Synthesis of Linear Aliphatic Polycarbonate …
Some important producers and trade names of polyols are Bayer (, ), BASF (, , , ), Huntsman (Jeffol), Perstop (), Invista (), Shell (), Dow (), and Stepan Company ().
Covestro opens CO2-to-polycarbonate polyol ..
The versatile urethane chemistry allows for the production of a wide range of products including flexible and rigid foams, solid elastomers, extrusion parts, coatings, and adhesives. Flexible, high-resilience foamed products include mattresses, upholstered furniture, carpet underlays and auto parts like cushions, backs, and armrests.
Rigid foamed products with a closed cell morphology are used as insulations for commercial and residential buildings.
Other applications of rigid foam include insulations for tanks, pipes, water heaters, refrigerators, and freezers.
Examples of solid elastomeric products are durable elastomeric wheels and tires for forklifts, skateboards, roller coasters and escalators. Elastomeric urethanes find also many uses in the automotive industry. Some examples are bumpers, fenders, steering wheels, instrument and door panels, and gaskets for trunks, windows and windshields.
Polyurethanes are also used as electrical potting compounds, adhesives, coatings, sealants, and for the fabrication of synthetic fibers (Spandex).
Most elatomeric polyurethanes are either polyester or polyether based. The soft segments comprise the larger portion of the elastomer and, therefore, determine the physical properties of the elastomer. For example, polyester-based urethane elastomers have better oxidative and high temperature stability than polyether-based polyurethanes, but have lower hydrolytic stability and low-temperature flexibility. However, polyethers are usually more expensive than polyesters.
The cheapest polyether is polypropylene oxide (PPO) polyol, also called polypropylene glycol. Due to the low polarity and high flexibility, even high molecular weight PPG polyols are liquid at room temperature, whereas most polyester polyols are crystalline greases. Another important polyether polyol is based on polytetramethylene oxide (PTMO), sometimes called polytetrahydrofurane (PTHF). Both PTHF and PPO polyols have low melting temperatures and very low Tg's (190 - 200 K). But PTHF has higher strength than PPG, probably due to its ability to crystallize under stress. It is the preferred polyol for the manufacture of elastic urethane fibers such as Spandex (Elastan) for stretchable fabrics.
Many polyester polyols are made from adipic acid and ethylene glycols (polyethylene adipate), or from butanediols and adipic acid (polybutylene adipate). Both diols are crystalline above room temperature. To reduce the Tg and to destroy the crystallinity, copolyesters are often prepared from a mixture of glycols and adipic acid. Another important polyol is polycaprolactone diol. It is a biodegradable polyester with a low melting point of about 330 K and a glass transition temperature of about 210 K. It is sometimes copolymerized to reduce the crystallinity in the caprolactone based oligomer. This diol is mostly used for the manufacture of speciality polyurethanes.