Two-step multiscale homogenization for mechanical behaviour of polymeric nanocomposites with nanoparticulate agglomerations

A multiscale analysis is performed to investigate the effect of nanoparticulate agglomeration on the mechanical properties of polymeric nanocomposites. The percolated interphase model is applied to consider the degradation of the elastic properties of the interphase zone caused by nanoparticulate clusters. Through parametric studies on various agglomeration states, we propose a new index called the 'clustering density', which indicates the degree of nanoparticulate agglomeration. As the clustering density increases, a significant degradation in the stiffness of the nanocomposites is observed from 10 to 30%. An efficient two-step homogenization method is proposed in the present study to effectively analyse large size representative volume elements (RVE) containing multi-clusters and free nanoparticles. The proposed computational scheme is based on multiscale homogenization and the clustering density concept. It is concluded that the two-step homogenization approach can provide accurate prediction of the mechanical properties of nanocomposites with heterogeneity from nano particle agglomeration with high computational efficiency.