The Changes of Microstructure and Physical Properties of Isotactic Polypropylene/β Nucleation Agent/Polyolefin Elastomer Induced by Annealing Following Processing

Blends of isotactic polypropylene (iPP)/beta nucleation agent (beta-NA)/polyolefin elastomer (POE) were prepared by injection molding. The microstructure and mechanical properties of these blends before and after being annealed at various temperatures and times were studied It was found that annealing simultaneously increased the tensile strength and impact strength. As known, the degree of orientation decreased from the skin layer to the core layer. The orientation of all layers decreased with the increase of annealing temperature and time. The results showed that annealing gave rise to chain rearrangement in both the crystalline and POE phases which, we suggest, played a crucial role in determining the mechanical properties of the blends.