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polycarbonates,group of clear, thermoplastic polymerspolymer
, chemical compound with high molecular weight consisting of a number of structural units linked together by covalent bonds (see chemical bond). The simple molecules that may become structural units are themselves called monomers; two monomers combine to form a dimer,
..... Click the link for more information. used mainly as molding compounds (see plasticplastic,
any organic material with the ability to flow into a desired shape when heat and pressure are applied to it and to retain the shape when they are withdrawn. Composition and Types of Plastic
..... Click the link for more information. ). Polycarbonates are prepared by the reaction of an aromatic difunctional phenol with either phosgene or an aromatic or aliphatic carbonate. The commercially important polycarbonates use 2,2-bis (4-hydroxyphenol)-propane (bisphenol A) and diphenyl carbonate. This polymer is a clear plastic with a slight yellow discoloration. It has excellent electrical properties and a high impact strength.