Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Nitrile rubber, also known as Buna-N, Perbunan, acrylonitrile butadiene rubber, and NBR, is a synthetic rubber copolymer of acrylonitrile (ACN) and butadiene. Trade names include Nipol, Krynac and Europrene.