Mechanical and tomographic characterisation of recycled Carbon Fibre Reinforced Polymer (rCFRP) using a fully mechanical environmentally friendly process

Abstract

The widespread use of carbon fibre-reinforced polymer (CFRP) composites in sectors such as aerospace and aviation calls for the adoption of sustainable recycling protocols. This research evaluates the mechanical and tomographic characterisation of recycled CFRP obtained via an innovative fully mechanical sustainable process. Thin (0.8 mm) and thick (2.0 mm) recycled non-woven fabric fibre laminates were subjected to uniaxial tensile testing in accordance with ASTM D3039M. The results revealed that the thick laminates achieved an UTS of 310-330 MPa and a Young’s modulus of 21.3–21.7 GPa in longitudinal direction, whilst the transverse properties were significantly lower. Despite the excellent cleanliness of the fibres, the mechanical performance of the composite laminates remains limited. Fractographic analysis using scanning electron microscopy (SEM) and internal volumetric evaluation using X-ray micro-tomography revealed severe spatial inhomogeneity in the distribution of the recycled fibres. Dense fibre bundles impeded the microscopic capillary infiltration of the resin, generating critical volumetric porosity and jagged shrinkage voids that act as severe stress concentrators. Consequently, it is essential to optimise the spatial uniformity within the mat of recycled precursors in order to reduce internal defects and fully exploit the structural potential of mechanically recycled CFRP.