Fine particles, dispersion

The process of thickening involves the concentration of a slurry, suspension, or sludge, usually by gravity settling. Because concentrated suspensions and/ or fine particle dispersions are often involved, the result is usually not a complete separation of the solids from the liquid but is instead a separation into a more concentrated (underflow) stream and a diluted (overflow) stream. Thickeners and clarifiers are essentially identical. The only difference is that the clarifier is designed to produce a clean liquid overflow with a specified purity, whereas the thickener is designed to produce a concentrated underflow product with a specified concentration (Christian, 1994 Tiller and Tarng, 1995 McCabe et al., 1993). 

The fine particles dispersed in a liquid first collide with each other and then have a tendency to aggregate. The stability of the dispersion depends on the interaction forces between the particles during these collisions. Five such forces are ... 

Both of these mills can achieve very small particle-size dispersion (below 100 nm, if the primary particle size of the powder is small enough). However, formulation with surfactants is absolutely necessary to achieve fine particle dispersions. Otherwise, the particles will simply reagglomerate after leaving the shear field of the machine. 

H. Masuda, A. Ebata, K. Teramae and N. Hishinuma, Alteration of thermal conductivity and viscosity of liquid by dispersing ultra-fine particles (dispersion of AI2O3, Si02 and Ti02 ultra-fine particles), Netsu Bussei 4, 227-233 (1993). 

Ceramic particles in organic liquid media behave differently from those in aqueous media. Many known ceramic-processing techniques involve fine particles dispersed in nonaqueous media. Some of the better known examples are tape casting of barium titanate and aluminum nitride powders and tape or slip casting, extrusion, and injection molding of ceramic high Tc superconductor powders. 

A latex is a dispersion of water-insoluble polymers in water. Very-fine-particled dispersions or latices are also called hydrosols. 

Y. Fukushige and N. Shimohara, Fine particle dispersion, ink composition using the same, and ink-jet recording method, US Patent 7 513 942, assigned to Fujifilm Corporation (Tokyo, JP), April 7, 2009. 

E. Nes, J.D. Embury The influence of a fine particle dispersion on the recrystallisation behaviour of a two phase aluminium alloy, Z. Metalikunde 66, 589-593 (1975)... 

E. Nes The effect of a fine particle dispersion on heterogeneous recrystallisation, Acta Met. 24, 391-398 (1976)... 

A colloid is any system consisting of a finely divided phase in a fluid. A colloidal suspension (or sol) consists of fine particles dispersed in a liquid. The particles, referred to as colloidal particles, undergo Brownian motion and have a slow (often negligible) sedimentation rate under normal gravity. The size range for colloidal particles is approximately 1 nm to 1 p.m. 

Latex blending of NR with polar synthetic rubbers presents several mixing advantages e.g. eco-friendly dispersion medium, fine particle dispersion, etc), but for other applications does not provide any cost advantage since coagulation, removal of water and drying are cost-intensive processes. ... 

FMR experiments performed on fine particles dispersed in a nonmagnetic matrix (e.g., Fe, Co, Ni in polymer matrices,a-FcjOj in silica supported Ni particles ) show a progressive broadening of the absorption line, accompanied by the shift of the resonance field to lower values, as the temperature decreases. 

The particle size of the monomer is reduced to colloidal dimensions by more vigorous stirring and use of synthetic surfactants (anionic, cationic or non-ionic) in place of protective colloids used in sus )ension polymerisation. Usually water soluble catalysts such as persulphate or hydrogen peroxide are u.sed. Thermal dissipation and viscosity problems are absent. Both the rate of polymerisation and the molecular weight of the product formed arc very high. The product, which is in the fonn of fine particles dispersed in water (called latex), can used directly as adhesive or an emulsion paint, or it can be isolated by coagulating with an electrolyte. The technique is employed for the industrial production of PVC,... 

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