Essential work of fracture analysis of the tearing of a ductile polymer film

The fracture behaviour of a 0.5 mm thick ethylene–propylene block copolymer, previously evaluated using the essential work of fracture method, has been analyzed again in more detail, using different plots, allowing the determination of the crack initiation displacement and stress. In such plots is evidenced that the specific essential work of fracture, we, corresponds to the energy just up to crack initiation value that can be related with J0. Also, it has been found a novel relationship between the plastic term, βwp and the crack initiation stress, σi.