Multi-matrix continuously-reinforced composites: A novel route to sustainable repair of composite structures

[Display omitted] •A design concept is presented where repairability, and simplicity of repair, are programmed right at the manufacturing stage.•Novel multi-matrix continuously-reinforced composites are introduced to address concerns for reliability of conventional repair strategies.•This proves the feasibility of seamless joining of repairable vitrimer patches and conventional epoxy composites.•The results indicate that the presented concept has a significant promise for property restoration and extending life of composite structures. The worldwide increase of composites usage is accompanied by an equal increase of composite waste. While there are many reasons for discarding composite components, a primary reason is damage, with interlaminar failure being particularly common. A novel Multi-Matrix Continuously-Reinforced Composite (MMCRC) repair methodology is proposed, which incorporates repairable vitrimer resin. The procedure enables interlaminar failure repair without utilizing typical patch repair, that introduces additional damage. To achieve this a vitrimer matrix is incorporated into the damaged-prone region at the manufacturing stage. Interlaminar failure is then established and repaired using vacuum pressure and heating using an oven. With an eye to real-world application (where removing a part to be placed in an oven may not be possible), repair was also conducted utilizing localized induction heating. Both methods successfully repaired the interlaminar failure, recovering the initial strength and generating an average performance of 167% compared to the intact sample. The reasons for the increased performance are described in detail, which lead to the conclusion that the feasibility of incorporating reparable regions at the manufacturing stage has been demonstrated successfully. It is shown an interlaminar failure repair can be achieved using a less detrimental and time-consuming processing than traditional repair methodologies.