Viscosity concentrated

Viscosity—Concentration Relationship for Dilute Dispersions. The viscosities of dilute dispersions have received considerable theoretical and experimental treatment, partly because of the similarity between polymer solutions and small particle dispersions at low concentration. Nondeformable spherical particles are usually assumed in the cases of molecules and particles. The key viscosity quantity for dispersions is the relative viscosity or viscosity ratio,... 

For higher (0 > 0.05) concentrations where particle—particle interactions are noticeable, the viscosity is higher than predicted by the Einstein equation. The viscosity—concentration equation becomes equation 10, where b and c are additional constants (87). 

Emulsions. Because emulsions are different from dispersions, different viscosity—concentration relationships must be used (71,87). In an emulsion the droplets are not rigid, and viscosity can vary over a wide range. Several equations have been proposed to account for this. An extension of the Einstein equation includes a factor that allows for the effect of variations in fluid circulation within the droplets and subsequent distortion of flow patterns (98,99). 

In the Shoe or one-shot method (4), formamide is used to coagulate sodium silicate. The silicate solution used in the Joosten method can be diluted with water to lower its viscosity. Concentrations of sodium silicate between 10—70% are used (viscosities of 2.5—50 mPa-s). Concentrations of formamide are between 2 and 30%. Other reactants such as CaCl2 and sodium aluminate are used in concentrations between 2.4—12 g/L of silicate solution. 

Theoretical treatment of the viscosity-concentration relationship for polyelectrolyte solutions would involve both the cumbersome statistics of highly elongated chains beyond the range of usefulness of the Gaussian approximation and the even more difficult problem of their electrostatic interactions when highly charged. There appears to be little hope for a satisfactory solution of this problem from theory. Fuoss has shown, however, that experimental data may be handled satisfactorily through the use of the empirical relation ... 

During drying an outward flow of Pt can exist, leading to loss of dispersion. The resulting system will depend on many factors, including impregnation time and pH value, viscosity, concentration of the impregnating solution, and the presence of other ions or solute in the solution. 

Figure 4. Reduced Viscosity-Concentration Curve for Poly(N-Phenyl-3,4-Dimethylenepyrroline).

In the Lagrangian approach, individual parcels or blobs of (miscible) fluid added via some feed pipe or otherwise are tracked, while they may exhibit properties (density, viscosity, concentrations, color, temperature, but also vorti-city) that distinguish them from the ambient fluid. Their path through the turbulent-flow field in response to the local advection and further local forces if applicable) is calculated by means of Newton s law, usually under the assumption of one-way coupling that these parcels do not affect the flow field. On their way through the tank, these parcels or blobs may mix or exchange mass and/or temperature with the ambient fluid or may adapt shape or internal velocity distributions in response to events in the surrounding fluid. 

Fig Reduced and inherent viscosity-concentration curves for a polystyrene in benzene. 

Figure 14.8 shows the shear viscosity-concentration dependencies for EDA... 

Here M is the mass of a mole of colloids, representing their molecular weight, and a is their radius. Now let us turn our attention to a polymer coil. The viscosity-concentration dependence of dilute polymers can be... 

In the study of thermodynamics we can distinguish between variables that are independent of the quantity of matter in a system, the intensive variables, and variables that depend on the quantity of matter. Of the latter group, those variables whose values are directly proportional to the quantity of matter are of particular interest and are simple to deal with mathematically. They are called extensive variables. Volume and heat capacity are typical examples of extensive variables, whereas temperature, pressure, viscosity, concentration, and molar heat capacity are examples of intensive variables. 

FIGURE 3.20 Reduced and inherent viscosity-concentration lines for a dilute polymer solution. 

Temperature, Heat capacity. Pressure, Dielectric constant. Density, Boiling point. Viscosity, Concentration, Refractive index. Enthalpy, Entropy, Gibbs free energy. Molar enthalpy. Chemical potential. Molality, Volume, Mass, Specific heat. No. of moles. Free energy per mole. 

Gamma radiation can be used with macroscopic amounts of polymer. This is particularly welcome when polymers are not compatible with the GPC technique. Larger samples can be characterized by viscosity changes, usually measured in dilute solutions. All that is needed is a suitable solvent. If the Mark-Houwink parameters are known, it is possible to calculate viscosity-average molecular weight, Mv, from dilute solution viscosities. However, even the raw viscosity-concentration data in terms of the reduced viscosity may be enough to indicate the sensitivity of a given polymer in qualitative terms. The reduced viscosity at concentrations c is isp/c where t]sp — (solution viscosity — solvent viscosity)/solvent viscosity. 

Figure 9.2. Viscosity-concentration relationships for FBZ1030 in butyl acetate, n-butanol, and hexafluorobenzene (T = 20°C).

Fig. 107. Viscosity-concentration ratio (togio VCR) (plain lines) and distribution of logio VCR of fractions of nitrocotton (broken lines), according to G. G. Jones and Miles [16a]. Designation...

Utracki LA (1991) On the viscosity-concentration dependence of immisdble polymer blends. JRheol 35 1615-1637... 

L. A. Utracki, On the Viscosity-concentration Dependence of Immiscible Polymer Blends, J. Rheol., 35, 1615-1637 (1991). 

As a consequence of the fast quadrupolar relaxation, 33S NMR signals are quite narrow only when the sulphur nucleus is in small molecules and is characterized by a highly symmetric electronic environment, that is to say, when X is quite small and rj is near to zero. This is the case for inorganic sulphates, sulphonates and sulphones. When these features are not verified, signals are broad and often undetectable, but in some cases it is possible to modify the experimental conditions (temperature, solvent viscosity, concentration) in order to obtain a narrowing of the signals. 

Figure I Viscosity-concentration (t vs c) profile at 26°C of an aqueous pectin dispersion showing the critical micelle concentration (c ).

Konjac flour gum is reported to be pH- and cation- (sodium, potassium, and calcium ions) insensitive this is consistent with its nonionic character (FMC, 1989), but an isolate did not show a characteristic linear viscosity-concentration profile in water it did show linearity in the presence of electrolytes (Jacon et al., 1993). The apparent partial specific volume of a 0.2-0.4% dispersion was constant over a wide pH range and increased with increasing temperature from 5 to 50°C it then remained constant (Kohyama and Nishinari, 1993). 

Source Specific viscosity Concentration. (10)w in normal NaCl DM(ioy in normal NaCl Molecular weight... 

The electroviscous effect can influence the results of viscosity determinations, but this can be avoided by using a sufficiently high concentration of salt12 when linear specific viscosity concentration versus concentration curves are obtained. Gelation effects with Fe++, Fe+++ and Cu++ ions also occur127 and so should be avoided. 

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