Table of Content

15 February 2023, Volume 44 Issue 02

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Fiber Materials

Preparation and properties of phosphorus-silicon modified flame retardant and anti-dripping polyester fiber

REN Jiawei, ZHANG Shengming, JI Peng, WANG Chaosheng, WANG Huaping

Journal of Textile Research. 2023, 44(02):  1-10.  doi:10.13475/j.fzxb.20220809410

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Objective Polyester fibers are flammable with a large number of molten droplets and smoke emission when burning. This research aims to improve the flame retardant properties of polyester fibers through the addition of phosphorus and silicon flame retardants, and to prepare polyester fibers with better flame retardant properties for fire safety in end uses.
Method The phosphorus-silicon flame retardant masterbatch was prepared by blending diethyl hypophosphite flame retardant, macromolecular silicone and polyester. Then, the phosphorus-silicon flame retardant masterbatch was added to the polyester according to an optimized mass fraction, and the flame retardant and anti-dripping polyester fiber was produced by melt spinning. The mechanical properties, thermal properties and flame retardant properties of the flame retardant polyester were characterized and analyzed by using scanning electron microscope, compound filament strength meter, differential scanning calorimeter, thermogravimetric analyzer, ultimate oxygen index meter and Raman spectroscopy.
Results The diethyl hypophosphite flame retardant selected in this work is found to be able to dehydrate the polyester surface into char, and the macromolecular silicone enhances the graphitization of the char layer, forms an orderly and stable char layer, enhances the flame retardant polyester flame retardant properties and inhibits the formation of molten droplets. Accordingly, the amount of smoke formed by combustion decreases, and the morphology of the char layer of the samples after combustion is shown in Fig. 5, and the results of the char layer structure stability study were shown in Fig. 6. It is discovered that macromolecular silicone mainly plays a role in the cohesive phase flame retardant process when polyester burns, forming a synergistic effect with phosphorus-containing flame retardant, generating an effective physical barrier, impeding the transfer of combustible gases, oxygen and heat, and inhibiting the occurrence of combustion reactions. The flame retardant polyester fiber spun by adding 3% diethyl hypophosphite flame retardant and 0.77% macromolecular silicone, the test results for the flame retardant properties of the modified samples are showed that the limiting oxygen index reached more than 31%, the vertical combustion test grade reached V-0 level, inhibiting the formation of molten droplets of polyester fiber during combustion, hence reducing the risk of secondary combustion brought about by the molten droplet phenome-non(Tab. 7).
Conclusion The flame retardant synergistic effect between phosphorus and silicon elements improved the spinnability of the flame retardant polyester fiber, and the modified polyester fiber has good flame retardant and anti-dripping properties. This work proved that the phosphorus-silicon element synergy is helpful to improve the flame retardant properties of polyester fibers, and provides ideas for the subsequent preparation of flame retardant polyester fibers by using different structural flame retardants from the viewpoint of conformational relationship and processing performance.

Effect of Lyocell fiber structure on its fibrillation at high speed spinning process

LI Ting, LI Wenrui, ZHANG Chenxi, CHI Kedong, ZHANG Mingming, LIU Haihui, HUANG Qing

Journal of Textile Research. 2023, 44(02):  11-18.  doi:10.13475/j.fzxb.20211001008

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Objective The research on the relationship between the condensed structure and the degree of fibrillation of Lyocell fiber at a higher spinning speed is relatively scarce. Selecting appropriate preparation conditions to change the condensed structure of fiber and regulate the degree of fibrillation can ease the main problems that restrict the industrial promotion and scale applications of Lyocell fiber. This research studied the influence of different preparation conditions on the condensed structure of Lyocell fiber and the degree of fibrillation, further established the relationship, which was then used to control the degree of fibrillation at high spinning speed.
Method In order to explore the relationship between the condensed structure and the degree of fibrillation of Lyocell fiber at high spinning speed, the fibers were spun with different N-methylmorpholine-N-oxide (NMMO) mass fractions, spinning speeds and blowing speeds. The degree of fibrillation was regulated by adjusting the structure. Using X-ray diffraction, wet friction tester and polarized microscope, the effects of NMMO concentration, spinning speed and blowing speed on the condensed structure and the degree of fibrillation were explored.
Results The condensed structure and fibrillation behavior of the fibers prepared under different conditions are obviously different. Increasing the concentration of the NMMO to a certain extent optimizes the fiber structure, leading to significant increase in the degree of orientation and transverse crystallite size as shown in Tab. 1, and in the degree of fibrillation of the fiber as illustrated in Fig. 2-3. The fiber with low crystal orientation and small crystal size has better antigen fibrillation properties. The coagulation bath with lower NMMO mass fraction is more suitable to prepare low fibrillation Lyocell fiber at high spinning speed. As the spinning speed increases, the crystallinity and the grain size of the fiber increases slightly as suggested in Tab. 2. However, the amorphous region is further oriented and the degree of fibrillation also increases(Fig. 4 and 5). To a certain extent, reducing the spinning speed can reduce the fibrillation of the fiber. Adjusting the air blowing speed has a significant impact on the structure of fiber as shown in Fig. 6, especially on the transverse grain size as shown in Tab. 3, which can control the degree of fibrillation as Fig. 7 reveals. In a certain range, the lower the blowing speed, the less the crystal orientation and the smaller the grain size, the more conducive to reducing the fiber fibrillation. Too low the blowing speed affects the forming of the fiber and the spinning stability.
Conclusion The condensed structure of Lyocell fiber directly affects the degree of fibrillation. The antigen fibrillation properties of the fiber prepared at high spinning speed is better in having low crystallization, low orientation and small crystallite size. To a certain extent, reducing the concentration of NMMO, spinning speed and blowing speed can reduce the degree of fibrillation. By comprehensively changing the degree of orienta-tion (especially the orientation of amorphous region) and the transverse grain size, the regulation of fibrillation is more obvious. Adjusting the concentration of NMMO is an easier way, among the above factors, to control the fibrillation behavior at high spinning speed. The Lyocell fiber prepared under mild spinning conditions demonstrates better antigenic fibrillation properties.

Preparation and filtration properties of polyethylene trifluoroethylene melt-blown nonwovens

YANG Xiaodong, YU Bin, SUN Hui, ZHU Feichao, LIU Peng

Journal of Textile Research. 2023, 44(02):  19-26.  doi:10.13475/j.fzxb.20220811008

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Objective In order to prepare high temperature resistant melt-blown filter materials to deal with the pollution of high temperature industrial dust, the thermal properties, dynamic thermomechanical properties, rheological properties and morphology of polyethylene trifluoroethylene (ECTFE) masterbatch were studied at first, and then the ECTFE melt-blown nonwovens were to be prepared by selecting appropriate process parameters. So far, there are few studies on ECTFE melt-blown nonwovens for air filtration.
Method The properties and structures of ECTFE masterbatch were determined by differential scanning calorimeter, dynamic thermo mechanical analyzer, thermogravimetric analyzer and melt flow meter. The ECTFE melt-blown nonwovens were then successfully prepared according to these studies on ECTFE masterbatch. The surface morphologies and pore size distribution of ECTFE melt-blown nonwovens were scrutinized by scanning electron microscope and pore size meter. The ECTFE melt-blown nonwovens was preheated at different tempera-tures (150, 170, 190, 210 and 220 ℃) using a muffle furnace. After that, the filtration efficiency and tensile properties of ECTFE melt-blown nonwovens was calculated by the dust particle detector and universal tensile tester.
Results The results show that with the increase of heating rate, the melting peak(T_p) of ECTFE masterbatch shifted to the right, and T_p was enhanced from 235.02 to 239.21 ℃, and the width of half peak increased(Fig. 3). The glass transition temperature of ECTFE masterbatch was found to be about 86.2 ℃(Fig. 4). The decomposition temperatures at initial and 5% weight lost were 300 and 372 ℃, respectively. It is obvious that for ECTFE masterbatch the temperature of the thermogravimetric zone was obviously higher than that of the melting process, which ensures the smooth process of ECTFE melt-blown nonwovens. When the test temperature increased from 250 to 290 ℃, the melt flow index elevated from 180 g/(10 min) to 376 g/(10 min), indicating that the melt fluidity of ECTFE masterbatch became better with the increasing of the temperature(Fig. 6(a)). The diameter of the fibers in ECTFE melt-blown nonwovens ranged from 4 to 12 μm, and its average diameter was about 7.12 μm. Additionally, the pore size of ECTFE melt-blown nonwovens was mainly in the range from 45 to 55 μm(as shown in Fig. 7). The filtration efficiency of ECTFE melt-blown nonwovens for PM₁₀ was maintained at 99.96% after it was preheated at temperatures of 150~210 ℃. Although the filtration efficiency of ECTFE melt-blown nonwovens for PM_2.5 and PM₅ decreased slightly with the increasing of preheated temperatures, it still exceeded 55.16% and 72.93%, respectively(Fig. 8).
Conclusion The glass transition temperature and melting peak of ECTFE masterbatch were about 86.20 and 235.02 ℃, respectively. Its complex viscosity decreased when increasing the shear rate and the ECTFE was categorized as a "pseudoplastic fluid". Besides, ECTFE masterbatch has excellent thermal stability at constant temperatures of 260, 270 and 280 ℃. ECTFE melt-blown nonwovens can be successfully fabricated under the conditions of heating temperature 260 ℃, hot air temperature 260 ℃, airway pressure 0.2 MPa, melt-blown pressure 0.5 MPa, acceptance distance 13 cm and translation speed 0.1 mm/s. The fibers in the ECTFE melt-blown nonwovens web were randomly interleaved and wound, and ensures that the ECTFE melt-blown nonwovens with high filtration efficiency. Therefore, it is believed that ECTFE melt-blown nonwoven should be an ideal filter material for high temperature resistant air filtration.

Electric field simulation of two-needle continuous water bath electrospinning and structure of nanofiber core-spun yarn

ZHOU Xinru, HU Chengye, FAN Mengjing, HONG Jianhan, HAN Xiao

Journal of Textile Research. 2023, 44(02):  27-33.  doi:10.13475/j.fzxb.20220803807

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Objective In order to understand the influence of electric field variation on the structure of nanofiber core-spun yarn with skin core structure with two-needle continuous water bath, finite element analysis software ANSYS is used to simulate the change of electric field distribution in the tip spacing. The morphology, diameter distribution, porosity and other structures of nanofiber core-spun yarns with different tip spacing were analyzed. The work aims to establish a theoretical basis for the optimization of process parameters of electrospinning, and provide a reference for the preparation of nanofiber core-spun yarn.
Method The continuous preparation of nanofiber core-spun yarn was achieved by using a self-made electrospinning equipment. The nanofiber core-spun yarn with polyester filament as the core yarn and polyamide 6 nanofiber as the coating layer was prepared by two-needle continuous water bath electrospinning method, aiming to acquire special properties combining the nanofiber and traditional yarn. Through the finite element analysis software ANSYS modeling analysis and scanning electron microscope observation, the theoretical and scientific study of the impact of needle tip spacing was carried out on the electric field distribution and nanofiber core-spun yarn structure.
Results By simulating the distribution and variation of electrospinning electric field with two needles, it can be confirmed that the maximum field intensity occurs at the tip of the needle. With the increase of tip spacing, the field intensity increases first then decreases and then increases as shown in Tab. 1. When the tip spacing was set greater than 40 mm, the field intensity peak with the increase of the tip spacing and gradually rise. However, considering the restrictions on the size of the electrostatic spinning equipment, and the limitation of fiber sedimentary area, tip spacing should not be too large. The needle tip spacing of 30 mm is better according to the analysis of the Tab. 1. The diameter and morphology of nanofibers can be adjusted by altering the tip spacing. According to the electron microscopy, when the tip spacing is 20 mm, the electric field interference leads to more bonding between the nanofiber. As the tip spacing increases, the interaction between the needles decreases, the morphology of nanofibers becomes more uniform and smooth, and the diameter of nanofibers decreases, as shown in Fig. 5. When the tip spacing is 80 mm, the diameter of the nanofiber reaches the minimum value of (74.43±10.79) nm. It is learnt that two-needle electrospinning requires special attention to the tip spacing while improving the yield of nanofibers to avoid the instability of jet flow caused by too small tip spacing. When the needle tip spacing is increased from 20 mm to 60 mm, the porosity of nanofiber core-spun yarn increased from 20.27% to 44.08%, indicating that the interaction between needles weakened with the increase of tip spacing, leading to improved porosity(as shown in Fig. 7).
Conclusion The simulation results show that the maximum field intensity appears at the tip, and the field intensity peak increases first, then decreases and then increases with the increase of the tip spacing. According to the electron microscopy, with the increase of the tip spacing, the interaction between the needles decreases, which can improve the porosity of the nanofiber core-spun yarn, and the diameter of the nanofiber decreases. The structure of the nanofiber core-spun yarn conforms to the changing law of the electric field strength. The results of electric field simulation have guiding significance for the study of the structure of nanofiber core-spun yarns. Due to the problems of electric field interference and equipment limitation in the experimental results, the study of process parameters is of great significance to the electric field variation in the process of electrospinning, which provide reference for subsequent research experiments. The further optimization of equipment and fiber structure and industrial production application are expected to be further discussed in future research.

