Molecular dynamics, microstructures and mechanical properties of segmented polyurethane elastomers under gamma irradiation

Abstract

The influence of gamma irradiation on molecular dynamics, microstructures and mechanical properties of polyurethane (PU) elastomers with polyether (poly(tetramethylene glycol), PTMG) and polyester (poly(butylene adipate), PBA) soft segments has been studied. Dynamical mechanical analysis and broadband dielectric relaxation spectroscopy were used to investigate the molecular dynamics of PU elastomers. Interestingly, the α-relaxation exhibited contrasting tendency with irradiation dose for PTMG-PU and PBA-PU, demonstrating that main chain scission took place for PTMG soft segments, but main chain crosslink for PBA soft segments. The results of small-angle scattering technique indicated that the volume fraction of hard microdomains increase rapidly with irradiation dose. The microstructures of PTMG-PU were more susceptible to gamma irradiation compared with PBA-PU. The deterioration of tensile properties was not only related to irradiation damage of soft segments, but also caused by the destruction of the microstructures of hard microdomains.