Linear viscoelasticity of emulsions

Abstract

Linear viscoelasticity of emulsions in shear deformation in the kilohertz range is demonstrated experimentally. In order to avoid complications due to inertia effects, emulsions with small droplet sizes are studied. The preliminary measurements are interpreted as being the result of droplet deformations. If this interpretation is correct, measurements of the dynamic viscosity of emulsions may be used to obtain information about the mechanical properties of the interfacial layer between droplets and the continuous phase. In particular, the evaluation of the interfacial tension of emulsion droplets from bulk properties might be possible using this technique.

Viscoelasticity and microstructure of non-ionic microemulsions

“…These results are, however, not unique for this system. Measurements on cyclohexane/NNP 7/water microemulsions show qualitatively the same trend as a function of temperature [28].…”

“…This means that our results can be interpreted in three different ways: I. It can be shown [28] By fitting the parameters of Oldroyd's second model, using equation (29), which is also valid at higher concentrations, we obtained three sets of values for the parameters. They are given in table 1.…”

“…This can be formulated in the following rheological equation of state for the interfacial layer: (24) So, the relation between the surface-stress tensor _P and the surface-strain tensor E can be describe in terms of five parameters; the interracial tension y, the dynamic-area elasticity ~e with corresponding viscosity a, and the dynamic-shear elasticity/~ with correspond-(25) ing viscosity ~. In equation (28) tr _E signifies the trace and _E the traceless part of E. Introduction of four additional parameters in the (26) expression for //* appears to lead to one more relaxation time and one more retardation time or, equivalently, in the expression for /7' and r/" of the type of equations (20) and (21), to one more relaxation mechanism.…”

The linear-viscoelastic behaviour of a dispersion of transversely rigid spherical capsules

“…A few reasonably well defined model systems are available to study interfaces experimentally. Dynamic shear experiments have been applied for the investigation of ionic and nonionic (micro-) emulsions [1,2]. In particular non-linear properties of capsule dispersions with cross-linked polymeric interfaces [3] have been studied.…”

Torsion pendula with electromagnetic drive and detection system for measuring the complex shear modulus of liquids in the frequency range 80?2500 Hz

“…Systems investigated are amongst others polymer solutions [1], microemulsions [2], ordered latices [3], blood and synovial fluids [4]. In the high-frequency range ) a number of instruments based on quartz crystal and nickel tube resonators are used [5].…”