Modeling of effective elastic properties for polymer based carbon nanotube composites

Effective elastic properties of the nanocomposites filled with carbon nanotubes (CNTs)are investigated by the asymptotic expansion homogenization (AEH)method. In order to implement the homogenization method, a control volume finite element method (CVFEM)is employed in contrast to the previous studies. It is assumed that the nanocomposites have geometric periodicity with respect to local length scale and the elastic properties of nanocomposites can be represented by those of the representative volume element (RVE). Random orientation of the CNTs embedded in the nanocomposites is considered by using the orientation tensor. The effective elasticity tensor predicted by the homogenization method is compared with analytical and experimental results. In the experiment, the CNT surface is treated by oxygen plasma to improve interfacial bonding between the CNT and the matrix and to disperse the CNTs homogeneously in epoxy resin because the perfect interfacial bonding is presumed in the homogenization method. Homogeneous CNT dispersion is experimentally identified by the field emission scanning electronic microscope (FESEM). It is found that the numerically calculated elastic modulus is in good agreement with that obtained by analytic model.