What are polyurethanes household uses

Polyurethane plastics are widely used today, particularly in the form of flexible or rigid foams. Flexible polyurethane foam is used as an upholstery material, and the rigid foam is commonly used as a heat-insulating material. Polyurethanes are also used in some paint compositions to impart surface hardness to the paint coatings. They can be made by reacting an isocyanate having at least two isocyanate (-NCO) groups with an alcohol having at least two hydroxy (-OH) groups, and have the following repeating structure: -Ri-NHC00-R2-OOCHN-

Here again the groups Ri and R2 depend on the particular polyurethane; for Perlon U, Ri is -(CH2)6and R2 is -(CH2)4-. Most of the plastics discussed above are thermoplastics, which means that they will soften whenheated and harden again when cooled. Some plastics, such as phenol-formaldehyde, are thermosetting once formed, they cannot be softened by heat without destroying the structure. An example of the use of these resins is in laminates, such as Formica.

Another thermosetting resin in wide use is unsaturated polyester, which is used with glass reinforcement in the manufacture of GRP boat hulls and car body panels and is also used with fibers, such as carbon fiber, in the production of high-strength composites. Some adhesive compositions, particularly epoxy adhesives such as Araldite, are also based on thermosetting plastics. Another common group of thermosetting plastics consists of the alkyd resins which are used in some paint compositions.

There are several groups of specialist plastics which are used for their high performance and are sometimes called Engineering Resins. Among these are the fluoropolymers, such as PTFE, which are used for their temperature resistance and nonstick property; acetal, which has high stiffness and dimensional stability; polycarbonate, which has good temperature resistance and toughness combined with transparency; and polyethers (PES and PEEK) and polyamides used for their high temperature resistance and low weight in, for example, aircraft.