Effects of dispersion concentration on the electroacoustic potentials of o/w miniemulsions

The Binding of Monovalent Electrolyte Ions on α-Alumina. I. Electroacoustic Studies at High Electrolyte Concentrations

“…At solids concentrations above φ = 0.02, the hydrodynamic and electric field disturbances generated by each moving particle are experienced by its near neighbors, retarding their motion. The result is a φ-dependent decrease in the complex dynamic mobility. − To account for these effects, O'Brien has recently developed a semiempirical model for relating the reduced dynamic mobility of simple metal oxide suspensions to the ζ potential at high φ conditions . The effectiveness of this treatment has been demonstrated for solids volume fractions up to 0.30 provided that electrical double layer overlap is insignificant .…”

Volume Fraction Effects in Electroacoustic Measurements

“…This is a much stronger φ-dependence than predicted by any theory. These observations suggest that (polystyrene) latices may not be the ideal model system and/or that the geometry of the cell affects the backflow (7,24). We do not think that any major changes in the acoustic impedance of the suspension can explain the observed discrepancies, because Carasso et al reported that the acoustic impedance of a 20% (by weight) emulsion was negligibly different from that of water (28).…”

Dynamic Mobility of Particles with Thick Double Layers in a Nondilute Suspension

“…Earlier studies of the ESA effect in concentrated suspensions (45)(46)(47) used the Matec ESA-8000 apparatus, which does not correct for the acoustic properties of the suspension and so cannot give an accurate measurement of the dynamic mobility in a concentrated system. A recent study using the AcoustoSizer (41) indicated that the "pairwise" theory with a Percus-Yevick pair correlation function gave consistent surface potentials, but further results are needed to establish the range of validity of that approximation.…”