THE RATE OF GAS INCORPORATION INTO MIXED FOAMS

Gas exchange in steady state foams was measured. Foams were beaten in a thermostated cylindrical vessel with a vertical rotating cage and ar gon or hydrogen gas of constant flow rate was led into the bottom of t he vessel. After reaching steady state, the gas stream was switched to nitrogen. The vessel was tightly covered and the effluent gas was mon itored by a katharometric cell. The break-through curve of nitrogen wa s registrated. A mathematical model was constructed for the simulation of the break-through curves. In the model, the rate of gas incorporat ion, I-ht the rate of by-passing through vertical channels, and the ve rtical mixing of the foam were taken into consideration. The value of I-h has been known from the parameters of the fitted break-through cur ve. The rate of surface formation was calculated as the, product of I- h and a(h). The results were compared to the rate of surface collapse in stationary foams.