Internal stresses in cold-drawn and irradiated polyethylene

Abstract

The influence of high-energy radiation on the internal stress level in cold-drawn, high- and low-density polyethylene, with and without subsequent annealing, has been determined using a stress relaxation method described earlier. The internal stress level (σ _i) is found to increase substantially with the radiation dose for doses below 40 Mrad, while the increase at higher doses is only moderate. It is suggested that the initial increase is due to a preferred cross-linking of the amorphous phase or the fold surface of the lamellae. An exception to this behaviour was observed for cold-drawn low-density polyethylene, where the internal stress decreased as the radiation dose was raised.