deformation and whatg-gradient can be formed. The latter determines the
magnitude of the tangential stress that an interface can withstand and the
strength of a Marangoni effect. We may mention the importance ofESDfor
formation of foams and emulsions, stability of thin films, and rate of
Ostwald ripening.
10.8.3 Stagnant Surfaces
In Section 10.7 it was explained how flow along an interface can induce ag-
gradient (Fig. 10.28b), and how such a g-gradient can arrest lateral
movement of the interface [Eq. (10.17)]. This is certainly true for an
FIGURE10.36 Relation between surface pressurePand surface excessGat the A–
W surface for three surfactants.