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Physical blends and thermoplastic vulcanizates (TPVs) based on EPDM and PP were prepared in a batch mixer. Dynamic vulcanization of TPVs using resol/SnCl2 was studied as a function of time. Static and dynamic vulcanization of EPDM in the absence of PP were also studied. Crosslinking of EPDM in the absence of PP is more efficient via static than dynamic vulcanization. For EPDM/PP-based TPVs the extent of crosslinking reaction versus time decreases as the amount of EPDM increases. Degradation of the EPDM network occurs during dynamic vulcanization, due to the combined action of shearing and high temperature, and increases as EPDM becomes more and more the continuous phase.

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EPDM and EPM were modified using different processing conditions and amounts of peroxide. Rheological measurements were performed in other to characterize and follow the reactions that took place during processing (branching/crosslinking and/or degradation). The experimental results evidenced that branching/crosslinking occurs for EPDM and degradation is the main reaction for EPM.

Morphology development during phase inversion is a very complex and not well understood process. EPDM/PP -based TPVs were prepared and characterize by different electronic microscopy techniques. Using a low Mw-EPDM, morphology development during phase inversion was successfully followed by scanning electron microscopy with a back scattered electron detector. IntroductionThermoplastics vulcanizated (TPVs) are produced via dynamic vulcanization, which is a process were the rubber is selectively cross-linked while melt mixing with a thermoplastic. Since the morphology changes from an initial thermoplastic-in-rubber dispersed droplet morphology to fine particles of EPDM dispersed in a PP matrix, during dynamic vulcanization phase inversion must take place [1]. As a result of the morphology obtained, TPVs combine the melt processability of the thermoplastics and the mechanical properties of the thermoset rubbers. Although, TPVs are already