Kinetic characteristics of moisture diffusion in flax fibres and their composites

The properties of flax fibre reinforced polymers are highly dependent on the relative humidity of the environment. The influence of absorbed moisture on the quasi-static mechanical properties has been quantified in literature. However, the absorption process of the fibre and the composites remain poorly understood. In this work, diffusion coefficients and diffusion paths of the moisture are measured and visualized both inside the fibres and in composites. Hygroscopic expansion coefficients of unidirectional (UD) flax-epoxy and flax-polypropylene (PP) composites have been successfully determined. Finally, treatments that reduce the hygroscopic swelling and equilibrium moisture content of the fibres are presented.status: accepte