Multiscale strategy to predict the fracture toughness and crack extension behavior of ozone-functionalized carbon nanotube/epoxy nanocomposites

Ozone-functionalized carbon nanotubes (OCNT) are increasingly being used as reinforcing agent in polymer nanocomposites, it is crucial to understand their fracture behavior and develop predictive models. Here, a multiscale analysis strategy to assess the fracture toughness (FT) and crack extension behavior of OCNT/epoxy nanocomposites owing to CNT bridging (pull-out of CNTs and rupture of CNTs) and interfacial debonding mechanisms (CNT debonding and plastic yielding of voids) is presented. The multiscale analysis strategy was based on molecular dynamics (MD) simulations, molecular mechanics (MM), the linear fracture mechanics theory, and the phase-field fracture model. The multiscale strategy assessment results indicate that the high degree of functionalization (DoF) of the OCNTs effectively improve the interfacial interactions, thereby pro-moting the FT enhancement and crack extension resistance behavior of the OCNT/epoxy nanocomposites via the CNT bridging mechanism. Meanwhile, the plastic yielding of voids is considered to play a significant role in the FT enhancement of polymer nanocomposites containing small-radius CNTs. It is expected that the results of this study will elucidate the complex phenomena in the FT and crack extension behavior of OCNT/epoxy nano -composites and provide an efficient prediction strategy.