Plexiglass, a name trademarked by the chemical company Rohm and Hass, is made up of methyl methacrylate. The methyl methacrylate is processed into this hard vinyl polymer through free radical vinyl polymerization.
Plexiglass is used as a shatterproof replacement for glass. The material is clearer than glass, so where glass reaches thickness limitations as a window fairly low, the plexiglass can go all the way up to 13 inches. This feature makes the material ideal for aquariums. The plexiglass can be thick enough to hold back thousands of gallons of water without blurring or distorting the view for the guests. It is also the same material used around ice rinks where hockey games are held, preventing pucks from flying into the crowd.