Predictive modeling and degradation mechanisms of rubber sealing materials under stress-thermal oxidative aging for long-term sealing performance

Rubber sealing materials are extensively utilized in engineering applications due to their superior sealing performance; however, their long-term durability poses a significant challenge. To address this issue, this study examines the aging behaviors of rubber materials, including stress relaxation and compression set, and incorporates these behaviors into a predictive model for impermeability performance. The rubber strain was analytically decomposed into elastic strain and viscoelastic strain, the latter representing permanent compression deformation. Based on this decomposition, a time-temperature conversion model was developed. Compression stress-thermal oxidative aging tests were conducted to validate the model, producing time and temperature-dependent expressions for permanent compression deformation and constitutive parameters of the rubber material. Additionally, degradation mechanisms were investigated using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM), revealing significant molecular-level oxidation, polymer chain scission, crosslink degradation, and the emergence of microstructural defects such as cracks and interfacial debonding. The validated model was then employed in numerical simulations, implemented through a UMAT secondary development program, to investigate the degradation trends of impermeability performance under varying time and temperature conditions. The results elucidate the degradation mechanisms and trends of impermeability performance, offering critical insights into the long-term behavior of rubber sealing materials. These findings provide theoretical guidance for optimizing the design and performance evaluation of rubber gaskets in practical engineering applications, thereby enhancing their durability and reliability in demanding operational environments.