Influence of ozone functionalization of carbon nanotubes on the fracture toughness improvement of polymer nanocomposites: A multiscale study

Abstract

In this study, we developed a multiscale modeling framework for predicting the fracture toughness improvement of ozone functionalized carbon nanotubes (O-CNTs)/epoxy nanocomposites (NCs) due to debonding of O-CNT and plastic void growth. The proposed multiscale modeling framework was developed by combining molecular dynamics (MD), mean field (MF) homogenization and fracture mechanics theory. Based on this multiscale modeling framework, the contribution of O-CNTs to the interphase elastoplastic properties was characterized and the fracture toughness improvement was quantified through the degree of functionalization of O-CNTs at the microscale. The results demonstrated that increasing the functionalization degree of O-CNTs could effectively improve the elasticity properties of the interphase and fracture toughness of O-CNTs/epoxy NCs. We demonstrated that the interfacial fracture energy is more important compared to the elastoplastic properties of the interphase for improving the fracture toughness of O-CNTs/epoxy NCs. The multiscale modeling framework proposed in this study revealed the dependence of fracture toughness improvement on the functionalization degree of O-CNTs at the theoretical level, where a reference guide was provided for the rational design of composite structures in experiments.