In situ reactive compatibilization and reinforcement of peroxide dynamically vulcanized polypropylene/ethylene-propylene-diene monomer tpv by zinc dimethacrylate

This work demonstrates an approach of in situ reactive compatibilization between polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) by using ZDMA as a compatibilizer and, simultaneously, as a very strong reinforcing agent. With 7phr ZDMA in the PP/EPDM (30/70, w/w) thermoplastic vulcanizate (TPV), the tensile strength and elongation at break were increased from 5.3 MPa and 222% up to 11.2 MPa and 396%, respectively. Increasing the PP concentration further improved mechanical properties of the TPVs with ZDMA. This tremendous reinforcing as well as the compatibilization effect of the ZDMA was understood by polymerization of ZDMA and ZDMA reacting with EPDM and PP during peroxide induced dynamic vulcanization. A peculiar nano-composite structure that the crosslinked rubber particles were bonded by a transition zone which containing numerous of nano-particles with dimensions of about 20-30 nm was observed from transmission electron microscopy (TEM). Scanning electron microscopy (SEM) results showed that increase of PP/EPDM ratio reduced the size of crosslinked EPDM particles. Moreover, we found that the ZDMA reinforced EPDM particles resulted in a higher tan peak temperature for EPDM phase and built filler-filler-like networking in the PP melt. POLYM. COMPOS. 34:1357-1366, 2013. (c) 2013 Society of Plastics Engineers