Physicochemical studies on microemulsions: test of the theories of percolation

Abstract

33) Cabane, B.; Wong, K.; Wang, T. K.; Lafuma, F.; Duplessix, R. Colloid Polvm. Sci. 1988. 266. 101. (34) Afshar-Rad, T.; Bailey, A. I.; Luckham, P. F.; Macnaughtan, W.; (35) Marra, J.; Hair, M. L. J. Phys.On the basis of percolation results of 32 water/oil microemulsion systems, a detailed analysis of the validity of the effective medium theory (EMT), EMT with dipoledipole interaction (EMTDD), and Bemasconi-Weismann (BW) theory has been made. It has been found that most of the systems obey either the EMT or the EMTDD (chain) formalism whereas a slender few follow the EMTDD (cluster) and BW formalisms. The results suggest that the internal structure of microemulsions can be either isolated, randomly dispersed spheres or spheroidal aggregates formed by dipolar interaction.

Physicochemical studies on microemulsions

“…This is the expectation for static percolation of mixtures of conductors and insulators [35][36][37]. The dynamic percolation of microemulsion may not comply with this requirement [3,[37][38][39]. There, Eq.…”

“…Paul et al [38] have observed the applicability of the chain formalism for most of the systems studied by them and others. The systems herein studied have produced excellent linear fittings (Fig.…”

“…The volume percolation of conductance has also been examined in light of the effective medium theory with the dipole-dipole interaction (EMTDD) of Granqvist and Hunderi for dispersed particles of different states of aggregation as simplified by Paul et al [38].…”

Influence of n-alkyl acids on the percolative phenomena in AOT-based microemulsions

“…In particular, microemulsions-as phase transfer catalysis systems-are able to enhance reactions between nonhydrosoluble organic substrates and hydrosoluble reagents and, as a result, the kinetics of numerous reactions in microemulsions have been studied [2,[23][24][25][26][27][28][29][30]. Electric conductivity measurements constitute a very useful technique for obtaining information about micellar interactions [31][32][33][34][35][36]. Generally, a microemulsion presents a very low specific conductivity.…”

Percolation Behavior in W/O Emulsions Stabilized by Interfacially Active Fractions from Crude Oils in High External Electric Fields

“…These floccumittivity e* tot (v) calculated from the Fourier transform of lated aggregates give rise to a higher static permittivity and the pulse shapes will, in addition to the dielectric part e*(v), longer relaxation time than can be expected from the simple include a contribution from d.c conductivity, s; i.e., models of noninteracting spherical inclusions. This has resulted in the development of new models taking into account flocculation and elongation of aggregates, which are repree* tot Å e*(v) 0 is ve 0 , [6] sented by a shape factor. This shape factor depends on the axial ratios of the aggregates and is 1 3 for spheres and 1 50 for where e 0 is the permittivity of free space.…”