Table of Content

10 July 2024, Volume 32 Issue 7

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Influence of structural parameters on the performance of braided core-sheath triboelectric sensing yarns

GAO Yue , TAO Qingyun , MENG Fenye , YAN Xiong , HU Jiyong

2024, 32(7):  1-12. 

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Respiration is an uninterrupted and important biomechanical behavior that occurs throughout human′s whole life, and is used as a diagnostic signal for a variety of diseases. With the development of wearable flexible sensors, new ideas are provided for the design of respiratory sensors that real-timely, non-invasively and comfortably monitor human respiratory motion. Compared to other types of sensors, triboelectric sensors have been widely adopted for self-powered respiration monitoring owing to their compelling features, such as decent biocompatibility, wearing comfort, low-cost, and high sensitivity to respiration activities in the aspect of low frequency and slight amplitude motion. Among them, yarn-based triboelectric sensors have attracted attention for their comfort and high flexible integration. However, most of the researches on triboelectric sensing yarns for respiration monitoring focus on structural design. How structural parameters affect their performance remains unclear, hindering the industrial production of triboelectric sensing yarns.
In order to meet the needs of daily long-term monitoring of human respiratory motion and large-scale production, a braided core-sheath triboelectric sensing yarn based on a single-electrode working mode was designed. According to its structure and process characteristics, the effects of the stretchable electrode twist and the braiding parameters of the outer braided layer on the performance of the sensing yarn are discussed. Firstly, six stretchable electrodes with different twists were prepared with the same structural parameters of the outer braided layer, and their tensile and electrical properties were tested. On this basis, the stretchable electrodes with the best performance were selected, and the sensing yarns with different braiding parameters were prepared by changing the number of braided yarns and the braiding angle. In order to satisfy the application in daily garments, the first step is to select the braiding parameters with stable structure and to meet the requirements of tensile properties. Then, investigating the effects of braiding parameters on the electrical property of the sensing yarns. In this paper, the effects of stretchable electrode yarn twist and braided layer parameters on the dielectric layer thickness, surface morphology and compression deformation of the braided core-sheath triboelectric sensing yarn are investigated. Moreover, correlation analysis was used to investigate the relationship between these factors and the electrical property of the sensing yarns. The results show that the elastic elongation of the sensing yarn gradually increases with the increase of stretchable electrode yarn twist, and the elastic recovery rate and short-circuit current decrease. For the braiding parameters, the elastic recovery rate of the sensing yarn is mainly affected by the braiding angle, and the electrical property by the multiple effects of the braiding parameters. The maximum short-circuit current is obtained when the number of braided yarns is 10 and the braiding angle is 45˚. In the contact-separation frequency range of 0.15~1.2 Hz, the short-circuit current of this sensing yarn increases with frequency and has good output stability during 2000 cycles of motion. The sensing yarn can respond to different respiratory states when it is worn on the human abdomen. The results show that the braided sensing yarn based on the knitting/twisting process can be used for human respiratory status monitoring, which is of great significance for the production of triboelectric respiratory monitoring sensors.
Generally, the effects of braided core-sheath yarn structural parameters on the performance of triboelectric sensing yarns are determined, and the application potential of this sensing yarns for human respiratory status monitoring is tested. The research results provide guide for the subsequent production of triboelectric respiratory monitoring sensors.


Influence of vortices within the rotor's condensation slot on yarn quality based on Ω vortex identification method 

QIAN Miao, YANG Zhenbin, SHI Huanqiang, XIANG Zhong, Zhang Jianxin

2024, 32(7):  13-21. 

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Rotor spinning utilizes airflow as a driving force to achieve operations such as fiber transport and aggregation. The characteristics of the airflow field during the spinning process directly impact the spinning results. The article employs simulation software to model the movement of airflow within the rotor, investigating the correlation between the airflow field inside the rotor and the quality of yarn. This research provides valuable guidance for enhancing the structure of rotor spinning.
         In order to more accurately identify and analyze the vortex patterns within the complex and dynamic flow field inside the rotor in air-jet spinning, a vortex identification method that combines the Ω vortex determination criteria with image processing is proposed. The method involves analyzing the flow field within the rotor obtained through simulation using FLUENT. This analysis provides insights into the number and area of vortices on the plane of the condensation slot and further explores
        According to the simulation analysis, the results indicate that the distribution of static pressure values on the rotor's surface is uneven, leading to varying pressures at different locations across the rotor. Within the fiber delivery channel, the static pressure gradually increases to -7 kPa as the channel diameter decreases. Notably, there is a substantial static pressure gradient change on the wall surface near the channel outlet.  Inside the rotor, the fastest airflow velocity is observed at the location of the condensation slot, forming a circular ring of high velocity. The middle section of the rotor experiences slower airflow velocities, extending to the entrance of the yarn guide tube. On the side of the rotor closer to the fiber delivery channel, there is a long strip-like region with higher airflow velocity.  Observing the vortices identified using the Ω method, it is evident that this approach has a superior ability to capture vortices within the plane. It not only captures the larger vortices displayed in streamline plots but also effectively captures smaller vortices within the condensation slot that may not be discernible in streamline plots. Additionally, vortices within the condensation slot are primarily concentrated at the outlet of the fiber delivery channel and at the intersection of airflow behind it. This phenomenon arises due to the relatively complex airflow movement in these two positions. As the rotational speed increases, the area of smaller vortices inside the rotor's condensation slot also increases.  The vortex area increases from 14.1 mm² to 18.5 mm², leading to an increase in yarn coefficient of variation from 15.33 to 15.99, resulting in decreased overall yarn uniformity. The increase in rotational speed also leads to an increase in the number of coarse and fine nodes on the yarn, resulting in a decline in yarn quality. When the rotor diameter is increased, the area of vortices within the rotor's condensation slot decreases. The vortex area reduces from 15.6 mm² to 10.7 mm², representing a reduction of 31.4%. The coefficient of variation decreases from 15.53 to 15.02, enhancing yarn uniformity and improving the spinning results. 
        The Ω vortex identification method exhibits excellent capturing capability for vortices on the plane of the condensation slot. After undergoing image processing, this method allows for the quantitative analysis of the vortex patterns within the internal airflow field of the spinning cup. Vortices within the condensation slot are mainly concentrated at the outlet of the fiber delivery channel and at the intersection of airflow behind it. Lowering the spinning cup's rotational speed and increasing its diameter can enhance the quality of the yarn


