Experimental technique for the determination of the viscoelastic properties of liquids in the frequency range 5-75 Mc/s

Abstract

A description is given of an experimental technique for the measurement of the viscoelastic properties of liquids in the frequency range 5-75 Mc/s. The method is suitable for liquids having steady-flow viscosities greater than about 1 P. A modulated pulse of plane shear waves is generated by a quartz crystal transducer and is internally reflected in a fused quartz bar. The changes in the complex reflection coefficient which occur when a liquid is applied to the reflecting surface are determined by a novel electronic system. Successive reflections give rise to a train of pulses which is received by the same transducer; the amplitude and phase of the radio-frequency oscillations within each pulse are determined by comparison against amplitude and phase reference signals derived from a highly stable oscillator. The method has been developed to achieve high accuracy and stability, and a principal advantage is the simplicity of the acoustic system. The performance is illustrated by a set of typical results and the advantages of the present technique over previous ones are discussed.