Table of Content

10 March 2024, Volume 32 Issue 3

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Kubelka-Munk dual constant theory for the construction of full color gamut rotor spinning and color prediction

WANG Yanyan, XUE Yuan, CHEN Yourong, SHI Huanqiang

2024, 32(3):  1-13. 

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Due to the heavy workload and time-consuming and material-consuming of traditional manual color measurement and matching, color spinning technology came into being. Color spinning technology is a spinning technology that blends several colored fibers in a specific proportion to produce fashionable colors. The fabric and finished product made by using color spinning do not need to be dyed again and is considered a green ecological short process technology. However, due to the inability to freely control color during the spinning stage, the actual production and application of color spinning are greatly limited. To address this issue, a four primary color ternary coupling superposition full-color gamut grid-based color mixing model was first constructed, which can perform color phase control, brightness control, and chromaticity control within the full-color gamut range.
On this basis, combined with the characteristics of the Kubelka-Munk dual constant theoretical model, 84 grid point mixed sample formulas were selected from the constructed grid-based color mixing model, of which 54 mixed samples were used as measured samples. With a three-channel CNC rotor spinning machine as the platform, four primary colors of cyan (C), magenta (M), yellow (Y), and white (W) were used as raw materials. Based on the constructed full-color domain grid-based color mixing model and color mixing chromatography, we prepared actual spinning samples. Then, we measured the color values of 54 measured samples, and used the least squares method to calculate the K and S values of each primary color fiber, in order to achieve the prediction of full gamut color or primary color fiber mixing ratio. We also selected the remaining 30 mixed samples as prediction samples to verify the ability of the traditional Kubelka-Munk dual constant theory model to predict the color or primary color fiber mixing ratio. From the comparison between the predicted reflectance of the mixed samples and the actual reflectance, it is found that the predicted reflectance of some mixed samples is significantly lower than the actual reflectance. In response to the problem of insufficient prediction accuracy of traditional Kubelka-Munk double constant theory, the article proposes to reconstruct the Kubelka-Munk double constant theory model for color prediction, and then partially replace the part of the traditional method where the obviously mixed color yarn has a lower reflectivity than the actual reflectivity with the interpolation method. The results show that compared with the traditional Kubelka-Munk double constant theory, the average color difference of the reflectance predicted by the new method has been reduced from 1.48 to 1.04, and the color difference of all mixed samples can be controlled within 2.0. We use the least squares method to predict the monochromatic fiber blending ratio of ten mixed samples, and then substitute it into the Kubelka-Munk dual constant theoretical model to calculate the predicted reflectance. According to the CMC2:1 color difference formula, the color difference between the predicted reflectance and the actual reflectance of the ten mixed samples was obtained, with the minimum color difference being 0.18, the maximum being 0.91, and the average value being 0.45. As the mixing ratio changes, the color difference of the mixed samples fluctuates up and down within its average range, and the color difference is small. The prediction effect of the blending ratio is good. This prediction method has better prediction accuracy than the traditional Kubelka-Munk double constant theory. The constructed four primary color grid mixing model and Kubelka-Munk double constant theory model can be applied to predict the color mixing and mixing ratio of multi primary color fibers.


Design of electrostatic charge-induced yarn breakage sensors

LÜ Jingze, DAI Ning, HU Xudong, XU Kaixin, XU Yushan

2024, 32(3):  14-20. 

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In the spinning process, yarn breakage detection, especially for fine yarns, is an essential means to improve the performance of spinning equipment. Considering the cost and factors affecting yarn tension, yarn breakage detection in the industry is mainly based on photoelectric non-contact yarn breakage detection. The actual spinning workshop has much cotton wool and dust, which is easy to cause diffuse reflection in the photoelectric detection channel and reduce the sensor's accuracy. At the same time, changes in light intensity in the workshop will also impact the signal received by the opposite photoelectric receiver. In recent years, the spinning industry's image processing related to yarn breakage detection research is also emerging. Still, with the above-mentioned photoelectric detection principle of the same shortcomings, the approach is even more demanding on the light and installation conditions and expensive, with hundreds of spindles in the spinning process being more challenging to promote.
To promote the yarn breakage detection technology for yarns, especially fine yarns, in the spinning link, it is necessary to reduce the dependence of the existing yarn breakage detection methods on the working link and installation conditions, and reduce the cost of yarn breakage detection. Based on the basic principle of electrostatic inductive detection, the electrostatic charge-induced yarn breakage sensor was constructed, and its overall structure, as well as the design of critical components such as primary signal amplification module, shaping and secondary amplification module, output and display module, were theoretically analyzed and experimentally tested. Finally, the test bench of the electrostatic charge induction yarn breakage sensor was construct to test the degree of influence of the moving yarn speed and its material on the electrostatic charge induction yarn breakage sensor in combination with the mechanism of electrostatic charge induction yarn breakage sensor performance based on the electrostatic charge induction strength.
On this basis, we statistically analyzed the output point voltage values of the critical module of the electrostatic charge-induced yarn breakage sensor under the simulated working spindle speeds of the spinning machine at 13,600 r/min and 15,000 r/min, as well as under the yarn breakage condition.
The research found that the speed of the moving yarn and its material are the main influencing factors of the electrostatic charge-induced yarn breakage sensor. Still, the influence is much smaller than the value of the voltage deviation at the output points OUT3 and OUT2 of the back end of the key module of the electrostatic charge-induced yarn breakage sensor when the two states of the moving yarn are broken and unbroken so that this characteristic can be used for the accurate judgment of the broken connection of the yarn.
The sensor seals the circuit and detection electrodes utilizing a closed aluminium case, which reduces dust and charge interference in the air, facilitates the collection of charge signals, and obtains output voltages with significant variations for identifying different types of yarns with minor charge variations. Therefore, the device has a better state detection effect for the yarn carrying static electricity in the spinning process.


