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Wednesday, December 19, 2012

Polycarbonate (PC)

Polycarbonate plastics, abbreviated PC, have chemical formulae that contain carbonate groups (–O–(C=O)–O–). They are covered by the trademarked names Lexan, Makrolon, and Makroclear. Lexan is the registered trademark for the polycarbonate produced by SABIC Innovative Plastics (formerly General Electric Plastics) by reacting bisphenol A (BPA) with phosgene. Alternatives to this synthesis method exist that do not employ BPA (because of possible health and safety effects in humans, depending on how the PC product is used) or phosgene (because of potential deleterious effects on the environment).

Dr. Daniel W. Fox from General Electric invented Lexan polycarbonate in 1953 and applied for a patent in 1955, after conducting a series of experiments while working on a project to develop new wire insulation material.  A result of independent research, Dr. Hermann Schnell from Bayer Germany also applied for a patent on a nearly identical molecule that same year.  Dr. Schnell was ultimately awarded the patent, when it was established he made his invention a week before Dr. Fox.  The two should rightly share the honor of being the “fathers of polycarbonate.”   

bisphenol A bisphenol A, (CH3)2C(C6H4OH)2

phosgene  phosgene, COCl2

polycarbonate polycarbonate (Lexan), [OC6H4C(CH3)2C6H4OCO]n

Polycarbonates are thermoplastic, meaning that they are easily worked and formed. A thermoplastic is a polymer that softens and turns to liquid when heated and conversely solidifies to a glass-like state when cooled. These materials are ideally suited to injection molding. Polycarbonates have a melting point of approximately 155 °C (310 °F). Polycarbonates are frequently employed in electronics, building materials, design and signage, and data storage. CDs, DVDs and Blu-Ray discs are made of polycarbonate. They have outstanding mechanical, optical, electrical and thermal properties and can be easily dyed.

polycarbonate raw material Polycarbonate raw material.  Image source:  tradeKorea.

Resin code 7

For the purposes of recycling, PC is in group 7. Click for more information about plastics recycling codes, published by the American Chemistry Council.

References

Daniel Fox (chemist). Retrieved December 12, 2012 from http://en.wikipedia.org/wiki/Daniel_Fox_(chemist).

Lexan resin innovation timeline. Retrieved December 12, 2012 from http://www.sabic-ip.com/gep/Plastics/en/ProductsAndServices/InnovationTimeline/lexan.html.

Polycarbonate. Retrieved December 12, 2012 from http://en.wikipedia.org/wiki/Polycarbonate.


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1 comment:

Polikarbon Levha said...

http://www.youtube.com/channel/UCSsp28r8dRKOP5QCGFFooXg

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