Structure development of cyclopolyolefins and polystyrenes in melt spinning and film stretching process

A study of the structure development and orientation of various cyclopolyolefins and polystyrenes during the melt spinning and film stretching process is presented.;While cyclopolyolefins (CPOs) have a long history, they have become important glassy plastics only recently. Highly stereoregular syndiotactic polystyrene(s-PS) synthesized by metallocene catalyst has been commercialized recently. It is known as a semi-crystalline material and has been found in various crystalline forms.;We investigated crystallization kinetics of s-PS by isothermal and non-isothermal crystallization in a quiescent condition. s-PS was found to have a faster crystallization rate compared to the isotactic polystyrene(i-PS) and a slower crystallization rate compared to isotactic polypropylene. By combining non-isothermal crystallization data and WAXD data, we could construct continuous cooling transformation(CCT) curves to define the crystalline structure during crystallization. We could predict the crystalline structure according to the crystallization rate.;The filaments were produced by a melt spinning process and the birefringence of filaments was determined and correlated with spinline stress. CPOs were found to have positive birefringence, and the level was much lower than that for polycarbonate and than the absolute value for atactic polystyrene(a-PS). In the case of syndiotactic polystyrene (s-PS), a negative birefringence developed at a much higher level than that for a-PS at the same stress level. The s-PS filaments exhibited increasing amounts of crystallinity and orientation with increasing drawdown ratio and spinline stress. This was determined using DSC.;We produced film by cast film extrusion followed by uni- and biaxial stretching. We investigated structure development in the film by DSC and wide angle x-ray diffraction. CPOs were found to be amorphous before and after the film stretching, and s-PS was found to develop a mesomorphic structure at a low level of stretching and a crystalline structure at a high level of stretching.;The mechanical properties of the melt spun filament and stretched films were determined for each material. In the case of CPOs, Young's modulus and tensile strength generally increased for most cyclopolyolefins. The elongation to break was decreased by increasing orientation in the stretching direction for most cyclopolyolefins.;In the case of s-PS and a-PS filaments, it was found that the Young's modulus and tensile strength generally increased by increasing drawdown or stretching ratio. The elongation at break was enhanced for both materials by increased chain orientation.