Motion simulation and morphological analysis of hooked fibers in a rotor spinner

GONG Xinxia, YANG Ruihua

2024, 32(3):  21-28. 

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Rotor spinning is a widely used new spinning method with the advantages of short process flow and high production efficiency. The fiber strands are directly fed into the carding device and released into a single fiber state, and are transferred to the rotor through negative pressure airflow for condensation and twisting into yarn. The fibers fed into the rotor spinning machine contain various forms of fibers, and are mainly divided into the three categories of straight fibers, front hook fibers, and rear hook fibers. In actual production, it is necessary to avoid the entry of rear hook fibers. If there are many rear hook fibers, the spun rotor yarn may have uneven evenness and easily produce coarse and fine knots. This is the experience summarized in the production process. Therefore, exploring the morphological changes of hook fibers in the rotor spinning machine, as well as the straightening and formation process of hooks, provides reference for improving the spinning mechanism of rotor spinning, and optimizing the rotor structure and process parameters.
We aimed to solve the fiber motion trajectory using the Lagrangian-Euler method, with the airflow as a continuous phase and the fibers as discrete phases. Firstly, we used the 3D modeling software SolidWorks2021 to establish a model of the rotor spinning machine. Then, we coupled and connected Rocky DEM 2022R1 and ANSYS Fluent 2022R1. As for the airflow field, we selected the Standard k-epsilon turbulence model, Standard Wall Function (SWF), and SIMPLE algorithm. The fiber model is of a rod chain structure, and is made of cotton fibers with a length of 28mm. The fiber model established in this article has the size and properties of real cotton fibers, and has been optimized on the fiber model. At the same time, the changes in fiber morphology under different initial forms were considered. The deformation pattern of the hook fibers in the fiber transmission channel under conditions 1-2 is basically consistent, with a small trend of movement towards the main section in the bent section; from the exit of the fiber transport channel to the slip surface, different hooked fibers undergo different morphological differentiation processes; the pattern of morphological changes in the coagulation tank is also roughly the same, with the fibers transitioning from wavy bending to a state close to the inside of the coagulation tank. When the front hook fiber completely enters the condensation groove, the hook part has been straightened and eliminated; after the non-straightened rear hook fibers in the fiber transmission channel enter the condensation tank, it is difficult to fully straighten the hook part. The straightness of the front hook fibers in the condensation groove is significantly higher than that of the rear hook fibers. Therefore, feeding fibers into the rotor spinning machine in the form of hooks can optimize the yarn structure. 
To sum up, numerical simulation is a very good research method. Firstly, computer simulation of the flow field and fiber movement process inside the rotor spinning machine can provide theoretical guidance for production optimization and design solutions, reduce experimental trial and error costs, and improve efficiency. Secondly, by conducting in-depth research on the airflow field and fiber movement process inside the spinner, the mechanism of rotor spinning yarn formation is gradually improved, providing a theoretical basis for the key components such as the fiber conveying channel and rotor in rotor spinning.


Influence of flow field state in fiber delivery tube on the opening and loosening of fiber tows

WANG Jin, CHENG Hepeng, LI Shuai, LU He, CUI Yongzhi, QIAN Cui'e, YU Hechun

2024, 32(3):  29-37. 

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In the chemical fiber industry, the opening treatment of viscose or Lyocell staple fibers is an important process before the finished fiber. The fiber delivery tube,  one of the most important units of the post-treatment equipment, connects the cutting machine and the feed tank, and is used to transport the staple fiber cut off by the cutting machine and the flushing water. The viscose or Lyocell staple fiber cut by the breaker is fed to the feed tank, and the fiber is dispersed during the transportation process, so as to achieve uniform fiber laying of the feed tank, increase the washing effect of the refining machine, and improve the quality of the finished fiber. However, the traditional fiber delivery tube mainly plays the role of transportation, and the requirements for open fibers are not high. It is very important to explore the opening mechanism of bundle fibers and the influence of flow field state on fiber movement state to promote the rational design of fiber delivery tube structure and improve the opening effect of fibers.
In this paper, based on 3D modeling software and Cradle CFD numerical simulation software, the flow field model and fiber model in the fiber delivery tube were established to simulate the motion state of 2,000 fibers tow with length of 38 mm in the fiber delivery tube. The fluid inflow condition at the inlet of the fiber delivery tube was set as velocity inflow 1 m/s, and the outlet was set as static pressure outflow-natural outflow. The flow field was calculated by using steady state, pressure solver, RNG k-ε turbulence model and wall function method. The convection term was discrete by using second-order upwind scheme and was solved by using PISO algorithm based on SIMPLEC. Through the vector analysis of the pressure field, velocity field and flow field, and the analysis of the motion state of the fiber bundle in the fiber delivery tube, the influence of the flow field in the fiber delivery tube on the fiber movement was explored. The results show that when the fiber bundle enters the vertical pipe, it accelerates under the water flow and its own gravity. Due to the pressure gradient and velocity gradient in the pipeline flow field, the local velocity difference between the conveying process and the conveying fluid in the pipeline results in the opening effect of the fiber dislocation. The velocity of flushing water varies greatly at the bend of the fiber delivery tube, and the resulting velocity gradient is conducive to the opening of the fiber bundle. The flow field velocity gradient of the horizontal pipeline is small, and the speed change is relatively stable, so that the overall fiber is elongated and opened, which improves the fiber opening effect in the transportation process, and guarantees the continuously uniform output. The sudden increase in the diameter of the pipe leads to the vortex of the pipe, which hinders the forward transportation of the fiber. Therefore, for the design of the fiber delivery tube, the sudden increase in the diameter of the pipe tube should be avoided to reduce the phenomenon of fiber entanglement. In this paper, the results of the study describe the basic mechanism of the fiber bundle of opening, and reveal the fiber delivery tube flow field state influence on fiber transmission. Such results can provide reference for the design of the fiber delivery tube of chemical fibers and the textile industry.


