organic glass[ȯr′gan·ik ′glas]
the technical name for transparent solid materials made from such organic polymers as polyacrylates, polystyrene, and polycarbonates and from the copolymers of vinyl chloride with methyl methacrylate. In industry, the term “organic glass” is usually understood as a sheet material produced by the block polymerization of methyl methacrylate.
The reaction is carried out in molds composed of sheets of silica glass, steel, or aluminum; elastic gaskets, the thickness of which determines the thickness of the sheet of organic glass, are placed between the sheets constituting the mold. To avoid defects in the organic glass caused by the significant shrinkage (~23 percent) of the reaction mass, set procedures must be followed. First, a prepolymer (a syrupy liquid with viscosity of 50–200 millinewtons-sec/m2, or centipoises) is obtained. Next, the prepolymer is poured into the mold and polymerized, or, instead, a solution of polymethyl methacrylate in a monomer (syrup solution) is polymerized in the mold. Depending on the intended use of the organic glass, plasticizers, dyes, opacifiers, stabilizers, and other components are added to the syrup or syrup solution. The mass is thoroughly mixed, placed in a vacuum, and filtered and is then poured into hermetically sealed molds, which are placed in chambers with circulating warm air or in a bath of warm water (isothermic conditions). After polymerization, the sheets of organic glass are removed from the molds and subjected to finishing operations.
Organic glass may be treated by vacuum or pneumatic forming and by stamping. It can be processed mechanically and can also be glued or welded. It is used as a structural material in aircraft, automotive vehicles, and ships. It is also used for enclosing hotbeds and for glazing greenhouses, domes, windows, and porches. Buildings are often decorated with organic glass, and the material is also used in fashioning instrument parts, prostheses, lenses and prisms used in optics, and pipes used in food processing.
Various brands of organic glass are produced in the USSR. Organic glass is called Plexiglas in the United States, the Federal Republic of Germany, and France, Perspex in Great Britain, and Clarex in Japan.