PERMEABILITY OF COMMON BLACK FOAM FILMS TO GAS .1.

An experimental method for measuring the permeability coefficient K fo r the permeation of air through black foam films is described. A serie s of measurements of K for sodium dodecyl sulfate plus sodium chloride aqueous solutions have been performed. Experimental results concernin g the dependences of K on surfactant concentration C, NaCl concentrati on C(el) and temperature T are reported. A stepwise decrease in permea bility K at the transition from common black film (CBF) to Newton blac k film (NBF) has been found, the K values of the thinnest NBF being 2- 3 times lower than those of the essentially thicker CBF. The results s how that gas permeation through black foam films is mainly determined by the properties of the surfactant layers: monolayers in the case of CBFs and a bilayer in the case of NBFs. The experimental results conce rning the permeability of CBFs are discussed on the basis of theories of gas permeation through monomolecular layers.