Thermal degradation of electron beam crosslinked polyethylene and (ethylene-vinylacetate) blends in hot water

Low-density polyethylene and (ethylene-vinylacetate) blends in pure form were exposed to electron beam radiation at doses between (80-150) kGy, at room temperature, in air. Postirradiation thermal aging was done through immersing the samples in hot water at 95degreesC. Mechanical properties and changes in chemical structure were determined after 1500 h. Accelerated oven aging test was carried out on thin films after immersing them in hot water for 1000 h. Heat aging treatment showed that the blends have a convenient thermal stability compared to polyethylene. Although elongation at break and tensile strength de-creased after heat aging procedure, obviously, this reduction was lower in blended samples than that of pure PE. In all samples, hydroxyl and transvinylene unsaturated end groups were formed during heat aging in hot water. Formation of these groups was less in blends at doses between 80-100 kGy, but was higher at 150 kGy than pure polyethylene. (C) 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2346-2352, 2003.