Definition for word: Rigid Foam

Rigid foam is available in panels of different sizes and thicknesses. There are three basic types of foam (extruded polystyrene, expanded polystyrene and polyurethane). Polyurethane foam has the highest R-value. Some foam panels are available with a reflective foil face that can act as a radiant barrier. Although rigid foam is more suitable for new construction, it can be used in retrofit applications, but accurate cutting and fitting are required. Gaps around the edges of rigid foam are often filled with spray foam.

Referrence from

A polyurethane (IUPAC abbreviation PUR, but commonly abbreviated PU) is any polymer consisting of a chain of organic units joined by urethane (carbamate) links. Polyurethane polymers are formed through step-growth polymerization by reacting a monomer containing at least two isocyanate functional groups with another monomer containing at least two hydroxyl (alcohol) groups in the presence of a catalyst.

Polyurethanes are widely used in high resiliency flexible foam seating, rigid foam insulation panels, microcellular foam seals and gaskets, durable elastomeric wheels and tires, automotive suspension bushings, electrical potting compounds, high performance adhesives and sealants, Spandex fibers, seals, gaskets, carpet underlay, and hard plastic parts (such as for electronic instruments).

Polyurethane products are often called "urethanes". They should not be confused with the specific substance urethane, also known as ethyl carbamate. Polyurethanes are neither produced from ethyl carbamate, nor do they contain it.

View this term in Wikipedia