Thickening efficiency

This is a process for concentration of sludge by removing water. Either gravity thickening or dissolved air flotation thickening can be used. The thickening efficiency depends on the nature of sludge to be processed [15]. 

Moisture content normal water content is up to 2% w/w. However, carbomers are hygroscopic and a typical equilibrium moisture content at 25 C and 50% relative humidity is 8-10% w/w. The moisture content of a carbomer does not affect its thickening efficiency, but an increase in the moisture content makes the carbomer more difficult to handle because it is less readily dispersed. 

Fig. 5.2 Effects of molecular weight, base stock type and base improver thickening efficiency...

In terms of chemistry, it is important to note that the intrinsic viscosity, [ ], or some other measure of molecular dimensions in solution, is the driving force in thickening efficiency, not the molecular weight per se. In other words, it should not be expected that two chemically different polymers of the same molecular weight will thicken in the same way. Indeed, if chemical structures are radically different, it is virtually certain that they will not. 

Thickening efficiency high Less polymer is needed to... 

The concentration dependence of the Brookfield viscosity (Figures 9 and 10) indicates a rapid drop in viscosity upon dilution below a critical concentration. Bagley (7) attributed such rheological behavior to a structure of swollen, deformable gel particles closely packed in intimate contact. Davidson (8) later attributed the thickening efficiency of a cross-linked poly(acrylic acid) to the dispersed rather than the continuous phase. In general, pseudoplastic and viscoplastic rheology is characteristic of dispersions with low... 

List 2. Factors Known To Affect the Thickening Efficiency or Rheology of Associative AST Emulsions (HASE Thickeners) ... 

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.

NW, Pigment Volume Content, and Latex. Pigment volume content (PVC) and latex type and grade are important for optimizing dry film properties. Percent NW is usually governed by the desired cost of the final product. The formulator usually does not use these variables to optimize paint rheology but should be aware of how they affect thickener efficiency. 

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