Lifetime prediction of thermo-oxidative degradation of a modified epoxy resin and its glass fiber composite in air atmosphere and correlation with long-term aging behavior

Thermal stability and material degradation are critical aspects of polymers and composites, influencing their processing, operating temperatures and overall lifespan. Due to their excellent mechanical and thermal properties, epoxy resins find widespread use in coatings, adhesives, and composites across various industries. This study examines the thermo-oxidative stability of high-Tg epoxy resin and glass fiber composite systems (GFRP), focusing on long-term degradation mechanisms in air atmosphere and kinetic modeling for accurate lifetime predictions. Here, the influence of commonly used additives such as polyethersulfone as toughener, and aluminum diethyl phosphinate (AlPi), as flame retardant on the thermo-oxidative degradation and resulting weight loss was investigated.

Model-free kinetic approaches were employed to characterize the thermo-oxidative degradation. In this study, model-free methods such as Flynn–Wall–Ozawa and Friedman are used because they offer flexibility and do not require detailed knowledge of the chemical reactions involved. Thermogravimetric analysis (TGA) was used for dynamic degradation measurements and weight loss predictions, while oven aging experiments in air atmosphere at three temperatures for up to 1000 h were conducted to verify the predictions.

The study highlights the challenges in extrapolating short-term degradation data to long-term behavior, especially under oxidative conditions. It also explores the influence of various additives and fiber reinforcement on thermo-oxidative stability, with the goal of enhancing future material formulations for high-performance applications. Additionally, it provides improved insight into the predictability of a material’s lifespan.