Degradation of Polyimide Composites under Thermo-Oxidative Ageing

High-temperature resins such as polyimides are used in the aerospace industry on account of their thermal stability and property retention at high temperatures. To understand the degradation of a polyimide and carbon fibre composite at high temperatures, samples were aged in air at 350°C for 300 hours. Weight loss was tracked throughout the ageing time and stepwise loading/unloading tensile tests were performed on selected samples. A significant amount of degradation was observed in all samples, with those that had been post-cured faring slightly worse. Crack density increased with ageing time and it was found that aged samples developed fewer new cracks when subjected to loading compared to pristine samples, due to the interaction of damage already incurred by ageing. The high degree of resin loss in the samples established that the material is not stable at 350°C and recommendations have been made for further work to understand more clearly the material response.Validerat; 20150626 (global_studentproject_submitter