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Polymethyl methacrylate (PMMA)
3-8 usd/kg
Polymethyl methacrylate (PMMA), acrylic, is a transparent plastic often compared to glass. Indeed, the two materials are used in many of the same applications – glazing, aquariums, household items, tableware and furniture, for example – with acrylic being lighter, more resistant to impact and easier to form into complex and intricate shapes. The disadvantages of acrylic, when compared to glass is that it is not inert (glass is virtually inert) and will crack and weaken if exposed to certain chemicals, it softens and melts at much lower temperatures (160 degC versus 1,700 degC for glass), and it is less scratch resistant.
As a transparent plastic, it is available in standard and custom colours, from muted tones through saturated fluorescents. Edge glow is the result of light passing through the surface and refracting internally until it meets a cut edge in tinted or semi-transparent materials. This phenomenon is utilised in signage, lighting and instrument panels, for example, that are made from acrylic. A cut edge may be the perimeter, or a score on the surface, such as made by laser cutting or engraving.
Sustainability concerns
Non-renewable ingredients
Raw material generates polluting by-products
Low circularity potential
Microplastics
Cast acrylic is plastic created by a chemical reaction between a catalyst and a monomer. Unlike extruded and moulded acrylic, which are formed by melt-processing (pellets melted and shaped into a die or mould), cast acrylic is poured (or injected) and hardens. For sheet materials, this is typically carried out between glass plates, to create a surfaces free from imperfections. Therefore, it is more expensive than extruded and utilised in glazing, aircraft windows, signage, facades and skylights. Certain grades are suitable for thermoforming by vacuum forming and drape forming, such as to make bathtubs, sinks (basins integrated into counter tops) and shaped glazing.
As a cast material, 3D shapes are also possible, such as model making, lighting, jewellery and dentures. It is used as an adhesive, with applications ranging from industrial products to hip replacements.
Compared to extruded acrylic, cast acrylic is harder and more resistant to scratches, has higher light transmission (92%), greater resistance to solvents and weathering, and laser cuts and engraves very well. It is available in a very wide range of thicknesses, up to 100 mm. However, production tolerances are greater and so cast acrylic sheets can vary more in thickness than extruded types.
It is available in a wide range of colours and patterns, and bespoke ingredients can be added at relatively low minimum order quantities (MOQ). Edge glow (lit edge) is a phenomenon often exploited in cast acrylic sheets. The edge of clear tinted plastic appears to glow in ambient lighting. It is caused by lightwaves being absorbed through the faces and transmitted out through the edge. The effect is enhanced by fluorescent pigment. Scored and etched lines on the surface of plastics cause the same effect. As well as lighting, products and retail, this trick is utilised in signage to illuminate graphics whilst keeping the light source hidden
Not all grades of casting acrylic are recyclable. Green Cast by Italian manufacturer Madreperla, is recycled and recyclable cast acrylic sheet. The company’s environmental product declaration (EPD) gives a carbon footprint of 2.13 kgCO2/kg for this material. It is produced with 100% R-MMA, recycled methylmethacrylate monomer produced by Madreperla in Italy. It is available in transparent, as well as a wide range of colours and finishes.
