Effect of Bimodal Carbon Black Particle Size on Rheometric and Vulcanization Characteristics of SBR Compounds

This paper considers the effect of filler bimodal particle size on the reinforcement behavior and vulcanization characteristics of ESBR compounds filled with different ratios of carbon black N220 and N660 at a fixed total volume fraction (ϕ=0.2). The rheometery results show that rotational shear torques, before and after vulcanization, as measures of viscosity and elastic modulus, show a synergic increase at the concentration ϕN220=0.05 which deviates from the linear mixing rule. Similarly, the rate of vulcanization is lower than that predicted by the mixing rule at this concentration. This phenomenon was correlated to the specific packing of carbon black aggregates, which brings about an enhanced reinforcement at this concentration