Viscosity constants

FIGURE 21.9 Temperature dependence of the viscosity constant K (solid) and K (dashed). Both constants are divided by those in solvent for scaling. 

Table 8.1. Contributions for calculating the viscosity constant I in Souders equation...

Huffn puff method, in oil recovery, 18 617 HUFT theory, 14 714 Huggins viscosity constant, 21 711 Hughes-Acree method, 12 266 Hull coatings, 7 203... 

Here

Flory viscosity constant, which usually falls within the range (2.1-2.5) x 1021 (when [q] is expressed in dl/g and 1/2 in cm), regardless of polymer species, solvent species, and temperature. 

Fig. 35. Dependence of the Flory viscosity constant

Throughout our calculations we will not assume any restriction on the viscosity constants except the usual requirements due to thermodynamic stability (see, e.g., [30]). Later on we will impose the incompressibility of the fluid by assuming a constant mass density p of the fluid. We emphasize that this procedure does not require any further assumption about the material parameters. 

There are also other quantities that are dependent on the goodness of solvents. Among them is the Huggins viscosity constant k7, which can be determined quite easily and, because of its interesting properties, seems to be suitable for direct determination of the goodness of a particular solvent [20],... 

Appendix (Table 13 Viscosity Constants of Linear Polymers).292... 

Just as this article was being completed, a review by Meyerhoff (13") appeared, containing a large but also incomplete tabulation of viscosity constants. In general, the article of Meyerhoff and ours are complementary, ours being somewhat more concerned with theoretical and his with experimental questions. 

Here the subsripts n, w and z have their usual meaning, and P represents the gamma function. We now denote by 0OW the value of the viscosity constant 0O that would be obtained from measurements of Mw and of (S2)w under theta conditions, and by 0Oi the value similarly obtained from measurements of Mw and of (S2)z. These are found to be... 

Peculiarities in the viscosity constant lead these early workers to believe that the polymer backbone did not contain pendant CH3 groups and that polymerization occurred through this group. It was theorized that due to the mobility of the allylic hydrogen (CH=CH—CH2H) the... 

In the same study Attwood et al. [55] investigated the effect of increasing the surfactant concentration on the overall viscosity of an o/w ME system and obtained values for the viscosity constant a of 3.19-4.17. The authors concluded that allowance for the hydration of the polyoxyethylene chain of the used surfactant reduced the value of the viscosity constant a toward the theoretical value of 2.5 for a solid sphere. They also concluded that changing the ratio of the nonionic surfactants did not significantly affect the viscosity of the system. 

Baker et al. [56] studied the viscosity of w/o ME systems containing water, xylene, sodium alkylbenzenesulfonate, and hexanol using Equation (1). They reported values of the viscosity constant a of 3.3-6.0, which is above the theoretical value of 2.5 for a sphere with an increase in the surfactant concentration. This finding was attributed to the increase in the ratio of surfactant layer thickness to droplet core radius as the surfactant concentration was increased. However, deviation in values of the viscosity constant a from the solid-sphere theoretical value of 2.5 could also be attributed to changes in the droplet shape or symmetry [57],... 

Some of the results shown in this figure have to be obtained from experiments that are very difficult to carry out. For example, to obtain the data illustrated in Fig. 6.1(c) we must vary the liquid density while keeping the viscosity constant. For the data needed in Fig. 6.1(e), the thermal conductivity has to be varied while the density, the thermal capacity and viscosity are kept constant. These curves are actually almost impossible to obtain experimentally because the majority of the studied parameters are dependent on each other. This problem could be solved using a much simpler approach with the dimensionless variables that are described below. In fact, we can combine the different parameters described in Eqs. (6.1) and (6.2) in non-dimensional combinations of variables (called dimensionless groups, products criteria)... 

If a concentration-selective detector, such as a DRI, is connected on-line with the viscosity detector, the ratio of the two signals yields the intrinsic viscosity distribution of the polymer sample. In polymer characterization, the intrinsic viscosity can be a property just as important as the molecular-weight distribution. Furthermore, polymer intrinsic viscosity follows the Mark-Houwink relation to the molecular weight, M, where K and a are Mark-Houwink viscosity constants ... 

Feed a slurry of cellulose plus nutrients and vary feed rate to hold viscosity constant. This couples solid with the solution but might be suitable for commercialization. 

H - a characteristic viscosity constant, and 0-a characteristic time constant... 

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