The effects of an external electric field on lecithin organogels formed by the addition of trace amounts of water or glycerol, inducing a formation of polymer-like micelles, have been studied by oscillating rheology. Field application brought about an increase in the organogel viscosity and shear moduli when the threshold field strength, Emin, was exceeded. A second critical field strength, Emax, determines a boundary between stable and unstable electrohelogical (ER) effects. The dependencies of Emax on the molar ratio of polar additive to lecithin differ for water- and glycerol-containing systems. In the former, Emax increases over the whole concentration range for the polar additive whereas for systems including glycerol Emax passes through a maximum. Frequency-sweep measurements on the lecithin organogels under an electric field revealed a new rheological regime at intermediate frequencies; both the dynamic moduli depend on f1/2. The same behavior has only previously been observed with polymer-containing systems. This finding - together with observations of the formation of filaments oriented in the direction of the electric field - has enabled us to suggest that the ER effects in lecithin organogels are caused by an alignment of parts or whole polymer-like micelles along the electric field lines. © Springer-Verlag 1999.
CITATION STYLE
Dürrschmidt, T., Hoffmann, H., & Shchipunov, Y. A. (1999). Electrorheological effects in lecithin organogels with water and glycerol. Progress in Colloid and Polymer Science, 112, 11–14. https://doi.org/10.1007/3-540-48953-3_3
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