Transient Conduction of Weakly Dissociating Species in Dielectric Fluids

The steady‐state and transient conductivities of solutions of an ionic surfactant in a dielectric fluid were investigated experimentally over a wide range of applied voltages for various cell thicknesses. The observed nonlinear dependence of steady‐state current density on applied field suggests the importance of dissociation‐recombination processes in the bulk. The transient current response was found to depend markedly on the applied voltage conditions. On the first application of a field a steadily decreasing current was observed; reversing the polarity of the applied field produced a well‐defined current peak. The peak times are not directly proportional to cell thickness or to the inverse of the applied field. Transient current behavior indicates a complex transport process involving bipolar ionic conduction in the bulk. In addition, conditions where space charge and electrohydrodynamic effects influence the transients are identified. The observed behavior is characteristic of many systems of weakly dissociating species in dielectric fluid.