Effect of coating layer number on dielectric properties and wave absorption properties of Ni powder/graphite matrix composites

SHI Lang a, JIANG Rongfan b

2024, 32(3):  38-44. 

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Graphite has good electrical conductivity, thermal conductivity and corrosion resistance, and is widely used in graphite electrodes, electromagnetic protection materials, superconducting materials and so on. To improve the wave absorbing properties of graphite-matrix composites, and analyze the effect of the coating layer number on the dielectric properties and wave absorbing properties of composites, the nickel powder/graphite matrix composites were prepared and researched. The nickel powder/graphite functional particles were prepared by mixing nickel powder and graphite according to the mass ratio of 1:4. By using PU2540 polyurethane as the substrate and adding appropriate thickener, the nickel powder/graphite coating sizing was prepared. The mass fraction of functional particles in the coating sizing is 40% of the total mass, and the viscosity of the coating sizing is 30,000 mPa·s. With the common polyester/cotton plain fabric in the market as the coating material base cloth, by adopting the textile coating process (scraping coating method) and using the automatic coating machine (coating machine speed of 60 cm/min), the nickel powder/graphite base coating sizing was evenly coated on the base cloth and dried in the oven at 80 ℃ for 10 min. Nickel powder/graphite based coating composites with 1, 2 and 3 layers were prepared, respectively. The dielectric constant of the composite was measured by BDS50 dielectric impedance spectrometer, and the reflection loss was measured by ZNB40 vector network analyzer. The effects of the layer number on dielectric properties and wave absorption properties of the composite were analyzed. 
The results show that the layer number has a certain influence on the electromagnetic shielding properties of Ni powder/graphite coating composites. In the applied electric field frequency range of 30 –1000 MHz, the real part of the dielectric constant of the composites with different coating layers decreases. When the frequency is 30 MHz, the real part of the dielectric constant of the samples is the largest, and the composites with three coating layers is the largest, indicating that it has the strongest ability to polarize electromagnetic waves and store charges. This is because the ability of the real part to store charge is directly proportional to the conductivity of the coated composite. The electrical conductivity of the composite is related to the volume fraction of the conductive filler, the size of the conductive particle, the shape of the particle and the dispersion uniformity of the particle, which will affect the degree of contact between the conductive particles. In the applied electric field frequency range 1–1000 MHz, the imaginary part and loss angle tangent value of the dielectric constant of the composite with different layer number increase. When the frequency is 1,000 MHz, the imaginary part of the dielectric constant of the samples is the largest, and the imaginary part and loss angle tangent value of the dielectric constant of the composite with three layers are the largest, indicating that it has the strongest loss ability to electromagnetic wave. This is because the imaginary part of the dielectric constant depends on the electric dipole moment of the rearrangement, which is proportional to the conductivity of the composite sizing. In addition, in the conductive network skeleton formed by graphite, due to the addition of nickel powder, the space between the graphite particles is fully filled, and the conductive property of the composite material is further improved. In the applied electric field frequency range of 10–3,000 MHz, the 2-coating-layer composite achieves the lowest peak value of reflection loss, up to -26.460 dB, indicating that it has the strongest absorption ability of electromagnetic wave. This is because graphite absorbs electromagnetic waves through the interaction with the electric field, and its main feature is that it has a high dielectric loss angle tangent, relying on the dielectric electron polarization or interface polarization attenuation to absorb electromagnetic waves. The smaller the volume resistivity of the material, the better the absorption effect, but the reduction of the surface resistivity of the material also increases the reflective ability of the material. Electromagnetic waves in free space are difficult to enter the interior of the material and cannot achieve the purpose of absorbing waves. Therefore, there is an optimal conductivity range, and its absorption efficiency depends mainly on the conductivity and dielectric constant of the material. The results can be used as reference for designing and developing economical and practical coating composites.



Preparation and hydrophilic properties of star-shaped PLLA-PEG block copolymer fiber membranes 

XING Dongfeng, LI Yunhuan, GAO Yu, WANG Fuxing, FU Qiang, JIN Dalai

2024, 32(3):  45-52. 

