Preliminary results on thermo-oxidative ageing of multi-hole carbon/epoxy composites

During their service life, fibre-reinforced polymers are subjected to the influences of numerous ageing factors such as temperature, pressure, oxygen or moisture, which generally result in a decrease of the composite properties. This study deals with the combined actions of two damaging parameters, temperature and oxygen. Thermo-oxidation is analysed in an original way by ageing in air plain and multi-hole laminates for 9000 h. Since perforated panels have a greater surface exposed to the oxidative environment, the degradation due to oxygen is increased, thus allowing a better understanding of thermo-oxidation mechanisms. Characterisation of the aged composite includes FTIR, microscopy, weight loss measurements, DMA, compression and SBS tests. Thermo-oxidative ageing leads to oxidation and cracking of the laminates surfaces, weight loss and decrease of both compression and SBS failure strengths. The glass transition temperature remains constant. Degradation is more important for the multi-hole panels and results in a greater decrease of the physical and mechanical properties for these laminates.