Superior quantities of acrylonitrile cause a rubber with superior oil resistance. Compounds with low acrylonitrile content have a better reduced temperature flexibility and resilience. Ethylene Propylene Rubber (EPM) is actually a copolymer consisting of ethylene and propylene. The ethylene propylene polymer is chemically inert since it incorporates no double bonds. https://beediadiamond.com/catalog/rubber-points