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Polylactic acid (PLA) is an important biodegradable polyester material with good biocompatibility, low toxicity, and good mechanical properties. Its main raw material is starch fermentation in plants, which is renewable and can be degraded by microorganisms (bacteria, fungi, etc.) in nature. As a raw material for plant photosynthesis, PLA enters the natural cycle. There is great potential for application in fields such as green plastics, tissue scaffolds, and biomedicine. However, PLA has poor hydrophilicity and a long degradation cycle, which limits its application in many aspects. So pure PLA materials can no longer meet the growing demand, and modifying them has become a trend.
The chemical modification of PLA mainly involves copolymerization with biodegradable substances to form linear or star-shaped copolymers. Research has found that compared to linear copolymers, star-shaped copolymers have smaller fluid mechanical volume and lower viscosity, indicating better thermal and degradation performance. In addition, plasticizer modification can be targeted at the performance modification of polymers to expand their application fields. Generally, it will choose to copolymerize with hydrophilic substances, such as the commonly used polyethylene glycol (PEG), which can be dissolved in interstitial fluid in the human body, and PEG with molecular weight below 4000 can be quickly eliminated from the body without any toxic and side effects. The addition of PEG can effectively increase the chain mobility of PLA, improve its ductility and stretchability, and thus broaden the potential application range of PLA.
To study the preparation process and hydrophilicity of star-shaped PLA multi block polymers, pentaerythritol (PET) was used as the initiator and stannous octanoate (Sn (Oct) 2) as the catalyst. Star-shaped hydroxyl terminated poly (L-lactide) (s-PLLA) was prepared through ring opening polymerization (ROP), and condensed with polyethylene glycol (PEG, relative molecular weight is 1000) to obtain four arm star-shaped poly (L-lactide) acid polyethylene glycol copolymers (s-PLLA-PEG). The s-PLLA-PEG fiber membrane was successfully prepared by electrospinning, and its surface morphology and hydrophilicity were tested and analyzed. A series of characterization methods were used to confirm the effective synthesis of polymers such as s-PLLA and s-PLLA-PEG. There are currently few reports on the research of PLA-modified fiber membranes. The results show that the melt temperature and glass transition temperature of s-PLLA-PEG decrease, and the flexibility is improved; the contact angle between s-PLLA fiber membrane and water is 132.10°, while the contact angle between the s-PLLA-PEG fiber membrane and water is 84.10°. Over time, the contact angle gradually decreases, and ultimately water is completely absorbed by the fiber membrane, exhibiting stronger hydrophilicity. Research has shown that when PEG is successfully grafted onto s-PLLA, the hydrophilicity of s-PLLA-PEG fiber membranes is significantly better than that of s-PLLA fiber membranes. This indicates that the presence of PEG can effectively improve the hydrophilicity and hydrophobicity of the surface of the s-PLLA fiber membrane, transforming it from a hydrophobic substance to a hydrophilic substance. Due to the excellent hydrophilicity of the s-PLLA-PEG fiber membrane, it has shown certain application prospects in medical dressings.


High-temperature resistance of ultra-high molecular weight polyethylene fibers

XUE Shuyun, YE Wei, WANG Zheng, XIA Pingyuan, GUAN Yongyin

2024, 32(3):  53-60. 

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Due to the unique structural characteristics of ultra-high molecular weight polyethylene (UHMWPE) fibers, fiber materials possess several excellent properties including lightweight, high strength, low temperature resistance, resistance to UV radiation, chemical corrosion resistance, high energy absorption, low dielectric constant, high electromagnetic wave transmittance, low friction coefficient, and outstanding performance in terms of impact resistance and cut resistance. The melting point of UHMWPE fibers is higher than that of ordinary polyethylene fibers at 134 ℃. However, compared to other high-performance fibers such as aramid and carbon fibers, UHMWPE fibers have poor high-temperature resistance, which limits their application range. Currently, research on the thermal stability of UHMWPE fibers in both domestic and international contexts mainly focuses on fiber spinning, low-temperature composites, and application environments. These studies are of importance in analyzing the thermodynamic properties of UHMWPE fibers. Recent studies have shown that UHMWPE fibers can be composite with thermoplastic polyurethane, polyvinyl chloride, and other resins to produce lightweight and high-strength membrane materials. However, in the process of hot-pressing composite processing, UHMWPE fibers need to withstand short-term high-temperature and high-pressure conditions. The processing environment temperature in these processes is high, reaching or exceeding the melting point of the material. As for the impact of transient high temperature in the thermal processing process on fiber structure and mechanical properties, no research reports have been found.
In response to the shortcomings of low melting point and easy creep of UHMWPE fibers, the mechanical stability performance of UHMWPE fibers under different hot-pressing temperatures and times was studied under the testing conditions of composite material hot-pressing processing environment. Through instruments such as differential scanning calorimeter, thermogravimetric analyzer, scanning electron microscope, X-ray diffractometer, Fourier transform infrared spectrometer and mechanical performance tester, the thermal stability performance and microstructure of UHMWPE fibers were characterized and analyzed. The results showed that the hot-pressing temperature and time had a significant impact on the performance of UHMWPE fibers. Under hot-pressing treatment of 150 ℃ or below, the mechanical properties of UHMWPE fibers changed little with the increase of hot-pressing time; under hot-pressing treatment of 160 ℃ or above, the long-term heat treatment led to a significant decrease in the mechanical properties of UHMWPE fibers. When the yarns were treated at 160 °C for 40 s, the breaking strength was 153 N, and the strength loss was 46.50%. When the hot-pressing temperature was higher than the melting point of the fibers, their strength dropped rapidly. When they were treated at 170 ℃ for 10 s, the strength dropped to 121 N, and the strength loss reached 57.80%.
The research on the effects of molding temperature and molding time during the processing of UHMWPE fibers on fiber structure, surface morphology, and mechanical properties has clarified that the temperature and time during the composite processing have a significant impact on the performance of UHMWPE fibers. Suitable composite processing techniques can promote the application of UHMWPE fibers in various fields. The research findings provide necessary references for determining the composite processing technology of UHMWPE fiber materials.


