What is Polyurethane?
Polyurethane (PUR) is a polymer composed of a chain of organic units joined by carbamate (urethane) links. While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are also available. Polyurethane products can be divided into two kinds: foaming and non-foaming. The most widely used polyurethane products are polyurethane foams.
The properties of polyurethane are greatly influenced by the types of isocyanates and polyols used to make it. Long, flexible segments, contributed by the polyol, give soft, elastic polymer. High amounts of crosslinking give tough or rigid polymers. Long chains and low crosslinking give a polymer that is very stretchy, short chains with lots of crosslinks produce a hard polymer while long chains and intermediate crosslinking give a polymer useful for making foam.
Polyurethanes are best known to the public in the form of flexible foams: upholstery, mattresses, earplugs, chemical-resistant coatings, specialty adhesives and sealants, and packaging. It also comes to the rigid forms of insulation for buildings, water heaters, refrigerated transport, and commercial and residential refrigeration. It is a resilient, flexible and durable manufactured material that can take the place of paint, cotton, rubber, metal or wood in thousands of applications across virtually all fields. It can be hard like fiberglass, squishy like upholstery foam, protective like varnish, bouncy like rubber or sticky like glue.
Otto Bayer and co-workers discovered and patented the chemistry of polyurethanes in 1937. Since its invention during the 1940s, polyurethane has been used in a wide range of items, from baby toys to airplane wings, and it continues to be adapted for contemporary technology. Polyurethane can be found in every room of the house and in practically every building. It seals surfaces such as wood, metal and paint to protect them from rot, corrosion or fading. As an adhesive, polyurethane resists moisture and heat, so it is ideal for use in the sun or underwater. It also insulates walls, temperature-controlled vehicles and consumer coolers.
In 2007, the global consumption of polyurethane raw materials was above 12 million metric tons, the average annual growth rate is about 5%. The production of polyurethane began in 1950s in China. And now there are near 300 companies producing polyurethane foams and products. The quantity of polyurethane foams demanded is increasing every year