Influence of Silica Characteristics on Tire Performance Indicators

Silica-silane filler systems were introduced in tire compounding as they result in a significant reduction in rolling resistance compared to carbon black. Since then, new silica types have been developed for further improvement of tire performance.

In this study, five silica types differing in specific surface area and structure were compared in a reference ‘green tyre’ compound in two modes: constant silica concentration and equal hardness by adjustment of the filler loading. The tan δ value at 60 °C was used as indicator for rolling resistance, and wet skid resistance was measured as side force coefficient on a laboratory abrasion tester.

The silica types with smaller aggregate dimensions are more difficult to disperse, but generally show higher reinforcing effect. Silica with the smaller aggregate size showed superior wet skid resistance in both compounding modes; however, the effect was smaller when hardness was adjusted. In this case, reduced concentrations of high surface area silica grades also result in lower values of tan δ at 60 °C, which correspond to better rolling resistance. 

In general, the dynamic properties of materials containing highly reinforcing silica types can be further improved by using less filler, but at the expense of tensile properties. Furthermore, a good dispersion of the nano-sized aggregates is the key to obtain rubber composites with superior overall properties.