Rheological and Shear-modified Dielectric Properties in Ferroelectric Liquid Crystal 8OBE

Abstract

Rheological properties, including the electrorheological effect, and the dielectric behaviors under steady shear flow are examined in the chiral smectic C (S_C^*) and the chiral nematic (N^*) phases of 4-n-octyloxyphenyl-4-(2"-methylbutyl) biphenyl-4'-carboxylate (8OBE). In the S_C^* phase the viscosity decreases linearly with increase in temperature, and above the S_C^*- N^* phase transition point TCN, it gradually decreases to lower values in the N^* phase. The flow in the S_C^* phase is non-Newtonian, which is in contrast to the Newtonian behavior in the N^* phase. The application of the electric field causes some increase in the viscosity in the S_C^* phase. These rheological and the simultaneously measured dielectric properties are discussed on the basis of the directional changes of the director and the smectic layer.