Self-interlocked MXene/polyvinyl alcohol aerogel network to enhance interlaminar fracture toughness of carbon fibre/epoxy composites

Interlaminar delamination is the most prevalent failure mode for carbon fiber reinforced epoxy (CF/EP) composites, which limits its applications. In this work, the interlaminar fracture toughness of CF/EP composites has been enhanced by the self-interlocked network arisen from Ti₃C₂T_x/polyvinyl alcohol (PVA) aerogel (TPA). The failure mode and toughening mechanism of interlocked TPA/CF/EP laminates has been explored from crack path behaviour and fracture morphology. The results show that the surface-modified MXene effectively improved the mechanical properties of TPA aerogels. The optimized loading of Ti₃C₂T_X (7.69 wt%) and TPA areal density (27 g/mm²) can significantly enhance the G_{IC Init}, G_{IC Prop} and G_IIC by 76%, 40% and 32%, respectively, without appreciably reducing the in-plane mechanical properties. The enhanced fracture toughness can be ascribed to cohesive failure at the interface facilitated by stitching-like effect of TPA, deflection and twisting of the main crack, the generation of numerous microcracks and pull-out of TPA skeleton and Ti₃C₂T_x, etc. Compared with the traditional interleave toughening, interlocked TPA not only achieves a comprehensive balanced mechanical enhancement of CF/EP laminates, but also avoids the toxicity of organic solvents.