Shear Stability of Highly Concentrated Emulsions

Resumo

Shear stability of water-in-oil highly concentrated emulsions was characterized by the rate of the droplet size decrease at a constant shear rate. Samples of different concentration (ranging from 0.85 to 0.94 wt %), prepared with different surfactants and three types of oils were analysed. The emulsions under study are visco-plastic media with a clearly expressed yield stress. The usually used Capillary number is not valid for such systems but instead Bingham number (ratio of the yield stress to interfacial forces) was used to characterise their stability. Within the frames of our experiment, it has been proven that the correlation between shear stability of emulsions and the Bingham number exists.