Research on visual recognition method of spinning frame under complex environment

YAN Xiaopeng, YANG Yaning

2024, 32(7):  22-32. 

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In the textile manufacturing industry, the process of yarn dropping in spinning machine is critical as it directly impacts yarn quality, production output, and factory operations. Traditional automatic fine yarn dropping machines, while capable of performing operations automatically, often suffer from imprecise of operations, resulting in missed of empty tube insertion or tube yarn extraction during the yarn dropping process. The current coping approach is to assign dedicated personnel to track, inspect, and address the issue, which increases labor costs and restricts the level of automation and intelligence in the workshop.
This paper aims to address the issues of yarn tube extraction missing and empty tube insertion missing in traditional automatic fine yarn dropping machines by introducing machine vision technology to accurately identify tube yarns and yarn spindles, thereby reducing the probability of missed extractions and insertions in subsequent operations. However, traditional image processing techniques face challenges in complex fine yarn workshop environments, such as complex target backgrounds, lighting variations, obstructions, and shooting angles. In addition, it is necessary to set parameters and thresholds based on experience during the identification process of yarn spindles and tube yarns, which increases the difficulty of recognition. Therefore, accurate identification of tube yarns and yarn spindles is crucial for automatic yarn dropping machines based on machine vision technology. To solve the interference problem of images gathered by visual sensors in workshop environments, this paper proposes a basic image processing method. By adjusting the contrast between the objects and the background, the characteristics of yarn spindles and tube yarns can be highlighted. This method also performs initial and secondary identification in the objects identification process to  obtain the object areas more accurately. In order to further improve the identification accuracy of yarn spindles and tube yarns, the basic image processing method is improved in image preprocessing phase and object identification phase respectively. In the preprocessing phase, image multiplication fusion is used to obtain high-contrast images to reduce the difficulty of subsequent image segmentation. For the interference introduced by the support rod of the spinning machine in the original image, find the nearest two horizontal contour bodies in the object region, and eliminate the smaller contour body in the object selection decision, until the remaining identification quantity is consistent with the set number.
The experimental results demonstrate that the identification accuracy of yarn spindles and tube yarns in different scenarios exceeded 98.40%, realizing the accurate identification of spindles and tube yarn in complex background. In future work, machine learning methods can be introduced to solve the problem that individual parameter setting cannot adapt to special scenes such as strong light and reflection, and further improve the recognition accuracy of spindles and pipe yarn.


Research progress on detection of yarn evenness

GENG Cong, , WANG Chengquna, XU Weiqiang,

2024, 32(7):  33-41. 

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The evenness of yarn is an important parameter for evaluating the quality and texture of yarn. Therefore, the accurate and rapid measurement of yarn evenness occupies a very important position in the entire textile industry. Currently, there are three main techniques used for measuring yarn evenness: capacitive detection, optical detection, and image processing detection. This article describes the basic characteristics of yarn, introduces the evaluation indicators for measuring yarn evenness, and provides a comprehensive overview of the design principles and basic structures of these three different techniques for measuring yarn evenness. Additionally, the article summarizes the research directions of each technique, presents and analyzes the research achievements of these three techniques in different areas, and summarizes their advantages, limitations, and applicable scenarios. Furthermore, considering the current development of yarn evenness measurement techniques, the article explores the future prospects and directions for the development of these three techniques.

    The progress of the textile industry is driving the upgrade and iteration of yarn evenness detection technology. Traditional methods for evenness detection are no longer able to meet the high-precision and high-speed requirements in industrial applications. Among the three main technologies, capacitive detection is the most widely used and applied in mainstream evenness detection instruments. Capacitive detection primarily utilizes air capacitance as a sensing component to obtain the evenness index of the yarn relatively easily. However, this method can introduce errors due to variations in moisture content and blending ratio of the yarn. With the advancement of high-precision optical sensors, optical detection has gained wider application. Optical detection involves projecting a light beam onto the surface of the yarn and using optical sensors to collect corresponding data for analysis, thereby obtaining the evenness of the yarn. This method is susceptible to errors caused by factors such as hairiness and tension. On the other hand, the method based on digital image processing utilizes computers and high-resolution image sensors to perform detection using machine vision. It can provide relatively accurate measurements of yarn evenness and detect yarn defects that may not be easily identified by the previous two methods. However, challenges such as slow detection speed and high system architecture costs currently limit its ability to accurately measure the evenness of high-speed moving yarn.

