On the strain rate sensitivity of high density polyethylene and polypropylenes

The strain rate sensitivity of thermoplastic materials namely high density polyethylene (HDPE), homopolymer polypropylene, and high isotactic homopolymer polypropylene and concurrent microstructural evolution is investigated. Strain rate sensitivity index followed the sequence, HDPE>homopolymer polypropylene>high isotactic homopolymer polypropylene. The strain rate sensitivity index parameter of the examined polymeric materials is consistent with the micro-mechanisms of deformation and modes of fracture. Deformation processes in HDPE involved fibrillation and craze-tearing, while homopolymer polypropylene and high isotactic polypropylene were predominantly characterized by craze-tearing and brittle modes of fracture.