| Vortex spinning technology is a new spinning method as a development in air-jet spinning technology. The sliver is drawn directly into the nozzle and twisted under the vortex action of the high-speed air stream in the nozzle. The special nozzle and spinning mechanism make it more suitable for spinning pure cotton yarn, which make it better than air-jet spinning technology. MVS (Murata Vortex Spinner) is the representative model of vortex spinning technology, which was made by Murata Company in Japan. Vortex yarns and vortex spinning technology have many advantages like low hairiness, outstanding pilling resistance, high moisture absorption and diffusion, quick drying characteristics and high speed of spinning. But the strength of vortex yarns is lower than that of ring spun yarns and the fabrics made by vortex yarns have a hard hand feeling. Although vortex yarns have many advantages, vortex spinning technology also needs to be improved constantly.In vortex spinning, the tip of the fiber is focused to the center of the yarn by the compressed air so that the center of the yarn is always made straight without twisted. The other tip forms the outer layer that wraps another fiber. The special structure of vortex spun yarns is reflected onto the properties of the yarns and fabrics. In this paper, the surface structure of the vortex spun yarns, the relationship between the surface structure and the torsion property of the yarns and the relationships between the mechanical properties of the fabrics and the torsion property of the yarns were investigated. We may have a deep understanding of the vortex spinning technology, the vortex yarns and the fabrics made by the vortex yarns through these experiments, and the results may be useful to the development of the textile machine and the quality control of the yarns and may promote the application of the vortex yarns. Main research contents and conclusions are as follows:(1) The surface structure of cotton/rayon blended vortex spun yarns was investigated in this part. The surface structure of the vortex yarns spun in different delivery speed was observed in optical microscope and the drawing instrument (Photoshop CS3) was used to measure and calculate the wrapping angle and filling ratio of the fibers on the surface of the yarns. The results show that the wrapping angle and filling ratio of the yarns spun in slower delivery speed are larger. As the rayon fiber content in the cortex yarns increases, the wrapping angel and filling ratio both decrease. Then the vortex yarns after dyed by the dyestuff were observed in the microscope. The results show that the wrapper fibers on the surface of the blended vortex yarns are mostly cotton fibers and the core fibers are mostly rayon fibers.(2) The torsional property of the vortex yarns was studied in this part. The KES-YN1torsion tester was used to measure the torsional property of yarns and the parameters of the torsional property were T (torsional rigidity) and2HT (hysteresis). Four different conditions were chosen to test the torsional property. The results show that the maximum torsional angle has a small influence on T and a large influence on2HT when the condition of tension is same. When the condition of the maximum torsional angle is same, the T and2HT increase as the tension of the yarns increases. Then the relationship between the torsional property and the structure of the yarns was investigated. The results reflect that the T and2HT both increase with the increase of the wrapping angle and the filling ratio, respectively. Then the reasons were analyzed in detail.(3) The mechanical properties of the fabrics made by the vortex spun yams were investigated in this part. The results show that the torsional property of the vortex yarns influences most on the shearing property of the fabrics. The values of G (shearing rigidity) and2HG (hysteresis) both increase with the increase of T and the values of B (bending rigidity) and2HB (hysteresis) both increase as the T increases. The tensile property of the fabrics is related both to the structure of the fabrics and to the torsional property of the yarns. The values of WT decreases with the increase of the rayon fiber content in the yarns. The RT of the fabrics is influenced more by the torsional property of the yarns before the fabrics were dyed. But after the fabrics were dyed, the RT of the fabrics is influenced more by the structure of the fabrics. The reason is that the yarns in the fabrics would have some torsional deformations in the process of shearing test, and the yarns may have tensile, bending and torsional deformations in the process of tensile and bending test because of the loop structure of the knitted fabrics. |
PDF Full Text Request