Sliding friction characteristics of styrene butadiene rubbers with varied surface roughness under water lubrication

We investigated the effect of the surface topography of rubbers on their wet sliding friction characteristics. For six types of rubber samples with different viscoelastic properties, rubber specimens with five levels of surface roughness were prepared and slid against a rough rigid surface under water lubrication. The friction coefficient increased with increasing surface roughness for each of the rubber samples, and the rank of the friction coefficient of different samples varied depending on the surface roughness. These results indicate that the effect of hysteresis friction becomes more significant as the surface roughness of the rubber increases, and the effect of the inhibition of adhesion friction caused by lubrication becomes more significant as the surface roughness decreases. Our findings demonstrate the importance of rubber surface topography in determining the friction coefficient under water lubrication. The results of this study may lead to new design criteria for high-wet-grip rubber tires.