Enhancing the interfacial strength of carbon fiber reinforced epoxy composites by green grafting of poly(oxypropylene) diamines

We report on a green method of using poly(oxypropylene) diamines (D400) as coupling and curing agent to functionalize carbon fiber in water. We propose to enhance the interfacial properties of carbon fiber composites, together with the tensile strength of carbon fibers. The microstructure and mechanical properties of carbon fibers before and after modification are investigated. The results show that D400 do not change the surface morphology, but significantly increase the polarity, wettability and roughness of the carbon fiber surface. The interfacial shear strength (IFSS) of modified carbon fiber/epoxy composite and the tensile strength of carbon fibers increase by 79.1% and 8.2%, respectively. It is believed that D400 can effectively improve the interfacial adhesion of the composites by improving resin wettability, increasing chemical bonding and mechanical interlocking. This green and simple method can have applications in continuous production of high-performance carbon fiber composites.