Maintaining Viscosity

For use as a plastics material, in lacquers, or for the preparation of water-insensitive films or filaments, ethylcellulose of a relatively high degree of substitution (1.8-2.8) and the aralkyl ether, benzylcellulose (degree of substitution 1.4-2.5) have had the greatest commercial development. 

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Solutions of welan are very viscous and pseudoplastic, ie, shear results in a dramatic reduction in viscosity that immediately returns when shearing is stopped, even at low polymer concentrations (230). They maintain viscosity at elevated temperatures better than xanthan gum at 135°C the viscosity half-life of a 0.4% xanthan gum solution is essentially zero, whereas a welan gum solution has a viscosity half-life of 900 minutes (230). The addition of salt to welan solutions slightly reduces viscosity, but not significantly. It has excellent stabiUty and theological properties in seawater, brine, or 3% KCl solutions... 

Seawater muds are composed of bentonite, thinner (lignosulfonate or lignosulfonate and lignite), and an organic filtration control agent. The typical formulation of a seawater mud is 3.5 Ib/bbl of alkali (2 Ib/bbl caustic soda and 1.5 Ib/bbl lime), 8 to 12 Ib/bbl of lignosulfonate, and 2 to 4 Ib/bbl of bentonite to maintain viscosity and filtration. Another approach is to use bentonite/thinner (ligno-sulfonate)/freshwater premix, and mix it with seawater that has been treated for hardness. This technique will be discussed in the saturated saltwater muds section. 

In the production of confections and gelatin desserts, acidulants are used mainly for enhancing flavor, maintaining viscosity, and controlling gel formation. In confections, such as hard candies, acidulants are used to increase tartness and to enhance fruit flavors. Acidulants also contribute to the ease of manufacturing. 

There is little separation of fiber and resin during flow in the mold. This is also attributable to maintaining viscosity. 

The use of lower temperatures and lower pH during ozonation of pulps helps to maintain viscosity (Godsay and Pearce 1984), apparently by reducing the attack of the ozone on the cellulose. 

Alkali-soluble emulsion that improves the high-shear viscosity of a formulation. Recommended in conjunction with the ACRYSOL ASE thickeners to maintain viscosity at high shear rates. Not recommended as a primary thickener in most applications. 

A food processing system, using a starch acetate (DS = 0.1) has failed to maintain viscosity within specifications. Reports of the system feilure indicate that the viscosity slowly increased over several hours and temperature and pH remained constant at 25°C and pH = 11. From this information, what may be the cause of the viscosity increase ... 

Strips or dollies of EPDM rubber compound of maintained viscosity can be fed to the first roll nip of a 3 bowl calendar. The thickness of the sheeting is adjusted by operating the motorised roll nip adjustment device fitted on the machine. 

Only keeping the process imit pipehne hot— i.e. only maintain a particular temperature to prevent solidification, to maintain viscosity of the liquid inside. Steam demand is less all the time. 

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