   The textile industry plays a crucial role in the national economy. As a pillar industry supporting economic and social development, it not only serves as the foundation industry for meeting people's living needs and improving their quality of life but also represents an advantageous industry for international cooperation and integration. In this context, the rapid and accurate assessment of yarn evenness has significant implications for the healthy development of the textile industry. This article analyzes three widely used techniques for measuring yarn evenness: capacitive detection, optical detection, and image processing detection. It summarizes their respective technical characteristics and makes comparisons among them. Each technique has its unique advantages and limitations. Future research should focus on further optimizing these techniques, starting from practical needs, to improve detection speed, precision, accuracy, and stability. It should also address the upcoming technical challenges to achieve more accurate, efficient, and automated measurement of yarn evenness. In addition, it is worth considering the integration of different techniques to form a diversified system for measuring yarn evenness, catering to the needs of different stages in textile production. For example, by leveraging industrial Internet of Things (IoT) technology, an open digital infrastructure can be designed to collect the maximum value from data gathered throughout the production process through machine networking and integration of information flow from the workshop to the cloud. Ultimately, the development and application of these technologies will contribute to improving the quality and efficiency of textile production, driving the overall development of the textile sector.


Melt spinning of polyvinyl chloride (PVC) fibers and their structure and properties

FAN Yangrui, QIAN Jianhua, YU Deyou, GUO Yuhai, DAI Hongxiang, LI Chengcai

2024, 32(7):  42-47. 

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Polyvinyl chloride is a non-toxic, odorless, and widely used thermoplastic material. It has advantages such as good flame retardancy, acid and alkali resistance, low price, good physical properties, and electrical insulation. It is currently one of the most widely used plastics. However, due to its poor stability to light and heat, it can decompose and produce hydrogen chloride when exposed to sunlight above 100 ℃ or for a long time, causing discoloration and rapid decline in physical and mechanical properties. When applying, it is necessary to add plasticizers, heat stabilizers, and other additives to improve the stability of PVC materials to light and heat. The traditional methods for PVC spinning and forming are wet spinning and dry spinning, but both methods require PVC resin to swell in acetone. However, acetone itself is toxic, and solvent recovery is harmful to the environment. The melt spinning method lags behind other technologies due to the poor heat resistance of PVC and its thermal decomposition and carbonization at high temperatures.
This article used heat stabilizers and plasticizers to modify PVC resin to make it resistant to high temperatures and enable smooth melt spinning. The melt spinning process of PVC fibers was studied. The melt flow index instrument was used to test the melting temperature of PVC granules to preliminarily determine the optimal spinning temperature. The effects of different spinning temperatures and drafting ratios on the structure and properties of PVC fibers were studied. And research on the breaking strength, elongation at break, crystallinity, surface and cross-sectional morphology, as well as acid and alkali corrosion resistance and flame retardancy of the fibers were conducted. Through comparative experiments, it is found that the optimal comprehensive mechanical properties of PVC fibers are obtained when the screw temperature is 160 ℃ and the spinneret temperature is 190 ℃. When the drawing ratio is 4, the breaking strength and orientation of PVC fibers are the highest. The best spinning parameters obtained from the experiment are as follows: the spinneret is 1 cm away from the water bath, the screw temperature is 160 ℃, the spinneret temperature is 190 ℃, the hot water bath temperature is 60 ℃, the metering pump pressure is 2 MPa, and the drafting ratio is 4. Under such conditions, the PVC fibers prepared have the best performance, and their breaking strength, breaking elongation, and Linear density are 1.16 cN/dtex, 32.1%, and 12 tex, respectively; PVC fibers have excellent mechanical properties, good flame retardancy, and excellent resistance to acid and alkali corrosion. They have minimal loss of quality and strength in acid and alkali solutions, especially in acidic solutions. 
The use of melt spinning technology to prepare PVC fibers has the advantages of simple process and low price. And the PVC fibers obtained through melt spinning have excellent properties and can be used to prepare corrosion-resistant and flame-retardant fabrics.


Preparation and biological properties of coaxial electrostatically spun chitosan/polyethylene oxide-sericin fibers

ZHU Lingqi, LIU Tao, XU Guoping, QIU Qiaohua, AWOKE ANTENEH TILAHUN, ZHOU Jiabao, WANG Yanmin

2024, 32(7):  48-57. 

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At present, bone defects caused by trauma, infection, bone tumors, etc. are very common, suffering from major diseases that cause serious bone damage often exceeds the bone's self-healing ability, but the bone tissue's own repair and regeneration ability does not reach the perfect repair, in this case, we need to find a better repair material to treat these bone injury diseases. As natural polymers, chitosan (CS) and silk fibroin (SF) are widely available and easy to obtain, and they will only degrade to water and carbon dioxide when implanted into the human body, so they have good biocompatibility and degradability. In this paper, CSPEO-SF nanofibers were prepared by coaxial electrostatic spinning technology. The shell layer of CS and PEO can ensure the fibers to have good hydrophilic properties, antimicrobial properties, and in vitro bioactivity, and the SF in the core layer serves as a core template to ensure the fibers to have certain mechanical strength, and then glutaraldehyde (GA) was used to transform some of the amino groups in the fibers into aldimine groups to improve the water resistance of the fiber membrane. Tests such as XRD and FTIR were carried out on the fibers before and after cross-linking, and it was found that the aldehyde-imide groups were successfully produced after cross-linking, and it was concluded from the SEM images that the fiber diameters increased after cross-linking, and the fracture strength increased, but the tensile strain decreased. Different nanofibers were prepared by varying the mass ratio of CS, PEO and SF, and it was observed from the SEM plots that the fiber diameter increased with the increase in the mass proportion of PEO and SF. After that the mechanical properties, porosity and swelling properties were tested, the increase of both CS and SF ratio decreases the flexibility, swelling properties and porosity of the fibers, but increases the mechanical properties of the fibers, and all the fibers were able to reach a porosity of more than 80%, and a swelling rate of up to 675%. Finally, comparing the results of the above tests, the more balanced C7P3S10 samples were selected to compare with the SF fibers for the subsequent antimicrobial performance and in vitro bioactivity tests. Antimicrobial experiments are reflected by the dilution coating plate method, firstly, the fibers are mixed with the appropriate amount of bacterial solution for 8 h, and then the cultured bacterial solution is coated onto agar medium for 24 h, and the number of colonies on the medium is observed and recorded, and compared with the blank control group, the rate of bacterial inhibition is calculated, and it is found that from the results of the experiment that although the antimicrobial performance of CSPEO-SF fibers after the cross-linking modification treatment is decreased, but it is still stronger than SF fiber. The in vitro bioactivity experiment was conducted by immersing the fibers in simulated body fluid (SBF) at a ratio of 1.5 mg/mL for a period of time to observe the generation of hydroxyapatite (HA), which revealed that the Ca/P ratio of HA on the surface of CSPEO-SF fibers was closer to that of human bone, and that the in vitro bioactivity of CSPEO-SF fibers was better than that of SF fibers. Through the above experiments, it can be concluded that CSPEO-SF fibers can have a wide range of applications in biomedical applications.

