Impact of carbon black substitution with nanoclay on microstructure and tribological properties of ternary elastomeric composites

Various particulate composites based on epoxidised natural rubber (ENR), carbon black (CB), and nanoclay (NC) were prepared keeping the total filler content constant at 35 phr (parts per 100 g rubber). Tribology and hysteretic (stress–strain) properties of the composites were analyzed. Morphology of these composites were also characterized by small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) to establish the structure–property correlations. SAXS results reveal enhancement in overall interfacial roughness (ds) with the increased substitution of CB by NC. Increased CB–NC interface causes enhancement in ds, leading to reduction in wear resistance of ternary composites. Reduction of wear resistance for NC populated samples is attributed to lower dispersion parameter (D0,1) values of NC in the matrix, realized through image analysis of TEM photomicrographs. Thus, for ternary particulate samples, a definite interrelation among the extent of wear, ds and D0,1 is realized. Frictional force (FT) and its adhesive component (FA) increase when CB is substituted by NC up to 15 phr. When NC fraction exceeds 15 phr, both FT and FA decrease substantially. This is attributed to the lubricity offered by the modified NC at higher NC concentration, which is explained using a predictive mechanism.