Improved Mechanical and Thermal Performance of Carbon Fiber/Epoxy Composites by In Situ Grown ZIF-90 Interface

Abstract

As microscale fillers, short-cut carbon fibers (CF) significantly enhance the mechanical and functional performance of lightweight, high-specific-strength, high-specific-stiffness carbon fiber/epoxy composites used in aerospace, automotive manufacturing, and other industries. Postcarbonization carbon fibers’ high graphitization, low surface energy, smoothness, and inertness cause poor epoxy (EP) reactivity, leading to brittleness, weak interfacial adhesion, and debonding that limit practical applications. To address these issues, carbon fiber-reinforced epoxy composite was designed and synthesized in this study. CF was surface-modified with ZIF-90, a metal–organic framework (MOF) material, and then composited with commercially available E51 epoxy resin. The introduction of ZIF-90 not only increased the surface roughness and active sites of carbon fibers but also participated in the curing and cross-linking reaction of EP, strengthening the interfacial interaction. The results show that the tensile strength of the composite is improved from 35.03 to 53.20 MPa, with an increase of 51.84%, and the elastic modulus is increased from 1979.07 to 2351.34 MPa, with an increase of 18.81%, indicating significantly enhanced mechanical properties. The average storage modulus (E′) of the composite is increased by 17.5% compared with the neat resin, benefiting from strong interfacial interaction. Finally, the curing kinetics of the composite was systematically investigated. This work confirms the feasibility of using ZIF-90 as a carbon fiber coating material to improve the overall performance of composites and provides a different direction for the selection of surface modification materials for advanced composites.