Temperature dependence of ultrasonic absorption in mixtures of glycerol and water

Abstract

A pulse comparison method has been used to measure ultrasonic absorption in mixtures of glycerol and water in the temperature range 25 to 60 °C at 0.8 and 5 MHz. The behaviour at 5 MHz is similar to what has been observed by Willis. At 0.8 MHz α/f 2 increases with the increase in temperature for concentrations up to 08% glycerol in water and shows a maximum at about 20% of water in glycerol at and above 50 °C. The height of the maximum increases with the increase in temperature. A similar maximum is observed in ultrasonic velocity. The present results are interpreted on the basis of an additional slow relaxational absorption mechanism such thatωτ ≫ 1 at 0.8 MHz. The maximum in the absorption and velocity corresponds to the formation of a complex of the type (CH2OH-CHOH-OH2OH)4 H2O, the formation of which is favoured at high temperatures. The dissolution and formation of this complex provides the additional relaxational mechanism.