Crystallization of syndiotactic polystyrene under high pressure and cooling rate

This study examined the effect of both pressure and cooling rate on crystallization kinetics of syndiotactic polystyrene (sPS). To that purpose, a homemade apparatus that can solidify polymer samples under cooling rates and pressures comparable to those achieved in common industrial processes, was employed. The morphology of the solidified samples was analyzed by pressure, volume, and temperature (PVT) test, densitometry, infrared (IR) spectroscopy, and X-ray diffraction. The results showed that the overall final crystallinity degree gradually decreases with increasing cooling rate, whereas the kinetics of the α and β forms are influenced in different ways by the pressure. A Kolmogoroff-Avrami-Evans kinetics model based on a modified Hoffman-Lauritzen approach was introduced for the description of the pressure effects. The results showed a good agreement between the experimental data and model prediction in all ranges of conditions investigated.