Single-component and fast-curing epoxy resin for liquid composite molding processes

Development of single-component and fast-curing epoxy resins is highly desired for many industry applications. In this work, we report an epoxy system based on diglycidyl ether of bisphenol A (DGEBA) and 1-(2-cyanoethyl)-2-ethyl-4- methylimidazole (1C2E4MIM). The inductive effect of electron-withdrawing cyano group distinctly increases the latency of 1C2E4MIM without sacrificing the curing rate. The results of differential scanning calorimeter (DSC) and dynamic mechanical analysis (DMA) measurements indicate DGEBA/1C2E4MIM epoxy system can be fully cured in 15 min. The rheological, thermal and mechanical properties of DGEBA/1C2E4MIM epoxy system were studied in detail. The results show that the shelf life of this epoxy system is more than 4 days at room temperature and more than 6 months at -18 °C. The cured epoxy resins show high glass transition temperature (>155 °C), tensile strength (>80 MPa) as well as excellent moist heat resistance. Finally, carbon fiber-reinforced polymer composites (CFRPs) were fabricated using this epoxy system as matrix via vacuum assisted resin infusion (VARI) process. The mechanical properties of CFRPs, including tensile, flexural, compressive and interlaminar shear properties, were investigated