Investigating local mechanical properties of polyimide in graphite/polyimide nanocomposites

This study aims to investigate the local mechanical properties of polyimide near the graphite sheet in the graphite/polyimide nanocomposites. The atomistic structure of the nanocomposites with minimized energy was created after performing NVT ensemble in the molecular dynamics (MD) simulation. In order to understand the influence of graphite on the molecular configuration, the corresponding density and order parameter of the polyimide near the graphite/polyimide interface were evaluated and the results were compared with the bulk value. In addition, the local mechanical property of polyimide polymer was evaluated based on the characterization of local stress distribution. Results indicated that there is a glassy layer of polyimide formed in the vicinity of graphite sheet. Within the adsorption layer, it was found that the polyimide chains are stacked compactly and oriented along the graphite surface so that the corresponding density is fairly high. Moreover, the polyimide near the graphite/polyimide interface exhibit higher stress state, which clearly illustrates the local mechanical property of polyimide close to the interface could be moderated dramatically by the graphite sheet.