Temperature dependent large strain cavitation in ultra high molecular weight polyethylene during tensile deformation

The large strain cavitation stemmed from the fragmentation of the highly oriented amorphous network in the quenched ultra high molecular weight polyethylene was investigated as a function of deformation temperature. The critical stress for initiating such cavitation was found to be dependent on the deformation temperature (Td) in a way being constant below Td of 90 degrees C but increased with Td above 90 degrees C. This peculiar deformation temperature dependency of critical stress for the large strain cavitation stress was found to be associated with the activation of the alpha II-relaxation in the deformed samples. The alpha II-relaxation temperature increased with the increase of Td, which was attributed to the increase of the stability of the fibrils formed at large strain. The difference between alpha II-relaxation temperature and deformation temperature showed a one-to-one correspondence to the critical stress of large strain cavitation indicating a stress was required to activate the alpha II- relaxation at a selected Td to initiate failure of the oriented network so that cavitation in the large strain regime.