Jin, HUANG Qiyu, YANG Hancheng, TIAN Jin, YANG Chunyong
      Journal of Textile Research. 2023, 44(05):  184-190.  doi:10.13475/j.fzxb.20220406201
      Abstract ( 260 )   HTML ( 38 )   PDF (3318KB) ( 157 )   Save
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      Objective Traditional costume culture is in danger of disappearing gradually and needs effective conservation methods. Currently, most of conservation methods rely on human resources, such as recording traditional costume by taking photos and scanning, causing that the conservation efficiency and culture exchanging are low and an efficient method to preserve the culture is lacking. Therefore, a new deep learning algorithm was proposed for highly accurate recognition of traditional costumes, and an online web identification system was designed based on cloud computing technologies. The proposed research should serve as a new alternative way for conservation and recognization of traditional costume culture efficiently.

      Method Firstly, a traditional costume image dataset was constructed and enhanced by the combination of multiple background replacement and geometric transformation. Then, three modified DenseNet169 network models were built by introducing the squee and excitation (SE), convolutional block attention module (CBAM) and coordinate attention (CA), respectively, and these models were later integrated together to form a high-performance algorithm. After that, based on cloud computation and web technology, an online recognition system for typical traditional costume images was constructed by combining image normalization pre-processing and the new algorithm.

      Results A traditional costume images dataset, which contains 92 160 images of a total of 15 styles, such as costumes of Zang, Man, Mongolian, Miao, Yi, Gejia, Li, Qiang, Hui, Dai, Zhuang, Han, She, Bai and Korean nationlities, was set up. The comprehensive recognition accuracies for the three improved models (using attention mechanisms SE-Dense Net 169, CBAM-DenseNet169 and CA-DenseNet169, respectively) were 89.50%, 89.83% and 90.17%, respectively (Tab.1). Although all their comprehensive recognition performances were good and similar, each model was limited by poor recognition accuracies for some specific different traditional costume categories. For example, the separated recognition accuracies of SE-DenseNet169 on Li and Zang costumes were only 77.5% and 80%, respectively. After weighting integration of the three models, the final algorithm obtained a high comprehensive recognition accuracy of 93.50% on the verification set. Compared with the previous best comprehensive recognition accuracy of CA-DenseNet169, an improvement of 3.33% was achieved. With the new algorithm, apart from relatively low separated recognition accuracy (about 87.50%) for Li costumes, the separated recognition accuracies for other traditional costume categories were all above 90.00%. Once the Korean costume image was input into the system, the most possible 3 prediction costume categories and the consumption time were displayed (Fig.4). 600 Real scene traditional costume images from different costume categories were tested, only 15 images' corrected categories were not shown in the most possible 3 prediction costume categories, which indicated a high comprehensive recognition accuracy of 98.00%. The value would be decreased to 93.50% if only using the most possible 1 prediction costume category as the output result. Meanwhile, the average processing and recognizing time taken by the system (deployed on an Aliyun server with dual-cores intel i5 CPU and 4 GiB RAM) for an image of 1 MB was around 11-13 s, which should be acceptable.

      Conclusion In addition to the problems of lack of effective methods to protect traditional costume culture and limited recognization channels, the research built an online recognition system of typical traditional costume images. The system could efficiently identify 15 types of traditional costume images, and it is convenient to operate, recognize and share. Besides recording, protecting and spreading traditional costume culture efficiently, the system could also be used as a digital tool to promote tourism, culture and economy in various ethnic regions. The research would provide a new alternative solution for conserving and recognizing traditional costume culture. However, at present, the system still has some limitations, such as, only few recognizable traditional costume categories, low recognition accuracy of individual traditional costume categories and slightly slow recognition speed. In the future, the number of recognizable costume categories should be expanded, the algorithm should be improved, and the interface and operation process of the system should be optimized.

