Effect of gamma ray on isothermal crystallization kinetics of syndiotactic polystyrene

Isothermal crystallization kinetics of gamma-irradiated syndiotactic polystyrene (sPS) has been investigated by differential scanning calorimetry. Amorphous sPS samples were irradiated in air with gamma ray at various doses from 0 to 800 kGy, at a rate of 30 kGy/h, and melt-crystallized at different temperatures and times. Kinetics parameters were determined using Avrami’s model with Gaussian functions and a modified Arrhenius equation. Isothermally crystallized sPS irradiated in air with gamma ray exhibited multiple endothermic melting peaks corresponding to various crystalline forms, and the radiation dose had a strong effect on their melting enthalpies, crystallinities, and crystallization kinetic parameters. The amount of the α-crystalline form increased with increasing crystallization time and those of the β- and β′ forms had an opposite trend. Both crystallization half time and crystallization activation energy of the α form in gamma-irradiated sPS increased with increasing radiation dose.