Development of a new hybrid yarn construction from recycled carbon fibres for high-performance composites. Part III: Influence of sizing on textile processing and composite properties

Abstract

The processing of recycled carbon fibres (rCFs) into hybrid yarn constructions is a promising recycling option, converting rCF into products with added value. Along with fibre length and strength, the sizing of rCF crucially affects their processing behaviour and subsequent composite properties. This article reports on the influence of sizing on the processing properties of rCF by mixing with polyamide (PA) 6 fibres to form a hybrid yarn construction. Moreover, resulting composite properties were studied as well. Thus, commercially available CF with thermoplastic and thermoset matrix compatible sizing in addition to pyrolyzed rCF without sizing was used for the investigations presented in this article. Results revealed that different sizing strongly influence the processing of rCF and PA 6 into hybrid yarn constructions. The opening and bending behaviour of rCF bundles with different sizing varied during the carding process so that various degrees of fibre shortening occurred. As expected, the sizing developed for thermoplastic matrix enabled the highest tensile and flexural strengths in thermoplastic composites. These findings greatly contribute to the understanding of rCF processing from different or unknown sources on industrial scale.