ABSTRACT
While a new tire may have excellent resistance to crack initiation and propagation between the steel belts, an aged tire of the exact same construction can exhibit dramatically reduced crack growth resistance, which in some cases may contribute to tire failure. Aging of the belt skim and wedge rubber was found to be quite general. Values for peel strength and elongation to break decreased with age while the cross-link density and modulus increased. The kinetics of aerobic oxidation in different rubber materials have been studied extensively by Gillen et al. through measurements of oxygen-consumption rates, modulus profile, and elongation to break over a wide range of temperature and time. All of the changes are driven by oxidation and the relative behaviors correlate well with one another from tire to tire. In general, the proportional changes in peel strength and elongation to break are larger than those for modulus and cross-link density.
