Diffusion Studies on Advanced Fibre Hybrid Composites

The moisture diffusion characteristics of simple (E-glass, Graphite and Kevlar) and hybrid (E-Glass-Graphite, Graphite-Kevlar and Kevlar-E-Glass) unidirectional com posites have been studied at 296 K and 343 K under water immersion conditions. The equilibrium moisture content (M _m ) and diffusion coefficient (D _x ) of Kevlar fibre com posites are respectively as high as 5 and 10 times those of E-glass/Graphite fibre com posites. The hybridization of impermeable fibres (E-Glass and Graphite) in a com posite does not cause significant changes in the M _m and D _x values of their simple com posites. Hybridization of impermeable fibres with permeable fibres (Kevlar), however, has a significant effect on the diffusion characteristics of their simple composites. The experimental data for simple and hybrid composites comprising both impermeable and/or permeable fibre composites show good correlations with the analytical Fickian Diffusion plot. The effect of edge coating on the moisture absorption is quite signifi cant in the impermeable fibre composites.