CELLULOSE NITRATE, is a flammable substance produced by the reaction of cellulose with nitric acid. It is also known as nitrocellulose. Its high molecular weight and solubility in organic liquids make it useful in molded articles, propellants, explosives, and protective films. In coated upholstery fabrics, photographic film base, and small celluloid articles, cellulose nitrate has for the most part been replaced by less flammable cellulose acetate and other plastics.
In the manufacture of cellulose nitrate, purified cotton linters or softwood cellulose is stirred into a mixture of nitric acid, sulfuric acid, and water. After a few minutes the excess acid is removed in a centrifuge, and the cellulose nitrate is steeped for 24 hours or more in boiling water to remove residual acid. Finally, it is rinsed with alcohol.
The chemical composition of cellulose nitrate is tailored to specific uses, principally by varying the degree of nitration of the starting cellulose. This is done by adjusting the water content of the nitrating acid. The theoretical maximum nitrogen content, 14.1% by weight, is not attained in practice. The nitrogen contents of commercial grades of cellulose nitrate are: 12.6-13.4% for smokeless gun propellants and highenergy rocket propellants; 11.8-12.2% for gelatin dynamite, collodion, household cement, and lacquer finishes for metal and wood; 11.3—11.7% for moistureresistant coatings on paper and cellophane; and 10.9-11.2% for fastdrying printing inks, celluloid, sealers, and fillers.