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

Aging of tire rubber compounds in real service is affected by multiple fact ors. This process cannot be accurately represented by conventional single-f actor tests. A novel cyclic aging test is proposed as a multiple factor, se rvice simulating, accelerated aging test method. It includes four sub-tests of oxygen bomb, dynamic ozone, ultraviolet light, and water solution attac k. 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 compound s are used as experimental materials. The experimental results show that th e proposed cyclic aging test is closer to dynamic outdoor aging than the co nventional dynamic ozone and thermal aging tests. The static modulus increa ses with thermal aging, and decreases with dynamic ozone aging time. For dy namic outdoor and cyclic aging, the modulus initially increases, but then l ater 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 with out elevating the temperature. (C) 2001 Elsevier Science Ltd. All rights re served.