ニトロセルロース

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説明

Early explosives used nitric acid. They were so unstable to handle that European scientists tried to find an explosive compound for better safety. Around 1846, it was discovered that concentrated nitric acid absorbed into cotton was not explosive until dried; thus, guncotton was developed by chemical binding of nitrate to cellulose. Preventing spontaneous explosions during the manufacturing process required extensive washing and drying of the cotton. In 1884, a French chemist made smokeless powders from nitrocellulose. Their more stable and slower burning properties enabled development of firearms and artillery ammunitions. Eastman Kodak film products used nitrocellulose as early as 1889. The film was used until 1933 for X-ray films and for motion picture films until 1951.
Nitrocellulose can take on various physical forms, from white fibers to thin sheets to thick liquid. Nitrocellulose can also be a white, yellow, or transparent plastic. Its rigidity varies from brittle to flexible. The unique properties enable nitrocellulose to be used now in a wide variety of products. The variability in physical properties comes from the content of nitrogen and determines the use. The molecular weight of nitrocellulose ranges from 459.28 to 594.28, and the molecular formula is expressed as [C6H7O2(ONO2)3]n. The hydroxyl group of glucose units react to form nitrocellulose chains and membranes.
Nitrocellulose is thus a fibrous solid polymer consisting of the cellulose ester of nitric acid. Its specific gravity is 1.66. Its form can be a white pulpy, cotton-like, amorphous solid in the dried state, or a colorless liquid to semisolid, depending on the degree of nitration. It has low water solubility; however, it is soluble in 25% of a mixture of 1 volume of alcohol and 3 volumes of ether, forming collodion. Nitrocellulose is also soluble in organic solvents such as methanol, acetone, glacial acetic acid, and amyl acetate.