Preparation and properties of polylactic acid/thymol antibacterial fibers

CHEN Huanhuan, CHEN Kaikai, YANG Murong, XUE Haolong, GAO Weihong, XIAO Changfa

Journal of Textile Research. 2023, 44(02):  34-43.  doi:10.13475/j.fzxb.20220704510

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Obective With the frequent occurrence of global acute infectious disease outbreaks, people are increasingly aware of individual protection. In order to protect textiles from microbial contamination and protect human health, it is important to endow textiles with antibacterial properties. However, with the gradual deterioration of white pollution, biodegradable environment-friendly polymer materials are receiving more and more attentions from researchers worldwide. Therefore, this research is committed to develop a green antibacterial fiber.
Method Polylactic acid (PLA) with good biodegradability and the natural antibacterial agent thymol were mixed evenly using a temperature control blending device before the PLA antibacterial fibers were prepared by melt spinning. The apparent morphology, chemical structure, crystallization, thermal and mechanical properties of PLA antimicrobial fibers with different thymol mass fraction were investigated by scanning electron microscopy, Fourier infrared spectroscopy, X-ray diffraction, single fibers strength meter and comprehensive thermal analyzer. The antibacterial properties of the fibers were tested by using oscillatory flask method.
Results After the addition of thymol, the two phases of PLA and thymol were interconnected without any obvious interface, and the two phase assembly led to good overall dispersion of thymol particles in the fibers, and excellent the compatibility between PLA and thymol, as evidenced in Fig. 2. In this study, the characteristic peak of C—H bending vibration on the benzene ring appeared at 800 cm^-1. The hydroxyl group of thymol can interact with the carbonyl group in PLA to form valence bonds, indicating the existence of chemical bonding interactions between thymol and PLA matrix. Furthermore, the electron microscopic morphology results indicated that the chemical bonding between thymol and PLA promotes their dispersion, as shown in Fig. 4. As the mass fraction of thymol increases, the melting temperature of PLA antibacterial fibers gradually decreases(as shown in Fig. 5). There were two stages of thermal decomposition of PLA antimicrobial fibers. The first stage occurs in 100-200 ℃, which is due to the volatilization and thermal decomposition of thymol in the system. The second stage takes place in 310-395 ℃, and the maximum degradation rate is shown around 375-381 ℃, and the mass loss gradually increases up to 99.28%. This is because of the decomposition of PLA macromolecules and short chain segments, and oligomers and lactide esters are produced during the melting process, as shown in Fig.6. With the increase of thymol mass fraction, the crystallinity of PLA antibacterial fibers gradually increases(as shown in Fig.7). When the mass fraction of thymol is 15%, the elongation at break of PLA antibacterial fibers can reach 320.98%, which was 90 times more than that of pure PLA fibers, and the flexibility is greatly improved, and these are shown in Fig. 8 and Tab. 3. Moreover, the higher the thymol mass fraction, the better the antibacterial properties of antibacterial fiber's. When the mass fraction of thymol is greater than or equal to 15%, the antibacterial rate of PLA antibacterial fibers becomes higher than 99.99%, which can inhibit the growth of Escherichia coli and Staphylococcus aureus completely. Besides, the antibacterial property of thymol on Staphylococcus aureus is better than that on Escherichia coli, as shown in Tab. 4.
Conclusion During the fiber formation process, thymol will adhere to the outer surface of the fibers to show antibacterial effect. With the increase of thymol mass fraction, the elongation at break of antibacterial PLA fibers shows a trend of rapid increase and then slowly decrease, and the elongation at break of PLA antibacterial fibers with thymol mass fraction of 15% can reach 320.98%, which is 90 times of pure PLA fibers. This indicates that the addition of thymol is beneficial to improve the flexibility of PLA. In addition, with the increase of thymol mass fraction, the melting temperature of PLA antimicrobial fibers gradually reduce and the crystallinity gradually increase, which illustrates that the addition of thymol promotes the formation of the α' crystalline form of PLA. When the mass fraction of thymol is more than 15%, the antibacterial property of PLA antimicrobial fibers reaches more than 99.99%, which can completely inhibit the growth of Staphylococcus aureus and Escherichia coli. In summary, the addition of thymol can impart excellent antibacterial properties to the fibers, improve the wearability of PLA fibers, and make them better used in textiles. Subsequent studies can optimize the wearability by improving the spinning conditions and processes to achieve the mass production of antibacterial fibers.

Alcoholysis and product recovery properties of polyethylene terephthalate/ SrAl₂O₄:Eu²⁺, Dy³⁺ hybrid fibers

LIAO Yunzhen, ZHU Ya'nan, GE Mingqiao, SUN Tongming, ZHANG Xinyu

Journal of Textile Research. 2023, 44(02):  44-54.  doi:10.13475/j.fzxb.20220704611

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Objective At present, the functional fibers containing various impurities are treated by landfill or incineration, which will not only affect the environment, but also cause the waste of functional materials. Some efforts have been made to recover waste luminescent fibers(polyethylene terephthalate(PET)/SrAl₂O₄:Eu²⁺,Dy³⁺), but the luminescent materials mixed in them are significantly affected by the violent reaction process. How to use a gentle way to complete the reaction and at the same time to ensure the consistency of functional materials is now the problem to be solved.
Method The waste PET/SrAl₂O₄:Eu²⁺,Dy³⁺ was used as the research object through combining ethylene glycol with hot ethanol, in order to recover the luminescent material SrAl₂O₄:Eu²⁺,Dy³⁺ and the alcoholysis product of PET. Different dosage of ethylene glycol were used to study the influence on the reaction temperature and reaction time of products, with the aid of scanning electron microscope, X-ray diffractometer, differential scanning calorimeter instrument, spectrophotometric color measurement instrument, the long afterglow brightness meter to analyze the microscopic morphology, phase structure, thermal stability, persistence, performance testing and characterization.
Results Both reaction temperature and reaction time had significant effects on the rate of alcoholysis and product recovery of PET/SrAl₂O₄:Eu²⁺,Dy³⁺. Under the condition where reaction time was 180 min and the reaction temperature was 190 ℃, the alcoholysis efficiency of PET/SrAl₂O₄:Eu²⁺,Dy³⁺ reached 100% and the recovery rate of the alcoholysis product reached 82%. However, the luminescence of SrAl₂O₄:Eu²⁺,Dy³⁺ was found seriously damaged under the same condition. At 180 ℃ and 180 min, the alcoholysis efficiency of PET/SrAl₂O₄:Eu²⁺,Dy³⁺ was 100%, and the recovery rate of the alcoholysis product was lower than that at 190 ℃, but the luminescence performance of SrAl₂O₄:Eu²⁺,Dy³⁺ was significantly improved. It is also discovered that the appropriate amount of ethylene glycol was able to promote the alcoholysis reaction, and the excessive amount of ethylene glycol can also inhibit the alcoholysis of PET/SrAl₂O₄:Eu²⁺,Dy³⁺. The investigation indicated that ethylene glycol and hot ethanol washing would not change the luminescence performance of the SrAl₂O₄:Eu²⁺,Dy³⁺, and the alcoholysis product was bis-hydroxyethyl terephthalate with high purity. Through the analysis of experimental data, it was found that ethylene glycol combined with hot ethanol is able to reduce the reaction time and reaction temperature required for the alcoholysis reaction, and improves the luminescence performance of the recovered SrAl₂O₄:Eu²⁺,Dy³⁺ and the recovery rate of the alcoholysis products.
Conclusion This research took waste PET/SrAl₂O₄:Eu²⁺,Dy³⁺ as the research object, ethylene glycol, hot ethanol and zinc acetate as raw materials, to optimize the alcoholics process for effective recovery of luminescent materials SrAl₂O₄:Eu²⁺,Dy³⁺ and PET alcoholysis products, and the performance of the recovery products were studied. The results provide a theoretical basis for the green recycling of waste mixed fibers and the recovery of functional materials.

Preparation of high melt index polylactic acid masterbatch and spinnability of its meltblown materials

ZHANG Yujing, CHEN Lianjie, ZHANG Sidong, ZHANG Qiang, HUANG Ruijie, YE Xiangyu, WANG Lunhe, XUAN Xiaoya, YU Bin, ZHU Feichao

Journal of Textile Research. 2023, 44(02):  55-62.  doi:10.13475/j.fzxb.20220808108

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Objective Meltblown polymer raw materials often require a relatively high melt index (MI), due to the fact that the polymer melt is extruded from the spinneret hole and then immediately subjected to high temperature and high speed airflow for rapid fiber formation. The melt flow must match its fiber formation speed, too high and too low MI will lead to the formation of melt droplets, seriously affecting the fiber formation process. In order to investigate the effect of different high melt index of polylactic acid (PLA) masterbatches on their meltblown spinnability, the preparation of PLA meltblown nonwoven materials for overall performance improvement was investigated.
Method PLA masterbatches with melt indexes of 200, 400, 600, 1 000 and 1 400 g/(10 min) were designed and prepared by catalytic degradation method using spinning grade PLA as raw material, and their capillary rheological properties, molecular weight and its distribution, thermal-crystallization properties and thermal stability were investigated. Further, PLA meltblown materials with different melt indexes were prepared and their morphological structure, fiber diameter and mechanical properties were investigated.
Results The melt of PLA meltblown masterbatch is typically "tangential thinning", which is characterized by a decrease in shear viscosity with increasing shear rate. The lower the melt index, the more significant the change in shear viscosity with shear rate, as shown in Fig. 2. No significant differences were found in glass transition temperature and melting point for PLA masterbatches with different melt indexes, and a significant cold crystallization peak appeared in the secondary temperature rise curves for MI=600,1 000 and 1 400 g/(10 min), as is shown in Fig. 4 and Tab. 2. It was also found that the crystallinity of the melt decreases as the MI increases. The higher the MI, the lower the molecular weight and the wider the molecular weight distribution (as shown in Fig. 3 and Tab. 1), which manifests itself in lower mechanical properties. The meltblown fiber with MI=400 and 600 g/(10 min) demonstrates the best uniformity and satisfactory mechanical properties, and the most fiber diameter around between 1 and 4 μm, as shown in Fig. 6-7.
Conclusion In recent years, most of the domestic research on PLA has focused on the modification and functional finishing of this raw material, but the research on the meltblown spinnability of PLA masterbatches with high melt index and their influence on the performance of meltblown materials have not yet seen any systematic research. The research on meltblown spinnability of high melt index PLA masterbatches and its effect on the performance of meltblown materials have not been reported systematically. This study provides a theoretical basis and application guidance for the selection of high-quality PLA meltblown raw materials and the evaluation of their performance.

Polyethylene glycol modified thermoplastic epoxy resin and its spinnability

HU Baoji, ZHANG Qiaoling, WANG Xu

Journal of Textile Research. 2023, 44(02):  63-68.  doi:10.13475/j.fzxb.20220806106

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Objective Thermoplastic epoxy resin has excellent mechanical properties and can be melted and reprocessed, but its melting processing temperature is relatively high which needs to be reduced. In order to develop thermoplastic epoxy resin as textile material and to reveal its potential application in the engineering field, on the basis of studying its mechanical and thermodynamic properties, the spinning temperature of thermoplastic epoxy resin needs to be regulated by melting dispersion polyethylene glycol (PEG).
Method Thermoplastic epoxy resin film was prepared by polymerizing-hot pressing process. The pellets of thermoplastic epoxy resin/PEG were further developed by the process of PEG melt-dispersion, and the epoxy resin/PEG filament was prepared by the process of melt-drawing. The mechanical and thermodynamic properties of thermoplastic epoxy resin film were analyzed. The influence of PEG on the spinnability of thermoplastic epoxy resin was discussed, and the mechanical and thermodynamic properties of PEG modified epoxy resin/PEG filament were analyzed.
Results The yield stress of the thermoplastic epoxy resin film is found to reach 64.6 MPa and the breaking strain 117.4%. The storage modulus of thermoplastic epoxy resin film at 25 ℃ is found as high as 2 296 MPa, and the glass transition temperatures 100.2 ℃. PEG significantly reduces the extrusion force of epoxy resin/PEG pellets. Compared with pure epoxy resin pellets, the extrusion force of epoxy resin/PEG pellets with 5% PEG content is reduced by 870 N at 300 ℃. The spinning temperature of pure thermoplastic epoxy resin pellets is as high as 300 ℃, and the extrusion force is about 1.92 kN at this spinning temperature. With the increase of PEG content, the extrusion force of epoxy resin/PEG pellets can reach about 1.9 kN during the spinning of pure epoxy resin pellets at lower temperature. Epoxy resin/PEG pellets with different PEG content can be spun into epoxy resin/PEG filament by melt-drawing process at the mixing temperature of 290 ℃ (PEG content: 2.5%), 280 ℃ (PEG content: 5%) and 270 ℃ (PEG content: 7.5%), respectively. Compared with pure epoxy resin pellets, the spinning temperature of epoxy resin/PEG pellets with 7.5% PEG content decreased by 30 ℃. PEG also improves the drawing effect of thermoplastic epoxy resin in spinning. In terms of diameter, the diameter of the epoxy resin/PEG filament with 7.5% PEG content is 50 μm lower than that of the pure epoxy resin filament. Compared with pure epoxy resin filament, the mechanical properties of thermoplastic epoxy resin/PEG filament are significantly improved; the breaking strain and breaking stress of the epoxy resin/PEG filament with 2.5% PEG content were increased by 60% and 20 MPa, respectively. PEG reduces the glass transition temperature of epoxy resin/PEG filament. Compared with pure epoxy resin filament, the glass transition temperature of epoxy resin/PEG filament with 7.5% PEG content is reduced by 20.9 ℃.
Conclusion Thermoplastic epoxy resin film developed in this research has high mechanical properties and thermal stability. The thermoplastic epoxy resin has the advantages of melting and reprocessing. At the same spinning temperature, the PEG-dispersed thermoplastic epoxy resin pellets have a lower extrusion force, so the spinning temperature can be controlled by the modification of PEG. The melt-dispersion process provides a new method for modification of thermoplastic epoxy resin by PEG. High spinnability of thermoplastic epoxy resin/PEG system was achieved by adjusting the spinning temperature of thermoplastic epoxy resin. The melt-dispersed PEG can significantly improve the spinnability of the thermoplastic epoxy resin, and the developed thermoplastic epoxy resin/PEG filament has higher mechanical properties.

