Polycarbonate (PC) is prepared by reacting bisphenol A and phosgene or by reacting a polyphenol with dichloromethane and phosgene. The basic monomer unit is [—OC6 H4 C(CH3 )2 C6 H4 COO—]n. PC is a linear, low crystalline, transparent, high molecular mass thermoplastic. It exhibits a good chemical resistance to greases, and oils but has a poor organic solvent resistance. Moreover, it is greatly restricted in its resistance by a severe propensity to stress crack. This property can be modified greatly by proper compounding but remains the most serious problem when considering the polycarbonate for chemical exposures. The exceedingly high impact resistance of this thermoplastic (30 times that of safety glass) combined with high electrical resistivity, ease of fabrication, fire resistance, and light transmission (90%) has promoted its use into a wide range of industrial applications. The most notable of these for industrial applications is the use of the sheet material as a glazing product. Where a high impact, durable, transparent shield is required, the polycarbonate material is used extensively. In addition, many smaller mechanical parts for machinery, particularly those with very intricate molding requirements, impellers in pumps, safety helmets, and other applications requiring light weight and high impact resistance have been satisfied by the use of polycarbonate plastics. The material can be used from –170°C up to a temperature of 121°C.
Industrielle Verwendung
Polycarbonate resins offer a combination of properties that extends the usefulness and fields of application for thermoplastic materials. This relatively new plastic material is characterized by very high impact strength, superior heat resistance, and good electrical properties. An interesting application area for plastic materials is the use of polycarbonate resin for fabricating fasteners of various types. Such uses as grommets, rivets, nails, staples, and nuts are in production or under evaluation. The ability of polycarbonate parts to be coldheaded has developed considerable interest in rivet applications. Another application is in bushings, cams, and gears. Here, dimensional stability is important as is the high impact strength of the resin. Good physical properties over a broad temperature range, low water absorption, resistance to deformation under load, and resistance to creep suggest its use for many applications of this type.
