Influence of Mold Temperature on the Internal Structure and Creep Variation in the Thickness Direction of sPS Injection Moldings

Abstract

Abstract In this work, an effort was made to study the effect of mold temperature variation on the creep behavior of syndiotatctic polystyrene (sPS) injection moldings. The resulting molecular orientation, crystallinity and molecular packing density in the moldings due to processing were characterized to understand the creep variation in the thickness direction. The moldings were sliced off in definite layers by milling from both the surfaces and the creep behavior was characterized. The results indicated that the development of internal structures and the resulting creep behavior is strongly interdependent with creep strain decreasing as the core of the molding is reached. A higher mold temperature generally freezes-in more crystalline regions and enhances the molecular packing density inside the part that affects the tendency to creep. The frozen-in molecular orientation on the other hand showed only a negligible effect.