Acrylics are plastics that contain one or more compounds of acrylic acid. The most common acrylic is polymethyl methacrylate (PMMA), which is tough, transparent and resistant to ultraviolet radiation. It is sold under brand names such as Perspex, Plexiglas, Lucite and Crystallite.
Some of the oldest plastic materials in use today are acrylics. First invented in 1936 and used during World War II for aircraft canopies, their main advantage is toughness, transparency and resistance to weather conditions. They are thermoplastics and can be remoulded when heated to their forming temperature. Acrylic plastic sheets can be produced in different varieties to meet specific requirements.
The main uses for acrylics are in skylights, internal and external windows, swimming pools, room dividers, washbasins and safety glass of all kinds. These materials can be coloured, cut and moulded as needed but share similar characteristics.
Transparency and Insulation
Plexiglas, Perspex and Lucite are as transparent as the highest quality optical glass. On average, they transmit 92% of white light radiation. In some forms of Plexiglass, the light transmission can be made to vary and diffuse with the sheet thickness and formation process. Other varieties of acrylics retain the same transparency irrespective of thickness.
Standard Plexiglas formulation absorbs just the short wave part of ultraviolet radiation. Newer formulations can block and filter both ultraviolet and infrared light. This property enables the wide use of acrylics in display cases as a protection against harmful light radiation. Acrylics are generally opaque to alpha rays, beta rays and neutrons but do transmit gamma radiation.
Acrylic sheets are easily coloured and can provide a further filtering of sunlight or other radiation. This property is useful in building designs that need to reduce light glare. Plexiglas sheets used in windows also provide 40% more insulation than the equivalent amount of standard glass.
Acrylic sheets, such as Plexiglas and Perspex, are six to 17 times stronger than all types of glass, including tempered glass. The breakage resistance is greatest when the acrylic sheet has smooth edges that are free of any notches. With continuous blows, acrylics break into large pieces with dull edges. The lightweight nature of the pieces mean that they disperse at low speeds, so the acrylics are a less dangerous hazard than shards of glass.
Weather and Chemicals
Acrylics have a greater chemical resistance than glass to most standard chemicals, such as inorganic acids and alkalis such as sulphuric acid and ammonia plus hydrocarbons such as hexane, octane and naphtha. But aromatic hydrocarbons and organic compounds like benzene and toluene can attack them.
Plexiglas, Perspex and other acrylics have excellent weather resistance and avoid discolouration for about 20 years. The sheets will not discolour even when exposed to close fluorescent lighting over a decade. Acrylics have a higher ignition temperature than most woods but have the same burning characteristics and will generate heat rapidly on ignition.
Acrylics are versatile materials and more hardwearing than glass. They can be cut, coloured and moulded to any shape and size and have a wide range of applications.
Idania Silvia writes regularly on thermoplastic materials and acrylic plastic for a wide range of websites and blogs.