      Garment group customization sizing mechanism based on simulated size data
      NIE Zimeng, DU Jinsong, ZHU Jianlong, YUE Chunming, GE Xuguang
      Journal of Textile Research. 2023, 44(05):  191-197.  doi:10.13475/j.fzxb.20220405201
      Abstract ( 141 )   HTML ( 9 )   PDF (3773KB) ( 46 )   Save
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      Objective In the context of the rapid development of group customization of garment, this paper aims to solve the current problem of regional size system establishment of group customization, optimize the group customization number sizing process, and improve the style unity of group orders.

      Method The Monte Carlo method was adopted to simulate the regional group size measurement data, and the regional group size system (RGS) was established based on the K-means clustering analysis results of the simulation data and the size proportion coefficient of the enterprise initial size system (EIS) and the sizing process of the group order was realized by using RGS. The sizing results were evaluated by comprehensive fit and aggregate loss.

      Results The scatter diagram of chest grith/garment length of 10 000 sets of data was simulated by Monte Carlo method. The scatter diagram distribution and frequency distribution statistics of simulation data and real data were consistent (Fig.4), suggesting that the simulated data from the simulation model could be used as the target data of the next experiment. The clustering center of the simulation data clustering analysis results was tested (Tab.2). Based on the clustering center and EIS, the regional group size system RGS was established through the size system establishment process. 19 Types of RGS were involved in the research (Tab.4). Each size contained 4 important primary dimensions, i.e. chest grith, garment length, across shoulder and sleeve length. It was found that 4 sizes determining the style of garment were mid waist, hipline, sleeve bicep, and cuff. The same circumference or width transverse parameter has 3 length index values to match, and there were more size combination. Compared with EIS, RGS established on the basis of simulation data demonstrated a significant effect on the overall coverage of regional population. The comprehensive fit results showed that RGS can cover most target groups (Fig.5). The size data of the orders containing 218 people of the enterprise were matched by EIS and RGS, respectively. The sizing process and the sizing results were suggested 1 person cut individually for special body type. When using EIS for matching sizes, the evaluation result of the fit degree was as follows: 108 people fedback with excellent fitting (48%), 102 people good, 1 person general, and 6 people not ideal. When RGS was adopted to match the size of the order, and the fit degree evaluation results showed that 211 people returned excellent feedback, 4 people good, and 2 people general, with the proportion of excellent of 97.2%. The excellent conversion rate of RGS is 47.4% (Tab.5).

      Conclusion The Monte Carlo method was adopted to simulate the regional size data accumulated by enterprise orders, and the enterprise size database was established. The simulation data reached the expected simulation goal, and the regional group size system could be optimized by using the simulation data. RGS establishment is shown to increase the coverage of target population, increase the fit degree of clothing, effectively improve the uniformity and consistency of garment customization, and thus reduce the probability of garment repair. The sizing mechanism considers the multidimensional size proportion of human body, changes the method of relying on a single dimension for the sizing process, and carries on the size matching through the proportion of different dimensions. The sizing process can effectively distinguish and classify the body size, and match the individual size with the size system. The sizing mechanism can provide theoretical basis for enterprise digital sizing process.

      Machinery & Accessories
      Yarn tension non-contacts detection system on string vibration based on machine vision
      JI Yue, PAN Dong, MA Jiedong, SONG Limei, DONG Jiuzhi
      Journal of Textile Research. 2023, 44(05):  198-204.  doi:10.13475/j.fzxb.20211205201
      Abstract ( 149 )   HTML ( 8 )   PDF (4015KB) ( 84 )   Save
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      Objective The objective of the research on the non-contact detection system for yarn tension based on machine vision is to improve the accuracy of tension detection for moving yarns. The current contact tension measurement makes direct contact with yarn during the detection process, which causes additional friction to the yarn and wears the measuring device at the same time, affecting the accuracy of tension measurement. The machine vision technology provides a new direction for yarn tension detection. Based on string vibration theory and machine vision image processing method, this poper aimed to study and design a non-contact detection system for yarn tension based on machine vision to achieve accurate tension detection.

