Rupture of Single Films and the Emulsion Lifetime

After considering experimental trends, let us proceed with a simple model. Consider the coalescence in a creamed OAV emulsion layer. We model the system 

According to this equation, the emulsion lifetime decreases with an increase in the frequency of the hole nucleation and in the emulsion droplet size. Sometimes it is difficult to follow the changes in the mesh size of the concentrated emulsion experimentally. In this case, one can monitor the rate at which the layer of free oil is formed at the top of the vessel. It is easy to show that the time for separation of half of the volume of the oil, t,/2, is close to t predicted by eqn. (7.21), if the height of the cream layer (A) is much larger than the size of the emulsion droplets h do. 

The problem of the evaluation of the emulsion lifetime is therefore reduced to determining the rupture frequency / In the spirit of the physical kinetics approach, it can be regarded as the product of a pre-exponent / and an exponent  

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