MEASUREMENT OF THE VISCOSITY OF FERROELECTRIC LIQUID-CRYSTALS IN FREESTANDING FILMS

A new implementation of the technique for the measurement of the Golds tone mode rotational viscosity in the S-C phase is presented. An elec tric field is applied parallel to the surface of a free-standing liqui d crystal film. The optical transmission change of the film is recorde d. The viscosity can be calculated from the reorientation time between optically separated positions of the director. A comparison with the viscosity values measured in thin cells is given. The values determine d in cells are always higher than the results obtained from free-stand ing films. This indicates the great influence of the forces of interac tion between the liquid crystal molecules and the surface layer in the cells.