Substantial Amounts of acrylonitrile result in a rubber with better oil resistance. Compounds with minimal acrylonitrile material have an improved lower temperature adaptability and resilience. Ethylene Propylene Rubber (EPM) is a copolymer consisting of ethylene and propylene. The ethylene propylene polymer is chemically inert because it has no double bonds. https://beediadiamond.com/catalog/rubber-points