Uniform growth of carbon nanotubes on carbon fiber cloth after surface oxidation treatment to enhance interfacial strength of composites

The uniform growth of carbon nanotubes (CNTs) on the surface of carbon fiber cloth (CFC) was carried out using quasi-vacuum chemical vapor deposition (CVD). It was found that the oxidation of CFC by H2O2 was critical to the uniform growth of CNTs. A large number of oxygen-containing functional groups were introduced on the surface of the fiber during oxidation, the content of activated carbon had increased by 27.06%, which could improve the wettability of the fiber and the binding property to the catalyst precursor. After prepared into composites, the interlaminar shear strength (ILSS) was increased by 6.28%, as measured by the short beam test. The analysis of the fracture surfaces revealed that the growth of CNTs enhanced the mechanical interlocking and improved the mechanical properties. For the CNTs-grown CFC/epoxy composite, the strength and toughness can be increased and the stress concentration can be reduced due to the long-distance diffusion of destructive cracks from the resin matrix to the carbon fiber. Finally, the mechanism of improvement in composite performance was explained from the perspective of multiscale enhancement.