---

In this paper, a new model for estimation of the electrical conductivity of polymer carbon nanotube (CNT) nanocomposites based on the conventional power-law model and Halpin-Tsai formulation has been proposed. Halpin-Tsai model was originally presented to calculate the tensile modulus of composites, which can be modified for estimation of the electrical conductivity by replacing the electrical parameters. The nature of “b” exponent in power-law model is defined according to CNT dimensions, CNT electrical conductivity and the interphase thickness and also the impacts of these parameters on the “b” and the electrical conductivity of nanocomposite are taken into consideration. The developed model interprets that the electrical conductivity of polymer-CNT nanocomposite increases as the concentration, length and electrical conductivity of CNT and the interphase thickness increase. Furthermore, reduction in CNT diameter and waviness results in growth of nanocomposite electrical conductivity. In order to validate the developed model, nanocomposite samples with different volume fractions were produced by solid-state technique of the melt-blending method. The results of calculations and experimental procedure show good agreement.