Conductivities in Emulsions

Abstract

The dependence of the conductivity of water‐propylenecarbonate emulsions on volume fraction f of the dispersed phase, on the conductivities of the continuous phase kc , and of the discontinuous phase kd , has been measured in the ranges of 0<f<0.5 and 0.172<kd/kc<101 . The results indicate that when f>0.2 neither Maxwell's equation nor Bruggemann's approximation represents the behavior of data satisfactorily. In an attempt to take into account the interaction of fields around particles of the dispersed phase, a simple approximation is proposed, based on Maxwell's equation. In the range of conductivities investigated in the present study the new equation represents the conductivity of emulsions with reasonable accuracy.

The conductance of suspensions with conducting particles

“…A comprehensive review on this subject has been given by Landauer [1]. Starting from Maxwell's relation for the conductivity [1][2][3][4], Bruggeman developed an asymmetric theory [1,[3][4][5][6] for the conductivity of a suspension. This theory is applicable for a larger range of volume fractions of particles than Maxwell's theory, but appears to be valid only for a wide distribution of particle sizes.…”

“…This theory is applicable for a larger range of volume fractions of particles than Maxwell's theory, but appears to be valid only for a wide distribution of particle sizes. Meredith and Tobias [6] have developed a model, also based on Maxwell's equation, for particles with a narrow size distribution. The occurrence of chain formation or other direct contacts between the particles leads to a percolation threshold, which can be defined with Bruggeman's symmetric or effective-medium theory [1,4,7].…”

“…Conductivities of ion-conducting emulsions were measured by Meredith and Tobias [4,6], Pearce [13], Bhattacharya et al [15], Lagourette [16] (who also determined the frequency dependency), Fang et al [17] (who found a very good w Also at the Koninklijke/Shell-Laboratorium, Shell Research B.V., 0021-891X/92 9 1992 Chapman & Hall affirmation of Bruggeman's symmetric theory), and Turner [18]. In this last investigation a simple theory was developed based on the calculation of the distances between ion-conducting spheres; it agrees well with the experimental results for high volume fractions.…”

Micro-scale mass-transfer variations during electrodeposition

“…To understand the dynamics of this process, it is necessary to separate the different components, and study each in isolation. Work in this laboratory dates back to the 1950's, when Tobias and associates [133,137,140] determined the resistivity of gas-electrolyte emulsions and the resistance caused by bubbles rising in the inter-electrode gap. In the 1960's, Cheh [ 129] studied the growth of non-interacting bubbles in a variety of concentration fields.…”

“…The reader is referred to their individual theses for specific details [127][128][129][130][131][132][133][134][135][136][137][138][139][140][141], and to review articles by Vogt and Sides for a broader introduction to the field of electrolytic gas evolution [ 164,166].…”