CRYSTALLIZATION OF SYNDIOTACTIC POLYSTYRENE UNDER PRESSURE

Effects of annealing under pressure on the polymorphic behaviour of crystalline syndiotactic polystyrene (sPS) have been investigated using X-ray diffraction and d.s.c. thermal methods. sPS exhibited the normal alpha-crystalline form when annealed at atmospheric pressure, but transforms to the beta-form when annealed at higher pressures. A planar zigzag chain conformation was retained after the pressure-induced alpha to beta-transition and the molecular chains packed more densely in the lateral direction.