Some relations connecting volume and enthalpy relaxation in the order parameter model of liquids and glasses J. Chem. Phys. 72, 6422 (1980); 10.1063/1.439141
Hypersonic sound velocity in liquid and rubbery polymersThe spontaneous Brillouin effect has been used to determine the variation of sound speed with temperature in the temperature range of -30° to + 160°C above the relaxation frequencies in dibromomethane, dichloromethane, and carbon disulfide, below any relaxation frequency of acetone and nitrobenzene, and in the region of dispersion in chloroform, carbon tetrachloride, benzene, and acetic acid. In some cases the speeds have been corrected for dispersion. The temperature coefficient of sound and the parameters that characterize the relaxation have been evaluated and compared with other determinations. The sound speeds as a function of temperature have also been measured in water and five viscous liquids; l-octanol, ethylene glycol, aniline, glycerol, and pentachlorobiphenyl. A SImplified form of the Isakovich-Chaban theory involving a single temperature-dependent relaxation time has been used to predict the dispersion in glycerol and pentachlorobiphenyl and the amplitude absorption coefficient in glycerol from ultrasonic data. The predicted speeds are in quantitative agreement with the measured values. The observed amplitude absorption coefficient is shifted to higher temperature as the more complete theory of Isakovich and Chaban would predict.* Based in part on a thesis submitted in partial fulfillment of Ph.D. requirements, region where the speed is frequency dependent. 6 ,8--10 The dispersion b.v/v in some cases amounts to only a few percent, and the temperature correction can be comparable to the total change in speed through the relaxation region.The sound speed and its temperature dependence in the ultrasonic region has been investigated by Padmini, Rao, and Rao,11 Herzfeld and Litovitz,12 and extensively tabulated by Nozdrev l3 and Krasil'nikov,l4The purpose of this paper is to describe the temperature dependence of the hypersonic speed in a number of liquids where disperson may occur and compare the values to those obtained in the ultrasonic region. These measurements will in some cases also yield a value for the relaxation times and the limiting speeds of the liquids. In particular the temperature dependence of the sound speed is determined in nine unassociated liquids; dibromomethane, dichloromethane, chloroform, carbon tetrachloride, nitrobenzene, benzene, acetone, acetic acid, and carbon disulfide. The speed as a function of temperature was also measured in water and in five associated liquids; l-octanol, ethylene glycol, aniline, glycerol, and pentachlorobiphenyl.
DISCUSSION OF THEORYThe relaxation processes in liquids can be attributed to a variety of mechanisms, involving energy exchange