High-performance, semi-bio-based degradable epoxy resins and their application to recyclable carbon fiber composites

Epoxy resins containing dynamic covalent networks enable recycling of carbon fiber composites. However, the simultaneous realization of high performance and mild condition recycling of composites is still a challenge. In the present work, we mixed citric acid epoxy resin with bisphenol A epoxy resin to form a hybrid resin (DER) that meets the requirements of medium temperature curing epoxy resin, and prepared a carbon fiber reinforced resin composite material (DER@CF) that can rapidly degrade and recycle carbon fibers under mild conditions. The T_g of the DER was 125.67 °C, and the tensile strength (79.63 MPa) was comparable to that of the bisphenol A epoxy resin (79.90 MPa). It degraded rapidly after 2 h in ethylene glycol solution at 120 °C. The tensile strength of DER@CF was 825 MPa, and clean fibers could be obtained after 8 h of treatment in ethylene glycol solution at 120 °C. The results of SEM, Raman and tensile tests showed that the recycled fibers were similar to the original fibers in terms of morphology, chemical structure and mechanical properties. © 2024 Society of Chemical Industry.