Environmental effects on the mechanical behaviour of pultruded jute/glass fibre-reinforced polyester hybrid composites

The environmental degradation of the mechanical properties of pultruded jute and jute/glass hybrid reinforced polyester composites with high fibre volume fraction (0.70) has been investigated with special focus on the effects of water ageing and moderate temperature (up to 80 °C). Water absorption tests were conducted by immersing specimens in distilled water at room temperature until saturation (4076 h). Water absorption curves and characteristic parameters such as coefficient of diffusion and equilibrium moisture content were determined. The composites exhibited a deviation from the Fickian behaviour with a positive role played by the addition of glass fibres in terms of moisture resistance. The influence of water uptake on tensile and flexural properties of composites was evaluated and a significant reduction in both strength and modulus was observed, with a superior strength retention offered by hybrid composites. Acoustic emission (AE) and scanning electron microscopy enabled to identify the weakening of fibre/matrix interface induced by water ageing. The effects of temperature were mitigated by glass fibres if compared with the higher degradation experienced by jute fibres.