Life Estimation and Thermal Degradation Kinetics of Ethylene-Propylene-Diene Monomer (EPDM) and Silicone Rubber (SiR) Blend

The major concern of the polymers is their degradation in the presence of thermal, mechanical or oxidative stressors even in the normal operating conditions. Life prediction of polymers e.g. insulations, jackets is vital for the continuous working of power plants. In this novel study, the accelerated aging procedure for the life estimation of EPDM and silicone rubber blend (ESB) in thermo-oxidative environment has been proposed. The procedure used the Arrhenius model and laboratory accelerated aging to predict the life of ESB. 50% elongation at break (EAB) was declared as the end-of-life criterion for this study. Thermal stability of the ESB has been investigated by monitoring infrared spectrum, mass loss curve, activation energy, melting point, density, tensile strength and shore hardness before and after thermal aging. The investigation showed that in addition to a loss in EAB, a considerable decrease in the activation energy, tensile strength and shore hardness has been observed. The life was calculated at three accelerated aging temperatures i.e. 130,140 and 150 °C and then this data was extrapolated to lower temperatures. The estimated life at 100 °C was found to be 282 days. This predictive approach is useful in determining the life of various polymeric materials and to build confidence for the use of certain polymers in the required service conditions.