Polycarbonate is any of a group of extremely tough polyester plastics. Polycarbonates provide excellent impact strength and heat resistance. They are naturally transparent. However, they can be dyed easily to produce a wide range of colors that may be transparent, translucent, or opaque. Products made from polycarbonates include automobile headlamps, baby bottles, camera parts, compact discs, computer housings, and protective eyewear.
Polycarbonates are synthetic polymers. A polymer is a long, chainlike molecule made up of repeating patterns of simple groups of atoms called monomers. In most polyesters, the monomers connect to each other with ester groups, units made of one carbon atom and two oxygen atoms. In polycarbonates, however, each connecting unit has an additional oxygen atom. Such units are called carbonate groups.
Polycarbonates are thermoplastic materials—that is, they soften and melt at high temperatures. They usually begin to soften at temperatures greater than 300 °F (165 °C)—a higher temperature than most other thermoplastics can withstand.
Manufacturers most often make polycarbonates by combining the chemical compounds bisphenol A and phosgene. The first polycarbonates were introduced in West Germany (now part of Germany) during the 1950’s.
See also Bisphenol A (BPA) .
