Fast fracture of thermoplastics as a micro-scale tensile drawing process

摘要: Abstract Some crystalline thermoplastics which show high resistance to slow tearing are susceptible brittle rapid crack propagation. These polymers may also lose much of their impact fracture with increasing speed. The thermal decohesion model attributes both phenomena micro-scale melting resulting from a plastic work rate within cohesive zone. provides quantitative predictions some conform very well whilst other, quite similar, do not. This difference is here attributed the differing tendency for necking stabilise craze. On this basis, rate-dependence in five polyethylenes, structure and molecular weight, can be characterised using criterion based on bulk true stress vs. strain data.