Development of a service-simulating, accelerated aging test method for exterior tire rubber compounds I. Cyclic aging

Abstract

Aging of tire rubber compounds in real service is affected by multiple factors. This process cannot be accurately represented by conventional single-factor tests. A novel cyclic aging test is proposed as a multiple factor, service simulating, accelerated aging test method. It includes four sub-tests of oxygen bomb, dynamic ozone, ultraviolet light, and water solution attack. The proposed cyclic test is compared against thermal, dynamic ozone, and dynamic outdoor aging by characterizing material property degradation as a function of aging time. Four formulations of exterior tire rubber compounds are used as experimental materials. The experimental results show that the proposed cyclic aging test is closer to dynamic outdoor aging than the conventional dynamic ozone and thermal aging tests. The static modulus increases with thermal aging, and decreases with dynamic ozone aging time. For dynamic outdoor and cyclic aging, the modulus initially increases, but then later decreases, showing traces of both of the previously mentioned results. It is also found that the size of the specimen has a significant affect on aging. Such effect can be utilized to accelerate the artificial aging without elevating the temperature.