      Method In order to investigate the relationship between yarn tension and vibration frequency in non-contact detection, the yarn in transverse vibration in the system was regarded as string vibration, and a mathematical model of yarn tension and vibration frequency was established and the theoretical relationship was derived. The yarn winding motion device was designed, the camera shooting field of view was planned, and the yarn tightening roller was designed to make the yarn vibrate freely in the detection range. A line array industrial camera was selected to complete the yarn image acquisition, and the strip light source was adopted to assist the illumination. A series of image pre-processing was carried out to smooth out the yarn image noise, edge extraction was selected to obtain the upper boundary of the image, and the frequency was calculated from the peaks and valleys of two adjacent frames to measure the yarn tension.

      Results In order to verify the accuracy of yarn tension measurement, test experiments were conducted using the constructed detection device, where the yarn was wound around the winding roller and placed in the middle of the pulley and clamping roller (Fig.7). A tension sensor was used for tension detection comparison, the yarn guide roller and the winding roller were driven by servo motors, and the line array light source provided stable light. The frame rate of the image acquisition by the line array camera was set to 100 frames per second, and the exposure time was 100 ms. Three strands of Kevlar yarn were used in the experiment, where the yarn length was 50 m, the yarn linear density was 8.2 tex, and the yarn diameter was 0.6 mm. During the experiment, the yarn moved at about 25 m/min, the winding speed of the winding roller motor was 180 r/min, and the winding speed of the clamping roller motor was 98.2 r/min. The fitted line of yarn vibration frequency and tension showed, where it was evident that according to the time sequence, the measured value of the tension sensor correponds to that of the vision measurement system (Fig.9). The results showed that yarn frequency was positively correlated with yarn tension, and the yarn vibration frequency was quadratically related to yarn tension, and the correlation coefficient of the fit reached 0.992. The deviation of the system measured values and the sensor measured values were different, and the collected frequency information effectively reflect the stability of the yarn tension was indicated (Tab.1 and Fig.10). The results showed that the current tension of the moving yarn determined by the vibration frequency is within the tension range of 5-30 cN, and the relative error rate between the visual system measured value and the tension sensor measured value was about ±10%.

      Conclusion When the yarn running state changes, the yarn moving speed will also change and so will the measurement value of the vision system. In the vision measurement system, when the yarn runs to the winding roller and clamping roller, the yarn is subjected to a relatively large force. When the yarn runs to the middle, the yarn tends to run smoothly and the tension will be relatively uniform, causing the detected yarn tension to fluctuate within a certain range. The non-contact yarn tension detection does not directly contact the yarn and will not change the original force state of the yarn. Theoretically, the measurement accuracy is higher than the direct contact method, which proves the feasibility of the non-contact detection system to complete the yarn tension measurement and has reference significance for the research of non-contact detection of yarn tension and has a broad prospect in engineering application.

      Detection methods for yarn capture state with automatic knotter
      TU Jiajia, LI Changzheng, DAI Ning, SUN Lei, MAO Huimin, SHI Weimin
      Journal of Textile Research. 2023, 44(05):  205-212.  doi:10.13475/j.fzxb.20211005501
      Abstract ( 191 )   HTML ( 5 )   PDF (4727KB) ( 40 )   Save
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      Objective With the continuous advancement of intelligent manufacturing process in knitting department, automatic bobbin changing and thread continuation of yarn frame are technical difficulties to be solved urgently. Aiming at the problem that it is impossible to detect the capture state of head yarn and tail yarn when using mechanical knotter to complete yarn joint on yarn frame, which leads to the inability to realize intelligent manufacturing in the knitting workshop, this paper proposes a detection method based on image pixel point measurement.

      Method Based on the working principle of mechanical knotting machine, a yarn detection and recognition mechanism which integrates the installation box, camera module and light source was proposed. The mechanism was fixed on the transparent tube between the fan and the suction nozzle. Through the small embedded module, images were collected and processed including pixel counting and signals output in real time. The developed technique facilitated the low-cost yarn capture state detection on the yarn frame.

