SYNDIOTACTIC POLYSTYRENE - CRYSTALLIZATION AND MELTING BEHAVIOR

The results of an investigation into the isothermal crystallization and thermal behaviour of syndiotactic polystyrene (sPS) are reported. The study was carried out using differential scanning calorimetry, optical microscopy and dilatometry. From the melt, sPS crystallizes according to a spherulite morphology. The spherulite growth rate and overall crystallization rate depend on crystallization temperature and sample preparation. During the crystallization process, segregation of impurities and non-crystallizable molecules at the spherulite growth front was observed. The nucleation rate, probably very fast, hindered the determination of crystallization kinetic parameters for some crystallization temperatures. Comparing the melt crystallization process of sPS with that of isotactic polystyrene (iPS) for the same value of undercooling, sPS crystallizes more rapidly than iPS, indicating the influence of the tacticity of the materials on the crystallization process. The equilibrium melting temperature T(m)-degrees was determined and found to be 275-degrees-C.