Prediction of elastic properties in polymer-clay nanocomposites: Analytical homogenization methods and 3D finite element modeling

Accurate predictive models can support the exploitation of Polymer-Clay Nanocomposites (PCN) in their evergrowing applications. The purpose of this paper is to validate commonly used analytical micromechanical models for the prediction of PCN's elastic properties with the help of 3D periodic Finite Element (FE) simulations of the same microstructures, considered as reference data. The effect of the interphase was taken into account in a two-step homogenization procedure that exploits the effective particle concept. The predictions of a range of procedures relying on the different micromechanical models (i.e. Mori-Tanaka, self-consistent and Lielens's) were tested. An elaborate series of FE simulations was performed to determine Representative Volume Elements (RVEs). In addition, a simplified procedure to guide the definition of the RVE based on statistical and transverse isotropy symmetry criteria was developed. The predicted elastic properties of PCN were studied as a function of the thickness and the elastic properties of the formed interphase around the nanoclay platelets. It was found that the Mori-Tanaka model was the most reliable method for the simulated cases. Furthermore, numerical model predictions were compared with experimental results extracted from the literature for aligned exfoliated Nylon-6 Montmorillonite nanocomposites. Finally, a comparison between the parametric study results and the experimental data was used to estimate the properties and the thickness of the interphase.