Interrelationships of morphology, thermal and mechanical properties in uncrosslinked and dynamically crosslinked PP/EOC and PP/EPDM blends

Abstract

Thermoplastic vulcanizates (TPVs) based on polypropylene (PP) with ethylene octene copolymer (EOC) and ethylene propylene diene rubber (EPDM) have been developed by coagent assisted dicumyl peroxide crosslinking system. The study was pursued to explore the influence of two dissimilar polyolefin polymers (EOC and EPDM) having different molecular architectures on the state and mode of dispersion of the blend components and their effects with special reference to morphological, thermal and mechanical characteristics. The effects of dynamic crosslinking of the PP/EOC and PP/EPDM have been compared by varying the concentration of crosslinking agent and ratio of blend components. The results suggested that the uncrosslinked and dynamically crosslinked blends of PP/EOC exhibit superior mechanical properties over PP/EPDM blends. From the hystersis experiments it was found that PP/EOC blends also perform better fatigue properties over PP/EPDM based blends. It was demonstrated that, the origin of the improved mechanical properties of EOC based blends is due to the combined effect of the unique molecular architecture with the presence of smaller crystals and better interfacial interaction of EOC phase with PP as supported by the results of thermal and fatigue analyses.