Preparation of CS/SA-doped PVA composite fibers based on microfluidic spinning technology and their drug release properties

JIANG Xueni, CAI Weiting, LIN Hong, ZHANG Desuo

2024, 32(7):  58-65. 

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In recent years, the field of medicine has witnessed significant advancements, leading to an increased demand for drug slow release materials. As a result, drug slow release materials have emerged as a prominent area of research in the biomedical field. This is primarily due to their distinct advantages, including enhanced drug utilization and excellent biocompatibility. Fibrous drug sustained-release materials prepared using microfluidic spinning technology, offer a safe and stable menas of loading drug molecules. Fibers, serving as drug release carriers, possess several advantages including a large surface area and excellent biocompatibility. Therefore, this paper aims to prepared composite drug-carrying fibers with drug slow-release properties were using coaxial microfluidic spinning technology. The fibers are composed of natural polymer carriers, namely chitosan (CS) and sodium alginate (SA), which possess excellent biocompatibility. Additionally, a polyvinyl alcohol (PVA) solution is mixed with different ratios of polyvinyl alcohol (PVA) solution to serve as the spinning solution. The present study aims to investigate the drug release effect of two composite drug-carrying fibers, namely PVA/CS/AS (PCA) and PVA/SA/AS (PSA), using ampicillin sodium (AS) as a drug model. Additionally, the study aims to analyze the influence of the two types of natural polymer materials and their contents on the morphology and structure of the drug-carrying fibers, as well as their mechanical properties and drug release properties.
  The finding indicate that both PCA and PSA drug-carrying fibers exhibit consistent formability and possess a favorable morphological structure. The drug was effectively preserved during the fiber molding process, preventing the crystallization of drug molecules, which is essential for maintaining a drug efficacy and facilitating drug release. With the augmentation of polyvinyl alcohol (PVA) content, there was a gradual enhancement in, the fracture strength and elongation at break of both PCA and PSA composite fibers. Moreover, the fracture strength of PCA composite fibers wass found to be higher than that of PSA composite fibers, whereas the fracture elongation of PSA composite fibers was significantly greater than that of PCA composite fibers. In addition, both types of fibers exhibited a favorable slow-release effect on pharmaceutical substances, with the rate of cumulative drug release increasing proportionally to the PVA content present in the spinning solution. Among the various types of fibers studied, PCA composite fibers exhibited a rapid drug release profile, with a significant amount of drug being released within a short period of time. Specifically, and when the mass ratio of PVA to CS was 5:1, the cumulative release rate of the drug from PCA composite fibers rearch 60% within 180 minutes. On the other hand, PSA composite fibers demonstrated a sustained drug release over an extended period of time, with a release duration of 58 hours. When the mass ratio of PVA to SA was 64:1, the cumulative release rate of drug from PSA composite fibers reached 94.1%. Compared to PCA composite fibers, the release time and cumulative release rate of drugs are improved, which is suitable for the treatment of chronic diseases and achieves the purpose of long-term effective drug release. The disparity in drug release performance between the two fibers can be attributed to variations in the performance and structure of the drug carrier material itself. Bying utilizing the two drug-carrying composite fibers and various components within the spinning liquid, it is possible to develop a system for slow drug release that can be designed to meet the needs of different drug delivery patients. This demonstrates the wide-ranging potential for the application of slow and controlled drug release.


Appearance simulation of section dyed yarn knitted fabrics based on b-spline coil model

Fuxing dong , Li yu , Xuefeng gu, Lianying zhao

2024, 32(7):  66-73. 

