Chemical recycling of carbon fibre/epoxy composites in a mixed solution of peroxide hydrogen and N,N-dimethylformamide

A two-step method to recycle high-quality carbon fibres (CFs) from carbon fibre/epoxy (CF/EP) composites in high yield under mild conditions was reported in this paper. Firstly, the composites were pretreated in acetic acid to be expanded and be layered to get larger surface area. Secondly, a synergistic oxidative degradation system is supposed to recover CF, which is a mixed solution of peroxide hydrogen (H2O2) and N,N-dimethylformamide (DMF) in a hermetic reactor. The structure and properties of recovered CFs were investigated. The results showed that clean CFs can be successfully recycled after the pretreated composites was treated at 90 °C for 30 min in a solution of H2O2/DMF (1:1, v/v). The decomposition ratio (Dr) of EP in composites was more than 90%. The surface of the CFs was smooth with few residues of EP observed by scanning electron microscope (SEM). The degree of graphitization of recovered CFs was decreased slightly tested by using Raman and X-ray diffraction (XRD) spectrum. The tensile strength of the recovered CFs was more than 95% of the virgin ones’ according to the single fibre tensile test.