Foamed plastics are based on thermoplastic or thermosetting resins with numerous tiny pores in them. Foaming is one of the important methods of plastic processing. The foamed plastic contains gas and solid. The gas exists in the foam body in the form of bubble holes. The bubble holes and bubble holes are mutually isolated, called closed holes, and the connected ones are called open holes. Therefore, there are two types of closed hole foam plastics. The opening or closing of a foam structure is determined by the properties of the raw material and its processing technology.
