Thermal Aging Analysis and Predictive Modeling of Epoxy Nanocomposites Characteristics

ABSTRACT This study investigates the thermal aging of glass fiber reinforced epoxy nanocomposites, focusing on chemical degradation mechanisms and the mitigating role of thermal conductivity for high‐temperature low‐sag conductor core applications. Composites with hybrid nanofillers containing multiwalled carbon nanotubes, graphene nanoplatelets, and aluminum trihydrate were aged at 120°C and 160°C for 3000 h. Thermal aging induced chemical degradation, with a 10‐fold increase in oxidation rate at 160°C due to chain scission. Carbonyl formation and hydroperoxide intermediates were formed in the composites. Tensile strength reduction of 8.6% in base composites is observed compared to 6.5% in the nanocomposite with hybrid nanofillers. Hybrid nanofillers reduce degradation by limiting oxygen diffusion, cooling the matrix, and stabilizing T _g , outperforming literature‐reported reductions of 7%–12% for similar composites. Thermal conductivity, modeled using Maxwell–Garnett, shows an enhancement of 40%–60% with nanofiller content and 10%–20% in the Bruggeman model. This slows heat diffusion, further mitigating aging. Transient heat flow analysis confirmed a 20%–30% longer diffusion time enhancing thermal stability. The nanocomposite retained 474.56 MPa tensile strength post‐aging, meeting high‐temperature low‐sag (HTLS) conductor standards. These findings elucidate the interplay between thermal aging, chemical degradation, and thermal conductivity, highlighting the potential of hybrid nanofillers for durable HTLS applications.