Behavior of a Deionized Liquid Crystal Subjected to Unipolar Injection in Nematic and Isotropic Phase

Electrohydrodynamic phenomena in insulating MBBA subjected to unipolar injection of ionic carriers are described. Near the transition temperature, the transient currents following a voltage step were similar in the nematic and isotropic phases, over a wide range of voltages and electrode separations. High-speed cinematography, Schlieren techniques, and the Kerr effect were resorted to in this investigation. Liquid motion was observed having a time lag and exhibited patterns closely similar to those previously observed in isotropic polar liquids. The velocities of hydrodynamic disturbances and of space-charge fronts varied over a broad range, depending on experimental conditions.