Studies on Comparison of Electrical Properties of Nanoclay Reinforced EPDM-g-TMEVS/PS and EPDM-g-TMEVS/PMMA Blends

Abstract

A novel graft copolymer of tris(2-methoxyethoxy) vinylsilane grafted ethylene-propylene-diene terpolymer (EPDM-g-TMEVS) has been developed by grafting of tris(2-methoxyethoxy) vinylsilane (TMEVS) onto EPDM using dicumyl peroxide (DCP) as radical initiator in a twin screw extruder. The linear polystyrene and polymethylmethacrylate blends based on EPDM-g-TMEVS have been synthesized with varying weight percentages of polystyrene (PS) and polymethylmethacrylate (PMMA) by melt mixing in a twin-screw extruder. The dynamically vulcanized and nanoclay reinforced blends of EPDM-g-TMEVS/PS and EPDM-g-TMEVS/ PMMA were developed by using DCP and organically modified montmorillonite clay in a twin-screw extruder. The linear, dynamically vulcanized and nanoclay reinforced EPDM-g-TMEVS/PS and EPDM-g-TMEVS/PMMA blends have been characterized by different experimental studies to assess their suitability for cable insulation applications. The effect of incorporation of TMEVS grafted EPDM on electrical properties such as volume resistivity, surface resistivity, arc resistance and dielectric strength of EPDM-g-TMEVS/PS and EPDM-g-TMEVS/ PMMA blends have been studied. The values of volume resistivity, surface resistivity, arc resistance and dielectric strength are increased with increasing percentage concentration of EPDM-g-TMEVS due to the presence of -Si-O-Si-linkages. The blends filled with nanoclay exhibit improved electrical properties due to the presence of inorganic moiety, which in turn enhance the insulation behavior. However, among the hybrid polystyrene and polymethylmethacrylate thermoplastic blends studied in the present investigation, EPDM-g-TMEVS/PS blends possess better insulating behavior than that of EPDM-g-TMEVS/PMMA blends due to thermally stable -Si-O-Si- linkages, hydrophobic and non-polarnature. The XRD studies were also carried out to confirm the formation of nanoclay reinforced blends. From the results, it was ascertained that the clay intercalation occurred in the case of polystyrene blends whereas clay intercalation with some degree of exfoliation occurred in the case of PMMA blends.