CRYSTALLIZATION OF SYNDIOTACTIC POLYSTYRENE

The crystallization of syndiotactic polystyrene (sPS) was studied over the temperature range from the glass transition (T-g) to the melting point (T-m). Using transmission electron and optical microscopies, the different lamellar and spherulitic microstructures which were formed over this temperature range were correlated with the measured crystall ization kinetics. The late of crystallization was measured isothermall y using thin samples in a. differential scanning calorimeter. The low temperature transformations were achieved by quenching first to the am orphous state, then reheating. The experimental measurements at both h igh and low temperatures of transformation could be closely fitted to the predicted rate constant. It was found that to estimate the crystal lization parameters most accurately, the data must be fitted simultane ously at high and low temperatures and a relatively high value for the equilibrium melting temperature (561 K) must be used. The nonisotherm al crystallization kinetics have been predicted from the isothermal ex periments using Nakamura's model in a manner similar to earlier work o n other polymers.