      Results After the knotter moves to the position near the end line, the image without yarn is collected, and the initial number of white pixels is obtained after processing. 200 Groups of data are randomly selected to obtain the curve (Fig.9). The abscissa is the number of tests, and the ordinate is the number of pixels. The initial value of the number of white pixels varies between 24 592 and 24 651, and the maximum variation is only 59. After getting the initial value of the number of pixels, the system controls to clear it to get the corresponding number of pixels when there is no yarn. Theoretically, the number of pixels after clearing is 0. However, due to a small amount of light leakage in the installation box and the high sensitivity of pixel measurement, there is still a numerical fluctuation. Therefore, 200 groups of data are randomly selected to obtain the curve (Fig.10). The number of pixels without yarn after zeroing varies from 0 to 55. Then the head line and tail line absorption experiments were carried out at 5 different positions. After the head line is captured, the number of pixels changes significantly, and is far greater than its maximum fluctuation value of 55. At the same time, the curve fluctuation amplitude is close to that in Figs.9 and 10, which proves that the head line capture state can be recognized by measuring image pixels. In addition, the position has a great impact on the number of pixels, with a range of 204-512. After the two yarns are captured successfully, the change trend of the number of pixels obtained is basically consistent with that of a single yarn, and the number of pixels corresponding to positions 2 to 5 changes significantly more than that of a single yarn, so the capture status of the head thread and tail thread can be detected and recognized normally. The number of pixel points corresponding to position 1 is less than or close to positions 3 to 5 (Fig.11), but there is still a significant difference compared with the number of pixel points of single yarn position 1 and two yarn position 1.

      Conclusion In this paper, taking the automatic bobbin change and thread continuation of the circular weft frame as an example, a yarn absorption detection algorithm based on image pixels is proposed according to the working principle of the mechanical knotting machine, and a special installation box and embedded module for yarn detection are designed, which achieves the online real-time recognition function of the bobbin head yarn and tail yarn absorption status before knotting. At the same time, through the experimental test and demonstration application of single and multiple absorption of common yarns with different colors, it is verified that this method has the advantages of high detection sensitivity, small size, low cost, etc. In addition, the detection mechanism and method are also applicable to wire break detection and other fields, so it has good promotion and application value. However, in-depth research on yarn contour, broken thread detection, yarn specification identification and the impact of vibration on the identification effect will be necessary for future work to further improve its applicability and stability.

      Comprehensive Review
      Research progress in zinc and copper containing wound dressings
      QIN Yimin
      Journal of Textile Research. 2023, 44(05):  213-219.  doi:10.13475/j.fzxb.20211101502
      Abstract ( 347 )   HTML ( 13 )   PDF (3194KB) ( 263 )   Save
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      Significance In order to develop the applications of functional zinc and copper containing fibers and wound dressings in the management of chronic wounds, this paper introduced the bioactivities of zinc and copper ions and their roles in the wound healing process, and summarized the types and production methods of zinc and copper containing wound dressings in the domestic and international market, in particular zinc and copper containing alginate fibers, chitosan fibers, and the various types of zinc and copper containing wound dressings and their ion releasing properties obtained by electrospinning, polymeric composites, nano technologies and other advanced processing methods. Both zinc and copper ions possess antimicrobial efficacy and are known to be able to promote wound healing. The incorporation of these two metal ions by the techniques reviewed in this paper can help manufacturers and medical practitioners in the wound management industry to fully utilize the novel health benefitting properties of zinc and copper ions.

      Progress Both zinc and copper ions have been used in the wound management industry for a long time by many forms of applications. Recent progresses are mainly focused in the sustainable release of zinc and copper ions by combining these two ions with alginate, chitosan and other novel substrate materials, and also by the use of nanoparticles of zinc oxide and copper oxide. The incorporation of zinc ions into alginate fibers and the subsequent release of zinc ions when in contact with aqueous solutions containing different levels of protein were summarized. The composition and properties of many types of zinc containing wound dressings reported in the documents were summarized. Regarding copper containing wound dressings, important progress has been made by incorporating copper oxide into fibers by blending and the subsequent extrusion to form copper containing fibers. In addition, copper ions can be absorbed into various types of alginate fibers that can be released when these fibers are in contact with aqueous solutions similar to wound exudate. Many other methods have been used in the documents to load and release copper ions from the base materials of wound dressings. The combination of zinc and copper ions with wound dressings have demonstrated important clinical benefits by accelerating the healing of burns and chronic wounds. Zinc and copper containing fibers and wound dressings possess antimicrobial properties similar to silver containing fibers and wound dressings.

