scholarly journals Guidelines for checking performance and verifying accuracy of rotational rheometers: viscosity measurements in steady and oscillatory shear (IUPAC Technical Report)

2014 ◽  
Vol 86 (12) ◽  
pp. 1945-1968 ◽  
Author(s):  
Martin Laun ◽  
Dietmar Auhl ◽  
Rüdiger Brummer ◽  
Dirk J. Dijkstra ◽  
Claus Gabriel ◽  
...  
Keyword(s):  
Shear Rate ◽  
Complex Viscosity ◽  
Angular Frequency ◽  
Temperature Calibration ◽  
Concentric Cylinder ◽  
Rate Range ◽  
Technical Report ◽  
Linear Viscoelastic ◽  
Reference Samples

Abstract The paper addresses techniques for checking the performance of rotational rheometers with cone–plate, plate–plate, or concentric cylinder geometry. We focus on the determination of the viscosity as a function of the shear rate and of the magnitude of the complex viscosity as a function of the angular frequency. After summarizing the relevant definitions and test modes, we show examples of measurements in the linear viscoelastic range, and applications of the Cox–Merz relationship. Sources of reference fluids with defined viscosities are presented, and their use in tests for verification of accuracy is demonstrated. Relevant issues, predominantly for Newtonian reference liquids, are the exploration of measurement limits, related either to the shear rate range or to reliably accessible viscosity levels. Viscoelastic reference samples are also discussed. Prerequisites for sample preparation and loading are addressed. In particular, we present recommendations based on experience from various laboratories. Finally, we discuss the problem of temperature calibration, presenting techniques that allow the determination of the true sample temperature for a given set temperature of the rheometer. This paper summarizes contributions from various industrial and academic laboratories.

EDGE Effect Correction for the Mooney Rheometer

1979 ◽  
Vol 52 (5) ◽  
pp. 962-972 ◽  
Author(s):  
N. Nakajima ◽  
E. R. Hareell
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
Shear Rate ◽  
Edge Effect ◽  
Mathematical Expression ◽  
Complex Viscosity ◽  
Stress Effect ◽  
Elastic Recoil ◽  
Concentric Cylinder ◽  
Large Rotor

Abstract The Mooney rheometer has been used universally as a tester for quality control of raw elastomers and compounds. White and Tokita showed that the tester modified to operate at a range of speeds could be used to obtain fundamental viscoelastic properties: steady-state shear stress-shear rate relationship, normal stress effect, and elastic recoil. We have also made effective use of this rheometer to obtain steady-state viscosity as a function of shear rate and complex viscosity as a function of deformation rate. In these investigations, the observed torque was converted to shear stress with a theoretical factor derived by taking into account both the parallel plate section and the concentric cylinder section. It was assumed that the edge effect was negligible. The viscosities calculated in this manner were compared to those obtained with other instruments and reasonably good agreement was obtained. Some time ago, Mooney and Treloar expressed the opinion that the viscosity obtained from the Mooney rheometer is somewhat larger than the correct value, attributing the disagreement to neglect of the edge effect. More recently, White and Tokita have restated the problem. In our recent work, the torque measurements were made with both the small and the large rotor. The viscosities calculated without considering the edge effect tended to be somewhat higher for the small rotor than for the large rotor. This observation implies that an edge effect exists, because measurements obtained with the small rotor, which has larger “edge volume”, would tend to be more significantly affected. In this paper a mathematical expression is sought for the edge correction, so that the correction factor may be calculated from the known properties of the material.

Estimation of Red Cell Deformability Based on Flow Curve of Whole Blood in the Higher Shear Rate Range.

2001 ◽  
Vol 27 (2) ◽  
pp. 228-235
Author(s):  
Shinichi Ookawara ◽  
Akihisa Yano ◽  
Kohei Ogawa ◽  
Koichi Taniguchi
Keyword(s):  
Shear Rate ◽  
Whole Blood ◽  
Flow Curve ◽  
Red Cell ◽  
Cell Deformability ◽  
Red Cell Deformability ◽  
Rate Range

Test of Strain-Time Correspondence Principle with Gel-Containing Elastomers

1986 ◽  
Vol 59 (2) ◽  
pp. 305-314 ◽  
Author(s):  
N. Nakajima ◽  
E. R. Harrell
Keyword(s):  
Large Deformation ◽  
Correspondence Principle ◽  
Small Deformation ◽  
Complex Viscosity ◽  
Shear Stresses ◽  
Growth Data ◽  
Stress Growth ◽  
Linear Viscoelastic ◽  
The Difference ◽  
Linear Viscoelastic Theory

Abstract With four NBR samples and one EPR, oscillatory measurements and stress-growth measurements were performed, the former being at very small deformation and the latter leading to large deformation. The Rheometrics mechanical spectrometer was used with a cone-plate fixture. The temperature was 100°C. The stress-growth data of NBR's, converted to complex viscosity-frequency data through the application of stress-time correspondence principle, were in good agreement with those observed in the oscillatory measurement. Thus, the stress-growth data including the large deformation were “linearized” to form a master curve. With the EPR sample, such a linearization was not necessary. The stress-growth data were adequately treated with the linear viscoelastic theory up to shear stresses approaching the steady state. The difference in behavior between the NBR's and EPR is caused by differences in type and extent of long branching and gel present in the samples.

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