Besides in food technology, the use of wheat gluten has been explored in non-food applications such as biopolymers and biocomposites [1, 2, 3]. In absence or at low concentrations of plasticizer, high-temperature compression molded wheat gluten powder upon cooling vitrifies into a rigid material. This rigid gluten biopolymer has also been combined with natural fibers to obtain green composites [4].

However, there are certain limitations for this type of composite, particularly regarding to its processability and environmental (moisture) resistance. Gluten composites still contain a significant amount of water after processing. In the case of gluten biopolymers, the mechanical properties were affected considerably by the residual moisture content [5]. Therefore, in case of gluten composites, their properties are also expected to change.

The aim of this research is to study the moisture absorption behaviour of gluten polymers and subsequently of flax fiber/gluten composites. Up till now, there are no conclusive results for rigid gluten materials on the effect of moisture uptake in gluten powder and in the thermo-molded polymers, as well as on the effect of moisture used to prepare prepregs and the effect on the final biocomposites.