Study on silk fabrics modified with reactive deep eutectic solvents and their dyeing properties 

XIE Jialing, YANG Sheng, FU Feiya, MA Tingfang, XU Zhaomei, LIU Xiangdong

2024, 32(3):  61-72. 

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Dyeing wastewater pollution is one of the important bottlenecks that restrict the sustainable development of the textile industry. Promoting the development of green solvents and achieving efficient modification are an important pathway for the green transformation of the textile industry. Deep eutectic solvents (DES) have low cost, easy preparation, and good biodegradability, making them promising in extraction and catalysis fields, but there is limited attention to the functional application of DES components. In this study, a low eutectic solvent composed of betaine (Bet) and lactic acid (LA) was used as both the reaction solvent and reactant for the modification of silk fabrics. The effects of traditional heating and microwave heating on the reaction efficiency were compared, and the morphology, structure, and dyeing properties of the obtained samples were analyzed. The results showed that microwave heating significantly improved the reaction efficiency, and the modified fabric obtained in 15 seconds exhibited characteristic peaks of C=O and CH3-N+ groups at 1,733 cm-1 and 1,475 cm-1 in the ATR-FTIR spectrum, as well as a new -CONH- peak at 1,650 cm-1. The XPS wide scan spectrum showed a shift and increased area of the C-N peak, as well as the appearance of the CH3-N+ group signal peak, confirming the successful introduction of betaine from the DES into the silk fabric. The modified fabric showed a slight increase in surface roughness, an increase in crystallinity from 71.57% to 78.57%, and a 2.8% improvement in tensile strength. The surface charge of the fabric increased from -26.35 mV to 5.57 mV, resulting in a 58-fold increase in dye uptake on the fabric, with the dyeing K/S value increasing from 0.075 to 4.071. The optimal dyeing process was determined as follows: Na2CO3 concentration of 2 g/L, dyeing temperature of 50 ℃, and dyeing time of 80 minutes. Furthermore, the study demonstrated that the breathability of the modified fabric remained relatively unchanged, while the moisture absorption increased from 268.37% to 335.12%. This study provides a new scientific basis for the modification of silk fabrics and the multifunctional application of low eutectic solvent components.

Bio-enzyme-assisted extraction of orange peel pigments and their cashmere dyeing properties

CHEN Qiulin, ZHU Qiuyu, ZHOU Fangyu, WANG Yuhong, CHEN Chao, YU Zhicheng

2024, 32(3):  73-80. 

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With the development of science and technology, people's quality of life is constantly improving and at the same time they have higher requirements for quality of life. Natural dyestuffs are non-toxic, non-hazardous and can be used in a wide range of applications, including textile dyeing, textile functional finishing and batteries. Orange peel, a major by-product of the fruit, is non-toxic and non-hazardous and has certain health benefits, but its role is not fully exploited and is mostly regarded as waste. Therefore, it is imperative that waste is recycled to its full potential in line with today's green trends.
To broaden the chromatographic and waste recycling purposes, this article uses orange peel as a raw material for extraction and dyeing of wool to improve its dyeing performance as a research object. The maximum absorption wavelength of orange peel extracts was determined by using a UV spectrophotometer to determine the maximum absorption wavelength and the colour family of the dyestuff; the maximum absorption wavelength of the extracts was then used to adjust the concentration of ethanol in the extraction solvent system and to investigate the effect of the enzyme dosage and the enzyme at different temperatures and times on the extraction efficiency; finally, the colour fastness of the cashmere was improved by combining metal mordant, tannin-metal composite mordant, and color fixing treatment of dye-fixing agents.
Experiments show that the optimum extraction effect of orange peel pigments is achieved and the enzyme on cellulase and pectinase can give full play to their role when the ethanol concentration is 50%, the material-liquid ratio is 1:20, the cellulase and pectinase quality ratio is 2:1, the temperature is 80 ℃, and the extraction time is 100 min. At the same time, the light fastness of cashmere under the optimal dyeing process can be improved by half grade by using alum dyeing, and the sun fastness of cashmere can be improved to grade 3 or above by using tannin-metal composite mordant and fixing agent M.


Preparation and performance of photoluminescence anti-counterfeiting fabric labeling based on (PEA)2PbBr4 single crystal

HU Xiaotinga, XU Lei, LI Nan

2024, 32(3):  81-90. 