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Section Dyed Yarn, characterized by unique colors and textures, is widely utilized in the field of fashion textiles. Fabrics made from section dyed yarn are highly favored for their vibrant and diverse color appearances. To address the randomness and energy consumption issues during the production and sampling process of section dyed yarn, as well as the low fidelity in simulating fabric authenticity, this paper proposes a simulation method for section dyed yarn knitted fabrics based on the B-spline coil model.
Initially, in order to extract the main surface texture information of the yarn from the original images, yarn images are acquired using a scanner. Image processing techniques, including threshold segmentation using the Otsu algorithm and morphological opening and closing operations, are then applied for the preprocessing of the collected section dyed yarn images.
Subsequently, to map the extracted main yarn texture into coil shapes, data points are extracted along the course of the knitting loops from the real fabric image. Using the least squares fitting technique, B-spline coil curves are fitted and constructed. During the mapping process based on these curves, appropriate pixel offsets are needed according to the B-spline normals to achieve the curved effect. As the collected yarn texture is linear, resulting in blank pixels at curved sections of the knitted loop after mapping, nearest-neighbor interpolation is employed to fill these gaps and ensure the integrity of the mapped coils.
Ultimately, a method of arranging coil images horizontally and vertically is used to simulate the fabric. Viewing fabric weaving as a process in which coil images increase from left to right and from bottom to top, starting from the lower-left corner, coils are arranged accordingly. To establish the interlocking relationship between coils, a Boolean matrix is utilized to eliminate pixel overlap positions in intertwined coils based on the simulated fabric organization. Under certain lighting conditions, different positions of the coils exhibit varying brightness effects on the fabric surface. To enhance the realism of the fabric, this study adjusts the grayscale ratios of the coils to create brightness variations. Linear interpolation is employed to achieve a smooth transition between shaded and unshaded areas for a natural gradient effect. Moreover, the proposed simulation method, after obtaining yarn texture and color parameters, enables the rapid display of serialized products by changing yarn colors and arrangement cycles.
The research results demonstrate that the simulated fabric is generally consistent with real fabric in terms of appearance and color arrangement. The simulation method, based on the real section dyed yarn texture, allows for the rapid change of yarn colors and the display of the fabric's color, texture, and pattern effects. This method effectively enhances the authenticity of simulating section dyed yarn fabrics, reducing the difficulty and cost of sample production for businesses.


The influence of air flow on the properties of cotton tight fabrics

Zhang caiqian, Meng Shaoni, Li Junrong

2024, 32(7):  74-79. 

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The cotton tight fabrics are used in outdoor windproof windbreakers, down anti-drill fabrics, high-end shirts, and other fields, and these fabrics will inevitably be affected by airflow in use. 8 pieces of cotton plain tight fabrics and 1 polyester staple fiber fabric were used to study and master the characteristics of the deformation degree and fabric parameters of cotton tight fabric under the impact of airflow. Place each fabric on an LD-1600X3 silent, oil-free air compressor, and set 0.1 MPa air pressure for continuous airflow impact 5 min, 10 min, and 30 min respectively. The air permeability was tested by the fabric breathability meter. The XD-1 microscope was used to observe and compare the image changes of the fabric after the airflow impact. The pictures taken by the microscope were imported into Autocad software to test and analyze the diameter of the warp and weft yarn in the fabric and the pore width between the adjacent warp and weft yarn lines. The center distance and pore area of adjacent warp and weft yarns were tested 10 times for each data and averaged. 
By analyzing the microscope images of each fabric, it can be seen that there are more hairs on the surface of the original cotton fabric, the yarn outline is not clear, and the holes between the yarns are closed by hairs. As 5 minutes, the diameter and shape of the yarns change little, the pores between the yarns become clear, and more through holes are formed, indicating that the effect of airflow in a short time reduces hair in the fabric pores and improves the permeability of the fabric. After 10 minutes of airflow impact, the warp and weft yarns appear straighter, the bending state of warp and weft interweaving is reduced, the pores change from irregular shape to square, and the hair in the pores is reduced. After 30 minutes of air impact, the warp and weft yarn lines become thinner, the hair in the pores between yarns is reduced, and the porosity is further improved. 
The quantitative analysis shows that the diameter of the warp and weft of cotton tight fabric decreases with the increase of air impact time, the distance between adjacent yarns increases, and the porosity of the fabric increases. There is a correlation between the porosity of cotton tight fabric and its air permeability. However, due to the influence of the hair of the fabric and the loose structure of the yarn on the airflow, the correlation between the porosity and the air permeability of the fabric is not high, and the porosity size of the fabric is not the main factor affecting the air permeability of the cotton tight fabric. Under the same conditions, the fabric with a uniform structure has better air permeability and stronger air shock resistance. The tightness and thickness of cotton tight fabric affect its stability after airflow impact, and the tightness and thickness of cotton fabric have little change in air permeability.


Effects of Differences in Cotton Fabric Structures on Moisture-absorption and Quick-drying Performance 

Luo Hao, Feng Hao, WU Wenyunjie

2024, 32(7):  80-85. 

