Abstract:

In this paper， three commercial polypropylene （PP） products with the medium?flowing and impact-resistant characteristics were selected to analyze the content of ethylene and the content， molecular weight and morphology of rubber phase. The thermal and mechanical properties of these three products were also investigated. The results indicated that the ethylene content determined the rubber phase content， and the rubber phase content and molecular weight of the rubber phase played an important role in the stiffness-toughness balance performance of the PP products. A good toughening effect could be achieved only when the ethylene content was higher than 50 wt% in the rubber phase. According to this conclusion， the structure and copolymer content of impact-resistant PP can be optimized to achieve an optimal balance between rigidity and toughness.

Key words: medium flow, impact polypropylene, rubber phase structure