An innovative spinning process for production and characterisation of ring-spun hybrid yarns from recycled carbon fibre

The growing focus on sustainability stresses the importance of using materials derived from manufacturing scraps and end of life. Nowadays, a large amount of carbon fibre waste is available, and therefore, it is pivotal to understand how to use it for value-added applications. This paper introduces an innovative spinning process for ring-spun hybrid yarns composed of recycled carbon fibres (rCFs) from manufacturing scraps and virgin thermoplastic fibres in different blending ratios. The ultimate goal is to assess whether such a process is able to produce ring-spun hybrid yarns suitable for the production of polymer composites for structural applications and to determine the blends range that addresses this goal. The actual innovation in this process lies in the use of a ring-spinning machine for the production of hybrid yarns, which were characterised by tensile tests and thermogravimetric analysis combined with differential scanning calorimetry. The results show that the range of rCFs for the production of ring-spun hybrid yarns with good mechanical and thermal properties lies between 50% and 70%. Fibre orientation is crucial, especially for the card web, as is the blending ratio for the whole process. The increase in the number of draw frame doublings and the actual number of remaining rCFs have an impact on the tenacity of the hybrid yarn. Finally, ring-spun hybrid yarns consisting of 70% rCF exhibit slightly higher tensile strength, but with a lower decrease in the quantity of rCFs than those composed of 50% rCF. Thus, they possess the best mechanical and thermal properties and composites made from ring-spun hybrid yarns with 70% rCF should perform better. Overall, this process has the potential to be industrially transposed but needs to be evaluated from an environmental perspective.