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Moisture-absorbing and quick-drying textiles take into account excellent hygroscopicity and fast conduction and wicking performance, rapidly absorbing and expelling sweat from the body's surface, keeping the skin dry and comfortable. Existing research on the factors influencing the moisture-wicking and quick-drying properties of cotton fabrics mainly consider porosity, density and tightness, etc., or comparative research on plain weave, twill weave and satin weave, etc., There are fewer studies on the effect of fabric structure differences on moisture-absorption and quick-drying performance, and the related research has a broad application prospect in the fields of clothing and home textiles.
To explore the influence of the average length of floating warp threads on fabric's moisture-absorption and quick-drying properties, The control variable method was used to maintain a consistent average floating line in the warp direction, while the average floating line in the weft direction was increased in turn. Four fabrics of plain weave, 2 / 1 weft heavy flat, 3 / 1 weft heavy flat and 4 / 1 weft heavy flat were designed and woven, The experimental results show that 4/1 weft heavy flat fabrics are much thicker than the other three fabrics, which is because the warp yarns within the long floating threads of the weft yarns of the 4/1 weft heavy flat fabrics are closely arranged, and the inter-yarn forces make the warp yarns easy to be stacked together. The moisture absorption performance of the fabric increases first and then decreases with the increase of the average float line of the weft yarn. The reason for the decrease is that the thickness of the fabric increases with the increase of the float line. The moisture diffuses along the warp and weft directions and accumulates along the thickness direction at the same time, and the equivalent diameter of the voids in the 4 / 1 weft heavy flat is greatly dispersed, which weakens the wicking performance of the fabric in this direction. Through the wicking height test, it is found that the difference of the warp wicking height of the four fabrics is less than 5 %, and the difference of the weft wicking height is more than 20 %, that is, the increase of the weft float line mainly affects the weft's core absorption performance, with less impact on the warp's core absorption performance. The fast-drying performance test of the four fabrics showed that 3 / 1 weft heavy flat > 2 / 1 weft heavy flat > 4 / 1 weft heavy flat > plain. With the increase of the average floating line in the weft direction, the fast-drying performance of the fabrics increased first and then decreased. The greater rate of water evaporation in the weft heavy flat fabric is due to the structure of the floating line in the weft direction is loose and there are a large number of voids, which makes the liquid water transfer easier in the fabric. Liquid water evaporates more easily because of the larger wetting area on the fabric surface. Although the average floating length of the 4 / 1 weft plain is the longest, the liquid water accumulates in the thickness direction and the spreading area decreases, so that its fast drying performance does not increase but decreases compared with the 3 / 1 weft plain fabric.
The moisture-absorption and quick-drying performance of the fabric is related to the length of the floating line of the fabric, it can be improved by increasing the average floating length. However, too long floating line will increase the thickness of the fabric, which will reduce the moisture absorption and quick drying of the fabric. While increasing the floating line to improve the moisture-absorption and quick-drying performance of the fabric, it is also necessary to consider controlling the thickness of the fabric.


The impact of steric groups on the dyeing properties of indophenine dyes

WEI Yanying , JIANG Hua

2024, 32(7):  86-96. 

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Polyester fabrics are usually dyed with disperse dyes. However, the affinity between disperse dyes and polyester are weak interactions, such as van der Waals force and hydrogen bond. During the finishing process, thermal migration of dyed polyester fabrics may occur if high temperature is used. In such case, the dye molecule will migrate from the inside to the surface of the fiber, resulting in unlevelness and poor color fastness. The use of dyes with a planar molecular structure can enhance the force between the dye and the fiber and effectively alleviate the heat migration phenomenon. Indophenine is composed of quinoidal bithiophene structure that end-capped with two indole-2-one groups. The molecular π-conjugation system of indophenine presents planar characteristic. In addition, indophenine is usually synthesized by indophenine reaction, which is easy to operate and has high product yield. Previously, our group discussed the dyeing properties of hydrophobic indophenine dyes on polyester fibers. The results showed that the dye-fiber interaction force between indophenine dye molecules and polyester fiber is very strong. However, due to the existence of strong intermolecular force which hinders the formation of single-molecule-state dyes, the dye exhaustion of indophenine dyes on polyester fabrics is not high enough.
In this paper, three blue dyes D1―D3 were synthesized through indophenine reaction. The structures of dyes D1―D3 were characterized by mass and infrared spectra. The lattice parameters and HOMO/LUMO energy level information of dyes D1―D3 were calculated. The thermal stability, acid and alkali stability and absorption characteristics in DMF of dyes were tested and analyzed. Polyester fabrics were dyed with dyes D1―D3 by high-temperature and high-pressure dyeing method. The dyeing process was optimized, and the dye uptakes, color depths, color fastnesses and migration values of the dyed fabrics were tested. The results showed that the optimized dyeing condition should be at pH of 5~6, dyeing temperature of 130 ℃ and dyeing bath ratio of 1∶50. Under the optimum dyeing condition, the dye uptakes are 84.8% (D1), 97.5% (D2) and 85.2% (D3) and the K/S values of dyed polyester fabrics are 17.1 (D1), 8.1 (D2) and 16.3 (D3). The fabrics dyed with dyes D1―D3 have excellent thermal migration resistance, and the migration values are less than 10%, which are obviously better than that of the conventional disperse dye C.I. disperse blue 56. In addition, the color fastnesses to soaping, rubbing and sublimation of polyester fabrics dyed with dyes D1―D3 are excellent, all of which are above 4~5. The introduction of methoxy or methyl groups on the thiophene unit can effectively tune the intermolecular forces between the dye molecules, promote the formation of single-molecule-state dyes in the dye bath, and thus improve the dyeing performance of the indophenine dyes.


Preparation and properties of reactive disperse dyes for nylon printing

DING Guoqing, JIANG Hua

2024, 32(7):  97-107. 

