Effect of nano-SiO2 modified emulsion sizing on the interfacial adhesion of carbon fibers reinforced composites

The influence of nano-SiO2 modified epoxy emulsion sizing on the interfacial adhesion properties of carbon fibers reinforced composites was investigated. The interfacial interaction between carbon fibers and the matrix was characterized by X-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM) and three-point short-beam shear testing. The results showed that the amount of hydroxyl groups was slightly increased on the carbon fibers surface after treatment with nano-SiO2 modified sizing. Compared to the unsized composites, the interlaminar shear strength (ILSS) values for the composites with unmodified sizing and nano-SiO2 modified sizing were increased by 9% and 14%, respectively. The holes and carbon fibers pullout were not observed in their fracture sections. Surprisingly, the fracture section of the composites with nano-SiO2 modified sizing was more compact and the fiber debonding was more difficult.