Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. organic material
7. plastic (material)
8. [plastic by form]

Narrower term/s

• structural foam
• polyurethane foam

Anotations

Scope note:

Lightweight and buoyant polymers containing uniformly dispersed air pockets, like a sponge. They are made from most types of polymers (rubber, polyethylene, polystyrene, epoxy, polyurethane, vinyl resins, silicone resins, and others). Steam, air or an inert gas is mechanically added or chemically produced in the plastic resins during manufacture to form a cured open cellular structure. They may be soft and spongy (foam rubber, polyethylene, etc.) or rigid and strong (polystyrene, epoxy). Closed-cell foams have individual non-connected bubbles while open-cell foams have an interconnected tunnels formed when the incorporated gas or steam escapes during cure.