Thermo-oxidative behavior of high-temperature PMR-15 resin and composites

The present study examines the thermo-oxidative behavior of high-temperature polymer matrix composite materials. Thermo-oxidative aging in neat resin is simulated with a diffusion-reaction model in which temperature, oxygen concentration and weight loss effects are considered. The thermo-oxidative behavior of the composite, on the other hand, is significantly different from that of the constituents as the composite microstructure, including the fiber/matrix interphase/interface, introduces anisotropy in the diffusion and oxidation behavior. Unit cell analyses are carried out using three-dimensional finite element analysis of repeated volume elements representing the fiber, matrix and interphase regions, and the resin oxidation model. Parametric studies illustrating the anisotropy in the oxidative region growth and the effect of fiber and interphase diffusivity on the oxidation layer growth are discussed. It is suggested that fiber-matrix debonding could provide additional diffusion paths to explain the extent of observed anisotropic oxidation growth.