      Conclusion and Prospect Zinc and copper ions are minor metal ions present in the human body and are closely involved in the function of many enzymes during the wound healing process. The loss of zinc ions are well known for the delayed healing of burn wounds. Copper ions are also shown to be able to promote the healing of chronic wounds such as leg ulcers and pressure sores. The overall results of this review showed that zinc and copper ions have excellent antimicrobial properties and can promote wound healing. Experimental results have confirmed that zinc and copper containing wound dressings have strong antibactenal effect against the various types of bacteria commonly present in wounds, and these dressings are highly useful in the management of leg ulcer, pressure sore, diabetic foot ulcer, burn and other types of wounds. Looking into the future, much research and development work is still needed to clarify the wound healing mechanism of these two metal ions. In addition, clinical research and formal clinical trials are also required to validate the clinical efficacy of zinc and copper containing wound dressings before these products can be commercialized. Regulatory approval procedures are also needed through the collaborative efforts of researchers, manufacturers, regulatory bodies and medical practioners around the world.

      Technology progress and application prospects of liquid disperse dyes
      AI Li, ZHU Yawei
      Journal of Textile Research. 2023, 44(05):  220-227.  doi:10.13475/j.fzxb.20220403902
      Abstract ( 257 )   HTML ( 15 )   PDF (4224KB) ( 204 )   Save
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      Significance Disperse dyes are special dyes for polyester fiber dyeing, commercially available mainly in powder and liquid forms. Powdered disperse dyes are widely used because of their excellent storage and application stability, while liquid disperse dyes are restricted by their stability. In recent years, with the great demand for energy conservation and emission reduction in printing and dyeing, liquid disperse dyes have attracted much attention, because of the advantages over the powdered disperse dyes in higher utilization rate of dye, low discharge of wastewater and waste residue and low energy consumption. Although the stability of liquid disperse dyes restricts its development to a certain extent, with the progress of the preparation technology of liquid disperse dyes, the stability has been effectively improved, and has been gradually replacing the traditional powdered disperse dyes.

      Progress The lapping technology of liquid disperse dyes were briefly introduced. Selecting suitable anionic/non-ionic surfactants and anti-sedimentation agents was recognized as the key factor to prepare liquid disperse dyes with excellent stability and application performance. The main processing parameters affecting the properties of liquid disperse dyes were analyzed, and the influence of rheological property and ambient temperature on the stability of liquid disperse dyes were clarified. As the second attempt, the principle of high temperature dispersion, low temperature dispersion and double electric layer diffusion of liquid disperse dyes were analyzed. It was indicated that the viscosity increasing temperature (T0 value) and the absorbance change rate of water dilution (A10) could be used as indexes to evaluate rapidly the stability of liquid dyes. Then, the energy conservation and environmental friendliness and advantages of liquid disperse dyes in high temperature and high pressure dyeing, round mesh and screen printing are analyzed, and the new applications in continuous hot melt dyeing are analyzed, and the prospect of dyeing and finishing in the same bath processing was pointed out.

      Conclusion and Prospect Although the preparation process of liquid disperse dyes is similar to that of powdered disperse dyes, liquid disperse dyes use less water and a small amount of additives (anionic/non-ionic mixture) as fillers. The difference in the performance of the two types of disperse dyes leads to the realization of low water consumption and near-zero emission printing and dyeing technology of liquid disperse dye, which could form a major energy conservation and emission reduction technology to meet the needs of printing and dyeing industry from the source. Liquid disperse dyes have been widely used, but their potential advantages have not been fully utilized. Therefore, the establishment of liquid disperse dye commodity standards, control of dye standardized quality, research and development of new bath dyeing and functional finishing technology are imperative to meet our 'carbon emissions and carbon neutrality' source pollution control printing and dyeing technology needs.

