Viscosity sodium chloride

The correct viscose age or ripeness for spinning varies according to the type of fiber being made. Ripeness can be assessed by estabHshing the salt concentration necessary to just coagulate the viscose dope. The preferred test uses sodium chloride (salt figure) although ammonium chloride is the basis of the alternative method (Hottenroth number). 

Xanthan gum dissolves in acids and bases, and under certain conditions, the viscosity remains stable for several months. Xanthan gum has exceUent StabiHty and compatibUity with high concentrations of many salts, eg, 15% solutions of sodium chloride and 25% solutions of calcium chloride (79). 

Commercially, HEC is available in a wide range of viscosity grades, ranging from greater than 500 mPa-s(=cP) at 1% soHds to less than 100 mPa-s(=cP) at 5% total soHds. Because HEC is nonionic, it can be dissolved in many salt solutions that do not dissolve other water-soluble polymers. It is soluble in most 10% salt solutions and in many 50% (or saturated) salt solutions such as sodium chloride and aluminum nitrate. As a rule, the lower substitution grades are more salt-tolerant. 

Examples of commonly used viscosity control additives are calcium ligno-sulfonate, sodium chloride and some long-chain polymers. These additives also act as accelerators or retarders so care must be taken in designing the cement slurry with these materials. 

Sodium a-olefinsulfonate, sodium silicate, sodium alkyl sulfate, sodium chloride, and sodium sulfate can be dissolved in water and cooled to give a gelled cleaning composition having high viscosity. Such mixtures are excellent cleaning compositions for ovens and other metal surfaces according to Watanabe and Schultz [95]. 

Solutions containing 0.15 g/dL polymer and between 0 and 0.342 molar sodium chloride or between 0 and 2.49 x 10 molar calcium chloride show declines in viscosity as salt content increases. Solution viscosity of nonionic copolymers declines, at most,... 

Figure 6. Viscosity of poly(starch g (2 propenamide)) in sodium chloride brine.

Viscosity of copolymer solutions decreases by, at most, 3 percent when electrolyte concentration changes from 0 to 0.342 M sodium chloride or 2.45 x 10 M calcium chloride. Viscosity of hydrolyzed polymer solutions decreases exponentially with increasing electrolyte concentration in water. 

Once the two salts are mixed in solution (acetone is a common solvent for this), the sodium chloride precipitates and is removed by filtration. The solvent is then removed under reduced pressure and, since salts have no vapour pressure, the ionic liquid remains in the flask. The problem with this reaction is that it is almost impossible to remove the last traces of chloride ions. The chloride not only influences the physical properties of the liquid such as melting point and viscosity, but is also a good nucleophile and can deactivate catalysts and affect reproducibility. A great deal of effort has been directed towards removal of the chloride contamination, including washes and chromatography, but none have proved to be completely effective [9], This has led to the development of some alternative synthetic routes. Simply exchanging Na[BF4]... 

Ciystallization from solution is an important separation and purification process in a wide variety of industries. These range from basic materials such as sucrose, sodium chloride and fertilizer chemicals to pharmaceuticals, catalysts and specialty chemicals. The major purpose of crystallization processes is the production of a pure product. In practice however, a number of additional product specifications are often made. They may include such properties as the ciystd size distribution (or average size), bulk density, filterability, slurry viscosity, and dry solids flow properties. These properties depend on the crystal size distribution and crystal shape. The goal of crystallization research therefore, is to develop theories and techniques to allow control of purity, size distribution and shape of crystals. 

The viscosity behavior described so far is valid only for uncharged polymers. If polyelectrolytes are analyzed, a quite different viscosity behavior may be found in polar solvents (e.g., polymeric acids in water). The q p/c values at first fall off with decreasing concentration as for uncharged polymers but then climb steeply again and may drop down later again (see Fig. 2.16). Addition of salt to the solution of polyelectrolytes (e.g., 1% and 5% sodium chloride in aqueous solution) restores, step by step, the normal behavior (see Fig. 2.16, curves b and c). 

Fig. 19. Zero-shear viscosity of aqueous xanthan solutions at different sodium chloride concentration C, [140]...

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