Relative viscosity definition

Now, if you ve managed to keep track of all those viscosity definitions, you re a better man than I am Gunga Din (You have to be familiar with the romantic imperialism of the books and poems of Rudyard Kipling to get this allusion.) So, we have summarized them all in Table 12-3. There are two sets of names, the ones we have used, which almost everybody else also uses, and a set devised by IUPAC, which they hoped everybody would use, but almost nobody does. Just remember that what you measure is the relative viscosity and what you want to know is the intrinsic viscosity. 

From Fig. 6-4, shear thinning begins at a reduced shear stress of around 0.01, where the relative viscosity rjr is around 10. By definition of r]r, we have... 

Here ),p, the specific viscosity, is equal to the relative viscosity minus one. Staudinger designates C as the concentration of the solution in basal moles or the number of moles of the polymeric repeating unit per liter thus, for a starch acetate, it is the number of grams per liter divided by 288. K , is a constant particular to a definite series of homologues measured in a definite solvent, and M is the molecular weight. Ordinarily, this equation is employed for viscosity values extrapolated to zero concentration. Although the relationship is by no means exact " ... 

It is obvious from Figures 4 and 5 that for mentioned monomer salts AG and MAG the non-linear increase of relative viscosity (r rei) is naturally observed with the rise of monomer concentration in initial reaction solution. (As it was already mentioned the solution remained transparent.) Thus, there is definite correlation in the character of polymerization initial rate change and values of r rei.. 

It should be remembered that unlike Nolte s proposed equation, Shah s results show definite shear rate-dependent relative viscosities. Also, power law exponent, ns, of slurry is not the same as the carrier fluid n as assumed by Nolte. Prud homme (26) has also reported decreasing n values with increasing volume fraction solids. 

Give the definitions and formulas for the relative viscosity, specific viscosity, reduced viscosity, inherent viscosity, and intrinsic viscosity. 

Ede [56] has also examined the limitations of m-cresol as the mobile phase in the SEC of nylon. He noted that Waters Inc. had recommended that the instrument be operated at 130°C to reduce the pressure drop across the columns and to improve the resolution of the chromatogram, and suspected that degradation of nylon was occurring under these conditions. Accordingly, the relative viscosities of the nylon m-cresol solutions were determined after heating for various times at 130°C. Three nylon solutions were prepared and examined by SEC. The solutions were also held in the injection loop of the SEC for 3 h prior to injection. In each case the sample which had been held in the sample loop eluted later. The retention time in the SEC was 2-4 h, and it was concluded that degradation definitely occurred during this time. 

By definition, viscosity of a material rf) represents its resistance to flow, though other kinds of viscosities have been defined for solutions to describe in various ways how the solubilization of a solute into a solvent at a given concentration (C) impacts the viscosity of the latter ( jo). The relative viscosity ( rei) is the ratio of the viscosity of the solution (j ) with respect to the viscosity of the solvent its value is useful to estimate the viscosity enhancement of a solvent on solute addition. 

To understand polymer structure, polymers are often dissolved in appropriate solvents, allowing molecular weight or degree of polymerization to be determined from dilute solution viscosity. The relative viscosity, is the ratio of solution viscosity to that of the solvent. The specific viscosity, is the ratio of the difference in solution and solvent viscosities divided by the solvent viscosity. These dimensionless quantities are often divided by the mass concentration of the polymer to obtain several additional terms that have units of dilution or volume per unit mass concentration the reduced viscosity, which is ratio of the relative viscosity to the concentration the inherent viscosity, which is the ratio of the natural logarithm of the relative viscosity and the intrinsic viscosity, [77], which is the common limiting value of the reduced (Huggins definition) or inherent (Craemer s definition) viscosity at infinite dilution of the polymer. The intrinsic viscosity is a concentration ratio it has been used to estimate molecular... 

This definition cannot be applied directly to mixtures, as phase equilibria of mixtures can be very complex. Nevertheless, the term supercritical is widely accepted because of its practicable use in certain applications [6]. Some properties of SCFs can be simply tuned by changing the pressure and temperature. In particular, density and viscosity change drastically under conditions close to the critical point. It is well known that the density-dependent properties of an SCF (e.g., solubihty, diffusivity, viscosity, and heat capacity) can be manipulated by relatively small changes in temperature and pressure (Sect. 2.1). 

Since the common engineering units for both mass and force are 1 lb, it is essential to retain gc in all force-mass relations. The interconversions may be illustrated with the example of viscosity whose basic definition is force/(velocity)(distance). Accordingly the viscosity in various units relative to that in SI units is... 

