Thickener Types

Hydroseparator The hvdroseparator is merely a thickener-type machine receiving more flow than can be clarified in the area provided, Thus the overflow contains fine solids, and the greater the feed rate per unit of area the coarser the solids in the overflow, ... 

Since 1977 several new thickener types have become widely used, including complex (sodium, lithium, calcium or aluminium), polyurea, modified clays, and other non-soap thickeners. To bring the picture up-to-date, Risdon carried out an evaluation in 1986 of three of the newer grease types not inciuded in the previous programme. They were lithium complex, aluminium complex and polyurea. They included one EP (extreme pressure) and one non-EP grease for each type of thickener, and all were of the same consistency grade, NLGI No 2. 

Thickener Types Flocculants are commonly used in thickeners, and this practice nas resulted in thickener classifications as conventional, high-rate, ultrahigh-rate, or high-density. These designations can be confusing in that they imply sharp distinction between each type, which is not the case. 

By matching base oil type, viscosity, VI, additives, and thickener type (for grease) to the lubrication objectives, the optimum composite performance can result. The primary functions of a lubricant in typical machinery applications include the following ... 

In the initial phase of this work, attempts were made to prepare emulsions of 5% mineral oil in water by using only poly (acrylic acid) thickeners. The mineral oil was a pure clear, white grade with a viscosity of 100 mPa s at room temperature. Polymers A and B from the studies reported in the first half of this chapter were screened for their ability to emulsify the oil. In addition, two other grades of poly (aery lie acid) thickener (types C and D, with number-average molecular-weights of 1.25 million and 3 million, respectively) (1), and a hydrophobically modified poly (aery lie acid) were studied. 

Table I compares typical test results for low-, mid-, and high-effective molecular weight thickeners in a vinyl-acrylic latex paint. Many of the same trends are present with cellulosic and HE UR thickeners when the effective molecular weight designation for HEUR thickeners is used. As the effective molecular weight of an HEUR increases, Stormer thickening efficiency, roller spatter, and water resistance increase, whereas ICI viscosity decreases. The major difference between these two thickener types is in their low-shear behavior. As effective molecular weight increases, cellulosic paints improve in leveling and decrease in sag resistance. HEUR paints decrease in leveling and improve in sag resistance. Other property differences between these two thickener types are highlighted in Table II.

Suspension II exhibits shear thinning followed by shear thickening type of behavior. Comparing Figures 8 and 10, in suspension II, Qg/Q (measured in capillary flows) and... 

The choice of resinous thickener type will depend largely on the solvent system involved. For non-polar organic solvents, linear polymer thickeners are suitable. For polar organic solvents, microgels can be used. For aqueous systems, linear (associative) thickeners, microgels or (if colloids are present) metal chelates can be used. These are all used principally for... 

Automated detection of masses poses challenges for CAD because they may appear as intraluminal types (lobulated, polypoid, or circumferential) or non-intraluminal types (mucosal wall-thickening type of growth pattern or masses that block the colon), both of which have a wide variation in shape characteristics. Only a few CAD schemes for the detection of colorectal cancers have addressed this challenge (Nappi et al. 2002b Nappi et al. 2004a). 

The suspension is highly concentrated, and resulted to be non-Newtonian (shear thickening type) as determined in solution of Example 10.4. The use of Equations 10.82 through 10.84 would be, therefore, most appropriate. The parameters of characterization n and K, from the rheogram of the suspension are 1.39 and 2 X 10"5 kg/m s "", respectively. 

There are two specific examples of liquids that often show simple MaxweU-like behaviour within the normal measuring range (lO - 10 Hz), with the expected shapes of the G and G" curves and a single relaxation time, viz. associative-thickener-type polymers (see chapter 16 for details) and worm-like surfactant micellar systems, otherwise known as threadlike or rod-like micelles (linear or branched). (The latter are also called living polymers because if they break imder large stresses, they can reform under conditions of rest or low stress (see chapter 18).) The typical response of such a system is shown in figure 14, where a representative relaxation time would be around 1 s, see [10]. 

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