Investigation of degradation of fibre-reinforced composites

Abstract

In this study composites of chopped E-glass, aramid and carbon fibre fabrics embedded in an epoxy matrix were fabricated and subsequently tested for different degradation mechanisms. Simulation of saline environmental conditions together with ultraviolet degradation was applied by using accelerating testing equipment. In addition a number of samples were also aged at two different Maltese sea locations for a few months. Characterisation was carried out on the specimens to understand the different effects of degradation. Results obtained showed a high presence of 0-H groups when specimens where exposed to UV only or UV with seawater, where these groups were responsible for photo-oxidization. The water quality affected the biological activity and the surface morphology for the samples tested. In-situ in fact a larger amount of cracks in the polymer matrix was noted at the high polluted sea. The severity of cracks was also dependent on the degradation mechanisms. The worse case was when both UV and moisture from seawater were present. This synergic mechanism resulted in a high number of cracks at scratches and pores. Water intake was found to be dependent on the fibre material and the number of void content. It is also highly dependent on the fibre orientation as it was established that specimens with 45° fibre orientation absorbed more moisture.