Flow behaviour of highly concentrated emulsions of supersaturated aqueous solution in oil

Abstract

A set of highly concentrated water-in-oil emulsions with supersaturated dispersed phase were investigated in this work to verify and/or develop the models that have been presented both in the literature and in this work. The material used to form emulsions consisted of supersaturated oxidiser solution, hydrocarbon oil and PIBSA-based surfactants. The interfacial characteristics for different surfactant types were first examined. Then, the rheology of samples was studied, and different scaling methods and fitting of experimental data were studied. On the basis of flow curve measurements and observed $\tau _\emph{v} \sim \dot {\gamma }^{1/2}$ scaling, a modified version of Windhab model was suggested which showed excellent fitting of experimental results. The linear dependences of τ _y0/σ versus 1/d ₃₂ for studied emulsions showed non-zero intercept which implies a non-linear dependence (resulting from interdroplet interaction) to fulfil the zero-intercept requirement. It was established that the zero intercept condition was fulfilled in the $\tau _{y0} \sim \sigma /d_{32}^2$ scaling, although the experimental results for different surfactants were not superimposed.