Poly(methyl methacrylate) (PMMA)

Poly(methyl methacrylate) (PMMA), also known as acrylic or acrylic glass as well as by the trade names Plexiglas, Acrylite, Lucite, and Perspex among several others (see below), is a transparent thermoplastic often used in sheet form as a lightweight or shatter-resistant alternative to glass. It is a polymer of methyl methacrylate and is produced by polymerization.

Properties

PMMA exhibits high transparency, excellent tensile strength, stiffness, and weather resistance. It has a density of 1.18 g/cm³, which is less than half that of glass. It also has good impact strength, higher than both glass and polystyrene. However, it is not as durable as glass and can be scratched more easily. PMMA is also known for its low water absorption, high light transmittance (up to 92%), and UV resistance.

Applications

PMMA is widely used in various applications due to its versatile properties. Some common applications include:

• Construction and architecture: Used for glazing, light domes, and roofing panels due to its lightweight, durability, and aesthetic appeal.
• Automotive industry: Components such as tail lights and instrument clusters.
• Medical devices: Bone cement, intraocular lenses, and dentures.
• Signage and displays: Retail displays, signage, and light fixtures because of its clarity and ability to be easily shaped and colored.
• Consumer electronics: Screens for mobile phones and televisions.

Production

The production of PMMA involves the polymerization of methyl methacrylate monomers. Two main methods are used: bulk polymerization and suspension polymerization. Bulk polymerization produces a more transparent and higher quality PMMA, while suspension polymerization is used for products that require higher impact resistance.

Environmental Impact

PMMA is non-biodegradable but can be recycled. The recycling process involves breaking down PMMA into its monomer, methyl methacrylate, through a process called depolymerization. The monomer can then be purified and reused to produce new PMMA. However, the recycling rate of PMMA is currently low due to the lack of collection and separation facilities for this type of plastic.

Health and Safety

PMMA is generally considered safe for use in many applications, including those in direct contact with food. However, the monomer methyl methacrylate is toxic, and care must be taken during the manufacturing process to minimize exposure.

See Also

• Acrylic paint
• Polystyrene
• Polyethylene terephthalate

Poly(methyl methacrylate) (PMMA) Resources
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