Polyurethane

From Wikipedia, the free encyclopedia

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.

Polyurethane formulations cover an extremely wide range of stiffness, hardness, and densities. These materials include:

• Low-density flexible foam used in upholstery, bedding, and automotive and truck seating
• Low-density rigid foam used for thermal insulation and RTM cores
• Soft solid elastomers used for gel pads and print rollers
• Low density elastomers used in footwear
• Hard solid plastics used as electronic instrument bezels and structural parts
• Flexible plastics used as straps and bands

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.