Dielectric Dispersion of a Polar—Nonpolar Liquid Mixture Near the Critical Solution Temperature

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Abstract
The dielectric dispersion of the mixture nitrobenzene and 2,2,4‐trimethylpentane has been measured at a single concentration over a temperature range from 40°C to the temperature of turbidity and at wavelengths of 575 m, 1.26, 3.22, and 10.0 cm. It was found that the dispersion can be characterized by a single relaxation time over most of the temperature range but that a distribution of relaxation times was necessary near the critical solution temperature. The distribution was also found to broaden as the temperature was lowered. The magnitude of the relaxation time was found to tend to a maximum value as the critical solution temperature was approached. The variations of the static dielectric constant and the density were also measured and found to exhibit the usual maxima. The data obtained are discussed in a qualitative manner in terms of cybotactic regions existing within the liquid and similarities between the dielectric and structural relaxation processes are pointed out.