Additive manufacturing of continuous carbon fiber reinforced two-component thermosetting epoxy resin E−20/E−51 composites

Additive manufacturing of continuous carbon fiber reinforced thermosetting epoxy resin composites has been widely investigated due to their lightweight properties and structural customizability. However, the adoption of a single solid epoxy resin usually results in poor prepreg impregnation and low mechanical strength, thereby limiting its further application. In this work, epoxy resin E−51 is introduced as a secondary component and blended with solid resin E−20 in different ratios as a resin matrix for prepregs is used to solve the problem of high viscosity and low flexural strength of a single resin. The results show that the viscosity of two-component epoxy resin was reduced by 25.7 %–56.7 % compared to pure E−20 at specific processing temperatures. Furthermore, a reasonable curing process parameters of 170 °C for 2h was determined based on the Kissinger and Crane methods. Additionally, the optimal printing parameters of 1.0 mm for hatch spacing and 0.5 mm for layer thickness were gained for the Fused Filament Fabrication (FFF), and the flexural strength and flexural modulus of the printed two-component resin specimens are 941.55 MPa and 64.38 GPa, respectively, which are 43.64 % and 14.88 % higher than those of pure E−20 specimens. Finally, it was demonstrated that the addition of epoxy E−51 improved fiber impregnation and increased crosslink density. This work provides an efficient method and guidance to improve the mechanical properties of FFF printed continuous fiber reinforced thermosetting epoxy resins, which is expected to further broaden their potential applications in the aerospace and defense industries.