Investigation on Molecular Structures of Electron-Beam-Irradiated Low-Density Polyethylene by Rheology Measurements

While the effect of high-energy irradiation on low-density polyethylene (LDPE) has been extensively investigated, the molecular structure changes under different irradiation conditions are less well understood. In this work, we have made systematic investigations on the molecular structure of electron beam irradiated LDPE under various irradiation conditions. The microstructures have been mainly characterized by rheological measurements using small amplitude oscillatory shear (SAOS) and analyzed by a weighted relaxation spectrum and a van Gurp–Palmen plot. It was found that the linear viscoelasticity of LDPE exhibited a strong dependence on the radiation atmosphere due to oxidative degradation in the presence of oxygen. An improved/destroyed network structure could be acquired when LDPE was irradiated in a nitrogen/oxygen environment, as compared with that in air. Differences became more significant when LDPE was irradiated at higher temperature (80 °C) due to the facilitated diffusion of free radicals wi...