Effect of rare earth surface modification of carbon nanotubes on enhancement of interfacial bonding of carbon nanotubes reinforced epoxy matrix composites

Rare earth (RE) lanthanum chloride was used to modify carbon nanotubes (CNTs) to obtain rare earth modified carbon nanotubes (RECNTs). The modified CNTs were characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results show that RE has a significant effect on improving the surface activity of carbon nanotubes. Through the chemical function of RE, the CNTs were successfully grafted with functional groups such as amino groups and carboxyl groups. This method can be used to connect any oxygen- or nitrogen-containing functional groups to the CNTs according to actual needs. Then, the modified CNTs were incorporated into epoxy resin (EP) to prepare composite (REACNTs/EP). The mechanical properties of the composites were tested by Zwick/Roell Z100 and Zwick/Roell Z20 test machine, and the tensile fractural sections were analyzed by scanning electron microscopy, and compared to the composites prepared with untreated CNTs (CNTs/EP), acidified carbon nanotubes (ACNTs/EP), acidification and RE synergistic modification of carbon nanotubes (REACNTs/EP). The results show that the ultimate tensile strength and tensile modulus of RECNTs/EP were increased by 33.9%, 73.7%, respectively, compared with pure EP, while the properties of REACNTs/EP were increased by 50.7%, 90.9%, indicating that RE has excellent effect on improving the mechanical properties of carbon nanotube-reinforced composites.