The association of montmorillonite studied by light scattering in electric fields

Reversing-Pulse Electric Birefringence of Montmorillonite K10 in Aqueous Media: Electric Moments, Field Orientation, and Changes in Sign and Profile of Signals Observed in the Low-Field Region

“…5 are associated with equilibrium shifts between the initial and final states, but not with orientational transition, caused by applied electric fields, attempts were made to fit the intermediary signals in the vicinity of the sign-inversion point by utilizing expressions for the two-state equilibrium (Eq. [11]) with appropriate F values. For this purpose, curves 2 and 6 were assumed to represent the initial and final pure states, i.e., ⌬(t) 2…”

“…6 (curves 1 and 2) were simulated with theoretical expressions [11] and [12] for the two-state equilibrium model to show that the peculiar profile can be explained in terms of a mixture of aggregated and unaggregated MK-10 particles in equilibrium. For the negative RPEB signal of the unaggregated form in the pure (initial) state, curve 2 at the dilute concentration (0.029 g/L) of Fig.…”

“…Theoretical RPEB curves (1-6) calculated with expressions [1][2][3] and [11] for the fluctuating ion polarization and a schematic reversing-pulse field (a). Parameters: q ϭ Ϫ1.8, ϭ 2.0, and * ϭ 0.5 for curve 1; q ϭ Ϫ0.7, ϭ 0.4, and * ϭ 2.5 for curve 6.…”

“…To elucidate the nature of the ionized clay particle, bentonite suspensions have extensively been studied with the electric birefringence (EB) and electric light-scattering (ELS) methods, which are powerful for obtaining vital information on the field orientation behavior and also the electric, optical, and hydrodynamic properties of diversely different polymeric materials (1,2). The EB and ELS methods usually utilize as the external electric field either a single-wave square pulse (3)(4)(5)(6) or an alternating-current sinusoidal pulse (7)(8)(9)(10)(11) to orient bentonite particles in aqueous suspensions. The results of these EB and ELS studies have been interpreted in general as being due to the permanent electric dipole moment associated with the disklike particles.…”

Transient scattering studies on crocidolite suspensions

“…Measurements of the accompanying changes in the scattered intensity can be used to evaluate the electrical characteristics of the sols. This electro-optic scattering method is not restricted to particles of specific shape and has been used for both rods (Wippler, 1956;Stoylov, 1964; and discs (Wippler, 1956;Schweitzer & Jennings, 1972a). The object of the present study is to show how it provides a quick and efficient means of studying minerals such as asbestos fibres when in dilute suspension.…”