Reinforcement of EPDM/SmBO₃ and EPDM/ATO composites by three types of POE: Assessment of longer chain content on crystallinity, cure, mechanical and electric properties

In this study, three types of ethylene-olefin copolymer (POE) were applied to reinforce ethylene-propylene-diene rubber (EPDM)/samarium borate (SmBO ₃) and EPDM/Sb-doped SnO₂ (ATO) compounds. Van Gurp plots were used to detect the longer branch content in the POEs. Increased longer branch content would disrupt the crystallization of POE and reduce its crystallinity. Rheological studies show increased amount of longer branches would raise the complex viscosity of POE. The larger number of longer branches would consume more peroxide and lower the maximum toque (M_H) in the cure curve. Moreover, the acidic ATO would retard the cure and reduce the chemical crosslinks, which would facilitate the motion of ethylene chains and enhance the crystallinity of POE in EPDM/filler/POE composites. The interaction of physical and chemical crosslinks would influence the swelling ratio and the mechanical and electrical properties of EPDM composites.