The effect of natural ageing on the mechanical properties of modified and unmodified fibre-reinforced polyester composites have been investigated to assess their ageing pathway. Four sets of composites: modified glass fibre-reinforced polyester(GRPm), unmodified glass fibre-reinforced polyester (GRPum), modified cotton fibre-reinforced polyester(CRPm),and unmodified cotton fibre-reinforced polyester(CRPum) at 40% fibre content by weight. Hand lay-up technique was adopted to fabricate the composites specimens. The mechanical properties results obtained for the four composites evaluated after twelve months period, revealed a significant improvement to environmental ageing, with the modified composites(GRPm and CRPm) showing the highest resistance to ageing. It was also observed that during the rainy season the mechanical properties of the composites reduces sharply, this reduction could be attributed to water absorption by the composites, which has an effect to the mechanical properties of composites.
KEYWORDS: Ageing, modified, fibre-reinforced, polyester, hand lay-up, Reinforcement.