High-speed melt spinning of syndiotactic-polystyrene; Improvement of spinnability and fiber structure development via bicomponent spinning with atactic-polystyrene

摘要

With the aim of obtaining syndiotactic-polystyrene (s-PS) fibers with well developed fiber structure, sheath-core bicomponent fibers consisting of s-PS and atactic-polystyrene (a-PS) were prepared through high-speed melt spinning. The bicomponent spinning provided significant improvement of spinnability in comparison with the single component spinning of both s-PS and a-PS, and the highest take-up velocity of 9 km/min was attained. In the low take-up velocity, region, where crystallization of the s-PS component did not occur in the spinning process, molecular orientation of s-PS components in the bicomponent fibers was suppressed in comparison with that of the single component fibers. The suppression became more significant with a decrease hi the s-PS composition and also by exchanging the position of the two components from sheath/core = a-PS/s-PS to s-PS/a-PS. Consequently, the starting of the orientation-induced crystallization shifted to higher take-up velocities. Once the crystallization started, molecular orientation of the s-PS component increased steeply, with an increase in the take-up velocity. On the other hand, molecular orientation of the a-PS component in the bicomponent fibers was enhanced in comparison with the single component spinning up to the take-up velocity, where the orientation-induced crystallization of the s-PS component started. When the crystallization of s-PS started, however, molecular orientation of the a-PS component was significantly suppressed. Mechanical properties of bicomponent fibers were improved in the high take-up velocity region, mainly because of the development of fiber structure in the s-PS component. Estimated highest tensile modulus of s-PS component in the bicomponent fibers was about 11.5 GPa.