How ABS plastic is made
ABS is a hard plastic with rubber particles grafted into it, which is why a LEGO brick survives being stepped on.
- stations
- 6
- things upstream
- 24
- raw sources
- 9
- steps from the ground
- 6
The short version
ABS is made from three ingredients: styrene, acrylonitrile and butadiene. Butadiene is first turned into rubbery particles, and then styrene and acrylonitrile are polymerized around them so the chains tie together. The powder is melted with pigments and cut into pellets for molders.
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Polymerize the rubber balls
Butadiene, a byproduct of steam cracking, is polymerized in water into tiny rubbery balls of polybutadiene. These soak up impact like shock absorbers.
Goes in -
Build the acrylonitrile
Propylene, ammonia and air react over a catalyst to give acrylonitrile, which contributes chemical resistance and stiffness to the plastic.
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Bring in the styrene
Styrene is built from benzene and ethylene, usually at a neighboring plant, and arrives as a liquid. It is the main ingredient by weight, usually between 40% and 60%.
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Graft the chains onto rubber
Styrene and acrylonitrile polymerize in the presence of the polybutadiene, growing short chains that cross-link with the rubber. The result is a long rubber backbone crisscrossed with hard side chains.
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Coagulate and dry the powder
The latex mixture is coagulated into a crumb, washed, and dried to a fine powder. Recipes shift the balance between toughness, stiffness and heat resistance.
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Compound with color
An extruder melts the powder with pigments, stabilizers and lubricants. Strands are chopped into pellets sorted for extrusion or injection molding.
Goes in
Worth repeating
- Lego bricks have been made mainly from ABS since 1963.
- ABS also makes computer keycaps, drain-waste-vent pipe, and plastic recorders, oboes and clarinets.
- ABS recipes vary from 15% to 35% acrylonitrile, 5% to 30% butadiene and 40% to 60% styrene.
Back to the ground
Follow every input upstream and abs plastic starts as these 9 raw sources.
Everything it is made of See it on the map
Open the whole family tree
Where it goes next
ABS plastic feeds 28 lines directly.
Keep walking
Sources
Cite this page: "How ABS plastic is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/abs-plastic