Effect of thermo-oxidative aging on compressive behavior of carbon fiber polymer matrix composites

Abstract

The effects of reinforcement architecture on the compressive behaviors of carbon fiber polymer matrix composites (CF-PMCs) under thermo-oxidative aging conditions were investigated. Samples of three-dimensional and four-directional braided carbon fiber/epoxy composites (BC) and laminated plain woven carbon fiber/epoxy composites (LC) were subjected to isothermal aging at 80℃, 100℃, 120℃ and 140℃ in air circulating ovens for various durations up to 1200 h. The process resulted in progressive deterioration of the matrix reins and fiber/matrix interfaces, in the form of chain scissions, weight loss and fiber/matrix debonding, which significantly led to the decrease of the compressive strength. In addition, the compressive strength retention rates of BC were higher than those of LC at the same aging conditions due to the differences of their reinforcement architecture. On the one hand, LC lost more weight than BC because the percentage of exposure of fiber ends to air in the LC samples was five times more than that in the BC samples. Moreover, the BC samples could resist the compressive load as an integral structure and did not show delamination damage as in the case of LC samples, although the resin was damaged and the adhesive force between fiber bundles and resin decreased after thermo-oxidative aging. Therefore, adopting the three-dimensional and four-directional braided preform as the reinforcement of CF-PMCs is an effective way to improve their compressive strength under thermo-oxidative aging conditions.