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Instrument for Precise Measurement of Viscoelastic Properties of Low Viscosity Dilute Macromolecular Solutions at Frequencies From 20 to 500 kHz.


pdf icon Instrument for Precise Measurement of Viscoelastic Properties of Low Viscosity Dilute Macromolecular Solutions at Frequencies From 20 to 500 kHz. (1207 K)
Stokich, T. M.; Radtke, D. R.; White, C. C.; Schrag, J. L.

Journal of Rheology, Vol. 38, No. 4, 1195-1210, July/August 1994.

Keywords:

viscoelastic properties; low viscosity dilute macromolecular

Abstract:

A high-frequency torsional rod apparatus (HFTRA) has been developed for measurements of moderately high-frequency viscoelastic properties of dilute, low viscosity polymer solutions. It employs a long cylindrically shaped resonating element driven by an X-cut (torsional mode) quartz piezoelectric crystal. Up to 11 different normal modes are employed, resulting in 11 discrete frequencies, ranging from approximately 20 to 500 kHz. Measurements are made in free decay; a key feature of the apparatus is the method for high precision measurements of damping coefficients and eigenfrequencies. The instrument is suitable for liquids. Measurements of the viscoelastic properties of polymer solutions employing the HFTRA and two other instruments capable of higher precision measurements show excellent agreement, demonstrating that the HFTRA is sufficiently precise for dilute-solution viscoelasticity studies; the working frequency range is such that most of the polymer relaxation time spectrum can be probed for many polymer/solvent combinations.