Ultrasonic Absorption of Glycerin in the Liquid and Vitreous State

The ultrasonic absorption of an associated liquid, glycerin, has been measured, in the liquid and vitreous state, at 31 Mc. The value of absorption found exceeds the theoretical value at high temperatures by a factor of 2.1. This indicates that both compressional and shear viscosity contribute to the absorption process. When the liquid was cooled, a peak in the absorption was found at −6.5°C; and at still lower temperatures the absorption fell to considerably lower than classical values. The appearance of a peak in the absorption experimentally verifies the fact that both compressive and shear viscosity are associated with a relaxation phenomenon. The relaxation times for the two processes are of the same order of magnitude, and the same is true of the activation energies.