Closed-loop recycling of reclaimed short carbon fibre reinforced polyamide composites

Considering the relevance of polyamide 6,6 (PA6,6) and short carbon fibre composites in the automotive and aerospace industries in the UK, as well as the increasing demand for more sustainable practices in these industries, this work studies the feasibility of recycling reclaimed carbon fibre reinforced polymer composites. Using mechanical grinding and injection moulding processes, composites with fibre loading ranging from 10 wt% to 40 wt% were cycled five times while the fibre length and mechanical and thermal properties were monitored at every step. The results for fibre length and thermal stability properties suggest that changes in the mechanical properties of the composite are associated with changes in the average and distribution of fibre length, with negligible effects from thermal degradation. In addition, this paper proposes the use of a dimensionless degradation parameter that, with the correct experimental validation, may be used by research and industry groups to estimate changes in the mechanical properties of similar composite systems when recycled in closed loops. • Recycling reclaimed carbon fibre composites is shown to be viable at scale. • Mechanical properties dominated by shifts in fibre length averages and distribution. • Thermal degradation of the matrix has negligible impact on mechanical properties. • A dimensionless degradation parameter is proposed for future closed loop systems.