Clathrate (δ) Form Crystal Transitions of Syndiotactic Polystyrene in Atactic Polystyrene Networks

Abstract

Syndiotactic polystyrene (sPS) δ crystals within atactic polystyrene (aPS) and atactic polystyrene networks (aPSNW) were prepared. The polymorphism behaviors of sPS within aPS and aPSNW were studied by in-situ wide-angle X-ray diffraction (WAXD) and differential scanning calorimeter (DSC). The sPS δ crystals transfer into γ and then α form crystals during the gradually heating process. The transition temperature of the δ to γ form crystals decreases with the increase in the aPS and aPSNW content in all samples. By contrast, the transition temperature of γ-to-α form crystals increases with the rising aPSNW content, whereas it is independent of the content of aPS. Meanwhile, the transition temperatures of δ to γ and γ to α in aPSNW are higher than those in linear aPS blends. When the samples were annealed at a temperature above 150 °C, the sPS δ form is not favorable to transform into the β form in aPSNW. The results indicate that polymorphism behaviors of sPS are disturbed within aPS networks.