Dispersion general

The use of dispersants is highly recommended in systems containing silt, sand, oil, grease, biological material, and/or other foreign material. Not only does increased dispersion generally increase the effectiveness of chemical inhibition, it also prevents nucleation of oxygen concentration cells beneath foulants. 

The process of sedimentation in a dilute dispersion generally produces a discernible, more concentrated dispersion, which is termed the sediment and has a volume termed the sediment volume . 

The solids contents of these dispersions generally are of the order of 50% to 60%, occasionally even higher, so that one may deposit from a certain thickness of wet adhesive quite a thick dry film of polymer. Solvent-based adhesives generally have lower solids contents (20% to 30%), and since the shrinkage after drying of water-based dispersions also is lower such adhesives can be formulated to fill gaps between materials as well as to bond them. 

The stability of a colloidal dispersion generally decreases as the electrolyte concentration increases.2 At low electrolyte concentrations, the electrostatic repulsion is responsible for the stability of the colloidal system. However, at sufficiently high electrolyte concentrations, the thickness of the double layer is significantly decreased, and the electrostatic repulsion no longer contributes to the stability of the system. 

The condition for incipient flocculation, i.e., the delineation between stable and unstable dispersions, generally corresponds to the theta condition for the stabilizer in solution. A large body of experimental data gathered by Napper and others (e.g., Napper, 1983) first established this correlation, and the theoretical predictions for the interaction potentials agree provided nl2u < 1. 

K. B. Bischoff and O. Levenspiel, Fluid Dispersion—Generalization and Comparison of Mathematical Models, Chem. Eng. Sci., Yl 245 (1962). 

While chemical agents other than beach cleaners or surface-washing agents are sometimes suggested for shoreline cleanup, they should not be used as they are not effective and can cause additional problems. Dispersants generally increase the penetration of the oil, which makes them unsuitable for use on shorelines. Solidifiers or recovery agents do not assist with oil recovery. 

J m 3. In other words, full coalescence would lead to an increase of the temperature of the system (provided it is isolated) by 1.5 mK. Hence the free energy decrease involved in changes in dispersity generally is quite small. 

Sediment The process of sedimentation in a dilute dispersion generally... 

The PVAc formulations currently available on the adhesives market are rather complex systems comprising a poly(vinyl acetate) dispersion, a film forming promoter, a cross-linking agent and/or a hardener. The use of modified poly(vinyl acetate) dispersions generally requires a thermal treatment to obtain the best results and the use of a specific cross-linking comonomer, such as N-methylolacrylamide (NMA), may cause a lower shelf-life of adhesives as well as formaldehyde emissions. 

Poultices (wet dressings) are hydrophilic heat-retentive bases in which one or more active ingredients, solids or fluids, are dispersed. Generally, they are heated before use and applied on the skin in a thick layer. 

The direct discharge of liquid and gaseous effluents from a nuclear facility and their subsequent dilution and dispersion is permitted by regulatory agencies provided that releases are controlled to ensure that human health and the environment are protected. But as alternatives to containment and isolation of most types of radioactive waste, dilution and dispersion generally are not viable disposal options. It should be noted, however, that dilution and dispersion have an important role in geological disposal concepts. They are a safety factor in any system that cannot guarantee "zero release", which is to say that they are a factor in any system that must function over many thousands of years. 

The waterborne polyurethane dispersions generally have a pH between 6 and 9, and higher solids content (35-50%) and lower viscosities (about 100 mPa.s) than the solvent-borne... 

Calcium carbonate, limited by the PPI to 5 phr, may or may not be surface-treated with stearic acid to improve handling and dispersion. Generally, a smaller calcium carbonate particle is obtained through a precipitation process (0.3-0.7 jxm), and smaller particles tend to offer better impact strength than ground calcium carbonate (1-3 xm or larger). 

Uses Scouring agent detergent dye dispersant general dispersant emulsifier Fhoperties Powd. 26% act. 

Uses Antistat, emulsifier for agric., metal cleaning, emulsion polymerization pigment dispersant general puqrose detergent Properties Liq. HLB 7.0 99% cone. 

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