Viscosity techniques

For the determination of polymer molar masses, very dilute solutions are used, typically of the order of 1% by mass. In using viscosity techniques, a number of functions are used. These are ... 

Figure 19. Comparison of molecular weight distributions of carboxyl-terminated polybutadienes by the solvent precipitation-intrinsic viscosity technique...

Ofte, D. Application of a viscosity technique to liquidus determinations in molten alloys. Trans. Met. Soc. AIME 236, 585—587 (1966). 

Figure 3-11 Illustration the Matching Viscosity Technique for the Eight-Blade Vane.

Polymers that have been suggested for mobility control in oil reservoirs include polyacrylamides, hydroxy ethyl cellulose, and modified polysaccharides which are produced either by fermentation or by more conventional chemical processes. In this paper the solution properties of these polymers are presented and compared for tertiary oil recovery applications. Among the properties discussed are non-Newtonian character for different environmental conditions (electrolytes and temperature), filterability, and long term stability. The behavior of these water soluble polymers in solution can be correlated with the effective molecular size which can be measured by the intrinsic viscosity technique. A low-shear capillary viscometer with a high precision and a capability of covering low shear rates (such as 10 sec - - for a 10 cp fluid) has been designed to measure the viscosities. The measurement of viscosities at such slow flow conditions is necessitated... 

The determination of viscosity from the couple exerted on concentric cylinders is used in many viscometers. For silicate glasses, a wide range of techniques are used for measuring viscosity. For low viscosities (1 Pa s to 1 MPa s), a rotating spindle technique, based on the above principle, is often used. For higher viscosities, techniques based on fiber elongation, compression of a cylinder and be im-bending are utilized. 

By carrying out the measurements in the presence and absence of polymer layers, one can obtain 8. In the presence of an adsorbed polymer layer, the hydrodynamic radius is the sum of the core radius and the adsorbed layer thickness, whereas in the absence of the polymer layer, 7 is simply the core radius. Again, as with the viscosity technique, this method cannot be directly applied to emulsions, which are polydisperse and with a radius that is large for significant Brownian motion. 

All analytical HPLC columns with particles < 20 pm (usually 5 or 10 pm) are packed by the slurry technique [19], which can be further classified into the high-viscosity technique and the balanced-density technique. In the latter, the particles are suspended in a fluid that has a density similar to theirs, so particle segregation by sedimentation decreases. In both techniques, the suspending fluid must be chosen in such a way that particle dispersion is maintained without aggregation and particle agglomeration is avoided by proper selection of the polarity of the sluiTy [19], [24]. 

Poncet et al. showed that similar results can be found through dielectric impedance or control viscosity techniques, since both point to the second-phase formation occurring at a similar reaction time [33],... 

The models based on empirical transformations lead directly to a molecular weight distribution without the need to assume a form for it or to use a regularization technique. In addition, the viscosity technique does not require a value for the plateau modulus. On the other hand, such models will not give reliable results for systems containing substantial amounts of low-molecular weight material. 

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