VISCOELASTIC COEFFICIENTS OF GLASS-FORMING NEMATICS

In this paper, we report measurements of the viscoelastic properties of nematic liquid crystals which exhibit a glass transition in the nematic phase. We have studied the Freedericksz transition in planar cells with a magneto-optical method. K1 was determined from the critical field, and the rotational viscosity, gamma-1, from the response time for the director orientation by the external field. We found a temperature dependence of gamma-1 of the Vogel type, with absolute values ranging over several orders of magnitude, and K1 values similar to those of conventional thermotropic low molar mass nematics.