Effects of the blend ratio and crosslinking systems on the curing behavior, morphology, and mechanical properties of styrene–butadiene rubber/poly(ethylene-co-vinyl acetate) blends



Blends of styrene–butadiene rubber (SBR) and poly(ethylene-co-vinyl acetate) (EVA) with different ratios were prepared with a two-roll mixing mill and were vulcanized by three different crosslinking systems, namely, sulfur (S), dicumyl peroxide, and a mixture consisting of S and peroxide (mixed). The vulcanization behavior of the blends was analyzed from the rheographs. The mechanical properties, including stress–strain behavior, tensile strength, elongation at break, modulus, hardness, and abrasion resistance, of the blends were examined. The morphology of the prepared blends was studied with scanning electron microscopy with special reference to the effects of the blend ratio and crosslinking systems. A relatively cocontinuous morphology was observed for the 20/80 SBR/EVA composition. The mechanical properties increased with increasing EVA content up to 60–80%, for all of the vulcanizing modes. The tensile fracture surfaces were analyzed under a scanning electron microscope to understand the failure mechanism. Various theoretical models were applied to explain the properties of the blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 827–837, 2004