Fabrication and closed-Loop recycling process of novel high strength and toughness carbon fiber-reinforced thermoplastic epoxy composites

Carbon fiber-reinforced epoxy composites are widely used in engineering applications owing to their excellent specific strength, modulus and cost performance. However, the brittleness and poor recyclability of the thermosetting epoxy matrix severely limit their sustainability. In this study, bisphenol A-type epoxy resin and bisphenol A were used as raw materials, and a 2-methylimidazole/tetrabutylammonium bromide catalytic system was employed to successfully prepare a high strength and toughness thermoplastic epoxy resin (TPE) via solution polymerization. The resulting TPE exhibited a weight-average molecular weight ( M w ) of 43078 g/mol and a polydispersity index of 1.29. In addition, the TPE exhibited outstanding mechanical and thermal performance, with high tensile strength of 76 MPa, toughness of 30.7 MJ m −3 and T d5% of 423  ° C. Carbon fiber-reinforced thermoplastic epoxy composites (CF/TPE) were fabricated via the prepreg compression molding process. The CF/TPE composites exhibited a tensile strength of 1022.7 MPa, flexural strength of 1042.5 MPa and interlaminar shear strength (ILSS) of 65.2 MPa. The TPE matrix can be efficiently dissolved in polar solvents, enabling the intact recovery of both carbon fibers and the TPE matrix. This approach provides a TPE to replace conventional thermosetting epoxy while also enabling an effective preparation-recycling route for sustainable use of carbon fiber composites.