ABSTRACT
The characteristics of foamed liquids can vary considerably from one example to another depending upon variations in their three inextricably interrelated properties described in terms of physics, chemistry, and structure. These variations include: gas volume-fraction; bubble size, distribution, and shape; the solubility of the gas in the continuous phase; and the ambient temperature and pressure, the interfacial properties. Foams are composed of at least two, and occasionally three, distinct phases: a liquid continuous phase in which is suspended a surfactant, and throughout which is dispersed a gaseous phase. In some foam systems a third phase may be present that is immiscible with the continuous phase but may be interactive with the disperse phase. Closed-cell foams are the worst possible candidates for freezing since they are both mechanically sensitive and good heat insulators, and therefore cool very slowly. Foams are exceptionally good heat insulators because of the gas trapped within the bubbles.
