Emulsions Characterized by Means of Time Domain Dielectric Measurements (Tds). Technical Applications

Abstract

The authors have in previous contributions determined dielectric properties of W/O-emulsions by applying the Time Domain Dielectric Spectroscopy technique. The main findings are summarized here. The influence of droplet shape and flocculation on the dielectric parameters characteristic of the emulsions is discussed. A technique developed for a dielectric investigation of electrically induced coalescence is demonstrated, together with experimental results from surveys on emulsions stabilized both by commercial and natural surfactants.

The microwave absorption of emulsions containing aqueous micro- and nanodroplets: A means to optimize microwave heating

“…A more complicated relaxation and absorption behavior is to be expected when the electric field drives droplet deformation, droplet-droplet interactions and flocculation [9,10]. As the systems discussed below are stable and do not change their colloidal (and dielectric) characteristics throughout the experiments (employing sufficiently weak fields), discussion of those effects is omitted in the present context.…”

Bubble Plume Tracking Using a Backseat Driver on an Autonomous Underwater Vehicle

“…For example, oil slicks on a sea surface are transported with the surface current (normally 2.5-4.0% of the wind speed) [7] and the subsurface oil particles move vertically and horizontally at randomized turbulent diffusive velocities in three dimensions [8]. Emulsification changes the spilled material into a semi-solid heavy material by increasing density (from 0.80 to 1.03 g/mL), viscosity, water content (60-85%) and thus its total volume (three to five times the original volume) [9]. As a result of these changes in properties, the formation of emulsion, also called 'chocolate mousse' by responders, has a significant influence on the choice of oil spill recovery method.…”

Visible Light Backscattering Monitored in Situ for Transitional Phase Inversion of BrijL4–Isopropyl Myristate–Water Emulsions

“…Conductivity of O/W emulsions can be calculated through mathematical models; equations have also been established for three-phase systems considering volume fractions of each dispersed phase . Electrical properties of emulsions under sinusoidal constraints have been studied, and the phase inversion temperature was detected from impedance at low frequencies by use of parameters such as double layer capacitance and charge transfer resistance. − However, the conductimetric method has some drawbacks. First of all, it needs to add an electrolyte such as NaCl in the aqueous phase to get a clear-cut detection of the phase inversion and is not totally reliable in very highly viscous systems for which creation of stagnant unmixed zones is favored .…”