Reformable and sustainable thermosetting carbon fiber composites from epoxy vitrimer

Vitrimers are an emerging class of thermosetting materials that undergo reversible dynamic covalent bonding to enable thermoplastic-like repair, joining, and recycling that is currently inaccessible to traditional thermosets. This work demonstrates the production of sustainable recycled carbon fiber/epoxy based vitrimer composites. A method of preparing B-staged vitrimer films enabled infusion of the vitrimer into a fibrous preform using scalable compression molding techniques to form fully cured, room temperature stored organosheets that were then consolidated into laminates. The influence of consolidation time on the thermo-mechanical properties of the resulting composites was evaluated using several techniques. Short beam strength testing was used to evaluate the interlaminar properties of the composites and assess the repairability of tested specimens. Additional processing time was shown to stiffen the materials at room temperature, due to thermo-oxidative crosslinking as opposed to further thermal cure. This led to an initial improvement in the short beam strength, but a reduction in energy absorption and ductility. The results of this work show that vitrimer composites may be effective in extending the life of in-service composite structures by mitigating or repairing damage.