Adhesion of Colloids Dispersion, Aggregation, and Flocculation

The resisting Power of fluid Mediums... is very nearly as the Diameter and the Velocity of the spherical Body together Isaac Newton, Opticks p. 365 (precursor of Stokes Law for viscous force on a particle, F= 3jrnD V, used in equation 10.2). 

from the first law of adhesion, particles always adhere, the natural state of particulate materials is aggregated as in Fig. 10.1 (a), with each particle stuck fast to its neighbors. However, when the particles become contaminated with liquid, the second law of adhesion applies and the adhesion is reduced. In certain circumstances, this reduction in adhesion proceeds so far that the particles remain separate or dispersed in the contaminating medium, as in Fig. 10.1(b). Such bizarre behavior is a challenge to the theorist because it seems to go against the basic laws of adhesion. The purpose of this chapter is to show that several complex mechanisms cause the particles to behave strangely. The most important mechanism is Brownian movement, followed by electric charging, followed by adsorption of polymer molecules at the surface. 

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