Determination of the optimal flax fibre preparation for use in UD flax-epoxy composites

Flax fibres are an interesting alternative for the widely used glass fibres. The specific stiffness of flax fibres is higher than for glass, which indicates a possible weight benefit[1]. Flax fibres are a natural renewable material (it takes only 100 days to reach his full height). During growth and the process from stem to fibre the total used energy is very limited (±10MJ/kg) compared to glass (55MJ/kg)[2]. In extra the culture of the flax is a very environmental friendly culture, which needs no irrigation and almost no pesticides and nutrients. Although the high potential of the flax fibres, the use of them in composites is very limited. The main reason is the limited length of flax fibres, which makes it necessary to apply twist on the fibres in order to obtain a continuous yarn. The presence of the twist leads to a drastic decrease in mechanical properties, especially for the stiffness. In this work the influence of the twist on the mechanical properties of flax fibres is investigated. Therefore flax from different stages in the fibre production process are taken, each with a different amount of twist. Attention is paid to the properties of the produced composites, but also to the dry strength, which is higher when more twist is applied. The main goal is to check if the use of flax which is not processed until a yarn is useful for composites.status: publishe