Gibbs-Marangoni Effect Theory

The Gibbs coefficient of elastidty, e, was introduced as a variable resistance to surface deformation during thinning  

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A different antifoaming mechanism was suggested by Kulkarni et al. (96). They found that surfactants adsorb on the surface of hydrophobic particles during antifoaming, and this adsorption results in deactivation of the particles. On the basis of this observation, they postulated that the adsorption of surfactants onto the hydrophobic particles is so fast that it results in surfactant depletion around the particle in a foam film, and this effect breaks the film. However, no direct proof was presented on this theory. Moreover, depletion of surfactant would cause the film liquid to flow toward the particle because of the increased surface tension (Gibbs— Marangoni effect), and thus cause a stabilizing effect. 

The fact that the emulsions are free of added surfactant or polymeric stabilisers is of some significance in that the droplet/solution interface is in this case a truly fluid one, whereas those bearing adsorbed stabilisers are invariably viscoelastic, exhibiting Gibbs-Marangoni effects. This should be of interest to those wishing to carry out experiments to test the various hydrodynamic theories of liquid droplets (e.g. diffusion, sedimentation, viscosity, electrophoresis), compared to solid parti-... 

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