Micromechanical behaviour of particulate polymer nanocomposites

A large number of works deal with material synthesis and characterization of polymer nanocomposites due to their improved thermo-mechanical properties, but the fundamental mechanisms for mechanical property enhancement are not yet completely defined. In particular, a special class of polymer/organoclay nanocomposites has been observed to exhibit an impressive improvement in different types of properties, physical and chemical ones. In the present work, a model is presented and applied to formulate the elastoplastic response of epoxy/clay nanocomposites, experimentally tested elsewhere. The model based on Mori-Tanaka theory, for the estimation of the elastic stiffness tensor for composite materials, is combined with the self-consistent model of Budiansky and Wu, valid for crystal plasticity. Then the macroscopic plastic response of the heterogeneous material is linked with the microstructural parameters, i.e., the plastic behaviour of the effective particle. The model was proved to successfully describe the tensile response of the epoxy/clay nanocomposites with varying clay weight fraction.