Silica Development For Sidewall Compounds

Abstract

Tire tread is the single largest contributor to tire rolling resistance. Because of this, most developments to improve tire rolling resistance have focused on the incorporation of precipitated silicas into the tread compounds. However, still approximately 50% of the tire rolling resistance is attributed to the energy dissipation of non-tread components. The next largest contributor to rolling resistance after the tread is the sidewall, which contributes to about 20% of the tire rolling resistance. For this reason, the sidewall is an excellent candidate to achieve additional fuel efficiency improvements by taking advantage of the known reduction in hysteresis obtained when using silica in place of carbon black. The sidewall is a compound rich in natural rubber which needs to have good weathering, tear, abrasion, fatigue, and ozone-induced cracking resistance. Hysteresis improvements cannot be achieved at the expense of resistance to these degradative forces. Initial studies showed that treated silica can deliver reduced hysteresis, but the impact on other key performance properties required further investigation. Results are presented here showing the effect of partially replacing carbon black with treated silica in a sidewall model formulation. Emphasis is placed in reducing hysteresis while maintaining other performance properties.