Foaming agent is a kind of additives that can form a cellular structure in plastics. They can
produce a large number of gases under specific conditions, in the formation of these
containing continuous or discontinuous pores (i.e. open or closed holes), so that the plastic
formed a gas-solid bonded porous structure material, which can reduce the density and
hardness of the plastic, or enhance its sound insulation and heat insulation.
According to the different ways of producing gas, foaming agents can be divided into physical
foaming agents and chemical foaming agents.
Physical foaming agent
The foam pore is formed by the change of physical form of a substance, such as the expansion
of compressed gas, the volatilization of liquid or the dissolution of solid.
Physical foaming agents include aliphatic hydrocarbons such as pentane and heptane.
Chemical foaming agent
Chemical foaming agent is also called decomposition foaming agent. They can be evenly
dispersed in resins and decomposed by heat to produce at least one gas. It can be divided
into inorganic foaming agent and organic foaming agent. Organic foaming agents are the
main foaming agents used in plastics, mainly azo, nitroso and sulfonyl hydrazide. In addition,
there are some foaming agent components whose foaming gas is released by endothermic
reaction between the two components. Inorganic foaming agent mainly refers to sodium bicarbonate