Innovative thermally stablized low twist hybrid yarns from recycled carbon fibre for thermosplastic composites

Abstract

Hybrid yarns consisting of rCF and thermoplastic fibre offer a good potentials to improve mechanical properties of carbon fibre reinforced composites due to high fiber length, homogeneous mixing and high rCF content [1]. However, the twisting of the yarn in conventional spinning processes leads on one hand to the damage in rCF during spinning because of its high brittleness and sensitivity to shear forces. On the other hand, mechanical properties e.g. tensile and flexural strengths of composites decrease significantly with the increase of twist as a result of low fibre orientation [2]. On the contrary, the yarn strength and the stability of the spinning process are strongly dependent on the level of yarn twist. In our previous paper [3], the development of low twist hybrid yarns (75-30 T/m) consisting of rCF and polyamide 6 (PA6) fibre for high performance thermoplastic composites has been reported. However, hybrid yarns with low twist levels suffer from low spinning stability and poor yarn strength, which limits their further processablity in weaving or knitting processes. Therefore, the focus of this work is the development of a method to reduce yarn twist but still ensuring a stable spinning process, high yarn and composite strengths.