      Development of personal comfort models based on machine learning and their application prospect in clothing engineering
      WANG Zhongyu, SU Yun, WANG Yunyi
      Journal of Textile Research. 2023, 44(05):  228-236.  doi:10.13475/j.fzxb.20220303402
      Abstract ( 230 )   HTML ( 23 )   PDF (3670KB) ( 120 )   Save
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      Significance Human, clothing and external environment form an interactive system. As a barrier between the environment and human body, clothing directly affects the thermal comfort of people. It is indispensable to evaluate the thermal comfort or personal safety. However, individual differences would lead to discrepancy in subjective feelings and efficiency could be impaired if frequent subjective assessment is needed in working process. Therefore, effectively predicting the thermal comfort of individuals and returning timely suggestions to improve the micro-environment between clothing and body would be necessary. Conventional thermal comfort models including steady-state heat transfer models, thermal adaptative models and dynamic thermal physiology models were established based on physical equations or data from general population, without considering individual differences. Therefore, new methods should be introduced to study the personal thermal comfort. Researches have been carried out on the application of machine learning algorithms to establish personal thermal comfort models, predicting individual thermal comfort through data-driven methods. Compared with conventional models, the prediction of the personal thermal comfort models is significantly improved. The models overcome the defects of the conventional models which are complicated and inflexible, predict thermal comfort in real time, and are beneficial to improve of micro thermal environment more efficiently.

      Progress The personal thermal comfort models established by machine learning could be regarded as a supervised learning process. Sample source, input features and output labels, machine learning algorithms and evaluation indicators are the main influencing factors encountered during the establishment. Sample source brings about the question of applicability. Models built upon laboratory data may not be fit for field studies, neither are models established with mild environments' data suitable for extreme conditions. The sample size for achieving stable prediction varied from models. Generally, input characteristic parameters included environmental parameters collected from the surrounding environment or meteorological platform, and individual parameters reflecting the state of the human, could be both considered when collecting input features. Subjective evaluation index as output labels depended on research purpose and the evaluation of human thermal comfort should consider at least two subjective indexes, including symmetric and asymmetric ones. When selecting machine learning algorithms, the sample size and applicability of the algorithm also should be taken into account, as well as the cost and interpretability. Evaluating the prediction performance helps to confirm the validity of models especially when conducting multi-index evaluation. Indexes such as accuracy, precision, recall are suitable for the binary-classification conditions, while Kappa coefficient could handle the multi-classification and imbalanced datasets. The models based on machine learning has a broad application prospect in clothing due to its personalization, flexibility and dynamic predictions. Developing intelligent temperature regulating clothing that could predict the thermal comfort of individuals in real time and change the control strategies accordingly has become a research hotspot. Personal thermal comfort models provide a feasible technical path by combining software and wearable hardware systems. Once achieved, the thermal security would be guaranteed and the work efficiency improved.

      Conclusion and Prospect Personal thermal comfort models based on machine learning algorithm is a new method to achieve individual thermal comfort prediction, which has the advantages of user personalization, multi-dimensional input parameters and dynamic prediction. At present, some progress has been made in the research of this model, which is summarized as follows. 1) The data of the model usually come from simulated experiment environment or actual working environment, but the prediction model based on the two kinds of data is not universal. Therefore, the reasons and solutions for the differences can be further explored to expand the application scope of the model. 2) Personal thermal comfort is mainly affected by the environment and individual factors. The selection of feature parameters should adopt multi-parameter combination with different properties, and the number of feature parameters should be controlled according to different algorithms. When applied in the field of clothing research, attention should be paid to comprehensively consider the influence of clothing on human thermal regulation. 3) A variety of indicators are involved when evaluating models' prediction performance, and the evaluation objects and applicability of which should be considered. In order to overcome the limitation and incomparability of single index evaluation, future studies might focus on multi-index comprehensive evaluation to evaluate the model's prediction and generalization ability. 4) Personal thermal comfort models established by machine learning algorithm has high application value in the field of intelligent clothing. The modeling technique's improvement could provide key technical support for development of intelligent temperature regulating clothing. Accordingly, the real time thermal comfort requirements of operators would be met, while operational efficiency and thermal safety could be guaranteed.