Electrical and thermal conductivities of a silver flake/thermosetting polymer matrix composite

The electrical and thermal conductivities of a silver flake/thermosetting polymer matrix composite were studied experimentally and analytically in terms of silver flake size and size distribution. The electrical volume resistivity and the steady-state thermal conductivity of the composite were measured at various silver flake loading. The analytical study was based on a three-dimensional resistor network model, which takes into account percolation and microscopic conduction mechanisms. The predictions based on the resistor network model were compared with the experimental data, resulting in a reasonably good agreement. It was found that flakes with smaller mean value in size and broader size distribution yield smaller threshold volume fraction of silver flake. It was shown that the predictions by the present thermal resistor network model yields better agreement with the experimental data than those by the effective medium theory such as Eshelby’s model, for a composite with high thermal conductivity ratio of filler to matrix.