INTERFACIAL EFFECTS ON THE RHEOLOGICAL BEHAVIOR OF HDPE EPDM CB COMPOSITES

Investigation of the effects of an interfacial modifier on the theological behavior of binary high-density polyethylene (HDPE) composites showed that the interfacial modifier significantly changed the melt state behavior of HDPE/carbon black (CB) composites. This suggests that the interfacial adhesion between the CB surface and the HDPE is significantly improved by the incorporation of the interfacial modifier. Although the dispersion of filler in the matrix was improved, HDPE was also temporarily crosslinked by the CB particles in the melt due to the strong interfacial interaction. For HDPE/ethylene propylene diene rubber (EPDM) composites, incorporation of CB caused limited change of the melt state behavior. Addition of interfacial modifier to the HDPE/EPDM/CB composite also resulted in a change of the melt state behavior compared with the unmodified composite, but the effect was not so pronounced as that in the HDPE/CB composites. The difference is well explained by the different phase structure. A core-shell dispersed phase structure with the filler as a core and rubber as a shell was formed in the modified composite, with the crosslinking effect predominating in the dispersed phase, while a separate filler and rubber dispersed phase predominated in the unmodified composite. The conclusion is further supported by the solid state dynamic mechanical analysis in a previous paper and SEM micrographs in this paper.