AbstractThermal oxidative aging and other chemical‐induced degradation greatly affect the service life of elastomer components. In this article, we presented a strategy to predict the long‐term mechanical behavior of elastomeric components, to foresee the failure of elastomer components in design stage. The accumulation and consumption of small molecule reactants in elastomers are described using a diffusion–reaction process. Free‐volume theory is applied to consider the diffusivity change during this process. Degradation of elastomers under elevated temperature up to 500 K, environmental pressure up to 4 atm, and different cross‐link densities are studied in this simulation. Methodology of prediction of mechanical behavior is proposed based on the affined network model.