Thermoplastic multi-material nonwovens from recycled carbon fibres using wet-laying technology

In this study, multi-material nonwovens were produced using a wet laying nonwoven batch process. The aim of this work is to investigate and develop nonwoven material solutions that can be used for a substitution of pure glass fibre (GF)-applications and also provide a more cost-sensitive option compared to nonwovens purely made from recycled carbon fibres (rCF). The multi-material-nonwovens of this study consisted of the functional components rCF and GF as well as a thermoplastic matrix, built by the admixture of PA6-fibres. All three fibre types were mixed directly within the nonwoven manufacturing process, respectively in the course of the initial weighed portions. Six different material compositions with individual amounts of rCF and GF were produced, but a constant overall fibre volume content (FVC) as well as a uniform grammage was defined. A hot pressing technique was used to consolidate these multi-material-nonwoven layers. Subsequently, the sheet materials were examined using tensile and 4-point bending tests, as well as wet-chemical fibre volume content determinations and micrographic sections. With regard to the mechanical performance, a near-linear increase is observed for increased proportions of recycled carbon fibres. In this context a potential for the use of multi-material-nonwovens consisting of rCF and GF can be found. It is demonstrated that rCF might be an adequate substituent for classical GF-applications. The results contribute to broadening the performance spectrum of rCF and thus to its substantial recycling route.