A novel and facile fabrication of polyphosphazene nanotube/carbon fiber multi-scale hybrid reinforcement and its enhancing effect on the interfacial properties of epoxy composites

The mechanical properties of carbon fiber (CF) reinforced composites are greatly dependent on the interfacial adhesion between fiber and resin matrix. Introducing nanoscale reinforcements into the interface is an effective approach to improve the interfacial adhesion of CF composites. In this paper, we proposed a facile and effective method for assembling poly(cyclotriphosphazene-co-4,4'-sulfonyldiphonel) nanotube onto CF surface as a novel multi-scale hybrid reinforcement through in situ template polymerization. The effects of surface modification on the surface and interface properties of CF and the resulting composite were investigated. After modification, the interfacial shear strength of fiber reinforced epoxy composites showed an increase of 26.4%. The reinforcing mechanisms were also analyzed, and the improvements on interfacial properties should mainly be attributed to mechanical interlocking effect. In addition, the modification even improved the fiber tensile strength by 6.6-16.3%, rather than deteriorating it.