Investigating the stress distribution of single walled carbon nanotubes embedded in polyimide nanocomposites

The stress distribution of CNTs embedded within polyimide matrix subjected to applied loading was investigated using molecular dynamics simulation. The purpose of evaluating the stress distribution of CNTs is to characterize the loading transfer efficiency between the nano-reinforcement and surrounding polyimide matrix, which basically is an essential factor controlling the mechanical properties of nanocomposites. Three different interfacial adhesions between the CNTs and polyimide molecular were considered, that is, vdW interaction, CNTs with surface modification, and covalent bond. The stress distribution of the CNTs was calculated by using the Lutsko atomistic stress formulation^1,2 and by taking the derivative of the potential functions as well. Results revealed that when the CNTs surface was modified, the higher load transfer efficiency from the polyimide to the CNTs was observed resulting in the higher modulus of the nanocomposites. It is noted that, if no surface modification on CNTs, the load transfer efficiency which basically depends on the intensities of the vdW interaction is relatively low. As a result, the surface modification on CNTs is an effective manner to improve the load transfer efficiency as well as the modulus of nanocomposite, which should be suggested in the fabrication of CNTs nanocomposites.