ELECTROOPTICS OF DISPERSED SYSTEMS .6. ELECTRIC BIREFRINGENCE OF NA-MONTMORILLONITE SUSPENDED IN WATER-ETHANOL MIXED-SOLVENT

In order to clarify the effect of ethanol on the electrooptic and hydr odynamic properties of Na-montmorillonite (Na-M), the transient and st eady-state electric birefringence (EB) of Na-M was measured in the wat er-ethanol mixed solvent system at a low particle concentration and at various ethanol contents. The hydrodynamic size of Na-M was decreased at ca. 10 vol% in EtOH content. This first EB attempt strongly suppor ts the notion that the Na-M layers are delaminated by the adsorption o f EtOH molecules onto the Na-M disk.