Characterizing interphase region in CNT/nylon-6 composites using molecular dynamics simulation

The load transfer mechanisms and effective mechanical properties of carbon nanotube (CNT)-reinforced polymer nanocomposites are strongly influenced by the interfacial region (interphase) between the embedded CNT and the polymer. In this article, elastic properties of an effective interphase present in nanocomposites are evaluated from molecular dynamics (MD) simulation studies of individual CNT, the polymer and the CNT/polymer nanocomposite. Different configurations of single-walled CNT are embedded in a nylon-6 matrix at different volume fractions of the CNT and the mechanical properties of the nanocomposites are evaluated. Subsequently, the elastic modulus of the interphase is evaluated using an inverse three-phase rule of mixtures, in which the volume fraction of the interfacial region is calculated based on the equilibrium van der Waals distance between the CNT and the polymer matrix. Based on the MD simulation results, a semi-empirical model has been developed to predict the effective interphase modulus for its applicability in continuum modelling of nanocomposites.