Foam materials are rubbers, polyolefins (PE and PP) and polyurethanes. They are usually open cell when obtained by a chemical expansion process. In this case they have a spongy structure, soft to touch. Instead if they are obtained by a physical expansion they are closed-cell.
Moreover, there is also a category of materials with semi-closed cell (for example Poron) which have an excellent elastic recovery.
Foam materials are used in a variety of sectors (medical, electrical, aerospace, automotive). Gaskets, die cutters’ ejections and packaging materials are produced with foams.