Electrical Conductivity of Carbon Nanotube- and Graphene-Based Nanocomposites

Abstract

Carbon nanotube- and graphene-based polymer nanocomposites are known to have exceptional electrical conductivity even at very low filler loading. In this chapter we present a widely useful composite model for studying this property. This model has the capability of determining both the effective electrical conductivity and the percolation threshold of the nanocomposites. It also embodies several other important elements of the process of conduction, including filler loading, filler agglomeration, anisotropic property of carbon fillers, effect of imperfect interfaces, and the contribution of electron tunneling. The backbone of the model is the effective-medium theory with a perfect interface; it can demonstrate the percolation feature and can also comply with the Hashin-Shtrikman bounds. To study the influence of filler agglomeration, a two-scale approach is further proposed. The imperfect interface is incorporated into the model by the introduction of a thin, weak interface surrounding each inclusion. To account for the effect of electron tunneling, Cauchy’s statistical distribution function is further introduced to reflect the increased activity of electron tunneling at and after the percolation threshold. It is demonstrated that the theoretical predictions based on the developed model are in close agreement with available experimental data.