Modulus-Fatigue Resistance of Silica-Filled Tire Tread Formulations

A modulus fatigue test method was found to be useful ranking fatigue resistance (damage resistance) of tread compounds. In a prior paper, it was shown extra mix time increased tensile strength and tangent delta at 30°C and F-S-SBR polymer increased tensile and reduced tangent delta at 30°C. With this understanding of extra mix time and F-S-SBR polymer, the fatigue test was improved. The method utilized the Metravib DMA and 150 instrument with multi test software. Tension test specimens were cycled in sinusoidal deformation under load-load control. Four silica tread compounds were compared for modulus fatigue resistance. The test appeared to be able to rank fatigue resistance of tire tread compounds; particularly, by modulus retention and tangent delta change (around 2x10⁵ to 5x10⁵ cycles). There appeared to be change in damage mechanics around 3x10⁵ cycles. Compounds with extra mix time and functionalized polymer exhibit better retention of properties (resistance to damage).