To produce foamed polymer materials such as foam plastics and sponge rubber, a foaming agent is typically added to the plastic or rubber. When the plastic or rubber is heated, the foaming agent releases gas, causing the material to form fine pores or a honeycomb structure. A foaming agent is a substance that can create a microporous structure in polymers within a certain viscosity range in their liquid or plastic state. To aid in the dispersion of the foaming agent, increase its gas evolution, or lower its decomposition temperature, foaming additives are usually incorporated.
Foaming agents can be classified into chemical foaming agents and physical foaming agents. Chemical foaming agents refer to substances that decompose upon heating to release gases such as carbon dioxide and nitrogen, forming fine pores in polymer materials. Physical foaming agents create foam pores through physical state changes, such as the expansion of compressed gases, the volatilization of liquids, or the dissolution of solids. Foaming agents are also divided into inorganic and organic types. Inorganic foaming agents include ammonium carbonate, sodium bicarbonate, sodium nitrite, etc. Organic foaming agents mainly include azo compounds, sulfonyl hydrazide compounds, nitroso compounds, etc. In production, organic foaming agents are most commonly used, with the main variety being azodicarbonamide (foaming agent AC).
