1) strength of yarn in sewing thread
The fiber fracture strength increases, although the slipping length increases, the number of slipping fibers in the yarn section increases relatively, but the total strength of the broken part of the fiber will be greatly improved. Therefore, the higher the breaking strength of fibers, the higher the strength of yarns.
2) the frictional properties of yarn in sewing thread
When the friction coefficient u increases, the slip resistance between the fibers is large, the slipping length Lc decreases, the ratio of the slipping fiber decreases, and the yarn strength increases. Increasing the crimp number of fibers can increase the sliding resistance between fibers, which is not only conducive to the smooth progress of spinning, but also to the improvement of Yu Chengsha strength.