Ethylene vinyl acetate/natural rubber/organoclay nanocomposites: effect of sulphur and peroxide vulcunisation

ABSTRACT: Ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay thermoplastic elastomer nanocomposites were melt compounded in an internal mixer, Haake Rheometer, at 1208C at a rotor speed of 50 rpm. The thermoplastic elastomer nanocomposites were dynamically vulcanized using sulfur and peroxide systems. In this article we demonstrate the effect of different vulcanizing systems on the processing properties, tensile properties, crosslink density, morphology, thermal degradation and swelling behavior of the EVA/SMR L/organoclay nanocomposites vulcanizates. The peroxide system showed better enhancement in tensile properties and resistance towards swelling compared to the sulfur system. However, the thermal stability of sulfur vulcanizates was better than that for peroxide vulcanizates. Results also indicate that the presence of organoclay increases the crosslink density in sulfur vulcanizates, whereas in peroxide system, crosslink density was not influenced by the organoclay loading. The optimum organoclay loading for both vulcanizing systems were achieved at 2 phr loading. Results from scanning electron microscope (SEM) and X-ray diffraction (XRD) studies showed that at 2 phr organoclay loading, nanostructures of individual silicate layers were achieved, whereas, at 8 phr organoclay loading, agglomeration was observed. KEY WORDS: thermoplastic elastomer, nanocomposites, organoclay, dynamic vulcanization, crosslink, tensile properties, thermal properties