A novel MD-based procedure to obtain the interphase Young’s modulus in nanocomposites

Abstract

Previous numerical and experimental investigations have shown that the performance of polymer-based composites is greatly affected by properties of the interphase region and its geometrical characteristics. Although, it has been well-established that there is a gradient in the interphase elastic constants, no full atomistic molecular dynamics (MD) based work has been done to capture this, yet. Therefore, the focus of this study is to develop a novel MD-based procedure to attain the changes in the Young’s modulus of the interphase and thus, its mean value in graphene/polymer nanocomposites. To this end, knowing the existence of a correlation between the polymer density and its modulus, first, the radial distribution function (RDF) of polymer atoms with respect to graphene ones is captured to find the density gradient in the interphase. Then, distinct computational cells having pure polymer at different densities are constructed to resemble the various interphase zones. Finally, conducting proper uniaxial tensile tests on these cells, the Young’s modulus of each interphase zone is obtained and implemented in an average method to compute the overall interphase modulus. The trend predicted by this method for variations in the interphase properties and its thickness is completely in good agreement with the available experimental results.