Torsional acoustic resonators are a well-known tools to measure viscosities.[1], [2] When contacted by a liquid, the resonance frequency and the bandwidth shift in proportion to the square root of the viscosity. 

The application of torsional resonators in polymer characterization (and in extruders, specifically) is at this point precluded by the high viscosity and the high pressure in such environments.  The project deals with strategies to overcome these obstacles.  A special mechanical design shall minimize the stress onto the sensor.  Advanced techniques for read-out and data analysis will allow data acquisition from highly over-damped resonators. 

Further, the use of a torsional resonator as a quartz crystal microbalance (QCM) is investigated.  For thick films (> 10 µm) torsional resonators are better suited for microweighing than the conventional QCM, because of the longer wavelength of shear sound.

The project is a collaboration between TUC and Flucon GmbH.  It is funded by EU.

 

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[1] B. Bode, Dissertation, TU-Clausthal 1984

[2] H.J. McSkimin, Journal of the Acoustical Society of America 24, 355 (1952).