Effect of α-MSt content in α-MSAN copolymer on the miscibility of PVC/α-MSAN blends

Abstract

A series of α-methylstyrene, styrene and acrylonitrile(α-MSAN) copolymers with different α-methylstyrene (α-MSt) content were synthesized by altering α-MSt and St ratios with emulsion copolymerization method. By melt blending these copolymers with PVC resin and di-isooctyl phthalate (DOP), PVC/α-MSAN and PVC/α-MSAN/DOP blends were prepared. The miscibility and morphology of the blends were investigated by dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The miscibility of PVC/α-MSAN blends is substantially improved with the increasing α-MSt content in α-MSAN copolymer containing identical AN content and the blends show homogeneous morphology as the α-MSt content in α-MSAN copolymer is up to 22.5wt%. α-MSAN copolymer containing 37.5wt% α-MSt is fully miscible with PVC throughout the whole composition range. When DOP was introduced into the PVC/α-MSAN blends, a single Tanδ peak over room temperature in DMA detection is found as α-MSt content in α-MSAN copolymer is from 15 to 75 wt%, and morphology result also shows that the PVC and α-MSAN copolymer is miscible under the influence of DOP.