Microwave absorption performance of loofah sponge derived carbon fiber composites

FENG Shuaibo, QIANG Rong, SHAO Yulong, YANG Xiao, MA Qian, CHEN Bowen, CHEN Yi, GAO Mingyang, CHEN Caihong

Journal of Textile Research. 2023, 44(02):  69-75.  doi:10.13475/j.fzxb.20220809007

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Objective The national policy of "carbon peaking and carbon neutral" aims to implement the concept of green and low carbon cycle development. This research aims to improve the social development efficiency through technological progress and governance optimization. This project proposes a green solution derived from porous biomass sources.
Method The highly porous loofah sponge as precursor, Co²⁺ as metal source and 2-methylimidazole as ligand were used to obtain loofah sponge/cobalt 2-methylimidazole(ZIF-67)composites by coordination self-assembly, and the composites were calcined at high temperature to obtain carbon fiber-based cobalt/carbon (LS-Co/C)composites. The structure and properties of the LS-Co/C composites was test and analyzed by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, vibrating sample magnetometer.
Results ZIF-67 was loaded on the surface of the loofah sponge(Fig. 2), and the higher calcination temperature improved the conversion of Co²⁺ into better crystalline Co particles(Fig. 3). The thermal decomposition stability of the carbon component became progressively higher with increased calcination temperature(Fig. 4), and the graphitization of the carbon fraction in the sample was increased with increasing calcination temperature(Fig. 5). The magnetic properties test result showing that the increase in calcination temperature favors the enhancement of the saturation magnetization intensity and the degree of Co crystallization forming. The increase in calcination temperature increased the values of the real and imaginary parts of the dielectric constant of the sample, and too low Co content leads to a smaller variation of the magnetic permeability(Fig. 7). It was concluded that the dielectric loss capability in LS-Co/C composites mainly depended on the conductivity loss, dipole orientation polarization loss and interfacial polarization loss(Fig. 8). The main factor affecting the wave absorption performance of LS-Co/C composites depended on the dielectric loss capability of the samples(Fig. 9), and its absorbing property is excellent when carbonized at 800 ℃(Fig. 10).
Conclusion Using biomass source loofah sponge as the precursor and Co²⁺ as the metal source, a raw material was obtained by coordination assembly and then calcined at high temperature to obtain the carbon fiber-based cobalt/carbon composite. The electromagnetic wave absorbing performance test yielded that the maximum reflection loss of LS-Co/C(carbonized at 800 ℃) reached -21.5 dB at a thickness of 1.5 mm and a frequency of 14.8 GHz, the effective absorption bandwidth was 5.2 GHz (12.8-18.0 GHz), and the excellent absorbing performance of the composite material originated from the enhanced electromagnetic wave loss formed by the special three-dimensional porous network loss structure and multiple interface polarization capability. This experiment provides a new synthetic method for the development of green, lightweight and efficient porous magnetic carbon-based absorbing materials.

Textile Engineering

Simulation of fiber motion in drafting zone based on cyclic iterative method

CUI Yuemin, CHENG Longdi, HE Shanshan, LÜ Jindan, CUI Yihuai

Journal of Textile Research. 2023, 44(02):  76-82.  doi:10.13475/j.fzxb.20220707507

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Objective The dispersion of fiber accelerated points during drafting is one of the main causes for yarn unevenness. Most of the previous studies are about accelerated point distributions of all fibers in a sliver, and there is a lack of research on the motion of single fibers. Therefore, based on the force of a single fiber in the drafting zone, a fiber motion model is established in this research, and the theoretical accelerated points of fibers under different pressure distributions are discussed, which may provide theoretical basis for process design in actual production.
Method Ignoring the difference of the pressure distribution in the transverse direction of a sliver, a drafting model, using software MatLab, was established according to the controlling force and guiding force of a single fiber in the drafting zone, and the position where the fiber is accelerated was determined. In the simulation, it is assumed that all fibers are accelerated at the front roller nip, and then the accelerated points of each fiber is calculated repeatedly by the iterative method, until the difference from the result of the last loop is less than a set error value.
Results The maximum absolute values of errors between the calculated results and the verification results in the opposite direction were all much smaller than the error value, which validates the model. The accelerated point of a fiber was related to its length(Fig. 7). The longer the fiber, the closer the fiber accelerated point is to the front roller nip. When the additional pressure was added close to the back roller, the accelerated point of the fiber with a length of less than 27 mm would move slightly backward compared to the case without the additional pressure. For a fiber longer than 27 mm, the accelerated point of the fiber moved rapidly towards the front roller nip as the length increases. As the position for adding additional pressure was moved forward, the accelerated points for shorter fibers also got closer to the front roller. When the additional pressure was added closer to the front roller, the theoretical accelerated points for fibers longer than 14 mm were all 0.5 mm away from the front roller. In the case of no additional pressure, although the average position of the fiber accelerated points was the farthest from the front roller, the coefficient of variation of the overall fiber accelerated points was the smallest at only 0.431%(Fig. 8). The front additional pressure was found beneficial for the fibers closer to the front roller, but due to the large difference in the accelerated points of short fibers and long fibers, the CV value was greater than that without the additional pressure. When fibers of slivers were longer with better uniformity, increasing the front additional pressure was revealed to be more conducive to the fiber accelerated points closer to the front roller and more concentrated. However, at this time the fiber dispersion was required to be higher to avoid defects such as "thick end" or breakage. With additional pressure added at the middle positions, fibers smaller than 27 mm have larger accelerated point changing rate with the increase of fiber length, and the dispersion of all fiber accelerated points was the largest compared with no additional and back additional pressure, although the average accelerated point is closer to the front roller.
Conclusion The position of the additional pressure in the drafting zone affects fiber accelerated points. Compared with increasing the additional pressure, the stable and gentle pressure distribution in the drafting zone is more conducive to the concentration of accelerated points, but the fiber accelerated points are farther from the front roller, which is more unstable in actual production. As the position of the additional pressure moves forward, the accelerated points of shorter fibers also move forward. Therefore, under the front additional pressure, the accelerated points of fibers are more concentrated and closer to the front roller, which is beneficial to reduce the unevenness of the sliver after drafted. The model established in this research could be used to predict sliver evenness after drafting, and to guide the adjustment of drafting parameters and optimization of the drafting mechanism in actual production. Due to the complexity of actual drafting process, this paper does not consider the difference of the pressure distribution in the transverse direction of a sliver and the cohesion between fibers. Therefore, there are certain gaps between the theoretical and the actual production results, and further research is needed in the future to fill the gaps.

Process design of spinning device based on runner fiber accumulation

ZHANG Qingqing, NI Yuan, WANG Jun, ZHANG Yuze, JIANG Hui

Journal of Textile Research. 2023, 44(02):  83-89.  doi:10.13475/j.fzxb.20220806907

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Objective At present, most spinning mills use negative pressure concentrated spinning. However, this spinning method relates to high the spinning cost due to high energy consumption. Thus a runner accumulating device was designed which does not depend on the use air pressure energy for yarn spinning. Specific experimental tasks in the research include spinning experiments by the device and yarn performance evaluation. The research is to be carried out to reduce yarn hairiness reduction, and it is envisaged that the high quality yarn production will reduce the reliance on negative pressure spinning.
Method Carded cotton roving was used as raw material to make yarns of 32.4, 24.3, and 19.4 tex. Spinning experiment included producing original yarn by traditional spinning machine and runner yarn by rotary transformation of ring spinning. These experiments were operated in spinning experiment machine DHU-X01. Two types of single yarn performance experiments were completed under the conditions of temperature about (20±2) ℃ and humidity of about (65±3)%, on hairiness testing, single yarn strength, yarn evenness, twist and 100 m weight test. The experiment required data analysis and collation to make comparison of two single yarn properties to verify the feasibility of the device.
Results The accumulating device has a good hair reduction effect on the 32.4, 24.3 and 19.4 tex cotton single yarns, with hairiness reduction effect above 4 mm. However, the strength of the runner yarn is weaker than the original yarn, and the breaking strength was decreased by approximately 1%-3%. This may be because of the lack of proper tension stretching between the front jaws and the runner jaws as the rotary wheel is driven by the front roller, causing low orientation of fibers in the yarn. When yarns were stretched by external forces, fiber utilization was reduced and yarn strength decrease, leading to slight worsening of yarn evenness. Experiment also showed that after the whiskers left the front jaws, they were not subjected to stable control immediately, causing increased CV value on yarn evenness. The twist test results show that runner device has no influence on yarn twist. 100 m weight was measured by yarn length gauge to investigate the difference in actual linear density. Compared with the experimental data, 100 m weight of runner yarn is 3% lighter than original yarn. There were two reasons for this phenomenon. On the one hand, the runner device moved the twist point forward to the place closer to the pipette and sucked air away together with some fiber. On the other hand, the device's clamping force between the two wheels was small and the wheel caused more friction on the whiskers, causing some fiber lost. Two experiments were carried out to analyze and verify the reasons. Through the data analysis, it is concluded that the friction between the runner and the fibers is the main reason for the decrease of 100 g weight. Subsequent experiments will solve this problem by increasing the clamping force of the runner.
Conclusion In summary, runner device has a noted improvement on cotton yarn hairiness reduction, and the spinning cost of the device is lower than that of the negative pressure compact spinning. Though runner yarn strength and yarn evenness are not as good as the original yarn, the deterioration of indicators is quite small within a reasonable range and it basically does not affect the use of single yarn. If the rotor wheel size is further reduced, for which the runner accumulating device is closer to the front jaw, it is expected to better results could be achieved. For producing yarns in a certain fineness range, it is promising that the low-cost runner accumulating device could replace RoCoS and negative pressure compact devices.

Scalable construction and performance of fiber-based flexible moisture-responsive actuators

PENG Yangyang, SHENG Nan, SUN Fengxin

Journal of Textile Research. 2023, 44(02):  90-95.  doi:10.13475/j.fzxb.20220805806

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Objective Smart textiles with thermal and humidity management function have attracted great interest from material researchers. Recently, the development of fiber-based artificial muscles based on fibrous twisting structure has provided new ways and effective methods for new development of the smart textiles. Fiber-based artificial muscles show sensitive and rapid actuating response to external stimuli based on the mechanism of anisotropic volume expansion. The current research aims to show that man-made fibers (e.g., carbon nanotubes, graphene, and shape memory alloys) and natural fibers (such as silk, spider silk, and cotton) can be used to prepare twisted fiber-based glexible actuators. However, the current fiber-based artificial muscles generally suffer from high cost, harsh stimulation conditions, chemical toxicity or complex manufacturing processes, which hinder the wide applications of fiber-based artificial muscles. Therefore, it is necessary to develop fiber-based artificial muscles with mild and moisture-response, high actuating response, stable actuating performance and low cost based on the use of environment-friendly fiber materials to promote the applications of the yarn muscles as a type of smart textiles.
Method A cross-scale processing strategy was harnessed to process viscose fibers into high-performance artificial yarn muscles. With the help of nano-micro structure regulation of fiber and the inherent multi-hierarchical structure designability, scalability, softness and mechanical robustness of textiles, the bottom-up textile configuration technology and stress engineering methods were used to develop a moisture-responsive artificial yarn muscle actuator with rapid response and large actuating strain. Furthermore, through the topological weaving/knitting configuration, the one-dimensional deformation of the yarn actuator was expected to extend to a fabric actuator with sizable dimension and multiple deformations. A large-scale processing method was to be identified for the formation of yarn and fabric actuators, so as to facilitate the design and development of smart textiles with moisture-response.
Results When alternatively exposed to dry and wet conditions, the artificial yarn muscles were found to be able to produce reversible torsional rotation. By applying water fog of 0.05 g/s to actuate the artificial muscles, the muscles demonstrated encouraging actuating performance. The maximum rotation degree of the hot-drawn artificial yarn muscles reached 1 657 (°)/cm, which is 1.7 times higher than that of the artificial yarn muscles prepared from the original viscose fibers without hot-drawn treatments, with an average speed of 331 r/min, exceeding the original viscose artificial yarn muscle (254 r/min). Through the integration of spinning technology and topological textile design, the mechanized production of artificial yarn muscles was achieved, and the fabric artificial muscle actuators were developed and fabricated, extending the simple deformation of the one-dimensional artificial yarn muscles to the high-dimensional diversified deformation in two-dimensional fabric artificial muscles.
Conclusion This paper proposes a cross-scale design strategy from micro structure (fiber aggregated structure) to macro configuration (fiber-yarn-fabric structure) to prepare moisture-responsive fiber-based artificial muscles with high actuating strain. The actuating performance of the artificial muscles is characterized and the application field and deformation dimension of fiber-based artificial muscle actuator are expanded through textile processing technology. The findings from this study provide a new method for improving the performance of fiber-based artificial muscles, and are also conducive to promote the development and application of fiber-based artificial muscles in smart textiles and related fields.

