B Diffusion of Gas Through the Lamellae

Another factor determining the stability of foams is the rate of diffusion of gas from one bubble to another through the lamella separating them. The rate of diffusion q of a gas between two bubbles of different radii, R and R2, is given by the equation 

A = the effective perpendicular area through which diffusion occurs between 

The value of J in the preceding diffusion equation depends on the resistance to gas transfer of the two interfaces and the liquid between them. Data indicate that this transfer of gas takes place through aqueous pores between the surfactant molecules in the surface films of the lamellae (Princen, 1967). Closer packing of the surfactant molecules in the film would therefore be expected to decrease the rate of 

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