Polycarbonate football helmet

Polycarbonate is a very hard and light plastic used for protection devices such as football helmets. It is made by reacting bisphenol A with phosgene in the reactions shown in Figure 1 1-... 

An item of sports equipment that has been improved greatly with regard to player safety is the crash helmet. American football helmets are polycarbonate or ABS shelled, while impact nylons are often used on motorbike crash helmets. Another item of sports equipment in the United States where safety has been improved is a Reduced Injury Factor baseball that has a novel polyurethane core material. 

Polycarbonate was commercialized in the 1950s, invented at almost the same time by GE Plastics in the USA and by Bayer in Germany. GE marketed the material under the trademark Lexan , while Bayer marketed the material under the trade name Makrolon . Polycarbonate is used in a wide variety of applications, including appliance housings, football helmets, automotive headlights, and CD and DVD discs. 

Lexan is a polycarbonate ester condensation polymer that is transparent and nearly unbreakable. It is used in bulletproof windows (a one-inch-thick Lexan plate will stop a. 38-caliber bullet fired from 12 feet), football and motorcycle helmets, and the visors in astronauts helmets. It is made from the two monomers shown below. Draw two repeating units of this polymer. 

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