Construction of flexible electronic fabric and its pressure sensing performance

LI Ganghua, WANG Hang, SHI Baohui, QU Lijun, TIAN Mingwei

Journal of Textile Research. 2023, 44(02):  96-102.  doi:10.13475/j.fzxb.20220104307

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Objective With the development of artificial intelligence, wearable technology has become a research hotspot, driving the rapid development of all types of sensors. Sensors used in wearable devices should not only have sensitive and stable sensing performance, but should also have excellent flexibility, air permeability, and integration with textiles. Polymer based flexible pressure sensors have significant advantages in flexibility and integration with textiles, and have been developed rapidly. However, most of these sensors are thin films or gel shaped, which seriously affects their breathability and wearing comfort.
Method Aiming at the problems of poor air permeability, poor moisture permeability and low wearing comfort of film-based and gel-based flexible sensors, a preparation strategy of all-textile-based flexible electronic fabrics based on piezoresistive effect was proposed. A structural model was constructed based on the electrode layer of 1+1 rib conductive fabric and the middle conductive layer of MXene modified cotton fabric (as shown in Fig. 1-3). The flexible electronic fabric with sandwich structure was formed by sewing and compounding various functional layers, and its wearing comfort and sensing performance were studied. Furthermore, its potential for industrial production in the future was expounded.
Results The sensitivity of the flexible electronic fabric in the low pressure range (0-3 kPa) is about 0.409 5 kPa^-1 (as shown in Fig. 4), which is caused by the working mechanism of the piezoresistive flexible sensor. A 2 g weight can make resistance change rate of the flexible electronic fabric exceed 3% (as shown in Fig. 6), which is mainly due to the excellent mechanical properties of the 1+1 ribbed conductive fabric. This enables the flexible electronic fabric to achieve large deformation under small external forces, resulting in rapid changes in resistance values to achieve excellent responsiveness. In addition, the MXene modification of cotton fabrics also gives the flexible electronic fabric a lower minimum pressure detection limit and better low-pressure monitoring performance. The response time of the flexible electronic fabric is less than 50 ms as Fig. 5 shows, sufficient for human motion signal monitoring. The stable resistance changes were maintained after 8 000 pressure cycles, indicating that the flexible electronic fabric maintains good resilience and conductive material wear resis-tance(Fig. 8). In addition, thanks to the full textile configuration of the flexible electronic fabric, it has better air permeability of 270.49 mm/s and moisture permeability of 3 420 g/(m²·24 h), representing better comfort. The flexible electronic fabric can realize the dynamic monitoring of the object, and it is convenient to predict the size and weight of the object qualitatively according to the image size and color depth as illustrated in Fig. 11. The flexible electronic fabric has excellent recognition ability for human body dynamic signals (as shown in Fig.12).
Conclusion This paper introduces a flexible electronic fabric with piezoresistive effect, which is composed of 1+1 ribbed conductive fabric and MXene modified cotton fabric. It has high sensitivity, fast response and excellent cycle durability. It is able to sense, record and distinguish the pressure of human movement, and achieve dynamic monitoring. On the basis of meeting the sensing requirements, the composition of the whole fabric can meet the needs of thermal-moist comfort and contact comfort of the human body. It has the potential to achieve large-scale industrial production due to its easy preparation process and stable performance, and has broad application prospects in the fields of sports training, medical care and military protection. In the future, the accuracy, sustainability, interactivity and data analysis and feedback of intelligent textiles need be further studied to meet the needs of the end-users with improved behavior.

Three-dimensional simulation of whole garment with fancy structures

LAI Anqi, JIANG Gaoming, LI Bingxian

Journal of Textile Research. 2023, 44(02):  103-110.  doi:10.13475/j.fzxb.20220801708

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Objective Whole garment formation technology has been an attention hotspot in the sweater industry because of the integral manufacturing and wear comfort of the product. With the fast development of the computer-aided design technology, fashion computer aided drafting(CAD) software has made the design and manufacture of textiles easier and more accurate. In order to represent the whole garment more realistically, more quickly and more conveniently using knitwear CAD software, this research focuses on the three-dimensional simulation of whole garment with fancy structures.
Method Loop models were established based on the classical Pierce loop model for knitted fabrics. By drawing loop grids and comparing the offset of loop grid mass point between undeformed loops and transformed loops, the transformed loop value of physical fabrics with fancy structures for whole garment was represented. Coordinates of control points of loops were calculated by combining the offset value of transformed loops with theory of vectors transformation in the two-dimensional space. Three-dimensional simulation of fancy structure was achieved by using JavaScript programming language.
Results Characteristics of all fancy structures used for whole garment was analyzed. The geometric model and grid-based model of plain stitch loop were built separately as shown in Fig. 1 and 2, and those of closed tuck loop were built separately as illustrated in Fig. 3 and 4. The deformation process of loops is showed in Fig. 5. The deformation was represented by loop grids according to the methods explained in Fig.6. The loop grid was transformed firstly, leading to the transformed of loops. In order to create the three-dimensional effect of the fabric, loop grids shown in Fig. 7 were drawn based on loop height and width, and the offset value of grid mass points was measured by comparing with the position of grid mass points of undeformed loop grid. Then, the average proportion of grid mass points was calculated and listed in Tab. 1. The control point coordinates of every transformed loop listed in Tab. 2 were calculated by the relation between offset proportion and control points as illustrated in Fig. 9. The transformation matrix was obtained, and related formulas of the calculation were established. The simulation tool was created by using Visual Studio Code software, as well as three-dimensional graphics engine library based on WebGL. The loop path was created by calling function CatmullRomCurve3 in the graphics engine library, which uses Catmull-Rom interpolation algorithm for path generation. The loops were created by calling function TubeBufferGeometry. Finally, three-dimensional simulation of whole garment with fancy structures with features such as fabric narrowing, fabric widening and partial knitting was completed, and it was illustrated in Fig. 10.
Conclusion Three-dimensional simulation of multiple types of fancy structures and whole garments could be completed by the methods introduced in this paper. The models of fancy structures are realistic with clear structures, with the correct relationship between loops. The simulated fancy structures could be applied in three-dimensional virtual display of whole garment. In the future, three-dimensional simulation of other forms of whole garment could be achieved using the methods.

Electromagnetic interference shielding properties of composites reinforced with glass fiber/carbon fiber fabrics

CAI Jie, WANG Liang, FU Hongjun, ZHONG Zhili

Journal of Textile Research. 2023, 44(02):  111-117.  doi:10.13475/j.fzxb.20220808907

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Objective The electromagnetic (EM) wave pollution and its secondary reflection bring great threat to human health and to information security. To reduce the secondary reflection pollution of carbon fiber fabric composites, enhancing the impedance matching of carbon fiber fabric is a feasible method.
Method Glass fiber has low dielectric properties; the impedance matching of carbon fiber fabric could be improved by using glass fiber to regulate the fabric structure of the carbon fiber fabric. In this work, five different fabric structures of glass fiber/carbon fiber (G/C) fabric were designed and were compounded with waterborne polyurethane. The morphology, electromagnetic interference (EMI) shielding, dielectric and photothermal conversion properties of glass fiber/carbon fiber composites were characterized by an ultra-depth of field microscope, vector network analyzer, simulated solar xenon lamp light source system and infrared thermal imager.
Results Glass fiber and carbon fiber interweave with each other to form the G/C fabrics structure which was arranged smoothly as illustrated in Fig. 1. The EMI shielding efficiency (SE) of the five G/C fabric composites showed effective EMI shielding. Their average EMI SE was greater than 20.0 dB in the X band (8.2-12.4 GHz) as can be seen in Fig. 3(a). The EMI total shielding efficiency(SE_T) curves of C fabric (its weft yarns are all carbon fiber) composites was relatively stable, with its SE_T being 33.4 dB at 9.6 GHz(Fig. 2(a)). The SE_T curves of G/C fabrics composites decreased firstly and then increased with the increasing frequency within X band after the introduction of glass fiber. The EMI SE value of G2C1 fabric (glass and carbon yarns were woven into the fabric alternately as weft) composite was up to 38.7 dB at 12.1 GHz, as shown in Fig. 2(a). The power coefficients values of absorptivity of G/C fabric composites increased by adding glass fiber. The structural changes in G/C fabric composites effectively regulate various dielectric polarization relaxation mechanisms (Fig. 5), which indicated that the use of G/C fabric structure could improve the impedance matching with the EM wave and reduce the second reflection. The surface temperature of G/C fabric composites responds rapidly under simulated solar xenon lamp light source as shown in Fig. 6. The surface temperature of G/C fabric composites gradually reached equilibrium after rapidly increasing under 2 kW/m² light intensity and decreased rapidly when the light source was turned off at 300 s and this was demonstrated in Fig. 6(a). With the increase of glass fiber content, their surface equilibrium temperature was decreased, which is consistent with the results of the SE_T. The fabric structure of G1C1 fabric composite was clear, indicating its rapid response to the light. The equilibrium temperature of G1C1, as shown in Fig. 6(a), reached 71.8 ℃ at 300 s under 2 kW/m² light intensity. In addition, the time-temperature curves of G1C1 fabric composite under different light intensities (1,1.5,2 kW/m²) showed that the equilibrium temperature (average temperature from 200 s to 300 s) |ΔT₁|,|ΔT₂| and |ΔT₃| were 8.0, 20.6 and 28.6 ℃, respectively. It is indicated that G/C fabric composites have significant differences in response to different light intensities. Light is also a type of electromagnetic wave. It can be inferred that G/C fabric composite material can quickly convert the energy of electromagnetic wave into joule heat dissipation to achieve excellent electromagnetic shielding performance.
Conclusion In this work, five G/C fabric composites were fabricated, each possessing efficient EMI shielding and photothermal conversion properties. The dielectric properties of G/C fabric composites were adjustable by structural parameters of G/C fabrics, and the research results demonstrated that such composites could effectively regulate various dielectric polarization relaxation mechanisms. The impedance matching performance of G/C fabric composites increased to match that of the electromagnetic waves and the secondary reflection of the EM wave was reduced. The method of designing fabric structure has great application potential in EMI shielding materials.

