A polyurethane (PUR and PU) is polymer composed of a chain of organic units joined by carbamate (urethane) links.
For the manufacture of polyurethane polymers, two groups of at least bifunctional substances are needed as reactants: compounds with isocyanate groups, and compounds with active hydrogen atoms. The physical and chemical character, structure, and molecular size of these compounds influence the polymerization reaction, as well as the ease of processing and the final physical properties of the finished polyurethane. In addition, additive such as catalysts, surfactants, blowing agents, cross linkers, flame retardants, light stabilizers, and fillers are used to control and modify the reaction process and performance characteristics of the polymer.
Polyurethanes are used in the manufacture of flexible, high-resilience 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, surface coatings and surface sealants, synthetic fibers, carpet underlay, and hard plastic parts. Polyurethane formulations cover an extremely wide range of stiffness, hardness, and densities. See also:
- Polyurethane rubber
- Crosslinked polyurethane