Physical properties of nematic mixtures. II. Polar–nonpolar systems

The dielectric, diamagnetic, and elastic properties as well as the nematic–isotropic phase transition temperatures of terminal polar–nonpolar nematic mixtures have been studied. The properties of the mixtures are compared to those of their components. Deviations from the ideal behavior or the additivity rule have been observed and are partially attributed to the reduced degree of association of the polar compounds in these mixtures and to additional interactions between the polar and nonpolar molecules. Packing effects can also influence the physical properties of the mixtures. The bend elastic constant is more sensitive to these effects than the twist and splay elastic constants. Clearing points obtained by extrapolation are shown to strongly deviate (up to 40 °C) from the experimental values.