Effect of high smooth treatment on polyimide staple yarns and its fabric properties

MIAO Ying, XIONG Shiman, ZHENG Minbo, TANG Jiandong, ZHANG Huixia, DING Cailing, XIA Zhigang

Journal of Textile Research. 2023, 44(02):  118-127.  doi:10.13475/j.fzxb.20211204510

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Objective Polyimide (PI) has excellent stability and mechanical properties and is widely used in various industries. PI staple yarn shows good mechanical properties, flame retardancy, high-temperature resistance and other properties. However, PI staple yarn is difficult to spin creating high level of yarn hairiness, and the yarn also has serious problem of static electricity. PI yarn hair is long, causing hair entanglement, resulting in unclear shed openings and yarn breakage during weaving, and the PI fabric is easy to pilling negatively affect the fabric appearance. Because of the above problems, this paper proposes an innovative idea of high smooth treatment of hairy PI single yarn at the end of yarn post-processing to efficiently achieve the transformation of low-quality PI yarn to high-quality PI yarn.
Method Based on this idea, a high smooth and clean yarn processing device was developed, and the mechanism of the key area of yarn leading and eddy current wrapping was simulated and analyzed theoretically. The device applied the wet heat eddy current to treat the multi-hair PI single yarn, and the PI single yarn and its fabric were obtained by double-twisting and weaving before and after the processing.
Results A three-dimensional numerical simulation model for the ingot fluid region of the high smooth treatment device was established (Fig. 3). The simulation results of the yarn drawing stage (Fig. 4) showed that strong suction was generated in the device before the yarn entered the wrapping device to ensure the smooth entry of the yarn into the device. The simulation results of the normal high smooth and clean spinning stage (Fig. 5) showed that the turbulence phenomenon under normal treatment was more obvious than that in the yarn drawing stage. Due to the presence of backflow and high-speed airflow, the hairiness of the wooly yarn was greatly reduced and the strength was improved after the device treatment. Based on theoretical analysis, the yarn and fabric experiment results was analyzed before and after the treatment. The yarn test results showed that the high smooth treatment significantly improved the yarn's apparent quality and made the yarn surface more smoothly (Fig. 6), and the harmful hairiness number of PI single yarn after the high smooth treatment was reduced by 97.69% (Fig. 7). After the treatment, the dry unevenness of the strands was improved (Tab. 3), the yarn strength was increased by 5.50% (Tab. 4), and the wear resistance of the yarn was increased by 48.84% (Fig. 8). The test results of the fabric showed that the fabric woven by the treated yarn was softer, smoother, more elastic (Fig. 9), and more smooth (Fig. 10). The warp and weft tensile mechanical properties of the treated fabric were greater than that of the original fabric (Tab. 5), and the air permeability of the fabric was increased by 66.09% after the treatment (Fig. 11). The pilling performance was effectively improved (Fig. 12). After the treatment, the fabric static electricity voltage dropped by 40.0%, and the friction electrostatic performance was improved (Tab. 6).
Conclusion PI yarn is processed by a high smooth treatment device, and the properties of yarn and fabric are compared through the simulation analysis embedded in the device. During the yarn initial stage, the flow line develops orderly along the helical route of the device, which is conducive to the generation of suction and smooth yarn route. In comparison, during the conventional high smooth treatment stage, the high-speed airflow of the air jet hole drives the high-speed rotating airflow, which wraps and holds the yarn surface hairiness. After the high smooth treatment, the degree of yarn hairiness is significantly reduced, the tensile property is improved, the unevenness of a single yarn is increased, and the wear resistance of yarn is improved. The treated fabric is smoother in appearance, with improvement in softness, smoothness, elasticity, breathability, and antistatic performance.

Properties and applications of yarn-based actuators based on skeletalmuscle-like structure

WU Jing, HAN Chenchen, GAO Weidong

Journal of Textile Research. 2023, 44(02):  128-134.  doi:10.13475/j.fzxb.20220804107

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Objective Artificial muscle actuators are highly desired for applications such as soft robotics, smart wearables and smart textiles due to their inherent flexibility and actuation properties similar to those of skeletalmuscle-like systems. The single component and poor structural stability of fiber-based actuators make it difficult to achieve industrial applications. As a result, yarn-based actuators with low yarn anisotropy and good mechanical properties owing to twisting have been developed. Among them, pneumatic actuators and electromagnetic motors provide low accuracy and bulky equipment, temperature-sensitive actuators prepared from shape memory alloys have high hysteresis under high temperature stimulation, and some moisture-sensitive actuators have low sensitivity, poor cycle recovery effectiveness, complex preparation processes and harsh experimental conditions. Therefore, there is a need for a yarn-based actuator with simple preparation process, stable structure, good cycle recovery effectiveness and promising possibility for industrialization.
Method Inspired by the skeletalmuscle-like systems, the research reported in this paper used hydrophilic viscose filaments and low melting point hydrophobic polyester filaments to prepare the yarn-based actuators by merging, doubling and low temperature thermal annealing. The actuation function of the actuator is achieved by using the asymmetric response of the two materials under external wet stimulating conditions. Specifically, under wet stimulation, the prepared yarn-based actuator using hydrophilic viscose filaments as the actuating source undergoes wet swelling untwisting and transmits torsional potential energy. During wetness reduction, the low melting point polyester filament acts as a spring frame and the fixed torsional deformation is reduced. The yarn-based actuator structure was characterized and the factors influencing the synergistic response of the viscose and polyester filaments to the actuation performance and cycle recovery effectiveness under wet stimulation were analyzed.
Results The results show that the yarn-based actuator has a hierarchical, alternating skeletalmuscle-like structure of viscose and polyester filament bundles (Fig. 2). During the preparation of the yarn, when the yarn was twisted to a critical level, the actuation performance increased with yarn twist, yarn density and viscose content (Fig. 3, Fig. 4 and Fig. 6), and the actuation cycle recovery effectiveness decreased with the increase of the yarn linear density and the viscose content (Fig. 5 and Fig. 7). The maximum contraction strain and maximum contraction stress within a single cycle reached 83.15% as shown in Fig. 6(a) and 9.61 cN as indicated in Fig. 6(b), respectively, and the maximum contraction strain and maximum contraction strain recovery rate >90% within 30 consecutive cycles with no significant fatigue loss during actuation and recovery (Fig.5 and Fig.7), confirming the advantages of the skeletalmuscle-like structure and demonstrating its stable actuation behavior. Depending on the relationship between the range of twist, the twist density, and the viscose content, yarn actuator parameters can be determined (Fig. 8). Sample 9 with 33 tex yarn density and 90% viscose content were twisted to 1 000 turn/m and 2 000 turn/m respectively, resulting in moisture-sensitive flexible robotic arms and smart textiles, such as the medical wound-healing material and humidity-regulating clothing(Fig. 9).
Conclusion The use of this type of yarn-based actuator with a skeletalmuscle-like structure improved the low sensitivity, poor cycle recovery effectiveness and harsh experimental conditions of the moisture-sensitive actuators. The characterization of macroscopic fiber and yarn as well as internal potential energy conversion illustrates the actuation mechanism of the actuation performance and reversion effectiveness, and this work serves as a theoretical benchmark for further enhancing yarn-based smart material properties. Additionally, the trial-preparation fabric actuators in the lab offer opportunities for higher-hierarchical deformation, multifunctional applications, and large-scale production of yarn-based actuators. The development of applications in cutting-edge industrial sectors such as smart textiles and pharmaceutical materials will be the main emphasis of the following phase, which will open up new possibilities and bring yarn-based actuators closer to everyday life.

Fabrication and performances of self-powering knitted sensing fabric with bionic scales

NIU Li, LIU Qing, CHEN Chaoyu, JIANG Gaoming, MA Pibo

Journal of Textile Research. 2023, 44(02):  135-142.  doi:10.13475/j.fzxb.20220700808

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Objective To meet the requirements for functions, intelligence, and wearability of wearable devices for smart outdoor apparel applications, a self-powering knitted sensing fabric with bionic scales(BSK-TENG) is designed from the inspiration of natural selection, which combines the scales structure with protection and flexibility. The flexibility of scale-structured fabric not only satisfies the common wearing, but generates electrical outputs to supply energy for outdoors sensors. It is envisaged that this type of fabric with full fiber structure will provide novel ideas for multifunctional wearable electronics while maintaining the intrinsic performance of textiles.
Method The complex three-dimensional bionic scale knitting fabric was fabricated by a double-bed computerized flat knitting machine, representing the industrial production. The triboelectric nanogenerators were used as a convertor based on a coupled effect of contact electrification and electrostatic induction, generate periodic electrical outputs during mechanical movements. The single-sided scales were consistent with the single electrode working mode, which proved to be facile to construct the self-powering scale-structured knitted sensing fabric. For the triboelectric series of materials, polyamide (PA) yarns and a polytetrafluoroethylene(PTFE) yarn were selected as a pair of contact materials, and Ag-plated polyamide yarns were employed as the electrodes for electronic signal transfer.
Results The influence of structural features of scale-structured knitted sensing fabric on electrical and mechanical properties were comprehensively investigated for novel applications. The results show that the BSK-TENG as a novel wearable device can be manufactured in mass scale and formed in a single process (Fig. 2). Through the linear motor (Fig. 3), the PA yarn establish contact with the scales working as the single electrode (Fig. 4), generating the electrical outputs. In order to analysis the effect of fabric structural parameters on the electrical output performance, fabrics with different vertical spaces and scaly layouts were designed and fabricated to regulate the output performance, and the electrical outputs were measured. The electrical performance is enhanced as the vertical spaces increase, which caused the increase of the contact area (Fig. 5). For different layouts of the scaly fabrics, the electrical outputs show no difference between the parallel type and the imbricate type (Fig. 6). In addition, BSK-TENG exhibits satisfactory the stability and force sensitivity for monitoring the force change to obtain a high gauge factor (Fig. 7 and Fig. 8). Considering the asymmetry of fabric surface, the bending performance of scale knitting fabric demonstrates obvious differentiation, indicating lower stiffness on the intrados side than that on the extrados side (Fig.9). It turns out that the scale knitting fabric has special anisotropic mechanical property. With small interval spaces, the overlapping scale distribution has an obvious strain-stiffening response, which offers strong support for joint protection. BSK-TENG is utilized as the wearable device, which requires suitable level of air-permeability for wearing comfort. Due to the scaly structure, fabrics with different surface designs demonstrated distinctive testing results, but not decreasing the fabric breathability (Fig. 10).
Conclusion Industrial production of self-powering knitted sensing fabrics was achieved using knitting technology, achieving the one-piece complex three-dimensional fabric structure. The effect of interval spaces between scales on the electrical outputs were discussed and analyzed. It is found that fabrics with cover factor 0.7 generates higher electrical outputs, with the contact area equal to the scale area. This indicates that the design of interval space plays an important role in regulates the electrical output performance of BSK-TENG. Furthermore, a good linear relationship between electrical outputs and external force is established and it can be utilized for fabricate the self-powered sensor. The scaly layouts have little influence on the output performance, however there is a significant difference in stiffness performance. The scale knitted fabric has an apparent strain hardening effect, especially for the scaly section of the fabric, which could lead to a potential joint protection application. The smart textile with both intelligence and functions can satisfy the conflicting requirements of protection and flexibility while maintaining textile intrinsic good performances. It is envisaged that the high-speed production of soft bionic scale-structured fabric with both intelligence and functions will bring opportunities for the future development of wearables.

Fabric defect detection based on deep-belief network

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

Journal of Textile Research. 2023, 44(02):  143-150.  doi:10.13475/j.fzxb.20220804308

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Objective In order to improve the quality of textile products, increase economic benefits, and reduce production costs in order to improve production efficiency, it is of great significance to achieve intelligent detection of fabric defects. A fabric defect detection method based on deep-belief network (DBN) is proposed, and the deep-belief network is trained by the improved restricted Boltzmann machine model to complete the construction of model recognition parameters, which can not only independently extract fabric image data features, screen effective information for transmission, but also have a short training time and fast model convergence speed.
Method In order to make the best training effect of the model, this paper enriches the samples by using the data augmentation method to meet the training requirements of the DBN model. The homomorphic filtering method is used to preprocess the image to reduce the low frequency and increase the high frequency, and sharpen the details of the image edges, making the defective image clearer and suppressing the background image. In order to solve the overfitting problem of the model and improve the generalization ability of the model, the DBN-Dropout model is used to set the output information in the network to 0, the contrastive divergence method is employed to initialize the visual layer of the training sample, the activation probability of neurons in the hidden layer of the model is calculated, and the activation status of neurons in the hidden layer and the visual layer is assessed. In Python language, a DBN model is built based on the TensorFlow framework, and the learning samples are obtained by processing the fabric defect images. In the weft knitting laboratory of the Knitting Engineering Technology Research Center at Zhejiang Sci-Tech University, the area scan CCD camera was combined with the 6 mm focal length lens (FL-HC0614-2M) produced by Ricoh Corporation of Japan, and 200 images were collected of different types of plain weft knitted fabrics produced by the RFSM20 high-speed seamless underwear machine developed by Zhejiang Rifa Textile Machinery Co., Ltd., including 50 images of normal flawless fabrics and 150 images of fabrics with various defects. The collected fabric image samples were grayscale images with a size of 512 pixels×512 pixels, and the 100 fabric images collected were detected by the DBN model.
Results Cross-entropy and Adam were used as loss functions and optimizers respectively, the activation function, loss function and optimizer of the model were studied with the fabric defect dataset, and then the activation function, Dropout value, learning rate and training batch number of the model were analyzed with the fabric defect dataset. The activation function was a Relu function, whose Dropout value was 0.3, pre-training learning rate was 0.1, fine-tuning learning rate was 0.000 1, and batch training number was 64, model and the parameter values were optimal. 512 pixel×512 pixel fabric images were used to conduct experiments in MatLab2019b environment, and the results of the experiments on the TILDA dataset using particle swarm optimization(PSO)-BP neural network and local contrast deviation method were compared with the algorithm proposed in this paper, and it is concluded that the proposed deep-belief network has better detection results and clearer target contour recognition for fabric defect detection under complex background than the other two methods. In order to evaluate the applicability of this algorithm, defect images weft knitted fabrics with different types of defects were used for detection. For the practical testing of 100 pictures, the experimental results were combined with the detection effect chart, which showed that the algorithm introduced in this paper has good detection results for fabric holes, oil pollution and yarn breaking defects, and its detection accuracy rate reaches 98%, which verifies the algorithm's adaptability, effectiveness and accuracy for fabric defect detection.
Conclusion The experimental results show that the DBN network model has a good detection effect on fabric defects, which can not only identify the shape and outline of fabric defects, but also detect different types of fabric defects, which shows the effectiveness of the algorithm.

