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CR-39, or allyl diglycol carbonate (ADC), is a plastic polymer commonly used in the manufacture of eyeglass lenses. The abbreviation stands for "Columbia Resin #39," because it was the 39th formula of a thermosetting plastic developed by the Columbia Resins project in 1940. The first commercial use of CR-39 monomer was to help create glass-reinforced plastic fuel tanks for the B-17 bomber aircraft in World War II, reducing weight and increasing range of the bomber. After the War, the Armorlite Lens Company in California is credited with manufacturing the first CR-39 eyeglass lenses in 1947. CR-39 plastic has an index of refraction of 1.498 and an Abbe number of 58. CR-39 is now a trade marked product of PPG Industries. An alternative use includes a purified version that is used to measure neutron radiation, a type of ionizing radiation, in neutron dosimetry. CR-39 should not be confused with polycarbonate, a tough homopolymer usually made from bisphenol A.〔(【引用サイトリンク】title=A Field study )〕 ==Synthesis== CR-39 is made by polymerization of diethyleneglycol bis allylcarbonate (ADC) in presence of diisopropyl peroxydicarbonate (IPP) initiator. The presence of the allyl groups allows the polymer to form cross-links; thus, it is a thermoset resin. The monomer structure is The polymerization schedule of ADC monomers using IPP is generally 20 hours long with a maximum temperature of 95 °C. The elevated temperatures can be supplied using a water bath or a forced air oven. Benzoyl peroxide (BPO) is an alternative organic peroxide that may be used to polymerize ADC. Pure benzoyl peroxide is crystalline and less volatile than diisopropyl peroxydicarbonate. Using BPO results in a polymer that has a higher yellowness index, and the peroxide takes longer to dissolve into ADC at room temperature than IPP. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「CR-39」の詳細全文を読む スポンサード リンク
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