ASA (Acrylonitrile Styrene Acrylate)
Plastics are not generally considered to be a group of materials that suffer from degradation; however, as any parent will know, leave a plastic toy outside in the rain, frost or blinding bright sun and you won’t have a shiny, brightly coloured piece of plastic anymore. The surface of many plastics age and fade in colour or display something called environmental stress cracking. ASA, however, is a hardier plastic than most with its main distinguishing factor being its ability to withstand outdoor use. It is this resistance to UV rays that separates it from standard moulding materials like ABS. As a result, it is often used in the automotive industry, where parts don’t need painting and hold their colour without fading.
The polyacrylates, or acrylics, family, of which ASA is one, occupies a large area of the plastics family as a whole, and is grouped through the general properties of transparency and toughness. ASA and its properties were developed with long-term use in mind, and like ABS, it is a blend of three monomers: acrylonitrile, styrene and acrylate. ASA resins have properties similar to ABS but with a rubber taking the place of the butadiene that exists in ABS. This rubber adds resilience to UV and oxygen degradation, which marks the main distinction and makes it a material suitable for outdoor use. It is this resistance to chemicals and impact, and ability to hold colours that means that ASAs should be a main consideration for external, weather-resistant applications.
Image: Range Rover Evoque with ASA wing mirrors
Key features
•Versatile processing
•Excellent UV resistance
•High clarity
•Good impact strength
•Excellent chemical resistance
•High heat resistance
•Recyclable
Sources
Readily available from multiple suppliers.
Sustainability issues
As with all petroleum-based plastics, there are concerns over sustainability. Thermoplastics can be remoulded, so are therefore recyclable.
Production
As with ABS, this engineering thermoplastic can be easily processed through processes such as injection moulding and extrusion due to its ability to flow well in its molten state, allowing for complex mouldings and large wall thickness ratios. It is a material that is often co-extruded with ABS or PC to enhance the weather resistance of these materials.
Typical applications
This is a material that is able to extend the long service life for products that will live outdoors, and applications can mainly be divided into three main markets: automotive, building/ construction and leisure. Specific products include garden furniture, sprinklers, garden lights or extruded glazing and satellite aerials. Other applications include microwave ovens, vacuum cleaners and washing machines.
Derivatives
–Geloy® ASA resin sabic
–Luran®
–Korad®
–KIBILAC®
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–Light resistant –Weather resistant –Widely available –Hardwearing –Easy to colour |
- Toxic smoke generation when burned –Concerns over sustainability |