Carbon fibres/RTM6 vitrimer and non-dynamic epoxy thermoset composites: comparative study of manufacturing, mechanical characteristics, water absorption, impact resistance, repairing and compression after impact

In aerospace, thermoset materials are prized for durability but face limitations in recycling, prompting exploration into alternatives. This study compares the mechanical behaviour of an aerospace-grade two-component epoxy system (RTM6-2) to that of a vitrimer counterpart with a disulfide hardener (RTM6-V), both reinforced by unidirectional carbon fibres plies and manufactured by resin transfer moulding. Conformity and quality of laminated plates are rigorously verified using non-destructive and destructive methods, underlying the excellent manufacturing process control of RTM6-V composite parts, similarly to conventional composites. Mechanical properties evaluation, including interlaminar shear stress tests, highlight the efficacy of RTM6-V in achieving good impregnation and outstanding fibre-matrix cohesion. Moreover, the study investigates water uptake presenting acceptable water content at saturation for aeronautical applications. Plus, the reprocessing and repair capabilities of CFR RTM6-V laminates are also assessed. Effectively, series of carbon/RTM6-2 and carbon/RTM6-V laminates were submitted to low velocity, low energy impact testing campaigns and subsequent repair evaluations demonstrate a limited potential for repairing matrix cracks and delamination in impacted laminates. Overall, this work provides insights into the performance and applicability of RTM6-V in aerospace composite applications, shedding light on its strengths and limitations.