Foam plays an important role in the washing process. Foam refers to a dispersion system in which gas is dispersed in liquid or solid. Gas is the dispersed phase, and liquid or solid is the dispersion medium. The former is called liquid foam, and the latter is called solid foam, such as foam plastic, foam glass, foam cement, etc.

(1) Foam formation
The foam we are talking about here refers to the accumulation of bubbles separated by a liquid film. This foam has a large difference in density between the dispersed phase (gas) and the dispersion medium (liquid), and the viscosity of the liquid is low, so the bubbles can always rise to the liquid surface quickly.
The process of forming foam is to bring a large amount of gas into the liquid, and the bubbles in the liquid quickly return to the liquid surface, forming a bubble aggregate separated by a small amount of liquid gas
Foam has two significant features in morphology: one is that the bubbles as the dispersed phase are often polyhedral, because at the intersection of the bubbles, there is a tendency for the liquid film to become thinner so that the bubbles become polyhedrons, when the liquid film Thinning to a certain degree will cause the bubbles to burst; the second is that the pure liquid cannot form stable foam, and the liquid that can form foam is at least two or more components. Aqueous solutions of surfactants are typical foam-prone systems, and their ability to generate foam has a certain relationship with other properties.
Surfactants with good foaming power are called foaming agents. Although the foaming agent has good foaming ability, the foam formed may not be able to maintain for a long time, that is, its stability is not necessarily good. In order to maintain the stability of the foam, a substance that can increase the foam stability is often added to the foaming agent. This substance is called a foam stabilizer. Commonly used foam stabilizers include lauroyl diethanolamine and dodecyl dimethylamine. Oxide.