Influence of the pressure-dependent contact area between electrode and composite surface on the electrical conductivity

In this work, the influence of the pressure-dependent contact area between electrodes and surfaces of the composite samples on the electrical conductivity of polymer/carbon black composites was investigated. It was found that the electrical conductivity depended on the pressure (P) applied by the testing device and the carbon black concentration (ϕ). Meanwhile, the logarithm of electrical conductivity exhibited a linear relationship with ϕ-1/3 regardless of the pressures. Furthermore, it was found that the electrical conductivity σ showed a specific relationship (logσ(P)=kP-1+logb) in the pressure range investigated regardless of the concentration. Based on this correlation, the maximum (true) electrical conductivity of the composite samples at a given concentration for infinite pressure can be revealed by extrapolation. Thus, a novel approach is given to eliminate strong variations in electrical conductivity measurements on composites due to imperfect contacts.