Multi-scale analysis of flax fibres woven fabrics for composite applications

Natural fibres are used as an alternative to man-made fibres in fibre reinforced composite materials in a variety of applications due to their good specific strength and stiffness properties and limited environmental impact. However, contrary to man-made fibres, used in the form of continuous filaments, natural fibres are extracted from plants in which they have a finite length. After their extraction form plants, they are paralyzed and twisted together to form roving or yarn. In this paper, the potential of manufacturing flax woven reinforcements optimized for composite applications is evaluated. A multi-scale analysis of the textile and mechanical properties is conducted to evaluate the impact of each transformation step and the respective contribution of fibre, yarn and fabric to the composite performance. The impact of a chemical treatment on the roving features is evaluated. Results show that this treatment doesn't impact significantly the fibre tensile strength and stiffness and improves its weavabilty. The difference between yarn and roving is also shown regarding the weavability and their impact on the composite tensile properties. The properties of these flax reinforced composites are finally compared with those available in the open literature for similar fibre composites. A promoting conclusion is then proposed. (paper)