POISE (P). A unit of dynamic viscosity. The unit is expressed in dyne second per square centimeter The centipoise (cP) is more commonly used The formal definition of viscosity arises from the concept put forward by Newton that under conditions of parallel flow, the shearing stress is proportional to the velocity giadieut. If lire force acting on each of two planes of aiea A parallel to each oilier, moving parallel lo each other with a relative velocity V, and separated by a perpendicular distance X, be denoted by F. the shearing stress is F/A and the velocity gradient, which will be linear for a true liquid, is V/X. Thus, Ft A = q V/X, where the constant if is the viscosity coefficient or dynamic viscosity of the liquid. The poise is the CGS unit of dynamic viscosity. 

Viscosity and Plasticity—Viscosity and plasticity are closely related. Viscosity may be defined as the force required to move a unit-area of plane surface with unit-speed relative to another parallel plane surface, from which it is separated by a layer of the liquid of unit-thickness. Other definitions have been applied to viscosity, an equivalent one being the ratio of shearing stress to rate of shear. When a mud or slurry is moved in a pipe in more or less plastic condition the viscosity is not the same for all rates of shear, as in the case of ordinary fluids. A material may be called plastic if the apparent viscosity varies with the rate of shear. The physical behavior of muds and slurries is markedly affected by viscosity. However, consistency of muds and slurries is not necessarily the same as viscosity but is dependent upon a number of factors, many of which are not yet clearly understood. The viscosity of a plastic material cannot be measured in the manner used for liquids. The usual instrument consists of a cup in which the plastic material is placed and rotated at constant speed, causing the deflection of a torsional pendulum whose bob is immersed in the liquid. The Stormer viscosimeter, for example, consists of a fixed outer cylinder and an inner cylinder which is revolved by means of a weight or weights. 

Partial molar entropies of ions can, for example, be calculated assuming S (H+) = 0. Alternatively, because K+ and Cl ions are isoelectronic and have similar radii, the ionic properties of these ions in solution can be equated, e.g. analysis of B-viscosity coefficients (Gurney, 1953). In other cases, a particular theoretical treatment which relates solvation parameters to ionic radii indicates how the subdivision could be made. For example, the Bom equation requires that AGf (ion) be proportional to the reciprocal of the ionic radius (Friedman and Krishnan, 1973b). However, this approach involves new problems associated with the definition of ionic radius (Stem and Amis, 1959). In another approach to this problem, the properties of a series of salts in solution are plotted in such a way that the value for a common ion is obtained as the intercept. For example, when the partial molar volumes of some alkylammonium iodides, V (R4N+I ) in water (Millero, 1971) are plotted against the relative molecular mass of the cation, M+, the intercept at M + = 0 is equated to Ve (I-) (Conway et al., 1966). This procedure has been used to... 

These simulations evidence the importance of p, as characterizing the molecular mobility. It should be noted that k/s is proportional to the square of matrix Young s modulus divided by viscosity, so that an alternative definition could have been p. = log k /r, where r = THn/Tium is the relative increase of matrix viscosity. 

Basically, all of these closely related problems occur because gas-flood injection fluids have very small viscosities at the temperatures and pressures at which they are used. For example, the viscosity of CO2 at 13.8 MPa (2,000 psi) and 38°C (100°F) is about 0.066 cp, whereas the viscosities of reservoir oils are at least an order of magnitude greater (16). This produces a ratio of the mobility of the CO2 to the mobility of the oil that is much greater than one. (The mobility of a fluid is defined as its relative permeability divided by its viscosity for the definition of relative permeability, see equations below.)... 

Ransohoff and Radke found that for C <10 lamella generation occurred only by the leave-behind mechanism. The lamellae moderately increased the resistance to flow, raising it by about a factor of five (40). (Here p is the viscosity of the nonwetting phase, U is the total superficial velocity, R is the bead radius, K is the absolute permeability, k is the relative permeability, L is length, and Y is the interSacial tension.) The use of this definition of the capillary number, instead of the usual C = jU/y, with J the viscosity of the wetting phase, was justified in the heoretical analysis ( ). 

By Newton s definition the viscosity or, more appropriately, the viscosity coefficient, jj, of a fluid in a laminar steady-state flow is expressed as the tangential force, F, per unit area. A, required to maintain a unit rate of shear (or velocity gradient), G, in the liquid. If the liquid fills the space between two parallel planes of area. A, one of which moves at a constant distance, r, from the other with a relative velocity, u, then we have... 

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