Cure and Degradation Kinetics of Sulfur Cured Nanocomposites of EPDM-NBR Rubber Blends

Abstract

Ethylene Propylene Diene Monomer (EPDM) rubber is widely used in nuclear plants due to its resistance to radiation, which is highest among elastomers. However, owing to its poor resistance to aliphatic hydrocarbons, components made of EPDM fail when exposed to environments that have the combined effect of radiation and hydrocarbons. The life of such components can be extended by blending EPDM with a hydrocarbon resistant polymer like nitrile rubber (NBR). By incorporating nanoparticles like nanoclay in the rubber blend, properties like hydrocarbon resistance, radiation resistance and mechanical properties can be improved. In this work, detailed analysis of cure characteristics, cure kinetics and degradation kinetics of EPDM - NBR blend based nanocomposites with nanoclay as filler is presented. Kinetic analysis gives a detailed insight into the mechanisms of the reactions of curing and degradation which affects the characteristics of the final product. The miscibility of EPDM – NBR blends with maleic anhydride as compatibilizer was ascertained by Differential Scanning Calorimetry. The cure and degradation kinetics of the nanocomposites were analysed as a function of nanoclay content. The order of the reaction was found to be one, for cure and degradation reactions. Also, the rate constant of the cure and degradation reactions increased with concentration of nanoclayand then declined with increase in nanoclay content.The observed results were correlated to the morphology of nanocomposites.