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Nylon, also known as aliphatic polyamide fiber, exhibits excellent performance, such as lightweight, elasticity, good thermal stability, and mechanical property. Nylon has been widely used in the manufacturing of sportswear, stockings, conveyor belts, tents, industrial fabrics, and others. Nylon can be dyed by using acid dyes, reactive dyes, or disperse dyes. Nylon fabrics dyed with acid dyes offer vibrant color shades. However, its wet fastness is relatively poor. By employing reactive dyes, the dye molecules can form covalent bonds with nylon fibers by reacting with the amino end groups. Therefore, good color fastness to wet treatment can be achieved. However, reactive dyes usually display limited deep dyeing on nylon. And, the deeper the color, the more noticeable the reduction in color fastness. Dyeing of nylon using disperse dyes provides good levelness and penetration, however, exhibits poor color fastness property due to the low affinity between dyes and fibers. Reactive disperse dyes, which are constructed by attaching reactive groups to hydrophobic chromophores, combine the advantages of disperse dyes and reactive dyes. Currently, the most common approach to design reactive disperse dyes involves combining triazine and azo structures. This design concept is simple, effective, and allows for easy synthesis. However, reported molecular designs often directly combine the triazine structure with the primary amino group on the azo structure, greatly impacting the electronic effect of the azo chromophore and consequently affecting the color of the dye.
This paper aims to design seven reactive disperse dyes, E1―E7, by introducing dichlorotriazine moiety onto the hydroxyethyl group of the azo chromophore, and synthesize the designed dyes by using a two-step method including condensation reaction and coupling reaction. The structures of these dyes were characterized and confirmed by nuclear magnetic resonance spectroscopy, Fourier infrared spectroscopy, and high-resolution mass spectrometry. Nylon fabrics were dyed with reactive disperse dyes using a printing process. The composition for the printing paste was as follows: dye E1―E7 x%, Na2SO4 3%, NaHCO3 2%, urea 8%, sodium alginate 2.2%, and water. The printing process was performed under the condition of drying at 60 ℃ and steaming at 102 ℃.
We tested the properties of the dyed nylon fabrics, such as levelness, color depth, fixation value, color fastness, migration value, and breaking strength. The colors of nylon fabrics dyed with dye E1―E7 showed various colors of yellow, red, purple, and blue, respectively, with a color difference ∆E ranging from 0.16 to 0.28, which indicated good level dyeing performance. Nylon fabrics dyed with E1―E7 exhibited excellent resistance to organic solvent extraction. In comparison, the color of conventional disperse dye Disperse Blue SE-3RT on dyed nylon fabric can be completely stripped off by DMF. As calculated, dye E1 has the highest fixation value, reaching over 90%, while dye E5 has the lowest color fixation value of 74%. The other five dyes exhibit fixation values of above 80%. Due to the covalent bonding between reactive disperse dyes and fiber, the dyed nylon fabric demonstrates a good color fixing property. The nylon fabrics dyed with dyes E1―E7 exhibited color fastnesses to washing, rubbing, and sublimation of grade 4 or above. The dye migration values of dyed nylon fabrics were less than 5%. The breaking strengths of the nylon fabrics dyed with dyes E1―E7 ranges from 416 to 446 N, with a decrease in strength of only 1% to 7.6%, as compared with the original nylon fabric. This indicates that the dyeing of nylon fabric using dyes E1―E7 will not significantly damage the mechanical property.
The above results provide a new approach for the molecular design of azo-type reactive disperse dyes and their application in dyeing of nylon fabrics.


Preparation of hydroxyl silicone oil reinforced reactive polyurethane coatings and their properties

WANG Lin, ZHANG Junfeng, HE Fang, WANG Zhuo, HUANG Zhichao, SUN Fu, QI Dongming,

2024, 32(7):  108-115. 

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Polyurethane, as an emerging organic synthetic polymer material, is known as the "fifth largest plastic" and is widely used in chemical, electronics, textile, medicine, construction, automobile, and many other fields because of its excellent performance. Polyurethane is broadly categorized as solvent-based one, water-based one and solvent-free one. Traditionally produced polyurethane is mostly solvent-based one. Solvent-based polyurethane seriously jeopardizes the physical and mental health of producers because of the addition of organic solvents such as N,N dimethylformamide and acetone to the production process, and the presence of residual organic solvents in the finished product may also be harmful to the physical and mental health of consumers. And water-based polyurethane replaces organic solvents with water, solving the problem of solvent pollution. However, because of the existence of hydrophilic groups, the coating's water resistance decreases, which makes it easier to dissolve abd affects the mechanical properties. Meanwhile, the water evaporation is slow, resulting in a long drying time and heavy energy consumption. Solvent-free polyurethane (reactive polyurethanes) solves the above problems of polyurethane by virtue of the absence of solvent incorporation. Mechanical properties are an important index of coatings, and it is necessary for the article to investigate the effect of hydroxyl silicone oil on the mechanical properties of solvent-free polyurethane coatings.
     Polyurethane coatings with high strength, high-temperature thermal stability, low-temperature resistance, hydrophobicity, and softness were comprehensively designed. Diphenylmethane diisocyanate and 1,3 propylene glycol were used as hard segments, and poly(tetrahydrofuran ether diol), castor oil, and bis-hydroxy-capped polydimethylsiloxane (PDMS) were used as soft segments. The two-component method was used for prepolymerization, followed by mixing, scraping, and reaction molding. A series of solvent-free polyurethane coatings were synthesized by partially replacing castor oil with PDMS, and the effects of PDMS content on the mechanical and thermal properties, low-temperature resistance, hydrophobicity, and feel of the coatings were investigated. The effect of hydroxyl silicone oil on the mechanical properties of polyurethane was investigated in a solvent-free system. The tensile strength and elongation at break of reactive polyurethane (Si-PU) coatings modified by silicone were effectively enhanced, with a maximum increase of 51.9% in tensile strength and 99.3% in elongation at break. With the increase in PDMS mass fraction, the mixing degree of soft and hard segments of Si-PU increased, and the degree of microphase separation weakened. As the mass fraction of PDMS increased, Tmax moved toward high temperature, and the thermal stability of the coating was enhanced; the glass transition temperature (Tg) of the coating gradually decreased, and its low-temperature resistance was significantly improved; at the same time, the hydrophobicity was improved, and the handfeel became softer, thus the serviceability was improved.
    The silicone-modified polyurethane coating prepared by the above method overcomes the shortcomings of solvent-based polyurethane and water-based polyurethane, and at the same time, its breaking strength, elongation at break, high-temperature thermal stability, low-temperature resistance, hydrophobicity, and softness have been improved to a certain extent. As the national requirements for environmental protection in the chemical industry become higher and higher, further research on solvent-free polyurethane technology is expected to be more in-depth and comprehensive in the future, so that it can be more widely used in various industries.


