Kinetic effects of selenium on degradation of ethylene-propylene copolymer

The antioxidation protection of elementary selenium added to an ethylene-pr opylene copolymer (EPR) at different concentrations (0.1, 0.2, and 0.5 phr) was studied. Oxygen uptake measurements were isothermally performed at 180 degreesC on polymer samples stabilized with increasing concentrations of S e. Experimental. data have revealed the enhancement in induction periods an d the decrease in oxidation rates for unaged elastomer samples. Stabilized polymer specimens exposed to gamma -radiation have presented the highest ef fects at 0.5 phr of selenium concentration for all irradiation doses (50, 1 00, 150, and 250 kGy). Influence of selenium on the competition between cro sslinking and oxidation occurred in gamma -irradiated ethylene-propylene el astomers discussed on the basis of kinetic treatment on studied thermal deg radation process. (C) 2001 John Wiley & Sons, Inc.