Determination and validation of comfort temperatures for quilts based on temperature rating model of sleeping bags

ZHENG Qing, YAN Fangying, KE Ying, WANG Hongbo

Journal of Textile Research. 2023, 44(02):  151-158.  doi:10.13475/j.fzxb.20220804208

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Objective Quilts, as one of the essential components of the bedding system, play an important role in the sleeping comfort of human beings. With the variations in geographic locations and season alterations, people have to select quilts properly to satisfy the thermal comfort for the sleeping environment. However, limited studies have investigated the quilt applicable temperatures. Sleeping bags have similar functions as quilts and their temperature rating model has been commonly applied in practice. Therefore, this study was carried out to explore the validation of determining comfort temperature for quilts based on the temperature rating model of sleeping bags.
Method Based on the sleeping bag temperature rating model, the method for calculating the lower and upper boundaries of comfortable temperature of quilts was proposed. In order to validate the calculation method, the thermal comfort of 3 types of quilts (i.e., silk, down and polyester) was studied. Each type of quilt involved 4 filling weights. The whole-night sleeping trials were performed by 10 participants to acquire their skin temperatures and subjective thermal perception when using each quilt in its designated temperatures.
Results The result showed that due to different thermal insulating property, different types of quilt had different upper and lower comfortable temperatures, and the difference between the upper and lower comfortable temperatures increased with the increase of filling weights (Fig. 4). Both the mean skin temperatures and distal-proximal skin temperature gradients (DPG) showed significant differences in using different types of quilt (Fig. 5 and Fig. 6). The average mean skin temperatures during 1-8 h in the usage of silk, down and polyester quilts were 34.0, 34.5 and 34.9 ℃ respectively as the lower boundary of the comfortable temperature, and they were 35.1, 35.5 and 35.6 ℃ as the upper boundary of comfortable temperature. The DPG during 1-8 h in the usage of silk, down and polyester quilts were from -1.8 to -0.8 ℃, -1.2 to -0.4 ℃ and -0.9 to -0.1 ℃ respectively for the lower comfortable temperature, and were from -0.8 to -0.2 ℃, -0.4 to 0.3 ℃ and -0.2 to -0.3 ℃ for the upper comfortable temperature. The subjective evaluation results demonstrated high agreement with physiological responses (Fig. 7 and Fig. 8). At the lower comfortable temperatures, most participants felt uncomfortably cool when using the silk quilts but generally comfortable when using down and polyester quilts. While at the upper comfortable temperatures, it was most thermally comfortable when using the silk quilts but uncomfortably warm when using down and polyester quilts. At the lower comfortable temperatures, the proportion of "no change" was the highest (>90%) for polyester quilts followed by down quilts (>50%), as shown in Tab. 3, but most participants preferred "warmer" when using silk quilts. At the upper comfortable temperatures, using silk quilts had the highest thermal satisfaction ("no change" >80%) but over 60% of participants preferred cooler when using polyester and down quilts. The differences in physiological and subjective responses in the usage of different quilts could be attributed to the variation in their water vapor permeability. Compared to the polyester and down quilts, the silk quilts have the highest water vapor transmitting rate, and thus require higher air temperature to maintain thermal comfort.
Conclusion The quilt comfortable temperatures calculated based on the sleeping bag temperature rating model had different applicability for quilts with different fillers. The lower comfortable temperatures were reasonable for down and polyester quilts while they were underestimated for silk quilts. The upper comfortable temperatures were suitable for silk quilts but were overestimated for down and polyester quilts. Thus, it is concluded that the water vapor transmitting index in the sleeping bag temperature rating model should be modified according to the moisture permeability of quilts. Moreover, considering the thermal comfort of different body parts, multi-node human sleeping models would improve the accuracy of determining the quilt comfortable temperatures.

Dyeing and Finishing & Chemicals

Preparation and properties of structural colored carbon fiber/polyester blended yarns based on photonic crystals

LIU Hao, MA Wanbin, LUAN Yiming, ZHOU Lan, SHAO Jianzhong, LIU Guojin

Journal of Textile Research. 2023, 44(02):  159-167.  doi:10.13475/j.fzxb.20220805509

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Objective Carbon fiber is widely used in aerospace, infrastructure, military equipment, sports and other fields due to its excellent physical and chemical properties. However, the color of carbon fiber is much too limited to meet the needs of various possible applications. At present, the colored carbon fiber is obtained by modifying its surface and then coloring it with chemical colorants. Although colored carbon fiber can be prepared by this method, the excellent properties of carbon fiber are negatively affected to a certain extent because of the surface modification before coloration. New technologies suitable for coloring carbon fiber are needed.
Method The coloring of carbon fiber was achieved through structural coloration. In this study, monodispersed poly(styrene-methacrylic acid) (P(St-MAA)) colloidal microspheres were prepared by soap-free emulsion polymerization, and were then used as building blocks to construct photonic crystal colored structures on carbon fiber/polyester blended yarns by a dip-coating method.
Results When the mass fraction of P(St-MAA) colloidal microspheres assembly solution was 70% and the self-assembly temperature was 40 ℃, brighter structural colors can be fabricated on the surface of carbon fiber(Fig. 3 and Fig. 6). It is seen that the process of self-assembly of P(St-MAA) colloidal microspheres on the yarn surface to form photonic crystals can be briefly categorized into preparatory stage, stacking aggregation stage and completion stage, and the corresponding structural color is formed with a series of color shifts(Fig.8-10). The colors presented by the yarn of the structural colored carbon fiber/polyester blended yarn varied with different observation angles, exhibiting a significant iridescent effect(Fig.11). The polydimethylsiloxane(PDMS)-encapsulated structural colored carbon fiber/polyester blended yarn can still maintain the original structural colors after washing and rubbing tests, indicating its outstanding color durability, as indicated in Fig.13-14.
Conclusion In this work, the photonic crystals composed of monodispersed P(St-MAA) colloidal microspheres were constructed via a dip-coating method to achieve structural coloration of carbon fiber. The mass fraction of P(St-MAA) colloidal microspheres solution-applied to fabricate photonic crystals on the carbon fiber was investigated and optimized at 70%. The effect of self-assembly temperature of carbon fiber on structural color effect was analyzed, and the research indicated that the self-assembly temperature had little effect on structural color. The process of self-assembly of P(St-MAA) colloidal microspheres on the yarn surface to form photonic crystals can be briefly categorized into preparatory stage, stacking and aggregation stage, and completion stage. Moreover, the structural colored carbon fiber/polyester blended yarn was encapsulated with PDMS to ensure the durability of structural colors. It was confirmed that the yarn color was still bright after multiple washing and rubbing tests, indicating the encapsulation of PDMS could effectively improve the stability of photonic crystals. The perfect combination of dip-coating method, carbon fiber and structural coloration is able to meet people's diversified demands for carbon fiber fashion and promote the industrial production of colorful carbon fiber materials.

Preparation and optical properties of full spectrum SiO₂ structure color films by additive color method

LI Yuejia, GAO Weihong, YANG Shu, LIN Tiantian, ZHU Jie, ZHAO Xiaoyan, ZHANG Zhiyue

Journal of Textile Research. 2023, 44(02):  168-175.  doi:10.13475/j.fzxb.20220904408

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Objective Structural colors have the advantages of brilliant colors and no pollution to the environment, and are of great interest in textile coloration. However, because one structural color corresponds to one particle size, the workload of using the method of preparing spheres with different particle sizes to achieve the full spectrum of structure colors is heavy, and the amorphous photonic crystals will be affected by non-correlated scattered light, resulting in poor saturation of structure color films, which is not suitable for the industrial development of structural colors. In this work, a simple method for preparing highly saturated, fully visible spectrum structural colors is proposed. The effective construction of highly saturated, full visible spectrum structural colors is achieved by mixing SiO₂ of different particle sizes in different ratios to adjust the crystal plane distance and adding ink to increase the saturation of structure color films. This method improves the preparation efficiency of structural colors and further promotes the rapid preparation of full visible spectrum structural colors.
Method In this paper, SiO₂ nanoparticles with uniform particle sizes of 304, 260 and 200 nm were synthesized by solvent modulation method. The three different particle sizes of SiO₂ suspensions were mixed two by two according to different mass ratios by using the principle of three-primary additive color method, and the ink was added to the mixed ratio of SiO₂ suspensions to absorb part of the incoherent scattered light and background light. Colloidal particles were self-assembled on glass sheets by gravity sedimentation method, and full spectrum amorphous photonic crystal structure color films were successfully prepared.
Results The wavelength of the reflection peak of the structure color film of the photonic crystal decreases uniformly with the increase of the proportion of smaller size SiO₂. The blue shift phenomenon occurs in the structural color, which is due to the increase of the proportion of smaller size SiO₂ making the lattice distance decrease uniformly. The wavelength of the photonic crystal also decreases following the Bragg's diffraction law. With the increase of ink content, the structural color lightness gradually decreases, and the chromaticity first increases and then decreases, and the structural color saturation is the best when the ink content is 0.4%. When the ink is added, the structural color appears reddish and yellowish. By measuring the CIE color space of the ink, it is found that the ink itself is reddish and yellowish, which explains the color redshift phenomenon of the SiO₂/ink amorphous photonic crystal film.
Conclusion In this study, SiO₂ nanoparticles with different particle sizes are prepared, and a full spectrum structural color film is prepared by the principle of additive color method and the saturation of photonic crystal structural color is improved by adding ink. The method is simple, efficient, and reduces cost of preparing full spectrum structural colors. It has great potential in the textile coloration and finishing industry, contributing to solving the problems of high pollution and high energy consumption in textile printing and coloration process, and promoting the industrialization of photonic crystal structural colors.

Preparation and properties of mussel-inspired durable antimicrobial fabrics

QU Lianyi, LIU Jianglong, XU Yingjun, WANG Yuzhong

Journal of Textile Research. 2023, 44(02):  176-183.  doi:10.13475/j.fzxb.20220806808

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Objective Fabrics offer a growth environment for pathogenic microorganisms, which bring health risks to humans and affect the use of fabrics. It is an important demand to develop antibacterial fabrics that are harmful to different pathogenic microorganisms but benign to humans. Metal-based nanoparticles including ZnO nanoparticles are one of the most widely used antibacterial agents in the field due to their efficient and broad-spectrum antimicrobial activities in attacking bacteria and fungi. However, they often do not strongly bond with the fabric, causing the material to show poor laundering durability and suffer low stability in performance.
Method Aiming for achieving efficient and durable antibacterial fabrics via a facile and applicable approach, a kind of one-pot hydrothermal reaction containing catechol, hexamethylenetetramine, and ZnCl₂ was performed, by which a kind of coatings composed of ZnO nanoparticles/catechol-formaldehyde resins (ZnO/CFR) were in-situ constructed on surfaces of both cellulosic and polyamide fabrics, and thus a series of mussel-inspired durable antimicrobial cotton, polyamide, and polyamide/cotton fabrics were obtained. In the system, catechol moieties of the resin are the origin of the superior adhesion capacity of the coating, contributing to the strong interfacial bonding with the material via covalent bonds and noncovalent interactions. Micro morphologies and chemical compositions of the fabric were studied by using scanning electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry, and the antimicrobial activities,laundering durability,tensile strength,hand feel,mammalian cell viability and formaldehyde content of the fabric were tested and analyzed,respectively.
Results It was found that all the coated fabrics turned yellow and some particles appeared randomly on surfaces of the fabrics (Fig. 1). ZnO/CFR coated samples presented Zn2p spectra with a double band corresponding to Zn2p_1/2 and Zn3p_3/2, having two peaks at 1 045.1 and 1 022.2 eV (Fig. 2). After the zone of inhibition determination test, no microbial colony grows in the area in contact with the fabric and no inhibition zone appears around the edge of the sample (Fig. 3). All the agar plates corresponding to ZnO/CFR coated fabrics before and after washing presented no or very few microbial colonies, while all the agar plates corresponding to uncoated fabrics had some microbial growth of microbial colonies (Fig. 4). ZnO/CFR coated sample kept a relatively high content of zinc and exhibited a very high bacteriostasis and fungistasis rate of 99.99% even after 50 accelerated laundering cycles (Fig. 5). ZnO/CFR coated fabrics showed no or very few decreases in weft and warp directional tensile strength compared with uncoated ones (Fig. 6), and achieved softness, resilience, and smoothness scores nearly equivalent to those of the untreated samples (Fig. 7). ZnO/CFR coated fabrics exhibited a little decrease in the relative cell viability value compared to the control sample, while no formaldehyde was detected in the fabric using a test with a detection limit of 20 mg/kg (Tab. 1).
Conclusion ZnO nanoparticles were anchored onto surfaces of cotton, polyamide, and polyamide/cotton fabrics by catechol-formaldehyde resins, where the morphology and distribution of the nanoparticles were different on the surface of cellulosic and polyamide fibers. ZnO/CFR coated fabrics presented an antimicrobial activity with non-dissolution behaviors to Gram-positive bacteria, Gram-negative bacteria, and fungi. ZnO/CFR coated fabrics had high laundering durability and showed high inhibiting activities to bacteria and fungi even after 50 times accelerated laundering cycles. ZnO/CFR coatings did not deteriorate the wearing comfort of the fabric and nor the human health.

