Effects of Surface Roughness on High-temperature Oxidation of Carbon-fiber-reinforced Polyimide Composites

Abstract

In high temperature applications, the oxidation of polymer composites changes their microstructures and degrades their mechanical properties. Both these effects detrimentally affect the service life. Oxidation experiments are time-consuming and cannot be conducted in a laboratory for all layouts of a composite. For this reason, the weight loss of a composite due to oxidation is predicted by the first-order approximation rule of mixtures. Theoretically, the shielding of fibers should slow down the oxidation of a composite than that of a neat resin. However interestingly, the predicted value of oxidation is far lower than that obtained experimentally. In the literature, some researchers have proposed the fiber-matrix interface model to explain the discrepancy while others have believed it is related to the preparation of the surface. This work presents a surface roughness model to clarify the relationship between the high-temperature oxidation and the surface roughness. Predictions concerning high-temperature oxidation are favorably supported by experimental data.