The Effect of Silane Coupling Agent Loading in a Silica Filled Model Tread Compound on Predicted Winter and Wet Traction

A series of silica filled tread compounds were prepared in which the silane coupling agent (SCA) concentration varied from 0% to 10.6% by weight of silica loading. The silane was bis(triethoxysilylpropyl)disulfide (TESPD). This investigation will examine the effect of SCA concentration in the critical temperature range of 0 to -20°C where predicted tire tread performance such as wet and winter traction are measured. The Dynamic Mechanical Analysis (DMA) low-temperature testing included Double Strain Sweeps (DDS), energy dissipation, creep measurements, and modulus fatigue. Mini DeMattia testing was also conducted to explore the flex fatigue behavior. Both the 8 and 10.6 wt% SCA compounds displayed high tan δ values in the DSS plots which were interpreted as improved low temperature traction. An increase in storage modulus at -20°C for 10.6 wt% SCA however supports 8 wt% as a more optimal SCA loading. Energy dissipation was highest for the 5.4 wt% SCA compound and slowly decreased for higher SCA levels. The addition of SCA to the compound has a significant effect on creep characteristics with the creep magnitude decreasing with increasing SCA concentration. The fatigue testing results point to the advantage of a softer compound, but in any event, both tan δ and the storage modulus slowly increased with fatigue time. Crack growth rate appears optimal for the 8 wt% SCA filled compound at ambient temperatures.