Synthesis of carboxylated polystyrene fluorescent microspheres and its application in fabric anti-counterfeiting

XIAO Ming, HUANG Liang, LUO Longyong, BI Shuguang, RAN Jianhua

Journal of Textile Research. 2023, 44(02):  184-190.  doi:10.13475/j.fzxb.20220807907

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Objective In order to address the complexity in preparation and high cost for current fabric based anti-counterfeiting technology, carboxylated polystyrene fluorescent microspheres were synthesized and loaded on fabric for anti-counterfeiting application. The fluorescent microspheres prepared by this paper have great anti-counterfeiting effect on different types of fabrics, offering obvious practical value for curbing fake products and for improving the economic value of fabric and clothing brands.
Method Carboxylated polystyrene fluorescent microspheres with negative surface charges were prepared at 80 ℃ by copolymerization of styrene and acrylic acid as reactive monomer, polyvinylpyrrolidone as stabilizer, azo diisobutyronitrile as initiator, deionized water and ethanol as solvent. The cationic surfactant octagyltrimethyl ammonium bromide was used as the modifier, and the fluorescent dye fluorescein isothiocyanate was adsorbed by electrostatic self-assembly method to prepare carboxylated polystyrene fluorescent microspheres with yellow-green fluorescence. The microspheres were loaded on different fabrics to produce fabrics with anti-counterfeiting function.
Results Fluorescent microspheres with different contents of fluorescent dyes were successfully prepared by electrostatic self-assembly method. The fluorescent microspheres were measured by Fourier infrared spectrometer and all contained isothiocyanate characteristic functional groups at 2 036 cm^-1(Fig. 3). With the increase of the content of fluorescent dye isothiocyanate, the surface negative charge value and particle size was gradually increased. When the content of fluorescent dye isothiocyanate was 10% of the carboxylated polystyrene microspheres, the surface charge was -22.1 mV and the particle size was about 1 406.0 nm(Fig. 2 and Fig. 6). The surface morphology of fluorescent microspheres with different contents of fluorescent dyes was observed by scanning electron microscopy, which showed that the surface of the microspheres was smooth, monodisperse and uniform in size, as shown in Fig. 5. The emission spectral wavelengths of fluorescent microspheres with different contents of fluorescent dyes measured by fluorescence spectrophotometer were all about 517 nm(Fig.4(b)), which was consistent with the emission wavelength of isothiocyanate fluorescent dyes(Fig.4(a)). The fluorescent microspheres were measured at different times (1-9 d) and pH values (3-11), which indicated that the prepared fluorescent microspheres had great fluorescence stability(Fig.4 (c) and (d)). The fluorescent fabric prepared by treating the fluorescent microspheres on silk, cotton and cotton/spandex fabric had no obvious phenomenon under ordinary light, but had bright yellow-green fluorescence under ultraviolet light (365 nm)(Fig.8). It was found that adding a small amount of water-based polyurethane aqueous solution could solve the problem that fluorescent microspheres were easy to fall off from the fabric. After hundreds of times of friction and a long time of washing, great fluorescence intensity was maintained(Fig. 9). After 400 times of friction and 30 min of washing, the fluorescence intensity still maintained at 81.8% and 85.7% of the original fluorescence intensity, demonstrating satisfactory color fastness to meet the requirement arising from transportation and storage in practical occasions.
Conclusion The preparation of carboxylated polystyrene fluorescent microspheres by electrostatic self-assembly method were easy to operate. The surface of the fluorescent microspheres was smooth, the particle size was relatively uniform, the fluorescence intensity was high, and the wavelength had an obvious emission peak at 517 nm, which was consistent with the emission wavelength of isothiocyanate fluorescent dye. Under different times and different pH value, the fluorescence stability was great, respectively treated in silk, cotton and cotton/spandex fabrics under ordinary light had no obvious change, but under ultraviolet light (365 nm) it was bright yellow-green, with obvious fluorescence anti-counterfeiting effect. Adding a small amount of aqueous polyurethane solution can improve the fluorescent microspheres treatment on the fabric easy to fall off the problem, providing a great performance. In conclusion, the carboxylated polystyrene fluorescent microspheres prepared in this research can meet the role of fluorescence pseudo-detection under different environments and different fabrics, and have broad application prospects and practical application value for fiber and fabric anti-counterfeit detection.

Dyeing and Finishing & Chemicals

Preparation of Fe/C porous carbon material and microwave absorption properties of coated cotton fabrics

DING Juan, LIU Yang, ZHANG Xiaofei, HAO Keqian, ZONG Meng, KONG Que

Journal of Textile Research. 2023, 44(02):  191-198.  doi:10.13475/j.fzxb.20220806608

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Objective With the rapid development of modern society and the increase of electronic equipment, the problem of electromagnetic pollution are causing increasing attention. In order to reduce the influence of electromagnetic radiation on people's health, textiles can be functionalized to shield the electromagnetic absorption waves. In view of the above ideas, electromagnetic wave absorption materials can be mixed in the polymer solution in the fiber production, and can be coated onto the textiles as functional finishing.
Method To improve the electromagnetic wave absorption performance of coated cotton fabrics, an iron based magnetic metal-organic framework (Fe-MOF) material was prepared following the solution mixing method. Fe/C porous carbon material was prepared by a high temperature pyrolysis. Polyacrylate was used as a binder to the Fe/C porous carbon material on cotton fabrics to prepare a flexible textile composite.The phase structure, microstructure and surface elements, magnetic properties and thermodynamic properties of Fe-MOF material and Fe/C porous carbon material were characterized and evaluated by X-ray diffractometer, field emission scanning electron microscope, vibrating sample magnetometer and thermogravimetric analyzer, respectively. The Fe-MOF material and Fe/C porous carbon material have been successfully separately prepared. The electromagnetic microwave absorption properties of the Fe/C porous carbon material and coated cotton fabrics are analyzed with a vector network analyzer, respectively.
Results At frequency 4.6 GHz, the Fe/C porous carbon material has a minimum reflection loss of -60.4 dB, an effective bandwidth less than -10 dB of 1.4 GHz with thickness of 4.3 mm (Fig. 6). Synergistic effect of dielectric loss and magnetic loss enhances the electromagnetic microwave absorption properties of the Fe/C porous carbon material (Fig. 7). The Debye relaxation process and magnetic loss exist in the Fe/C porous carbon material according to the Debye theory and eddy current loss (Fig. 8), respectively. The reflection loss and impedance matching coefficient reflect the impedance matching performance of the Fe/C porous carbon material with different thickness. When the thickness is 4.3 mm, the matching coefficient is close to 1 (Fig. 9), indicating excellent impedance matching property of the Fe/C porous carbon material. Most incident waves enter the Fe/C porous carbon material, and the synergistic effect of dielectric loss and magnetic loss inside the material is optimum. The minimum reflection loss of the coated cotton fabric is -53.94 dB, the effective bandwidth less than -10 dB is the X-band, and the optimal coating thickness is 4.5 mm (Fig. 10). The thickness of the Fe/C porous carbon material-coated cotton fabric reaches more than 3.5 mm, and the coated cotton fabric has excellent electromagnetic microwave absorption properties (Fig. 10).
Conclusion The research reported in this paper not only provides a basis for the research of the microwave absorption properties of the MOF derivatives, but also provides a basis for the study of the microwave absorption properties of flexible textiles. However, there are still many aspects to be studied in the future, such as the synthesis of biomass-based carbon materials, other preparation methods of the MOF derivatives and different fabrics coated finishing. The research on the application of microwave absorption materials to textiles needs further exploration. For example, the effective absorption bandwidth less than -10 dB is 1.4 GHz, which needs further improvement. To enhance the optimal thickness corresponding to the optimal absorption intensity, the effective absorption bandwidth may be reduced by doping, changing ligands and other methods. Meanwhile, the intersection of material science and textile chemistry will be the key factor for the breakthrough of electromagnetic microwave absorption materials in the textile field.

Dyeing and Finishing & Chemicals

Color gamut expansion and color prediction of natural dye-dyed wool fibers

JIANG Yang, CUI Biao, SHAN Chuanlei, LIU Yin, ZHANG Yanhong, XU Changhai

Journal of Textile Research. 2023, 44(02):  199-206.  doi:10.13475/j.fzxb.20220807508

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Objective The exceptional benefits of wool fibers in terms of warmth retention, air and moisture permeability, and distinctive garment appearance make the wool fibers appealing. The value of finished wool clothing can be increased by using natural dyes to color the wool fibers. Natural dyes' limited color gamut, however, prevents them from being widely used due to issues in printing and dyeing wool fibers.
Method In order to enrich the color gamut of wool fibers dyed with natural dyes, natural red, yellow and blue, the three primary dyes, were chosen to dye wool fabrics and fibers with the one bath dyeing based on the use of fiber color matching method. The color prediction of fabric dyed with mixed dyes and mixed colored fibers was made based on Kubelka-Munk single constant theoretical model and Stearns-Noechel model, respectively.
Results The pH values have an effect on the depth of shade(K/S) for wool fibers colored with natural dyes(as shown in Tab. 1). The K/S value of the sample colored with natural red and blue dyes was increased from 3.89 to 17.82 and from 2.07 to 10.73 respectively as the pH value reduced from 4 to 2, while the sample dyed with natural yellow dye was decreased from 3.62 to 1.51 as the pH value decreased from 4 to 2. When the dye solution comprises natural red dyes, the hue angle h value of the fabric dyed using the one bath dyeing method ranged in 0°-24° and 324°-360°. The brightness value L^* of the mixed color fiber system was higher than that of fabric dyed using the one bath dyeing method, the color saturation value (C^*) decreased, and the hue angle range increased when the ratio of each dye used in the one bath dyeing method was equal to the ratio of the fiber dosage in the mixed colored fiber system. This may be because each fiber is dyed separately before being mixed, reducing dye competition and expanding the color gamut of woolen clothing dyed with natural dyes. The K/S curve of fabrics dyed using the one bath dyeing method matches the fitting curve by the Kubelka-Munk single constant theoretical model (Fig. 3), demonstrating a linear relationship between the K/S value of wool fabric dyed with mixed natural dyes and the K/S value of dyed with the single red, yellow, and blue natural dyes. Additionally, the reflectance curve of the mixed colored fiber was fitted using the Stearns-Noechel model. Reflectance change of the mixed colored fibers in the 400-700 nm wavelength range was almost in line with the reflectance curve determined using the Stearns-Noechel model(as seen in Fig. 4).
Conclusion The CIELAB color gamut space showed non-uniform distribution of the color coordinate of wool fabric dyed using the one bath dyeing method. Natural red dyes have a greater affinity for fibers than yellow, and blue natural dyes. Across comparison to wool fabric colored using the one bath dyeing method, the color coordinate of mixed colored fiber was spread more evenly in the color gamut space. The hue angle value of mixed colored fiber ranged in 0°-50° and 316°-360°. Using the one bath dyeing method and mixed colored fiber treated with natural dyes respectively, the Kubelka-Munk model and the Stearns-Noechel model could be used to predict the color of wool fabrics. This study also suggests novel approaches for further enhancing production efficiency and lowering color matching costs.

