Stability of Foams and Emulsions
The coalescence of drop–drop (emulsions) or bubble–bubble (foams) is crucial for the stability of dispersions in both stationary and flowing multiphase systems. In some cases, stable two-phase systems are desirable, for example, to achieve the largest possible mass-transfer area. On the other hand, stable emulsions or foams can hinder efficient phase separation. In addition to the type and concentration of surface-active substances, the coalescence behavior also depends on the viscosity ratio of the dispersed phase to the continuous phase. In both cases, the dominant factor is the mobility of the interface during film drainage between two colliding fluid particles. Reduced mobility, for example due to a concentration-induced Marangoni effect, slows down drainage and thereby stabilizes the dispersion by inhibiting coalescence. Thus, the stability problem can be reduced to the interfacial rheological properties.
Contact
Prof. Dr.-Ing. Philip Jaeger
Telefon: +49 5323 72 3060
E-Mail: philip.jaeger@tu-clausthal.de