Absorption of Ultrasonic Waves in Organic Liquids (II) Liquids with Negative Temperature Coefficient of Sound Absorption (a) Glycols, Cyclohexanol and Cresol

Ultrasonic absorption coefficients (at about 8 Mc/sec) were determined by the pulse technique in glycols, cyclohexanol and m -cresol in dependence of the temperature. Also the ultrasonic velocity (at 1.43 Mc/sec) in these liquids was determined by the ultrasonic interferometry. The experimental absorption coefficient α exp in these liquids decreased with increasing temperature quite in a similar manner as the classical sound absorption due to viscosity α vis . In most of the liquids investigated, however, α exp was higher than α vis , and the excess absorption was attributed to the bulk viscosity due to the hydrogen bond association in these liquids. The ratio α exp /α vis , was nearly independent of the temperature for all these liquids, the mean values of this ratio being given by: ethylene glycol 4.88; diethylene glycol 2.23; triethylene glycol 0.98; polyethylene glycol 0.89; propylene glycol 1.46; cyclohexanol 1.14; and m -cresol 1.32. The low value of this ratio for polyethylene glycol is considered ...