SOFT MODE DIELECTRIC RESPONSE AND ROTATIONAL VISCOSITY OF A FERROELECTRIC LIQUID-CRYSTAL POLYMER

Using dielectric relaxation spectroscopy, the soft mode rotational vis cosity has been determined in the smectic A phase of a ferroelectric liquid crystal polymer. The dielectric strength and relaxation frequen cy of the soft mode have been measured in the smectic A and C* phases in the presence of a bias electric field. The experimental results ha ve been discussed in terms of the Landau free energy expansion of the smectic A to C* phase transition. The main problems encountered in di electric measurements in the frequency range 10 Hz to 10 MHz are expla ined in some detail. It is found that a bias electric field enhances t he measurements resolution especially in polymeric system where the co nductivity, in this case, is higher than in the low molecular weight c ompounds.