Lecture 24: Introduction to Foams

This lecture is the second half of Chapter 9 on emulsions and foams with the focus here being on foams. Our interest will be in liquid foams consisting of gas bubbles, usually air dispersed in aqueous solutions. Liquid foams possess exciting properties, which makes them well suited for a wide variety of products, including foods, cosmetics, cleaners, and applications such as oil recovery, firefighting, separations, etc. These require special additives that promote and control the foaming process. Foam can also be a significant nuisance in processes such as chemical production, distillations, washing, papermaking, coating, etc. In these cases, foam can be eliminated or prevented from forming through the use of special additives. This lecture is a practical introduction to foam formation and collapse, including a discussion on the connection between structural characteristics and the performance of foaming agents and testing.