Foaming agents are substances that create pores in the target material, which can be divided into three categories: chemical foaming agents, physical foaming agents, and surfactants. Chemical foaming agent is a compound that can release gases such as carbon dioxide and nitrogen after heating and decomposition, and form fine pores in the polymer composition; Physical foaming agent is a compound formed by the change of physical form of a certain substance through the expansion of compressed gas, volatilization of liquid or dissolution of solid in foam pores. All foaming agents have high surface activity, which can effectively reduce the surface tension of the liquid, and arrange the double electronic layers on the surface of the liquid film to surround the air, forming bubbles, and then forming foam from a single bubble.
