Kabalnov-Wennerstrom theory

The Kabalnov-Wennerstrom theory predicts that the sharpness of the transition from unstable to stable emulsions is controlled by the value of When the surfactants are compared in a homologous series, k increases and ao decreases with the surfactant chain length. Accordingly, the sharpness of transition from unstable to stable systems is expected to increase with the surfactant chain length. 

The stability of emulsions containing nonionic surfactants is minimum at the HLB temperature where the interfacial tension reaches a minimum. The coalescence is enhanced at low interfacial tensions because deformation of the droplets can occur more easily. Thermal fluctuations on the surfactant monolayers may increase, producing a hole in the thin film that separates the drops. This hole may heal and the droplets will not coalesce, or it may propagate in the film, producing its final rupture, as described by the Kabalnov-Wennerstrom theory [67,74]. A linear dependence in the Arrhenius plot [logarithm of the macroemulsion lifetime, ln(T,/2) as a function of the inverse of temperature] is predicted. The activation energy of the film rupture can be calculated from the slope of such a plot [67,74]. 

A.S. Kabalnov and H. Wennerstrom Macroemulsion Stability The Oriented Wedge Theory Revisited. Langmuir 12, 276 (1996). 

Kabalnov A, Wennerstrom H. Macroemulsion stability the oriented wedge theory revisited. Langmuir 1996 12 276-292. 

A. Kabalnov and H. Wennerstrom, Macroemulsion stability The oriented wedge theory revis-... 

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