Ultrasonic Spectrometer for the Measurement of Dynamic Viscoelastic Properties of Liquid Films Conference Paper uri icon


  • Rheologically complex fluids are often exposed to frequencies that are higher than those accessible by mechanical rheometers. Time-temperature superposition is not always an option due to phase transitions, structural or chemical changes. Here we present a reliable, accurate and relatively simple apparatus, capable of measuring the dynamic, viscoelastic properties of thin fluid films at ultrasonic frequencies, ie 2-60 MHz, utilizing the inclined- incidence pulse wave-reflection technique. A thin film of the sample is placed on top of a fused quartz prism, creating a plane of discontinuity of specific acoustic impedance. Bursts of harmonic plane shear waves at ultrasonic frequencies propagate from the inclined sides and impinge upon this impedance discontinuity at an oblique angle, and are reflected. The pressure amplitude and the phase of the reflected waves are determined by the acoustic …

publication date

  • January 1, 2003