Modular design on clothing to reduce washing frequency

HU Yueying, TANG Ying, JIN Qian

2024, 32(7):  116-125. 

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The production, use, and recycling stages in the lifecycle of clothing significantly impact the environment. According to a lifecycle assessment by the WRAP organization in 2016, the environmental impact of washing behaviours during the use phase of clothing is greater than that of production and recycling. Changing design methods to influence the frequency of clothing washing plays a critical role in extending the lifespan of garments and reducing the environmental impact of the clothing industry. Clothing can be divided into two types of modules: fixed and optional, each with its control properties. A modular design method aimed at reducing the frequency of washing has been proposed to decrease resource consumption and pollution throughout the garment's lifecycle. This not only helps to improve the sustainability of clothing but also offers consumers a variety of choices.

An initial survey was conducted to investigate the daily washing habits of clothing users. The questionnaire consisted of three parts: basic information, research on clothing washing frequency, and audience evaluation. The reliability and validity of the questionnaire were analyzed using SPSS, yielding a Cronbach's alpha coefficient of 0.802 and a KMO value of 0.747, demonstrating the reliability of the data. Cross-analysis results indicated that tight, fitted, and longer styles, as well as light colors such as white, beige, light blue, pink, and black, and the use of cotton and polyester fabrics, lead to a higher frequency of washing. Tops are frequently washed due to easily soiled collars and cuffs, while bottoms are washed due to stains on the hem and crotch areas.

The survey results revealed numerous factors affecting the washing frequency of clothing. This paper focuses on garment style design, excluding color and fabric factors, and summarizes two modular design directions to reduce washing frequency: detachable design and functional modules. Detachable design focuses on the connection methods between modules, utilizing accessories and process modules to achieve partial detachment, thereby avoiding the need to wash the entire garment. Considering convenience, integration, and comfort, connections such as buttons, zippers, and ties were used, and appropriate connection methods for specific parts of the garment were explored. Functional modules change the properties of fixed modules by incorporating designs with specific features, such as breathable hollow structures and adjustable designs, or by adding optional modules with self-cleaning capabilities, to reduce the need for washing. These innovations not only lessen the environmental burden but also enhance the practicality and sustainability of clothing.


Comprehensive evaluation of sports bras' function based on objective weighting method

SHANG Lulu, CHEN Xiaona, SUN Tiantian, LU Yaya, ZHENG Xue

2024, 32(7):  126-134. 

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Single function evaluation on bras does not cater for women's comprehensive requirements for sports bras during exercise. Although comprehensive evaluations on thermal function of bras have been documented, breast movement reduction and dynamic pressure comfort, as two of the most representative functions of sports bras, have not been reported to be included into the comprehensive evaluation on sports bra function. This study aimed to explore a comprehensive evaluation method for sports bra functions. A subjective evaluation experiment was also conducted to verify the validity and feasibility of the results.
Taking function as the starting point, the article established a comprehensive evaluation system for the function of sports bras by considering the shock-proof function, pressure comfort and heat and humidity comfort of sports bras and choosing the four representative indexes of displacement, pressure, air permeability and moisture permeability, respectively. The experimental subjects were five C-cup women, and the experimental samples were seven sports bras. The subjects wore the seven sports bras in turn and ran on the treadmill at 7.5 km/h and 10.0 km/h respectively. The vertical breast displacement and cup pressure during running were collected and calculated, and the air permeability and moisture permeability of two cushions of each bra were tested.  Entropy method and variation coefficient method were employed to calculate the weights of various indicators, subsequently deriving comprehensive evaluation values for the seven samples of sports bras. Finally, the feasibility and effectiveness of the objective weighting method in assessing the functionality of sports bras were validated through subjective evaluation experiments.
Comprehensive evaluation method for sports bra function used in this study could be categorized into six key steps, which were determining representative parameters, collecting parameter data, normalizing collected data, calculating weight coefficient of each parameter, calculating comprehensive evaluation score for each bra sample and ranking bra samples according to comprehensive evaluation scores. The results show that the weights of each index obtained by the two methods are consistent when the speed of movement is 10.0 km/h. Through the test of the data of each index of the seven samples, it is found that the air permeability and moisture permeability of sample clothing 2# are the best, and the displacement is second only to sample clothing 1#; the displacement, pressure and moisture permeability of sample 7# are the worst. According to the comprehensive evaluation of the functional performance of the sports bra, the comprehensive rankings obtained by the entropy method and the coefficient of variation method are consistent with the order of superiority being 2#, 1#, 4#, 3#, 6#, 5#, and 7#. In addition, in the subjective validation experiment, the subjective evaluation results are in agreement with the two objective evaluation ranking results to a large extent. The validity and accuracy of the two comprehensive evaluation methods are demonstrated.
This study provides two new objective weighting methods for synthetical assessment of sports bra function. Both the entropy method and variation coefficient method can obtain comprehensive evaluation scores of sports bra function. The evaluation results of the two objective weighting methods under the two running speed conditions are consistent, and the overall ranking of each sports bra is relatively stable. The results of objective evaluation and subjective evaluation are consistent to a large extent, which verifies the feasibility of the comprehensive evaluation method of sports bra function based on the objective weighting method. This finding confirms the notion that the objective weighting method is a scientific and rational method to evaluate sports bra function synthetically, which effectively avoids the interference of subjective factors and provides a new direction for product evaluation and optimization.