Tread Wear and Wet Skid Resistance of Butadiene-Styrene Elastomers and Blends

Abstract

Abstract 1. Car, wheel position, driver, inflation pressure, and shoulder drop have a statistically significant effect upon wear loss and need to bo taken into consideration before material factors affecting wear can be studied. 2. Variations in macrostructure of the polymers are not found to have a significant effect on wear as compared to microstructure variations. 3. At least two material factors control wear loss of tire treads. 4. When polymers are tested near their glass transition temperature (within 80° C), wear loss is dominated by viscoelastic properties. Viscoelastic properties can be related to wear loss through Tg or the combined effect of the cis, trans, vinyl, and styrene content. 5. At higher test temperatures (over 100° C above Tg) wear loss is dominated by a material factor that has a positive correlation with temperature. This is particularly noticeable when treads are worn under mild conditions. However, there is evidence that this wear factor is present at the testing nearer to Tg but is masked by the dominant viscoelastic effect. 6. The combined effect upon wear of the different material factors leads to an optimum wear resistance for any polymer in the butadiene—styrene system in the range of 75°–105° C above the Tg for that polymer. 7. For polymers tested at the same ambient temperature, (T), the effect of viscoelastic properties decreases non-linearly as T−Tg increases. 8. In the range of test severity studied, severity has little effect upon the inter-relationship of material factors. 9. In the range of test temperature where Tg dominates wear loss, skid distance on wet asphalt pavement is inversely related to wear rating.