Investigation of surface properties and elastomeric behaviors of EPDM/EOC/PP thermoplastic vulcanizates with different octene contents

Phase morphology, phase compatibility, and elastomeric properties of the ternary EPDM/EOC/PP TPVs were investigated, to determine the influence of octene comonomer content in the EOC molecules on these properties. Such effects are expected as the comonomer impacts the chemical interactions and the chain flexibility of EOC. Viscosity ratio and interfacial properties of the phases were determined, and later related to the morphological structure and the phase compatibility in the ternary TPVs. Increasing octene comonomer content in the EOC reduced surface and interfacial tensions in the TPVs, thereby improving the work of adhesion and the phase compatibility. The study also confirmed that the morphological structure of the TPVs had core-shell elastomer particles dispersed in a continuous PP matrix. Furthermore, elastomeric behavior of the TPVs with various octene contents in the EOC was also assessed. The results revealed improved stress relaxation with low molecular damping and with low permanent set when EOC with higher octene comonomer content was included. Therefore, in the present study the EOC as third component improved phase compatibility and strengthened elastomeric properties of the TPVs. (C) 2017 Wiley Periodicals, Inc.