"In order to study the viscoelastic properties of polymer solutions and greases, a dynamic apparatus was built for making measurements of complex viscosity. Characteristic impedance was measured by a force transducer, an accelerometer and a phase meter. Large amplitudes to 0.5 inch can be obtained with this apparatus. The largest amplitude used was 1.27 x10⁻¹ cm. The frequency range was 30 Hz - 1500Hz. The lowest dynamic viscosity to be measured was 0.5 poise. In order to determine the capabilities of the instrument, complex viscosities of polymer solutions and greases were measured. The polymer solutions studied were polyisobutylene (PIB) L-80, PIB L-200, and polydimethyl siloxane (SR) 130. Comparisons of results for NLGI System A grease and Mobilgrease 24 showed that at the same level of dynamic viscosity the NLGI grease had twice the elastic response of Mobilgrease. For NLGI grease about 60% of the total energy input was dissipated under the experimental conditions. About 80% of the total energy input was dissipated for Mobilgrease 24. Comparing the shapes of curves for the steady shear viscosity vs. shear rate with the dynamic viscosity vs. frequency for FIB L-80 (3 g/dl and 5 g/dl), there was a trend toward agreement of η and η' at vanishingly small values of γ and Ω. For 17% solution of NLGI grease and a 25% solution of Mobilgrease 24, η' and η only have similar shapes. η' and η can be shifted into coincidence along the γ - Ω axis with shift factor of 2. The dependence of complex viscosity on amplitude was investigated for the 5 g/dl PIB L-80 solution. Both η' and η" decrease with increasing amplitude when amplitude is beyond a limit; the η" was more sensitive to amplitude. That means the dynamic storage modulus data are more critical than dynamic viscosity data in determining the limitation on amplitude for linear viscoelasticity. For instance, when shear wave length equaled 1.5 cm, the limitation on shear strain for linear viscoelasticity was 9.5% for the PIB L-80 solution"--Abstract, pages ii-iii.
Patterson, G. K. (Gary Kent), 1939-
Johnson, James W., 1930-2002
Zakin, J. L.
Strunk, Mailand R., 1919-2008
Chemical and Biochemical Engineering
Ph. D. in Chemical Engineering
National Science Foundation (U.S.)
University of Missouri--Rolla. Department of Chemical Engineering
University of Missouri--Rolla
xii, 195 pages
© 1971 Kuo-Shein Shen, All rights reserved.
Dissertation - Open Access
Library of Congress Subject Headings
Viscoelasticity -- Measurement
Polymers -- Viscosity
Lubrication and lubricants -- Viscosity
Print OCLC #
Electronic OCLC #
Link to Catalog Record
Shen, Kuo-Shein, "A measurement of complex viscosity with large amplitudes" (1971). Doctoral Dissertations. 1840.