Study on Key Technologies of Graphene Toughened Carbon Fiber Composites at Ningbo Materials

Carbon fiber composites are used in aerospace, automotive, marine, energy, construction and other fields due to a series of features such as light weight, high strength, fatigue resistance, corrosion resistance, and strong designability. However, due to the smooth surface, inertness, and chemically active functional groups of the carbon fiber, the interfacial bonding strength between the carbon fiber and the matrix resin is low, and there are many defects at the interface, which often becomes a weak link of the composite material. The intelligent manufacturing and equipment team of composite materials of the Advanced Manufacturing Institute of Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences has made new progress in the key technologies of graphene toughened carbon fiber composites.

In previous studies, it was found that the grafting of graphene nanoparticles onto carbon fiber surfaces can effectively improve the interface properties of carbon fiber composites (ACS Applied Materials & Interfaces, 2012, 4, 1543). In order to realize a large-scale route of graphene-modified carbon fiber, a graphene modified sizing agent is used to modify the surface of the carbon fiber to improve the interface properties of the carbon fiber composite material. The researchers prepared graphenes that can be stably dispersed in both aqueous solution and sizing agent by modifying the surface of graphene. By modifying the size of graphene, surface-modified graphene was prepared (Figure 1). It can be stably dispersed in different sizing agent systems, and successfully achieved the stable dispersion technology of graphene in sizing agent. Two kinds of graphene modified sizing agents with good stability were successfully developed by the inverse conversion method and self-emulsification method (Fig. 2), and the interfacial adhesion performance of carbon fiber composite materials was effectively improved, and the interface shear strength ( IFSS) can reach 92.3 MPa (Fig. 3), and the sizing rate of carbon fiber is less than 1.5%, and the saturated water absorption is less than 2%. The graphene toughened carbon fiber was used to optimize the processing and molding process conditions. A graphene-strengthened and toughened carbon fiber composite material with excellent overall performance was obtained. The interlaminar shear strength of the composite material was as high as 73.5 MPa; the increase in fracture toughness between the I-type layers was 33.3. %. This R&D result has applied for an invention patent (CN 201610296461.7).

The above work has received strong support from Ningbo Graphene Major Science and Technology Project (2014S10004).