Temperature impact on the mechanical and fatigue behavior of a non-crystallizing rubber

Temperature is one of the main parameters affecting the mechanical behavior of rubbers. The impact of this parameter is particularly important in the case of cyclic loads. In this study the mechanical and fatigue behavior of a carbon filled acrylonitrile butadiene rubber (NBR) was investigated. Tensile tests revealed a general decrease of the ultimate properties with temperature. Moreover, the maximum chain extensibility, evaluated through Mooney-Rivlin plots, showed a similar trend and a minimum at intermediate temperature. The dynamic properties of the material were investigated through DMA measurements. Temperature sweep revealed an Arrhenius dependence of the dynamic moduli for temperatures above Tg + 30 °C. Master curves of the dynamic properties were generated through the application of the time-temperature superposition principle, by shifting horizontally the isothermal frequency sweeps. The fatigue behavior at different temperature was assessed through the crack growth approach and a lower crack growth resistance was found at higher temperatures. Finally, a new procedure for building fatigue master curves has been investigated by exploiting the temperature dependence of the loss modulus.