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The development and application of fabric security labels with identification function ensure the safety of textiles. Ultraviolet photoluminescent textiles refer to the fact that the fabric emits a specific color of light after being excited from a colorless state when it is irradiated by ultraviolet light, so as to achieve the purpose of anti-counterfeiting. Previous studies have shown that the (PEA)2PbBr4 single crystal with ultraviolet photoluminescence performance has excellent characteristics such as high color purity and high crystallinity, and can be prepared by simple process, mild conditions and mass production.
To prepare efficient and lightweight fluorescent anti-counterfeiting fabric labels, phenethylammonium bromide was prepared by β-phenethylamine and hydrobromic acid, and it was dissolved with lead bromide at a molar ratio of 2:1 to N, N-dimethylformamide to configure a precursor solution. By adjusting the solvent ratio of o-dichlorobenzene to N, N-dimethylformamide, two-dimensional layered (PEA)2PbBr4 single crystals of different sizes and densities were grown by anti-solvent gas-assisted crystallization. The single crystal with the best distribution and luminescence performance was selected, and the single crystal solution under this condition was spin-coated and encapsulated in a 0.1 mm thick PVC film to prepare a single crystal/PVC composite film, and a fabric label with photoluminescence anti-counterfeiting function was obtained by hot rolling with the fabric. The crystallization properties, distribution, morphological structure and luminescence characteristics of single crystals and composite films and fabric labels were studied by fluorescence microscopy, laser particle size analyzer, XRD, SEM, ultraviolet-visible photometer and transient fluorescence spectrometer, and their application effects in textiles were discussed through washable wearable and wear-resistant tests.
The results show that (PEA)2PbBr4 single crystals have a series of periodically repeated, uniformly spaced and well-defined strong diffraction peaks belonging to the two-dimensional layered perovskite structure, with excellent crystallinity and high preference orientation. And the morphology is regular, the edges are sharp, and the elements forming single crystals in the energy dispersive spectrum are evenly distributed; single crystals with a size of 5-10 μm are about 200 nm thick; the absorption and emission peaks are located at 394 nm and 412 nm, respectively. The larger the solvent ratio of o-dichlorobenzene to N, N-dimethylformamide, the smaller the single crystal size is; when the single crystal size is about 5 μm, its distribution state, crystallinity and luminescence performance are the best. The absorption peaks and emission peaks of the single crystal/PVC composite film are located at 391 nm and 414 nm, respectively, and the spectra shows that the single crystal inside the PVC film still has high quality and high color purity. The composite film used as the fabric security label uses ultra-small amounts of single crystals to emit a strong and uniform blue-violet light under the excitation of 365 nm ultraviolet light, realizing effective anti-counterfeiting function. It is tested and applied to fabric security labels to meet washable and wear-resistant standards.


Research on the urine leakage frequency monitoring system based on intelligent flexible fabric sensors

ZHOU Jinli, WANG Zheng, ZHOU Zhiting, LI Yunfei, XIONG Fan, LI Hongping

2024, 32(3):  91-101. 

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Urinary incontinence (UI) refers to a condition in which urine cannot be controlled and leaks out on its own when abdominal pressure increases during exercise, sneezing, coughing, laughing, etc. According to statistics, approximately 200 million people worldwide suffer from urinary incontinence. The proportion of female patients is significantly higher than that of male patients, and the prevalence gradually increases with age. In China, the incidence of urinary incontinence in adult women is about 30.9%, that is, one in every three women suffers from this disease. Urinary incontinence is usually long-lasting, difficult to diagnose, non-fatal, and difficult to treat. Therefore, compared with normal people, the quality of life and sleep quality of patients with urinary incontinence are significantly lower, and their depression is more severe, which seriously affects their daily life.
The treatment of patients with urinary incontinence is a difficult medical problem, and currently, patients with urinary incontinence have low medical seeking rates. Most patients' lack of knowledge about urinary incontinence is an important factor affecting their intention to seek medical treatment. UI is judged based on the International Advisory Committee on Urinary Incontinence Questionnaire (ICI-Q-SF), which includes four questions, namely, to assess the frequency of urinary leakage, the amount of urine leakage, the impact of urinary incontinence, and the cause of urinary incontinence. Tables can be used to investigate the incidence of urinary incontinence and the extent to which it affects patients. Hospitals use a urine pad test to evaluate urinary incontinence. In clinical practice, a one-hour urine pad test is generally used to determine urine leakage. That is, the patient is allowed to drink pure water for 15 minutes and then perform 30 minutes of appropriate exercise such as walking and climbing stairs, and the test lasts for 15 minutes by repeating standing and sitting ≥10 times, coughing ≥10 times, running in place for one minute, bending down five times, and finally washing hands for one minute to end the test. The test detection process is cumbersome, involves long waiting time, low repeatability, and even has a certain degree of subjectivity.
With the development of science and technology, the technological innovation of smart wearable textiles has been widely used in monitoring urinary incontinence. This is an innovation in the medical field that applies advanced technology. Its core is to integrate flexible sensors and electronic components into textiles and enable it to monitor urinary frequency and other related data in patients with urinary incontinence. Smart wearable textiles include sensors embedded in textiles that can detect the flow of urine, changes in resistance, or other related parameters. Through data transmission and processing, the occurrence of urinary incontinence events can be captured and recorded, including the frequency and amount of urine leakage. Some systems can also be integrated with mobile apps or cloud services so that data can be accessed and monitored at any time by healthcare professionals or patients themselves. Because these devices incorporate technologies such as flexible sensors, wireless communication, and data processing, they are portable, miniaturized, intelligent, and capable of real-time monitoring. Compared with traditional monitoring methods, this technology is more private and does not involve embarrassing testing processes. Therefore, smart flexible wearable textiles have begun to be used to monitor the condition of urinary incontinence patients, bringing convenience and accuracy to urinary incontinence monitoring, which is expected to improve patients' quality of life and promote the development of medical care.
The frequency of urinary leakage is an important indicator for evaluating the condition of urinary incontinence patients. The higher the frequency of urinary leakage, the more serious the condition. In order to accurately diagnose the frequency of urinary leakage in each urinary incontinence patient and further address this problem, we proposed a method using intelligent flexible fabric sensors, silver-plated yarn and non-woven fabric as sensing materials for functional electrodes and designs. We designed the sensing structure and sensing pattern, and used hot melt technology to embed these functional electrodes into disposable diapers specially used for urinary incontinence patients to create functional smart diapers. At the same time, we improved and optimized the main control chip nRF5283, and wrote a data median filtering program to preprocess the urinary frequency signal. Based on the change in resistance value in the functional electrode that reflects the frequency of urine leakage, we optimally selected the conduction spacing and pattern of the sensor and conducted performance tests. Experimental results show that each electrode module of pattern C with a conduction spacing of 0.6 cm can be detected more than 15 times, with an average accuracy of 86.2% and a sensitivity of 73.5 kΩ/0.1 mL, achieving the expected goals. This smart flexible fabric sensor can be used to assess the basic health status of urinary incontinence patients and provides a simple method to prepare smart flexible fabric sensors to monitor urinary frequency.


