Design and structure optimization of warp knitted unidirectional moisture conducting fabrics

Objective This research is carried out in order to explore the influence of warp knitting structure and raw material configuration on the wet performance of fabrics. Method This paper took differential capillary effect as the design principle, 5.6 tex (14 f)tex polyester, 8.3 tex (288 f)polyester, 9.7 tex cotton, 4.5 tex spandex as raw materials, and 8 sample fabrics were made on the HKS4EL knitting machine, with manufacturing specifications E28, width 1 066 mm, knitting machine speed is 550 r/min. In terms of structure, four warp structures were designed, GB1 used warp velvet structure and warp flat tissue, and GB2 used warp structure and warp satin tissue to form four structural configurations. Results Water absorption rate shows that the lowest water content of the eight samples was higher than the top for most of the time in 120 s. The timely transfer of the liquid from the inside to the outside of the fabric reflects the better unidirectional conductive ability of the fabric. Moisture time shows that the wetting time at the top of the eight samples was greater than that at the bottom, which shows that the inner layer of the fabric can remain dry for a long time. It can be seen in the water absorption rate at the top of the samples is higher than that at the bottom(Fig. 5). The maximum wetting radius and propagation speed of the top of the fabric are basically greater than those at the bottom of the fabric(Fig. 6, Fig. 7), which reflects the fabric's good single-guide wet ability. In general, the maximum wetting radius and propagation speed of the fabric are affected by the fabric structure, fabric thickness and yarn type and the cumulative one-way transport index reflects how easily liquid wets in a fabric. The highest index of f6 of the eight types of fabrics, the maximum wetting radius and propagation speed of f6 were significantly higher than those in the other samples(Fig. 8). This is due to the relatively loose fabric structure used in the f6, The gap between the yarn is relatively large, and the line density of the two yarn materials used can form a poor capillary effect, it allows the liquid to quickly transmit to the outer layer; the overall water management capability of the fabric is shown in Fig. 9, the results fluctuate between 0.2 and 1.0. The overall water management capacity of f1, f3 and f5 is higher than that of f2, f4 and f8, which indicates that the inner layer is better than the satin structure, and the less the number of the fabric inner layer is beneficial to enhance the wet performance of the single guide. Conclusion Through the comparison and evaluation of 8 samples, it is found that the factors affecting the wet performance are the difference of the inner and outer yarn, the yarn density difference, and the structure and thickness of the fabric. In different raw material configurations, although the sample containing cotton yarn has good wetting time and absorption rate, its low wetting time difference, maximum wetting radius and diffusion speed will affect the comfort of the fabric to the human body, the fabric containing spandex will increase the tightness of its fabric, and the overall water management ability is reduced by about 10% under the same structure. In the configuration of different structures, it can be found that the overall water management performance of the inner layer is better than the inner layer using the satin tissue, which reduces the obstruction of moisture transport, and enhances the conduction of water in the fabric. Among all samples, the outer layer is closed horizontal tissue, and the inner layer is open horizontal tissue, the wet performance of single guide is best. © 2023 China Textile Engineering Society. All rights reserved.