Weissenberg rheogoniometer

The Weissenberg Rheogoniometer (49) is a complex dynamic viscometer that can measure elastic behavior as well as viscosity. It was the first rheometer designed to measure both shear and normal stresses and can be used for complete characteri2ation of viscoelastic materials. Its capabiUties include measurement of steady-state rotational shear within a viscosity range of 10 — mPa-s at shear rates of, of normal forces (elastic... 

Aslam, S. Vossoughi, S. Willhite, G.P. "Viscometric Measurement of Chromium(III)-Polyacrylamide Gels by Weissenberg Rheogoniometer", SPE/DOE paper 12639, 1984 SPE/DOE Fourth Symposium on Enhanced Oil Recovery, Tulsa, April 15-18. 

The rheological properties, during the sol-gel transition, are investigated with a Weissenberg rheogoniometer in oscillatory shear (linear behaviour). 

The Weissenberg Rheogoniometer is well suited to research on homogeneous viscoelastic fluids and elastic melts. For oscillatory shear a second motor-drive mechanism is added. This allows the use of 60 frequencies in the range of 7.6 x 10-5 to 40 Hz at amplitudes between 2 x 10-3 and 3 x 10-2 rad. An electronic circuit improves the precision of oscillatory measurements, particularly at frequencies near the natural resonance frequency of the instrument itself (298). 

Meissner, J. Modification of the Weissenberg rheogoniometer for measurement of transient rheological properties of molten polyethylene under shear. Comparison with tensile data. J. Appl. Polymer Sci. 16, 2877-2899 (1972). 

This instrument employs an oscillating sphere, cylinder, paddle or reed. The range of a typical instrument (Weissenberg Rheogoniometer) is given in Table 6.7. The... 

The viscosity measurements were carried out using a cone-plate viscometer (Model R-16 Weissenberg Rheogoniometer-Sangamo... 

Fig. E3.2b The viscosity r and first (primary) normal stress difference xu — t22 of LDPE evaluated using the Weissenberg rheogoniometer (cone and plate). LDPE is Tenite 800 of density 0.918 g/cm3, and M = 25, 800. [Reprinted with permission from I. Chen and D. C. Bogue, Trans. Soc. Rheol., 16, 59 (1972).]...

Viscoelastic Properties. Viscoelastic properties of S/A binders have been studied on Weissenberg rheogoniometer. Figure 6 shows the variation of viscosity coefficient with shear rate for some binders. 

FIGURE 10.23 Steady-shear-viscosity measurements for polyacrylamide (Separan AP-273) solutions from Weissenberg rheogoniometer and capillary-tube viscometer. tp is the characteristic time calculated from the Powell-Eyring model [37]. 

An analogous result is obtained if the plate rotates and the cone and plate viscometer is the Weissenberg Rheogoniometer. It consists of a plate that can be rotated at different speeds by means of a constant speed motor-cum-gear assembly (Figure 3.34). The speed or rotation is measured accurately by means of a transducer. 

Controlled strain (or, more properly, controlled displacement) oscillatory shear instruments, exemphfied by the Weissenberg Rheogoniometer [Macsporran and Spiers, 1982] readily facilitate tests in which independent measurements of both changing length scales and time scales of applied deformation can be performed. In this way it is, in principle, possible to separate effects due to strain and strain rates as the frequency of oscillation may be held constant while the maximiun (cyclic) shear strain amplitude is varied. Alternatively, the frequency of deformation can be varied at constant maximum shear strain amplitude. 

The Rheometrics Mechanical Spectrometer we originally used was a standard laboratory instrument, as is the Weissenberg Rheogoniometer, which could also have been used at that time. The polymers were also readily available, the solvent was not exotic or toxic, and measurements were made at room temperature with no particular precautions. The three techniques which we employed to stretch the shear rate range were ... 

J.F. Hutton, "On Using the Weissenberg Rheogoniometer to Measure Normal Stresses in Lubricating Greases as Examples of Materials which have a Yield Stress." Rheol. Acta., 14, 979-992 (1975). 

Fig. 19. Shear viscosity r] and first normal stress difference Ni(y) vs shear rate y for a low density polyethylene at 150°C (177,178), where O parallel plate A cone and plate and Weissenberg rheogoniometer. To convert Pa to dyn/cm, multiply by 10 to convert Pa-s to P, multiply by 10. Courtesy of Rheometric Scientific.

Weissenberg Camera. A camera for X-ray diffraction analysis of crystal structures. The crystal is rotated, in the X-ray beam. The film is rotated and moved parallel to the axis of rotation. Weissenberg Rheogoniometer. In essence a cone and plate viscometer (q.v.), but with accessories and control systems to allow it to measure, as well as viscosity, elasticity and a wide range of flow properties such as dilatancy, thixotrophy, relaxation phenomena, etc in steady rotation or in torsional oscillation, over wide but controlled ranges of temperature and shear. 

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