Polycarbonates are a family of engineering plastics having functional groups linked together by carbonate groups [-O-(C=O)-O-] into a long molecular chain.
These polymers are most commonly prepared by either (1) phosgenation of bisphenol A, a dihydric phenol, or (2) by direct ester exchange of diaryl carbonate and dihydric phenol. The material is characterized by outstanding heat resistance including high heat deflection temperature, good mechanical properties especially impact resistance, dimensional stability, and transparency. It has the best impact resistance of the various transparent plastics. It also has low moisture absorption and good thermal/oxidative stability. Easily worked, molded, and thermoformed, they are very widely used particularly in applications needing excellent heat resistant, impact resistant and optical properties. The most common resins are Makrolon from Bayer, Panlite from Teijin Chemical Ltd., Lexan from Sabic Innovative Plastics, and Calibre from Dow Chemicals.