Comonomer distribution effect on the ageing behavior of ethylene-propylene random copolymers

Ethylene-propylene random copolymers (EP-RACOs) of high flowability resp. melt flow rate (MFR) are important polymers for advanced thin-wall packaging articles. As impact strength retention over time is an important success factor here, two series of EP-RACOs based on different types of Ziegler-Natta catalysts (ZNC) were studied in ageing at ambient temperature. Through a combination of comonomer distribution and selective nucleation, the γ-phase content and consequently the long-term stability of injection molded parts can be improved significantly.