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High‐Speed Melt Spinning of Syndiotactic‐Polystyrene; Improvement of Spinnability and Fiber Structure Development Via Bicomponent Spinning with Atactic‐Polystyrene

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 in 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.