Enhancing tire tread performance with combined nano and micro-silica particles in styrene butadiene rubber/butadiene rubber compound

The influence of fumed nano-SiO2 on the performance of a typical tire tread compound, fabricated by mechanical mixing process, was investigated in the present research. The tire tread compound contained styrene-butadiene rubber (SBR)/cis-butadiene rubber (BR) blend reinforced with a well-developed commercial highly dispersive silica filler at 70 phr loading. Nano-SiO2 with higher specific surface area, e.g., similar to 240 m(2)/g, was substituted partially with silica particle at three different concentrations of 5, 10, 15 phr. Improvement in various aspects of the control sample including crosslink density cal-culated based on the swelling test and tube theory, bound rubber content, and physico-mechanical properties was observed for nano-SiO2 loading below 10 phr due to its effective role in refinement of filler dispersion state and enhancement of rubber-filler interactions. However, most of the properties were sacrificed at 15 phr nano-SiO2 loading even with respect to the control sample which emphasized the effectiveness of nano-SiO2 within an optimum loading. Moreover, nano-SiO2 at optimum loading ex-hibited great improvement in initial decomposition temperature about 50 degrees C, consid-erable improvement in rolling resistance (more than 8%) and enhancement in wear resistance which could be crucial for tire tread manufacturers.