Cumulative thermal damage modeling under non-isothermal conditions for polyethylene degradation prediction

Polyethylene (PE) is widely used in critical engineering applications, including gas and water systems. However, it is prone to thermal and oxidative degradation at high temperatures, which poses serious risks. To address the issue, this study develops a cumulative thermal damage model to accurately predict PE degradation under varying temperature conditions. The research approach combines the Arrhenius equation with thermal decomposition kinetics. This study employs isothermal thermogravimetric analysis (TGA) data to derive prediction formulas for material survival time under both thermal and oxidative degradation. The incremental damage over the entire PE’s temperature–time history is linearly derived from the cumulative damage index ( D ), where failure is predicted to occur when D ≥ 1. The model is tested through controlled TGA experiments that simulate different non-isothermal processes, varying the constant heating rates, stepped heating, and serrated heating. The results indicate high model accuracy: the relative error between the predicted failure time and the experimental time for a 5 % mass loss is within 6 %. The findings suggest that the cumulative thermal damage model can be a reliable engineering tool for estimating the remaining service life of PE components by offering improved risk assessment in applications where materials are exposed to nonlinear or transient thermal conditions.