How is nitrile rubber made from acrylonitrile and butadiene?

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Nitrile rubber (NBR) is a synthetic rubber produced through the polymerization of acrylonitrile and butadiene.1

The manufacturing process involves the following steps:

Emulsification: Acrylonitrile and butadiene are emulsified in water.1
Polymerization: The monomers are linked into large, multiple-unit molecules through the action of free-radical initiators.1

The resulting copolymer typically contains between 15 and 50 percent acrylonitrile. Adjusting this ratio allows manufacturers to balance properties; higher acrylonitrile content increases oil resistance and strength but reduces flexibility at low temperatures.1