Comparison of Mechanical Properties and Rheological Behavior of Trans-Polyisoprene/Polypropylene and Ethylene Propylene Diene Rubber/Polypropylene Thermoplastic Vulcanizates

The degree of dynamic vulcanization, mechanical properties, rheological behavior, and the ageing-resistant performance of trans 1,4-polyisoprene (TPI)/polypropylene (PP) and ethylene propylene diene rubber (EPDM)/PP thermoplastic vulcanizates with a blend ratio of 60/40 were investigated comparatively. The results showed that TPI had fully dynamically vulcanized when mixed with PP in the Hakke mixer chamber (175 degrees C, 60 rpm) while EPDM had only partly dynamically vulcanized due to its saturated main chain backbone. With increased sulfur content, the torque at the end of the curing curves of the two thermoplastic vulcanizates (TPVs) increased in the curing characteristics measuring process as the degree of crosslinking increased. Comparing the two blends, TPI/PP-TPVs were possessed of a better mobility, a little lower tensile strength and tear strength, a little higher 100% modulus and hardness, and much lower elongation at break. EPDM/PP-TPVs had better ageing-resistant characteristics due to EPDM's saturated main chain backbone.