3. Formulation-composition cards

As we shall see later, emulsions are memory systems, whose properties often depend on the way they have been prepared. For example, two emulsions with exactly the same formulation and composition can have very different properties (type, viscosity, stability).

To avoid this complication, we'll start by considering emulsions obtained by stirring pre-equilibrium W/O/W systems. In this case, there is no transfer of chemical species between phases, and the emulsified system differs from the same system at equilibrium only by an increase in the W/O interfacial area. In practice, the S/H/E system is left at rest at constant temperature for one or two days, so that equilibrium can be achieved by simple diffusion of species. The phase behavior of the equilibrium system can then be observed. To speed up the process, it is preferable to place the surfactant and any cosurfactant...