Biobased Epoxy for Recyclable and High-Performance Fiber Reinforced Composites

Fiber-reinforced polymer composites (FRPCs) are widely used in aerospace and lightweight automotive materials, and renewable energy due to their exceptional strength-to-weight ratio. Epoxy resins, the most common matrices in FRPCs, offer excellent mechanical performance but suffer from two major drawbacks: their thermoset nature makes composites unrecyclable, preventing fiber recovery, and their petroleum-derived origin raises environmental and sustainability concerns. In this work, we developed a biobased epoxy resin which incorporated dynamic covalent bonds, synthesized from l-malic acid and sorbitol polyglycidyl ether, and applied it to the fabrication of FRPCs. The resulting resin and its composites exhibited outstanding mechanical performance, comparable to or even surpassing those of conventional petroleum-based systems. More importantly, the reinforcing fibers (carbon and basalt fibers) were fully recovered through a solution-based process and reused to fabricate next-generation FRPCs without loss in mechanical performance. Furthermore, the recovered resin solution could be directly reused for photocuring-based 3D printing without additional purification or separation steps.