Determination of the optimal flax fibre preparation for use in unidirectional flax–epoxy composites

Abstract

The specific stiffness of flax fibres is comparable to that of glass fibres. However, the application of flax fibres in composites still poses two important problems. The orientation of the fibres in the composite is not impeccable and the fibre–matrix adhesion is too weak. This research focuses on the former. To produce a continuous yarn for the textile industry, technical flax fibres are spun. The twisting of the fibres increases the yarn strength but the orientation of the fibres with regard to the fibre axis decreases. Experiments show that the slightly twisted yarns and the spun yarns possess the best processability but have lower mechanical properties than untwisted ribbons. The values fit very well to certain models which predict stiffness with regard to the twist angle.