Key Factors Governing the Stability of Free-Disperse Systems

1 KEY FACTORS GOVERNING THE STABILITY OF FREE-DISPERSE SYSTEMS 

FIGURE 4.3 To the definition of the disjoining pressure, H(h), in a thin flat-parallel plate according to Derjaguin. 

The derivative -dAa h)/dh = is the force per unit cross-sectional area, also known as Derjaguin s disjoining pressure [4,5], Within the context of this definition, both Ao(/t) and W(fi) are positive in the case of a repulsion and negative in the case of an attraction. Molecular attraction forces prevail at long distances, while repulsive forces prevail at very short distances (the so-called Born repulsion). The principal theory that describes the interactions in a thin film is the well-known Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which focuses on the analysis of the competitive contribution of molecular (dispersion) attractive forces and electrostatic repulsion to the interaction between surfaces separated by a liquid film. 

The value of IAOf(fio)l = Aof = F characterizes the extent of cohesion between the surfaces in direct contact at the primary free energy minimum. 

FIGURE 4.4 The molecular (dispersion) component of the free energy of interaction—the negative component, Aofih) = AFf(moi)(A) the definition of the Hamaker constant and the complex Hamaker constant. 

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