Anisotropy study of electrical conduction in oriented polymers. I. Analysis of bulk electrical conduction parallel to the surface of film

A method of measuring current flow parallel to the film surface which is related to bulk conductivity is developed in the case of a four-electrode system attached symmetrically on both sides of a film. Two-dimensional analysis is carried out for potential and current distribution in the film with realistic boundary conditions. An apparent conductivity parallel to the film surface is defined using electrode geometry, applied potential, and total current. A relation between the apparent and the true conductivities of the film is obtained theoretically as a function of electrode geometry and is compared with the experimental results. It is shown that there is a good coincidence between them in the case where the thickness of the film is larger than the gap between the electrodes. With the aid of the method proposed here, it becomes possible to measure the anisotropy of conductivity in films.