Applicability of interface spring and interphase models in micromechanics for predicting effective stiffness of polymer-matrix nanocomposite

Abstract Using a multiscale modeling framework that combines molecular dynamics (MD) simulation and micromechanics-based homogenization method, the effective elastic properties of polymer-matrix nanocomposites are predicted for a wide range of interfacial bond stiffness (energy). We consider the homogenization method with two interface models, the interface spring model and interphase model, to account for the interfacial effect, and test the validity of both models by comparing them to the finite element analyses. We then calculate the bulk moduli of Nylon6 (matrix)–SiC (nanoparticle) nanocomposite using MD simulations by varying the interfacial bond stiffness and size of the SiC nanoparticle. By comparing the bulk moduli from MD simulations with the theoretical predictions from the homogenization method, we find the interfacial bond stiffness range within which each interfacial model is relevant. We also investigate and explain the effect of particle size on the effective material properties at different interfacial bond stiffnesses. The effect of interphase and interfacial imperfection (damage) observed from the MD simulation on the effective properties are analyzed. Finally, we predict the effective properties of the Nylon6-SiC nanocomposite by varying the level of SiC particle agglomeration and study how the effect of agglomeration changes over the interfacial bond stiffness.