Influence of temperature on durability behavior of carbon black filled natural rubber

Despite numerous studies dealing with rubber durability prediction, information about fatigue behavior versus temperature are still scarce. This could be explained by the difficulty to perform reliable tests at different temperatures. In this study, relaxing Wohler curves have been achieved for a standard carbon black filled NR with a skin temperature ranging from 10 degrees C to 102 degrees C. During the setting of the experimental protocol, a so-called "thermal accommodation" was observed during the first thermal cycle. Creep and relaxation levels are well above the classical expected ones if the sample is clamped before starting the thermal cycles. Moreover, at high temperatures both thermal and ageing brittle failures have been observed. The upper limit of the temperature range was therefore defined according to the cyclic stiffness evolution to set apart the results disturbed by an ageing induced during the tests. A continuous decrease of the duration life with the increase of the test temperature was finally observed, which is not a classical result.