Simultaneously tuning interfacial and interlaminar properties of glass fiber fabric/epoxy laminated composites via modifying fibers with graphene oxide

A series of graphene oxide (GO) with various oxidation degrees were synthesized in this work and then grafted onto the surface of glass fiber fabric (GFf), and subsequently a resin infusion process was engaged in the fabrication of GFf/epoxy laminated composites. Interlaminar and interfacial properties as well as interlaminar microstructure of laminated composites were investigated in detail. Results showed that various oxygencontaining functional groups on the GO surface due to oxidation degrees endowed GO with different dispersion states in composites and strengthening/toughening efficiency, thus greatly influenced composites' interlaminar and interfacial adhesion. Also, the desorption and diffusion of GO from the fiber surface into matrixenriched interlaminar region during the resin infusion process were evidenced. Making use of a moderate weight ratio of oxidation agent (KMnO4)/graphite (2:1), the optimal oxidation degree of GO was achieved for reinforcing fiber/matrix interface and matrix-enriched interlaminar regions. Under this case, the interlaminar shear strength and work of fracture of resultant composites were raised by 28.2% and 138.3%, respectively; storage moduli in glass regions and at the beginning of rubbery regions were enhanced by 22.3% and 104.5%, respectively; the significantly fiber/matrix interfacial adhesion and glass-transition temperature were obtained, compared with those of the control sample. This work provides a guiding strategy for optimizing strength and toughness of fiber-reinforced composites by regulating GO oxidation degrees.

Automated summary

In this study, graphene oxide (GO) with different oxidation degrees was synthesized and grafted onto the surface of glass fiber fabric (GFf) for the fabrication of GFf/epoxy laminated composites. The interlaminar and interfacial properties as well as interlaminar microstructure of the composites were investigated. The results showed that the dispersion state and strengthening/toughening efficiency of GO in the composites were influenced by the various oxygen-containing functional groups on the GO surface due to oxidation degrees, thus affecting the composites' interlaminar and interfacial adhesion. The optimal oxidation degree of GO was achieved by using a moderate weight ratio of oxidation agent (KMnO4)/graphite (2:1), which improved the interlaminar shear strength, work of fracture, storage moduli, fiber/matrix interfacial adhesion, and glass-transition temperature of the composites.