Polycarbonate
Polycarbonate is a synthetic thermoplastic compound recognized for its durability and lightweight characteristics, making it an effective alternative to glass. As a type of polymer, it is formed from smaller molecules through a chemical reaction involving bisphenol A and phosgene gas, resulting in a transparent material that is impact-resistant. Although first synthesized in 1898, practical applications for polycarbonate emerged only in the mid-20th century, primarily after its rediscovery by Hermann Schnell and Daniel W. Fox in 1953. It is utilized in various products, including eyeglass lenses, shatterproof bottles, and electronic components, due to its ability to withstand extreme temperatures and retain shape without crystallizing. Polycarbonate is particularly valued in the eyewear industry for its lightweight nature and resistance to shattering, making it a preferred choice over traditional glass lenses. Its versatility extends to automotive applications, such as in headlights and taillights, as well as in compact discs and DVDs. Additionally, polycarbonate can be modified for enhanced features, such as blocking ultraviolet rays while maintaining optical clarity.
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Polycarbonate
A polycarbonate is a synthetic thermoplastic compound used as a durable, lightweight alternative to glass. A thermoplastic is a plastic that melts and becomes pliable at a specific temperature, and it solidifies upon cooling, thus retaining its shape. While polycarbonate was first discovered in the late nineteenth century, it was more than half a century later that the compound was able to be used in practical applications. Its impact-resistant and transparent properties allow it to be used in a variety of common products, such as eyeglass lenses, shatterproof glass, and compact discs and DVDs.
Overview
A polycarbonate is a chemical compound known as a polymer, a substance created by the combination of smaller molecules into a chainlike network. It is produced by a chemical reaction involving an organic compound called bisphenol A and phosgene gas, made by combining carbon monoxide with chlorine. The chemical formula for polycarbonate is C15H16O2, meaning its structure contains fifteen carbon atoms, sixteen hydrogen atoms, and two oxygen atoms. This structure contains molecular groups such as phenyl and methyl groups. Phenyl groups are molecules with six carbon and five hydrogen atoms (C6H5), and methyl groups contain one carbon and three hydrogen atoms (CH3). Phenyl groups have a high degree of attraction to other substances and combine easily with methyl groups. This process leads to a lack of mobility in the individual molecules, resulting in a substance that can be easily melted and molded. It also allows polycarbonates to maintain their shape without crystallization when cooled, meaning the substances remain transparent.
Polycarbonate was first synthesized in 1898 by German chemist Alfred Einhorn. Scientists, however, were unable to discover any commercial use for the substance and research on it was abandoned. In 1953, two scientists, working independently, rediscovered polycarbonate within weeks of each other. Hermann Schnell, working for the German chemical and pharmaceutical company Bayer AG, and Daniel W. Fox, with the General Electric Company in the United States, are credited with the discovery. Bayer trademarked its substance under the name Makrolon, and General Electric used the name Lexan. Initially, polycarbonate was used in electrical and electronic products such as fuse boxes and plugs, and as a coating for greenhouse windows and public buildings.
By the 1970s and 1980s, polycarbonate's durable, yet transparent, properties allowed it to be used in a variety of applications. Automobile manufacturers used it as a covering for headlights and taillights. It was used to make shatterproof bottles and food containers that could withstand freezing or reheating in microwaves. They were also used in the creation of compact discs and DVDs for music and other media, and as coverings for cell phones and computer tablets. One of the most common applications of polycarbonate is in optical lenses for eyeglasses. The substance's light weight, shatter resistance, and ease at which it can be made to fit eyeglass rims makes it far superior to glass lenses. It can also be modified to block ultraviolet rays while maintaining its optical quality.
Bibliography
Bendler, John T., and Donald G. LeGrand, editors. Handbook of Polycarbonate Science and Technology. Marcel Dekker, 2000.
Clark, Jim. "The Names of Aromatic Compounds." Chemguide, www.chemguide.co.uk/basicorg/conventions/names3.html. Accessed 8 Dec. 2016.
---. "The Names of Organic Compounds." Chemguide, www.chemguide.co.uk/basicorg/conventions/names.html. Accessed 8 Dec. 2016.
Goes, Frank Joseph. The Eye in History. Jaypee Brothers Medical Publishers, 2013, pp. 159–78.
"A Guide to Polycarbonate in General." Polymer Technology and Services, www.ptsllc.com/intro/polycarb‗intro.aspx. Accessed 8 Dec. 2016.
"Polycarbonate (PC)." PlasticsEurope, www.plasticseurope.org/what-is-plastic/types-of-plastics-11148/engineering-plastics/pc.aspx. Accessed 8 Dec. 2016.
"Polycarbonate Plastics and Bisphenol A Release." Bisphenol-A, www.bisphenol-a.org/human/polyplastics.html. Accessed 8 Dec. 2016.
Pye, Andy. "Polycarbonate--An Overview." Prospector Knowledge Center, 26 Feb. 2021, knowledge.ulprospector.com/11442/pe-polycarbonate-an-overview/. Accessed 3 Jan. 2022.
Rogers, Tony. "Everything You Need to Know about Polycarbonate (PC)." Creative Mechanisms, 21 Aug. 2015, www.creativemechanisms.com/blog/everything-you-need-to-know-about-polycarbonate-pc. Accessed 8 Dec. 2016.