Effect of organoclay and compatibilizers on microstructure, rheological and mechanical properties of dynamically vulcanized EPDM/PP elastomers

Dynamically vulcanized thermoplastic elastomers (TPVs)/oraganoclay nanocomposites were successfully fabricated from polypropylene with ethylene propylene diene monomer (EPDM). Two types of compatibilizers, ethylene propylene diene monomer grafted maleic anhydride and polypropylene grafted maleic anhydride, were incorporated to improve the dispersion of commercial organoclay (15A). In the present work, the role of interfacially located organoclay on the coalescence in TPV nanocomposites was investigated systematically with contact angle measurements and theoretical models to ensure their localization at the polymer/polymer interface, which is experimentally verified by scanning electron microscopy and atomic forced microscopy. Using a rheological method it was shown that coalescence of the dispersed phase is slowed down when organoclay is present at the interface. With the increase of organoclay contents, the size of EPDM droplet decreased due to the in situ formed brush-like interface around the compatibilized EPDM droplet. It was shown that the mechanical properties were improved due to good dispersion of organoclay in the compatibilized TPV nanocomposites.