Stability of non-aqueous dispersions. Part 4.—Rate of coagulation of rutile in aerosol OT + p-xylene solutions

Abstract

Measurements of electrophoretic mobility and of coagulation rate have been made on dispersions of pure rutile in solutions of Aerosol OT (sodium di-2-ethylhexyl sulphosuccinate) in p-xylene. Stability ratios have been related to zeta potentials, the signs of which were controlled by the presence or absence of trace amounts of water in the system. An improved theoretical method was used for calculating the stability ratio. The observed relationship between stability ratio and zeta potential shows satisfactory agreement with that predicted by the Derjaguin-Landau-Verwey-Overbeek theory.

Adhesive Force between Hydrophilic Surfaces in Alcohol–Water Solutions

“…According to Eq. [1], the magnitude of F ad must be 50 -200 times larger than that of the probe apex, but it is found to be even smaller than F ad of the probe apex. To know the reason for this reduction of F ad , the AFM images of the surface of silica particles were taken (Fig.…”

“…According to Eqs. [1] and [3], both the bridging force and van der Waals force vary linearly with the radius of curvature of a particle, so that the adhesive force will increase extraordinarily if the probe apex is replaced by a colloidal particle. Here the adhesive force between a mica plate and a silica particle 4.1 or 9.1 m in diameter on the colloid probe is measured in 1-butanol and 1-pentanol solutions, as shown in Fig.…”

“…It is known that the bridging force between a sphere and a plate, F br , may be given by the Laplace equation (27) F br ϭ 4R␥ cos , [1] where R is the radius of spherical surface, ␥ is the interfacial energy of the bridging surface, and is the contact angle of water on the plate in the solution. Then the total attractive force between the surfaces F ad is given by the equation…”

“…The interaction between particles in nonaqueous media and their stability has been investigated by various researchers (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), but the detailed features have not been clarified yet. This is probably because the experimental methods employed are too macroscopic to clarify the microstructure of molecules near the surface which will be responsible to a great extent, for the interaction and adhesive forces.…”

Hydrodynamic and surface interaction forces on a particle in a pore

“…Equations [ 8 ] and [ 9 ] can be made dimensionless by introducing a characteristic length L ( = the particle diameter) and a characteristic velocity U0 (= the maximum velocity at the inlet). These quantities are employed to make linear parameters dimensionless by dividing them by L, velocities by dividing them by U0, pressures by dividing them by p U 2, and volume forces f by dividing them by U~/L.…”