Patent ID: 7902300

Claim:
A method of degrading a polypropylene copolymer which comprises extruding said polypropylene copolymer with a cyclic ketone peroxide to form a solid product of said polypropylene copolymer having a melt index greater than 15 g/10 min with an Izod notched impact strength at 23° C. that is at least 50% higher and a flexural modulus that is at least 30 Mpa higher than the Izod notched impact strength at 23° C. and flexural modulus of a corresponding polypropylene copolymer degraded with a linear peroxide under similar conditions, wherein the extrusion is carried out at a temperature of from 160° C. to less than 200° C. and the polypropylene copolymer is a polypropylene heterophasic copolymer containing from 5 to 20 wt % of ethylene.