Improved interfacial adhesion of epoxy composites by grafting porous graphene oxide on carbon fiber

The fiber-matrix interphase governs the performance of composites. Herein, porous graphene oxide (prGO) was innovatively employed as active nanoscale reinforcement for the chemical grafting onto the carbon fiber to improve the interfacial adhesion, owning to its large surface area, anti-restacking ability and different chemical functionalities from GO. The obtained prGO/fiber hybrid reinforcement presents 110.4 MPa of interfacial shear strength, respectively 78.64 % and 22.53 % superior to those of untreated fiber (61.8 MPa) and GO/fiber reinforcement (90.1 MPa). The increase is mainly ascribed to the formation of rich interfacial interactions (covalent bonds, electrostatic adherence and hydrogen bonds) in virtue of the synergism of polyethylenimine (PEI), the improved surface energy and the wettability of prGO/fiber with epoxy resin. In addition, a "rigid-soft" transition zone formed by prGO and PEI for stress dissipation also contributes the improvement in interfacial adhesion. The advantages of prGO displayed in this paper provides more access to further gain composites with great interfacial bonding via in-depth and meticulous design of prGO.