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Speaker: Riande Dekker MSc

Title: Emulsion stability and rheology

Abstract: Emulsions cover a broad range of industrial applications, thereby resulting in a large variety of research topics in the field of emulsions. Developing and producing good quality emulsions however comes down to a thorough knowledge of preparation procedures, stability mechanisms and rheological behaviour. In my thesis, we describe our research insights in these aspects for high quality emulsions.

During my presentation, I would like to focus mainly on emulsion stability. We examine the limits of emulsion stability, thereby inducing destabilisation. In particular, we look at highly concentrated surfactant-stabilised oil-in-water emulsions. A thin layer of emulsion is placed between two glass plates. By slowly decreasing the sample thickness, the emulsion is squeezed. This results in preferential removal of water, resulting in very thin films between the oil droplets. Eventually the films break, inducing coalescence and finally full destabilisation of the emulsion. Initially, we focus on the mechanism behind destabilisation. A coalescence cascade because of breakage of a very thin film between two oil droplets results in the destabilisation of our emulsions. Afterwards, the focus of this destabilisation research shifts to the application of our technique in industry. Therefore, it is important to gain more knowledge on the time scales and forces involved in the destabilisation process. Although our experiments are performed on a small scale, the main concept can be very interesting for companies to destabilise large quantities of emulsion.