EXPANSION OF A FOAM DUE TO ABSORPTION OF AN OUTSIDE GAS

The absorption of air by a liquid foam was studied experimentally at v arious temperatures between 8 and 55 degrees C. It causes expansion of the foam and a gradient in cell size. The rate of expansion remains a pproximately constant following an initial transient. A theoretical an alysis of the phenomenon is presented which assumes that the permeabil ity of the liquid films to air is inversely proportional to their thic kness and exponentially dependent on temperature. It is then possible to obtain experimental values of the permeability and of the activatio n energy for permeation which is similar to 85 kJ mol(-1). This is con siderably larger than the activation energy for diffusion of air in pu re water. (C) 1995 Academic Press, Inc.