A simple method for the evaluation of heat resistant property of elastomers

The paper shows a simple method that provides us the induction period, rate of weight increase at an earlier stage of thermal oxidation of elastomer and the rate of weight loss by oxidative degradation from a certain period of aging time. Ethylene-propylene elastomer (EPR) was aged in air at various constant temperatures ranged from 90 °C to 130 °C. The weight of samples was measured periodically at room temperature. The weight increased after a certain period of induction period at the early stage of aging. The activation energy obtained from the reciprocal of the induction period and that of the rate of weight increase was the same. The values were 113 kJ/mol. The weight started to decrease from the maximum point. The activation energy for the tangent of decrease curve was 60.3 kJ/mol. This method was applied to study the effect of pre-irradiation of EPR in air on the heat resistant property of the sample. The relatively low dose of 40 kGy decreased the induction period.