Instrument for Precise Measurement of Viscoelastic Properties of Low Viscosity Dilute Macromolecular Solutions at Frequencies From 20 to 500 kHz.
Instrument for Precise Measurement of Viscoelastic
Properties of Low Viscosity Dilute Macromolecular
Solutions at Frequencies From 20 to 500 kHz.
Stokich, T. M.; Radtke, D. R.; White, C. C.; Schrag, J.
Journal of Rheology, Vol. 38, No. 4, 1195-1210,
viscoelastic properties; low viscosity dilute
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.