Characterization of oxidative processes associated to low-severity tire tread wear

Abstract

As the tire tread wears throughout its lifetime, particles are generated due to small-scale fracture processes. Friction and wear may also involve physico-chemical degradation of the material. In this paper, the chemical effects associated to low-severity wear of filled Styrene Butadiene Rubber (SBR)/cis-Butadiene Rubber (BR) materials were investigated. Laboratory wear tests were performed using a home-made rotary tribometer in which intermittent sliding contacts on a slightly rough granite surface are applied. This enables imitating real conditions in terms of kinematics and dynamics of the contact for tire treads. The resulting wear patterns were analyzed through X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). The results show that sulfur oxidation occurs concomitantly to wear. Besides, thermal measurements reveal no significant temperature increase at the sample surface during the wear tests. This suggests that the observed chemical changes are not thermally activated but are instead due to mechanical phenomena related to interface shear. Analysis of the wear debris indicates that their chemical composition is consistent with that of the wear patterns.