SLOW CRACK-GROWTH IN POLYETHYLENE - A NOVEL PREDICTIVE MODEL-BASED ONTHE CREEP OF CRAZE FIBRILS

An extensive series of homopolymers and copolymers has been investigat ed to test earlier indications of a possible link between resistance t o slow crack growth and creep of macroscopic oriented samples. It was found that in the majority of cases a good correlation exists between a single creep parameter and slow crack growth. The existence of such a correlation supports the model presented, in which crack growth is p rimarily controlled by the creep of fibrils spanning the craze zone. T he limit of improvement achievable by increasing molecular weight and the greater effectiveness of short-chain branching to improve fibril c reep have been highlighted. (C) 1994 John Wiley and Sons, Inc.