EMULSION SYSTEM EVAPORATION 33 -2.0 -2.4 I I 0 5 10 15 20 lime / minu[es Figure 7. The increase of emulsifier concentration due to the evaporation of solvents was a logarithmic function of time. For pure water, r is of the order of 2 ß 10-3 s ß cm- • whereas with a diffusion , coefficient three orders of magnitude smaller, along with a tremendous increase in the path length, one can expect slow evaporation through a lameliar film (14). This is indeed what we observed. However, this simplistic model must be applied with caution, since the formation of the lameliar film has not been proven to be uniform, and hence the switch from an evaporation accompanied by convection to a diffusion- controlled one does not take place at the same time for all the surface exposed. SUMMARY The phase transition in a cosmetic emulsion system was followed during evaporation of water and the solvent. The result demonstrated the transition to more ordered structures with a reduced amount of water and organic solvents. REFERENCES (1) M. M. Breuer, in Encyclopedia of Emulsion Technology, Vol. 2, P. Becher, Ed. (Marcel Dekker, New York, 1983), p. 385.

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