DEVELOPMENT OF STRUCTURAL HIERARCHY IN INJECTION MOLDED DYNAMICALLY VULCANIZED PP/EPDM BLENDS

摘要

Injection molded PP /EPDM are composed of optically dark skin layer followed by the core regions of lower nucleation density. The crystalline regions at the skin is highly oriented but disordered due to rapid quenching of the material against the mold wall. In certain blends, the decrease of mold temperature causes the skin to form disordered smectic structure. In general, the level of crystalline orientation increases towards the middle of the shear crystallized dark regions followed by rapid decay of orientation at the inner boundary of the shear crystallized region that is established at the moment flow ceases. It was also shown that the decrease of rubber fraction results in higher crystalline orientation in PP regions.