Synopsis A method for measuring the variation of electrical impedance (Z) of thin layers (0.1 mm) of O/W emulsions during evaporation in a controlled environment is presented. The evaporation of an emulsion base (A) either as such and containing 1% glycerin (B) or 1% sodium pyrrolidonecarboxylate (C) was investigated for 120 min at constant air temperature (25 degrees C) and relative humidity (55%). The measured impedance of the emulsion layers increased by three orders of magnitude during the evaporation cycles. The relationship between impedance and water content of the evaporating emulsion layers was investigated. Each emulsion showed a complex linear relationship between log Z and water content, the relationship being represented by two (three, for emulsion A) linear portions in the graph. Plots of water content vs. time, temperature vs. time and rate of water loss vs. water content of the emulsion layers are presented. The data appear to indicate that evaporation proceeds via distinct stages, whose correspondence to different mechanisms of water evaporation is discussed. The potentiality of the present method for water analysis, and for investigating structural changes in emulsions during evaporation, is also discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.