polycarbonate

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polycarbonate

[¦päl·i′kär·bə·nət]
(organic chemistry)
[OC6H4C(CH3)2C6H4OCO]x A linear polymer of carbonic acid which is a thermoplastic synthetic resin made from bisphenol and phosgene; used in emulsion coatings with glass fiber reinforcement.

Polycarbonate

 

a polyester of carbonic acid and dihydroxy compounds of the following general formula:

Polycarbonates may be aliphatic, mixed, or aromatic, depending on the nature of A and A′. Only aromatic polycarbonates have gained practical importance; they are produced commercially by interphase polycondensation, phosgenation of aromatic dihydroxy compounds in a pyridine medium, or transesterification of diaryl carbonates (for example, diphenylcarbonate) by aromatic dihydroxy compounds. The most commonly used dihydroxy compound is 4,4′ -isopropylidenediphenyl, also called dian or bisphenol A. Polycarbonates based on the bisphenol A have the formula

These polycarbonates are thermoplastic linear polymers (molecular weight, 35,000–70,000) that are characterized by very high impact strength (250–500 kilojoules per sq m, or kilograms-force per cm per sq cm [kgf.cm/cm2]), yield strength (strength in flexure, 77–120 meganewtons per sq m [MN/m2], or 770–1,200 kgf/cm2), and very good dielectric properties (dissipation factor, 0.0009 at 50 hertz). Polycarbonates are optically transparent, cold-resistant (stable at temperatures slightly below – 100°C), and self-extinguishing; they dissolve in most organic solvents such as methylene chloride and chloroform, and are resistant to acids, salt solutions, and oxidizing agents.

Polycarbonates are processed by all the standard methods used for thermoplastic resins (for example, injection molding, extrusion, and compression molding). They are used in the preparation of films, fibers, and various products in many sectors of industry, mainly in electric engineering. In 1973, world production of polycarbonates (mainly in the Federal Republic of Germany, the USA, and Japan) was 100,000 tons.

REFERENCES

See references under .

O. V. SMIRNOVA

polycarbonate

A category of plastic materials used to make myriad products, including CDs and DVDs.
References in periodicals archive ?
Bayer MaterialScience develops, produces and sells Makrolon polycarbonate sheets, Axpet and Vivak polyester sheets, as well as Bayloy high-quality plastic sheets.
Makrolon Polycarbonate - a Multi-talent Thanks to its versatility, Makrolon polycarbonate now has a world market share of 30 percent and is one of the best-selling products of the Bayer Group.
Simple, low-cost processing by injection molding is another benefit to Makrolon Rx-1805 ,giving it a competitive edge over expensive polymers like polysulfones and copolymides.
When combined with Nomad's charging products, durable, lightweight Makrolon polycarbonate helps deliver a mobile charger that's fit for on-the-go lifestyles," says Kevin Dunay, Electrical Market segment leader, Polycarbonates, Bayer MaterialScience.
The new Makrolon multi UV 3/16-20 triple-wall sheet, which replaces the company's UV 3/16-16 series, is said to be impact resistant and application friendly, as well as providing effective weather protection on both sides of the translucent sheet.
The new polycarbonates for LED cooling elements, such as Makrolon TC 8030, are an alternative to aluminium.
This new approach will be commercialized this year when a major lighting OEM uses it for an outdoor product with an LED lens injection molded of Bayer's Makrolon LED2643 PC.
The module is produced with two-component injection-compression molding: (1) the transparent outsider skin is made with a polycarbonate, Makrolon AG2677; (2) the large area frame is then produced with Bayblend DP T95 MF.
At the end of 2006, the company was producing 1,200,000 tons of Makrolon a year.
diameter cylinder is injection-molded by Delta Pacific Products Inc, Santa Clara, CA, in a clean room environment using the Makrolon 2558 resin, which provides good impact strength, dimensional stability and a glass-like transparency.
Makrolon is the backbone of Bayer's broad product portfolio and a material that has been an important part of the innovative design and environmentally conscious construction of the Solar Decathlon house.
The Makrolon UV clear solid sheets from Bayer MaterialScience do not only make the EURO SuperSilent wind power plant a structure that is barely noticeable, they also turn the plant into an efficient and sturdy lightweight installation with an impeccable ecological balance sheet, from production to disposal.