Partially Dynamically Vulcanized Thermoplastic Elastomer Based on Natural Rubber-Polypropylene-Clay Nanocomposites

Thermoplastic vulcanizate (TPV) nanocomposites based on 60/40 (%wt) natural rubber (NR)/polypropylene (PP) blends were prepared by dynamic vulcanization. Sodium montmorillonite (Na-MMT) was use as a filler to improve TPV properties. The addition effect of Na-MMT on the TPV properties was examined. The results indicated that the blend exhibited a co-continuous phase structure. The presence of clay in the NR phase decreased crosslinking level of NR, but improved mixing of NR and PP during dynamic vulcanization. The addition of clay marginally enhanced the 100% modulus and tensile strength, but decreased elongation at break due to more homogeneous blend morphology. The optimal level of tensile strength improvement was obtained when loading of clay was 5 phr. The permanent set of the blends did not changed significantly with the clay dispersion. The storage modulus and resistance to oil and heat improved with incorporation of clay, proportional to clay loading.