Colloid agglomeration flocculation

Some authors distinguish between coagulation and flocculation and use the latter term for colloid agglomeration by bridging of polymer chains. 

Some colloidal systems such as polymer solutions and surfactant solutions containing micelles are thermodynamically stable and form spontaneously. These types of colloids are called lyophilic colloids. However, most systems encountered contain lyophobic colloids (particles insoluble in the solvent). In the preparation of such lyophobic colloidal dispersions, the presence of a stabilizing substance is essential. Because van der Waals forces usually tend to lead to agglomeration (flocculation) of the particles, stability of such colloids requires that the particles repel one another, either by carrying a net electrostatic charge or by being coated with an adsorbed layer of large molecules compatible with the solvent. 

Flocculation Agglomeration of colloidal material by adding a chemical that causes the colloidal particles to produce larger particles. 

Appearance of coaqulum. Towards the end of the reaction besides a colloidal solution of microgel particles some flocculate may be found. With the electron microscope two kinds of flocculates can be distinguished. The first type looks like coagulated secondary agglomerates and the second like polymerized monomer droplets (with diameters of about 2000-5000 A), (These polymerized monomer droplets are also found in the case of 1,3,5-trivinylbenzene.)... 

The object of this study was to clarify some aspects of the mechanism of shear-induced flocculation in colloidal dispersions. Vinyl chloride homopolymer and copolymer latices were prepared by emulsion polymerization using sodium dodecyl sulphate as emulsifier. Agglomeration behavior in these latices was studied by measuring the mechanical stability using a high speed stirring test. The latex particle size was measured by an analytical centrifuge. Molecular areas of emulsifier in the saturated adsorption layer at the surface of homopolymer and copolymer latex particles were estimated from adsorption titration data. 

In kinetic studies of the formation of silver bromide, Meehan and Miller found that formation of colloidal material was complete within 6 msec or less. They further concluded that fast flocculation, in which every collision of particles results in an agglomeration, occurs during the mixing process and for a few seconds thereafter. Berry and Skillman and Berriman determined that the total number of silver halide crystals remained essentially unchanged after the first minute of doublejet precipitation. 

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