FIG. 12 Schematic diagram of the cell for formation of films in the capillary of a porous plate.

Many physical factors are involved in the control of surfactant foam film stability. This means that foam film stability can be determined by the following factors: surface rheology, the Marangoni effect, disjoining pressure, and hydrophobic interaction. A dominant factor for maintaining the foam varies with the thickness of the liquid films as shown in Fig. 14 [162]. The rate of thinning (drainage) of liquid films is drastically influenced by the rheolog-