Numerical-experimental estimation of the mechanical properties of an epoxy nanocomposite

The possible reasons for the violation of additivity laws for the density and elastic modulus of polymer nanocomposites (epoxy resin filled with silicon oxide nanoparticles) are considered. The fact that each nanoparticle is surrounded by a distinctive boundary layer is used to describe this phenomenon. The thickness and density of the layer are determined by measuring the density and elastic modulus of a polymer with different volume fractions of filler. A model for determining the strength of an epoxy nanocomposite by using the theory of short fibers is proposed. This model allowed us to describe the nonmonotonic relationship between the ultimate strength of the epoxy nanocomposite and the volume fraction of filler. It is shown that the filling of epoxy resin with silicon oxide nanoparticles beyond 5 vol. % decreases the strength of the composite in comparison with that of pure epoxy resin.