Dielectric relaxation time in normal and supercooled simple liquids and its relation to other liquid properties

• Main Author: Mallikarjuns, S.
• Published: Royal Holloway, University of London 1964
• Subjects: 541; Physical Chemistry
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.703924

Measurements have been made on viscosity, density, static dielectric constant and dielectric constant at wavelengths of 3.279 cm and 0.847 cm. For some liquids measurements have also been made at 29.89 cm and 19.88 cm. The critical wavelength has been calculated from the results and its temperature dependence compared with that of viscosity. The present viscosity measurements allow investigation of the dependence of viscosity of liquids on temperature over a great range of temperature, and the viscosity at normal pressure of a large number of liquids can be described successfully by Batschinski's relation where A and b are constants and V is the specific volume. No discontinuity is apparent between ordinary liquid and supercooled liquid states. Reasonably consistent values of critical wavelengths are obtained from the two experimental wavelengths over a range of temperature from +50°C to -50°C, except for Iodobenzene, Quinoline and iso-quinoline. The measurements done for these three liquids at wavelengths of 29.89 cm and 19.88 cm suggest that there may be a second dispersion region leading to abnormally high values of at the shorter wavelengths. The results also suggest that in all cases studied less free volume is required for molecular rotation than for viscous flow so that the critical wavelength varies less rapidly with temperature than the viscosity does.