A simulation mathematical model for the heat dissipation of thermal protective clothing 

WANG Yiping, DING Ying, YU Zhicai, WANG Zhen, XU Lihui

2024, 32(3):  102-109. 

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In recent years, with the rapid development of the manufacturing industry, a large number of new technologies and new equipment have been used, and the labor group of high-temperature operation has also been increasingly large. The high temperature working environment is harsh, and the high ambient temperature will cause the skin on the human surface to be damaged by high temperature contact. Thermal protective clothing can greatly protect workers in high temperature environments. Heat dissipation is an important factor to be considered in the design and operation of thermal protective clothing. At present, the evaluation of heat dissipation mainly relies on a large number of experimental tests, which cannot be repeated and costs a lot of money. Establishing the mathematical model of heat dissipation of thermal protective clothing in high temperature environment can be used to design thermal protective clothing with better heat dissipation effect in a short research and development period, but the heat dissipation model of the relationship among the external environment, fabric layer and skin has not been established so far.
This paper studied the heat dissipation of protective clothing under high temperature and hot conditions. Based on Fourier heat conduction law, heat conduction equation and other theories, the whole mathematical model of heat conduction and heat dissipation from the environment through the protective clothing fabric layer to the dummy skin was constructed by using the micro-element method, and the temperature change diagram of each layer and interface of the thermal protective clothing with time was drawn during the whole simulated heat dissipation process. The results of model simulation and prediction were verified by actual measurement. At the room temperature of 60℃, the simulation of the outermost layer of protective clothing, that is, the left boundary, reached stability at 59.52 ℃, the second layer of protective clothing reached stability at 59.11 ℃, the third layer of protective clothing reached stability at 58.2 ℃, the fourth layer of protective clothing reached stability at 53.72 ℃, and the skin layer reached stability at 43.71 ℃. It can be concluded that with the increase of the thickness of protective clothing, the skin temperature will gradually decrease, and the air layer has an obvious cooling and heat dissipation effect. In the verification experiment, the temperature sensor DS18B20 was used at 60℃ for a thermostatic dummy with the same fabric condition and the same body temperature, and the digital signal showed that the skin temperature of the dummy was 43.99 ℃. Compared with the predicted temperature of 43.71 ℃ under the same conditions, the error was less than 0.5 ℃. When the experimental room temperature was adjusted to 75 ℃, the measured skin temperature of the dummy was finally stable at 48.08 ℃, and the overall temperature change trend was almost consistent with the model, so it was concluded that the established model was highly accurate. The reason for the error is that as long as only the drying model is considered and the wet transfer is not considered, the experiment dummy does not evaporate sweat, so the error is smaller and it is more reasonable to use the drying model.
Based on the results of simulation and experimental verification in this paper, it can be concluded that the established heat dissipation model of thermal protective clothing in high temperature environment has high accuracy, which has referencial significance for reasonable evaluation of the heat dissipation protection effect of thermal protective clothing.


Classification of breast shape and evaluation of bra fit based on spatial vector angle

GU Mingyuea, LIU Xiuhuia, XU Shiqia, PAN Yitinga, ZOU Fengyuana, b, c

2024, 32(3):  110-117. 

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The curved shape of female breasts is complex, and the breast shape of women wearing the same cup bra is also different. The existing size parameters such as linearity, circumference, volume and two-dimensional angle are difficult to effectively represent the three-dimensional shape of the breast, thus affecting the fitness of the bra. The purpose of this paper is to propose a subdivision method based on spatial vector angle representation of breast shape, so as to realize the classification and discrimination of three-dimensional breast shape of young women.
In this paper, three-dimensional point cloud data of 209 young women aged 18-25 were scanned and obtained. With the help of auxiliary points, lines and planes, six breast spatial vector angles were constructed as clustering indicators. The optimal clustering number was determined by elbow method and K-means was used for clustering. Learning vector quantization (LVQ) was used to construct a breast shape discrimination model, and the fitness of the subdivided bra was evaluated through digital clothing pressure and real fitting experiments.
In this paper, the breast type 70B, which occupies the largest proportion under the Chinese standard in the sample, was taken as the research object, and the spatial vector angle was used to represent the stereoscopic shape of the breast. Six spatial vector angles that could represent the stereoscopic shape of the breast were constructed, including four local spatial vector angle parameters that represented the upper left, upper right, lower left and lower right shape of the breast divided by BP point as the center. Two global spatial vector angle parameters were used to characterize breast stiffness and sagging. By using k-means clustering, the breast shape can be divided into moderate and introverted (50.00%), flat and low-cut (16.07%), and full and expanded (33.93%) one. Digital clothing pressure and real fitting experiments show that the fit of the subdivided bra is better than the benchmark bra. The LVQ neural network model was established to identify breast shape of young women with an accuracy of 93.33%.
In this paper, the three-dimensional shape of female breasts is represented by the spatial vector angle to realize the morphological subdivision and discrimination of female breasts. The constructed model of breast shape LVQ neural network can provide theoretical reference for bra customization. Digital clothing pressure and real fitting experiments show that the subdivided bra is better than the benchmark bra, which provides a reference for different types of breast bra fitting structure design.


