Processing of styrene butadiene rubber–carbon black nanocomposites with gradation of crosslink density: Static and dynamic mechanical characterization

The concentrations of sulfur and accelerator were varied in the nanocomposites of carbon black (CB)-filled styrene-butadiene rubber (SBR) matrix to introduce the gradation of the crosslink density. These curatives were varied from 1 to 11 phr (per hundred rubber) along the span of 3-mm thick sheet using the construction-based layering method. The static and dynamic mechanical characterizations of these functionally graded polymeric nanocomposites (FGPNCs) were carried out. With increasing crosslink density along thickness, hardness and modulus increase while the ultimate properties like tensile strength and elongation at break droop down. The dynamic mechanical analysis of FGPNCs exhibits the increment in the storage modulus than the uniformly dispersed polymeric nanocomposites (UDPNCs) employing the same average amount of curatives. The peak position of tan δmax remains at the same temperature while the value mitigates in FGPNCs. In FGPNCs, tan δ peak intimates the broadness in the transition region.