Morphology development of POE/PP thermoplastic vulcanizates (TPVs) during dynamic vulcanization

Polyolefin elastomer (POE)/polypropylene (PP) thermoplastic vulcanizates (TPVs) is considered to be a better alternative to commercial ethylene-propylene-diene monomer (EPDM)/PP TPVs owing to its better overall performance and low-cost. In this study, we deeply studied the morphology development of POE/PP blends during dynamic vulcanization (DV) and its influencing factors such as the degree of crosslinking, crosslinking rate and shear rate. The results show that POE/PP TPVs exhibits smaller rubber nanoparticles (RNPs) and their agglomerates than that of EPDM/PP TPVs because of the better compatibility between POE and PP. The morphology development during DV of POE/PP TPVs is dominated by the formation and agglomeration of POE RNPs caused by the combined effect of dynamical in-situ crosslinking and the shear-induced break-up of POE phase. Higher degree of crosslinking, higher shear rate and moderate crosslinking rate of POE phase facilitate the rapid formation of smaller RNPs and RNPs agglomerates, and accelerate the occurrence of faster phase inversion. This study provides guidance for the preparation of high performance POE/PP TPVs by controlling the microstructure.