Virtual fitting research based on the diffusion model and ControlNet network

GUO Yuxuan, SUN Lin

2024, 32(3):  118-128. 

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With the development and iteration of image generation models, models  like Stable Diffusion based on the  diffusion model have become the mainstream image generation models, providing a new way for clothing design and rendering. The diffusion model usually uses the text prompt word as the image generation condition and the generated picture has randomness. It is difficult to accurately generate the virtual fitting effect of a specific style. The application of ControlNet neural networks makes the generation of images more controllable. The trained Controlnet network can use the image information such as Canny edge map, depth map, and Openpose map as additional generation conditions of the diffusion model to control the human body posture, edge features, front and rear position relationship of the generated image. This paper briefly describes the development history and principle of the diffusion model, and explores its feasibility for generating virtual fitting renderings. To achieve the purpose of visualizing the clothing style diagram as the garment effect and realize the rapid generation of virtual fitting effect, This paper attempts to use ControlNet neural network to control the diffusion model to generate virtual fitting effect of virtual models wearing specified clothing styles.
  The virtual fitting of three dresses was taken as an example for experimentation. Firstly, the images of real clothing models with expected posture were sampled, and the key human body images and pose depth maps of real models were extracted as the generation conditions. Then, the Controlnet control Stable Diffusion model was used to generate a virtual clothing model image that matches the intended pose. Subsequently, the edge image of the virtual model was generated by the Canny algorithm, and the edge image was edited and modified in combination with the dress style diagram. The edge image of the virtual model wearing the specified style dress was drawn, and it was used as the edge generation condition. The virtual fitting effect of the dress conforming to the specific style, color and fabric was generated by the text prompt-controlled diffusion model, and the style of the dress with the virtual fitting effect was changed in real time by modifying the edge image, so as to provide an intuitive reference for fashion designers to modify and adjust designs. In addition, the detailed feature control experiment of the virtual model was also carried out during the experiment; experiment on the control effect of text prompt word weight on clothing fabric and color was carried out. Finally, the generation effect of the proposed method was compared and evaluated with the effect of 3D modeling virtual fitting clothing.
The results show that the diffusion model combined with the ControlNet network can control the pose characteristics of the virtual model, allowing the virtual fitting effect of the expected clothing style to be generated by editing the Canny edge image control. Compared with 3D modeling, the virtual fitting effect is more expressive, the operation is more intuitive and faster, and it is more suitable for providing designers with intuitive clothing display in the style design stage, assisting designers to adjust the design style, color, fabric and process, and improving the efficiency of clothing design.


Research progress of virtual clothing under the background of metaverse

GU Shanqia, b, HU Lianxina, b, WANG Zefenga, b, CHEN Xua, LOU Jiongnana, b, LIU Qiloga, b, ZHANG Gegea, b

2024, 32(3):  129-140. 

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Virtual clothing is a virtual reality application based on computer technology. Its background and purpose are to provide people with a new fashion experience. With the rapid development of virtual reality technology, virtual clothing has begun to show more and more application scenarios, such as virtual fitting and metaverse. Virtual clothing can not only provide consumers with a better shopping experience, but also reduce the cost of the brand and reduce environmental pollution. Therefore, there are great potential and development space for the research and application of virtual clothing .
The research of virtual clothing began in the 1980s. Early studies mainly focused on physical simulation technology of cloth. For example, in 1986, WEIL proposed a method based on cloth synthesis. Subsequently, TERZOPOULOS et al. extended it to elastic deformation and inelastic deformation, such as the elastic deformation model proposed in 1987 and the inelastic deformation model concerning viscoelasticity, plasticity and fracture proposed in 1988. Researchers are committed to improving the realism and fidelity of virtual clothing, and effectively reducing the amount of calculation and simulation complexity. 
With the continuous advancement of technology, the research of virtual clothing has gradually shifted to application. Aiming at the bottleneck problem of virtual fitting, many studies have focused on optimizing the fitting process. For example, KOO et al. proposed the problem of semi-drag skirt cutting angle in 2009, while WANG and LIU developed a virtual fitting platform based on CLO3D in 2020.
In the context of the metaverse, the research of virtual fashion is increasingly focused on the integration of cutting-edge technologies such as artificial intelligence and blockchain, like artificial intelligence-based textile feature modeling, and probability distribution model of virtual try-on experience. In addition, with the development of blockchain technology, the application of non-homogeneous tokens (NFT) in the field of virtual fashion has also begun to receive attention. For the display of virtual fashion, virtual try-on systems based on technologies such as augmented reality (AR) and virtual reality (VR) in existing research have broad application prospects.
Virtual clothing is always committed to providing a new fashion experience. In the past few decades, researchers have made a lot of progress from physical simulation to the application of metaverse. In the future, virtual clothing will continue to grow and develop, and will be applied in more markets and application scenarios. At the same time, the emergence of various emerging technologies will also bring new opportunities and challenges to the development of virtual clothing. Therefore, researchers need to continue to pay attention to the development trends and needs of the virtual clothing field, and propose more innovative solutions to promote the rapid development of virtual clothing technology.