TABLE OF CONTENTS By Brent S. Murray, Eric Dickinson, Zhiping Du, Rammile Ettelaie, Thomas Kostakis, and Julien Vallet
PROCTER DEPARTMENT OF FOOD SCIENCE, UNIVERSITY OF LEEDS, LEEDS LS2 9JT, UK
Disproportionation is the migration of gas from regions of high concentration to low concentration, via diffusion, where the higher concentration is provided by a higher local curvature and hence a higher Laplace pressure. Adsorbed films of either low-molecular-weight surfactants or polymers at fluid fluid interfaces offer little resistance to the diffusion of gases through them. Thus, even if the bubbles are stable to coalescence and aggregation, in a foam with a fluid continuous phase, the gas will diffuse between bubbles of different sizes, with the result that the smaller bubbles tend to shrink and the larger bubbles tend to grow. Such foams would therefore seem to be inevitably unstable. Of course, if the continuous phase has become solidified in some way, in practice usually by cooking, or by freezing, then the bubble-size distribution can be effectively arrested in...
