The AC and DC Conductivity of Nanocomposites

Abstract

The microstructures of binary (conductor-insulator) composites, containing nanoparticles, will usually have one of two basic structures. The first is the matrix structure where the nanoparticles (granules) are embedded in and always coated by the matrix material and there are no particle-particle contacts. The AC and DC conductivity of this microstructure is usually described by the Maxwell-Wagner/Hashin-Shtrikman or Bricklayer model. The second is a percolation structure, which can be thought to be made up by randomly packing the two types of granules (not necessarily the same size) together. In percolation systems, there exits a critical volume fraction below which the electrical properties are dominated by the insulating component and above which the conducting component dominates. Such percolation systems are best analyzed using the two-exponent phenomenological percolation equation (TEPPE). This paper discusses all of the above and addresses the problem of how to distinguish among the microstructures using electrical measurements.

Effect of Filler Orientation on the Electrical Conductivity of Carbon Fiber/PMMA Composites

“…For composites with filler fractions ϕ > ϕ c , the experimental results are fitted by plotting log (σ) against log (ϕ − ϕ c ) and regulating ϕ c until the best linear fit is obtained. Another model is the general effective medium (GEM) equation presented by McLachlan [9]:…”

“…The volume fraction of CFs is denoted ϕ and the percolation threshold ϕ c . For 3-D systems [9], the exponential factors are generally set to s = 0.87 and t = 2. Chopped CFs with high aspect ratio (AR = length/diameter) is one of the most widely used conductive fillers.…”

Universal and Anisotropic Simulation Platform for the Study of Electrical Properties of Conductive Polymer Composites

“…The ordinate axis shows the number of elements, and the abscissa shows the ratio of current mesh quality and the smallest mesh quality [25]. For the 3D model, it could also be approximated as the reciprocal of the ratio of the minimum element volume to the current element volume.…”

Tunneling and percolation transport regimes in segregated composites

“…In compacted mixtures of micrometric conducting and insulating powders [5][6][7][8] the electrical connectivity is established by direct contact connections between the conducting particles [4]. In this situation, σ displays an insulator-conductor transition when the concentration φ of the conducting phase is such that a macroscopic cluster of connected particles spans the entire sample, allowing the charge carriers to flow between the electrodes.…”