PMMA

PMMA, or polymethyl methacrylate, is a transparent, rigid thermoplastic widely used as acrylic glass. It is produced by polymerizing methyl methacrylate monomers to form long chains, giving a clear, strong material that can replace or augment glass in many applications. The polymer is sold under various trade names such as Plexiglas, Lucite, and Acrylite.

PMMA can be manufactured by bulk, solution, suspension, or emulsion polymerization and is commonly shaped into extruded sheets, cast sheets, blocks, rods, fibers, and pellets. It processes well by melting or solvent methods and is compatible with thermoforming, bonding, and coating techniques. The material is prized for optical clarity and good aging characteristics, though standard grades can yellow with prolonged UV exposure unless stabilized.

Key physical properties include high light transmission and excellent optical clarity, a refractive index around 1.49, a glass transition temperature near 105°C, and a density of about 1.18 g/cm³. PMMA is relatively stiff and has good surface hardness, but its impact resistance is lower than that of polycarbonate; impact-modified or reinforced grades are available for tougher applications. It remains relatively chemically resistant to many solvents, though strong solvents can attack it. Weathering and UV exposure can degrade PMMA unless stabilized with UV absorbers or hindered amine light stabilizers.

Common practical applications span architectural glazing, skylights, car and airplane windows, aircraft and automotive lighting lenses, signage, display cases, and architectural barriers. In medicine and dentistry, PMMA is used for bone cement and denture bases, while rigid PMMA contact lenses were historically common. Recycling can involve mechanical reprocessing or depolymerization back to monomer under appropriate conditions.