Analysis of hybrid yarns properties for good-quality recycled carbon fibre-reinforced plastic composites

This paper aims at assessing the performance of recycled carbon fibres and hybrid yarns in view of their application in carbon fibre-reinforced plastic composite materials for structural components. In detail, the hybrid yarns were manufactured by means of an innovative spinning process the authors have developed in a previous study. Recycled carbon fibres from manufacturing scraps or waste blended with a thermoplastic fibre (i.e. polyester or polyamide) to a weight of 50-50% were used as input. Quantitative laboratory tests, including scanning electron microscopy, tensile test, thermogravimetric analysis and differential scanning calorimetry, show that hybrid yarns are characterized by good mechanical properties. In particular, hybrid yarns composed of recycled carbon fibres blended with polyester are less ductile and, at the same time, more rigid than those where recycled carbon fibres are blended with polyamide. Furthermore, the percentage of recycled carbon fibres present in the final result is about 7-14% lower than the value originally entered. Finally, the paper paves the way for future research. First, it is fundamental to evaluate the mechanical properties of hybrid yarns composed of higher percentages of recycled carbon fibres. Second, the assessment of the mechanical properties of the carbon fibre-reinforced plastics that are being produced soon as well as the electrical conductivity of the hybrid yarns for both textile and composite applications, could be of interest.