Enhancement of anti-wrinkle properties of cotton fabrics by reactive dyeing with two vinyl sulphone groups

WANG Jinkun, LIU Xiuming, FANG Kuanjun, QIAO Xiran, ZHANG Shuai, LIU Dongdong

Journal of Textile Research. 2023, 44(02):  207-213.  doi:10.13475/j.fzxb.20220408407

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Objective Cotton fabrics are popular among consumers due to its good breathability, moisture absorption and wearing comfort. However, cotton fabric elasticity is poor, prone to wrinkles during the washing process. In order to improve the anti-wrinkle properties of cotton fabrics, reactive dyes with different reactive groups were used to dye cotton fabrics by cold pad-batch process to improve anti-wrinkle properties of cotton fabrics while dyeing.
Method In this study, the chemical properties and surface morphology of dyed cotton fabrics were characterized with the help of X-ray diffraction, Fourier infrared spectroscopy and scanning electron microscopy. In addition, the effects of the number, type and distance of reactive dye groups on the anti-wrinkle properties of dyed cotton fabrics were investigated by testing the wrinkle recovery angle and K/S value of dyed cotton fabrics.
Results The wrinkle recovery angle of cotton fabrics dyed with Reactive Blue 19 did not change significantly with the increase of dye mass concentration (Fig. 1). The wrinkle recovery angle of cotton fabrics dyed with Reactive Red 198 and Reactive Black 5 increased with the increase of dye mass concentration, and the wrinkle recovery angle of cotton fabrics dyed with Reactive Black 5 was higher than that of cotton fabrics dyed with Reactive Red 198. Among the four two vinyl sulphone groups, i.e. Reactive Black 5, Reactive Orange 131, Reactive Blue 203, and Reactive Red AS, reactive dyed cotton fabric obtained darker apparent color, and their K/S maximum values were 25.2, 23.8, 24.1, 23.3 respectively (Fig. 3). The wrinkle recovery angle of the cotton fabrics dyed with the four dyes increased rapidly with the increase of the dye mass concentration. When the dye mass concentration reached a certain value, the wrinkle recovery angle of the fabric remained unchanged (Fig. 4). The wrinkle recovery angles of cotton fabrics dyed with Reactive Black 5, Reactive Orange 131, Reactive Blue 203 and Reactive Red AS increased from 165° to 210°, 208°, 205° and 198°, respectively, representing increases of 27%, 26%, 24% and 20% respectively, corresponding to the distance between the two vinyl sulphone groups in the reactive dyes (Tab. 1). The X-ray diffractograms of cotton fabrics dyed with Activated Black 5 were basically the same as the untreated ones, all of which showed four crystalline surfaces, exhibiting the form of cellulose I (Fig. 5(a)). The absorption peaks of benzene ring and C=C at 1 609 and 1 567 cm^-1 appeared in the cotton fabric impregnated with Reactive Black 5 dye dried immediately relative to the untreated cotton fabric (Fig. 5(b)). However, the absorption peak of C=C at 1 567 cm^-1 disappeared in the cotton fabric impregnated with Reactive black 5 after cold pad-batch process. In addition, the cross-section of cotton fabric changed from flat waist-like to elliptical after Reactive Black 5 dyeing (Fig. 5(c)).
Conclusion Compared to single reactive groups, double reactive group dyes can improve the wrinkle resistance of cotton fabrics. Compared with the Reactive Red 198 dyed cotton fabric containing isobutyl groups, the Reactive Black 5 dyed cotton fabric containing two vinyl sulphone groups has better anti-wrinkle properties. By comparing the Reactive Black 5, Reactive Orange 131, Reactive Blue 203 and Reactive Red AS, the 4 two vinyl sulphone group dyes, the greater the distance of the reactive group, the better the anti-wrinkle properties of the dyed fabrics. Among them, the Reactive Black 5 dye dyed fabric has the best anti-wrinkle effect. The cross-section of cotton fabrics becomes round from a flat waist-like shape after dyeing. The dye reacts covalently with the hydroxyl groups on the macromolecular chain mainly in the amorphous region of the fiber, and the cross-linked structure formed enhances the anti-wrinkle property of the cotton fabric.

Preparation and application of flame retardant waterborne polyurethane by alcoholysis of waste polyethylene terephthalate fiber

PANG Mingke, WANG Shuhua, SHI Sheng, XUE Lizhong, GUO Hong, GAO Chengyong, LU Jianjun, ZHAO Xiaowan, WANG Zihan

Journal of Textile Research. 2023, 44(02):  214-221.  doi:10.13475/j.fzxb.20220807408

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Objective The increasing amount of waste polyethylene terephthalate (PET) textiles has resulted in a huge waste of energy and resources. Due to the limitation of recycling methods, the reuse of recycled products is also affected. In order to improve the yield of waste PET fabric and to reuse the recycled products, the aim of this research is to optimize the reaction conditions for depolymerization of waste PET fabric, to synthesize, using the depolymerized product as raw material, stable waterborne polyurethane (WPU), and to conduct flame retardant modification of the waterborne polyurethane for flame retardance.
Method Under the conditions of choline chloride and zinc acetate as catalysts, glycolysis was used to depolymerize waste PET fabric. The effects of reaction time, catalysts content and other influential factors were investigated on the product yields, and the products were characterized using Fourier transform infrared spectro-meter(FT-IR). Waterborne polyurethane was synthesized by the alcoholysis product ethylene terephtha-late(BHET) and isoflurone diisocyanate (IPDI) and so on, and tris(hydroxymethyl)phosphine (THPO) and SiO₂ were used to improve its flame retardant property. The conditions were optimized for making stable waterborne polyurethane emulsion, and the effects of initial n(NCO)/n(OH), content of the flame retardants and SiO₂ on the flame retardant property of WPU were systematically studied, and characterization was carried out using FT-IR and thermal gravity analysis. Flame retardant modified waterborne polyurethane on PET fabrics was studied with the assistance of scanning electron microscope (SEM).
Results The best depolymerization process took place when the mass ratio of EG and PET was set to be 4∶1, molar ratio of choline chloride to zinc acetate 1∶1, reaction temperature 185 ℃, and reaction time 4 h. The FT-IR results indicated that the depolymerized product was bis(hydroxyethyl) terephthalate (BHET), whose yield was up to 87.6%. When the THPO content was less than 24%, the SiO₂ content less than 6%, and the n(NCO)/n(OH) was 3-7, the flame retardant modified waterborne polyurethane formed a uniform and stable emulsion. When the THPO content was 24%, SiO₂ content was 4%, and n(NCO)/n(OH) was 6, the flame retardant modified PET fabric demonstrated promising flame retardant properties, with the residual carbon rate reaching up to 13.9%, which is 127% higher than original PET fabric, and the LOI value of the modified PET fabric reached up to 29.7%, which meets UL-94 V-0 level. The SEM results suggested that the PET fabric was uniformly coated by the flame retardant modified polyurethane emulsion after treatment, and the voids between the fabric and yarns were filled by the polyurethane, and the emulsion and the fabric were integrated together.
Conclusion This research has led to the following achievements: 1) waste PET fibers are depolymerized via alcoholysis; 2) the depolymerized product are successfully synthesized into flame retardant modified waterborne polyurethane; 3) the flame retardant modified waterborne polyurethane is used to treat PET fabrics which demonstrate promising flame retardant performance. The route can be applied to create general flame retardant fabrics.

Preparation and properties of flame retardant/anti-ultraviolet cotton fabrics with tea polyphenol based flame retardants

JIANG Qi, LIU Yun, ZHU Ping

Journal of Textile Research. 2023, 44(02):  222-229.  doi:10.13475/j.fzxb.20220810308

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Objective Cotton fabrics are one of the most important textiles; they are widely used in clothing, furniture, and decoration. However, cotton fabrics have a low limiting oxygen index (LOI) of only 17%, and they are highly flammable, which is easy to cause fire accidents. Meanwhile, the most widely used existing halogen-containing flame retardants are facing many restrictions due to the generation of halogenated hydrocarbons during burning. In addition, cotton fabrics have poor anti-ultraviolet (UV) properties and cannot protect the skin from UV damage. Therefore, it is necessary to design an additive to improve the flame retardancy of cotton fabrics with the anti-UV properties.
Method Tea polyphenols (TP), phenyl phosphonic acid (PPOA) and iron (Ⅲ) sulfate hydrate(Fe(SO₄)₃) were selected to prepare tea polyphenols-iron-phenyl phosphonic acid complex (named TP-Fe-PPOA). Phosphoric acid or polyphosphoric acid produced by the thermal degradation of PPOA are known to be able to promote char formation of materials, and TP generates free radicals and slows down burning. The benzene ring absorbs UV light and improves the anti-UV properties of fabrics. Flame retardant cotton fabrics were prepared by the dip-coating technology, and the flame retardant, anti-UV and mechanical properties were investigated by limiting oxygen index evaluation, vertical flame tests (VFT), cone calorimetry test (CCT), anti-UV performance test and universal testing machine.
Results Test results show that TP-Fe-PPOA was evenly adhered to the surface of cotton fabrics (Fig. 1). There is a synergistic effect between TP-Fe and PPOA. Cotton/TP-Fe cannot achieve self-extinguishing(as shown in Fig. 5 and Tab. 3). There is a serious phenomenon of negative burning, and the cotton fabrics are completely destroyed in VFT. Cotton/PPOA slows down the flame spread significantly compared with cotton fabrics. However, the LOI value of Cotton/PPOA is still only 21.9%. When they were treated with TP-Fe-PPOA, cotton fabrics became self-extinguishing, the damage length was only 6.7 cm in VFT, and the LOI increased from 17.6% to 24.7%. Meanwhile, the peak heat release rate value of Cotton/TP-Fe-PPOA was 11.8% lower than that of cotton fabrics(Fig. 6 and Tab. 4). The results indicated that after the flame retardant treatment, smoke release was effectively mitigated. The smoke production rate value of flame retardant fabrics was smaller than that of cotton fabrics, and the total smoke production value was also significantly reduced, which can greatly reduce the probability of death by asphyxiation in a fire. Moreover, the cotton fabrics left almost no char residues after CCT, while Cotton/TP-Fe-PPOA left more compact char residues(Fig. 8). These char residues act as a barrier to slow down the transfer of heat, oxygen, combustible gases and smoke, protecting the underlying fabrics. Fortunately, while achieving the flame retardant and anti-UV properties, the air permeability of Cotton/TP-Fe-PPOA was decreased by only 13.1% (Fig. 9). However, the mechanical properties of the flame retardant cotton fabrics were deteriorated severely due to the acidity of PPOA (Tab. 5). The elongation at break of Cotton/TP-Fe-PPOA in both warp and weft directions was decreased by about 28.8% and 12.6% compared to that of cotton fabrics. In addition, anti-UV was also greatly improved (Tab. 6). The UV protection factor (UPF) of Cotton/ TP-FE-PPOA increased from 7.47±0.19 to 37.85±2.34, which is close to the standard of UPF≥40 for sun protection products.
Conclusion The above results show that TP-Fe-PPOA can make cotton fabrics with better flame retardant effect and better anti-UV properties at the same time. These flame retardant cotton fabrics with anti-UV properties are suitable for use as curtains, which not only meet the needs of flame retardant, but can also block UV light, slow down the aging process of indoor fabrics and protect people from UV light. Unfortunately, the mechanical properties of these flame retardant cotton fabrics are severely lost, especially the loss of tensile strength. Therefore, it is necessary to consider the use of neutral or alkaline additives to reduce the acid brittleness of cotton fabrics in order to retain the original mechanical properties of the fabrics in the future research. Considering that Cotton/PPOA performs well in VFT and LOI, it can be concluded that phosphorus-containing flame retardants have good effects on improving the flame retardant properties of cotton fabrics. Therefore, PPOA can be replaced with less acidic phosphorus-containing flame retardants or the acidity of PPOA can be reduced through the reaction to achieve the purpose of reducing the loss of mechanical properties of flame retardant fabrics.

Key components and structural characteristics of river mud used in production of gummed Canton silk

LI Zheyang, MA Mingbo, ZHOU Wenlong

Journal of Textile Research. 2023, 44(02):  230-237.  doi:10.13475/j.fzxb.20220804708

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Objective River mud is crucial for the formation of the coating on the gummed Canton silk. However, there is still a lack of understanding of the organic components in the river mud. In order to understand the key organic components and structural characteristics of the river mud used in the production of gummed Canton silk, and to clarify the difference between the river mud used in gummed Canton silk and ordinary river mud, an investigation on river muds was carried out.
Method River mud was collected from Shunde and Xiqiao, and locally from Hangzhou, which were then separated and purified. Using Hangzhou local mud as the control, river mad components characterized the obtained were characterized and obtained with the use of ultraviolet-visible (UV-vis) spectra, infrared spectra and X-ray photoelectron spectroscopy (XPS), and compared the similarities and differences between them.
Results The UV-vis spectra (Fig. 2) shows that 200-220 nm belongs to the E2 band absorption of the benzene ring, and 240-270 nm belongs to the B band absorption of the benzene ring. In addition, the oxygen containing functional group content index A₂₅₃/A₂₀₃ and humus aromaticity index values of river mud of gummed Canton silk were higher than those of local river mud. Infrared spectra (Fig. 3), indicates that the attached components of the fabric surface coating showed obvious spectral characteristics of humic acid and fulvic acid components. The unattached component demonstrated the spectral characteristics of the humic component. XPS full scan spectra (Fig. 5 and Tab. 2) suggests that humic acid and fulvic acid contained inorganic elements such as silicon and chlorine in addition to carbon, oxygen and nitrogen. After several times of alkali dissolution and acid precipitation, there was still some iron in the humic acid component of the river mud used for gummed Canton silk, while there was no iron in the humic acid component of local river mud. According to fitting results of carbon element peaks (Fig. 6 and Tab. 3), humic acid and fulvic acid in river mud used for gummed Canton silk contain higher aromatic carbon content and the proportion of C—O/C—OH/C—N, C=O, C(O)N, C(O)O four chemical forms.
Conclusion It was determined that humic acid and fulvic acid in the organic matter of river mud participated in the construction of the coating on the gummed Canton silk, while humin did not participate in the reaction. Compared with the local Hangzhou river mud, there are great differences in the structure and properties of humic acid and fulvic acid components in the river mud of gummed Canton silk production area. First of all, its humic acid and fulvic acid are more aromatic. Secondly, there are significant differences in the content of various functional groups, especially fulvic acid, which has higher hydroxyl, carboxyl, peptide bond and other oxygen-containing functional groups on the molecular structure of fulvic acid in river mud. Finally, its humic acid component has stronger iron ion binding capacity. The high aromatic degree of humic acid and fulvic acid in the river mud used in the production of gummed Canton silk makes the coating of gummed Canton silk more black and bright. Its high oxygen functional group content and strong iron ion complexing ability enable river mud humic acid and fulvic acid to form a stable complexing structure with dioscorea cirrhosa pigment and silk, thus forming a solid coating.