Effect of stress relaxation on accelerated physical aging of hydrogenated nitrile butadiene rubber using time-temperature-strain superposition principle

While the stress relaxation is a common phenomenon for polymers, its effect on the stress/strain accelerated aging of the hydrogenated nitrile butadiene rubber (HNBR) cannot be ignored. In this paper, the aging tests of HNBR at various temperature and strain levels were performed. To consider the influence of relaxation behavior during the accelerated aging process under external strains, a modified time-temperature-strain superposition principle considering stress relaxation (TTSSP-R) was proposed. With the general Maxwell model and the constructed master curve of relaxation modulus, the effect of stress relaxation on accelerated aging can be described. It was demonstrated that the proposed TTSSP-R approach provides an accurate evaluation of physical aging of HNBR with the consideration of stress relaxation. It could help the material designer to better understand the long-term performance and reliability of rubber components. Keywords: Accelerated aging, HNBR, Stress relaxation, Time-temperature-strain superposition principl