Fiber Structure Development of Syndiotactic Polystyrene after Necking during the Laser-Heated Drawing Process

Abstract

The tensile strength of syndiotactic polystyrene (sPS) fibers increasedwithincreasingthedrawratio from 4.3 to 4.7 despite saturation of the molecular orientation and crystallinity of the drawn fiber. To analyze the mechanism, fiber structure development was investigated by in situ wide- and small-angle X-ray scattering. By drawing the amorphous sPS fiber, the metastable mesomorphic form appeared 0.07 ms after necking, and most of this form transformed to the α'-form crystal at 1.0 ms. With this transformation, the d-spacing of the equatorial plane increased, while the d-spacing of the (002) plane decreased until 2.0 ms after necking. After the transformation, the long period, orientation factor, and crystallite size along the meridional direction increased until 10 ms, which can be explained by rearrangement of the fiber structure. By increasing the draw ratio, the higher drawing stress and higher fiber temperature should promote rearrangement, which results in the drawn fiber having higher tensile strength.