Thermooxidation degradation and life prediction of nitrile butadiene rubber based on Kinetics model

To study the aging principle of sealing performance of nitrile butadiene rubber (NBR), a mathematical model is proposed based on the correlation between mechanical performance and microscopic flaws. We assume that oxidative cross-linking and molecular chain scission are two main microscopic flaws of NBR, which could result in performance degradation. In this paper, we use Kinetics model to relate the degradation process with both microscopic flaw mechanisms. Finally thermal-oxidative aging model of NBR is developed for lifetime evaluation. We evaluate our model using compression permanent distortion data which are obtained by accelerated thermal-oxidative aging tests at 60°, 70°, 80°, 90° and 100°. Comparing with current existing aging model, the experimental results show that our model could simulate the degradation trend of sealing performance accurately. Predictive residual of our model is smaller than 1% at various temperatures and even smaller than P-t model at 70° and 80°.