seals for automotive body applications and building applications should be dimensional stable , provide low compression set , and offer outstanding sealing characteristics over a broad temperature range . they must be capable of sealing out noise , wind and water , while providing long - term ultraviolet light resistance . this invention discloses a highly crosslinked nitrile rubber composition which can be easily blended with polyvinyl chloride to make compositions having excellent characteristics for automotive body seals and building industry applications including dimensional stability , low compression set , outstanding sealing characteristics , good low temperature flexibility , and good recyclability , said highly crosslinked nitrile rubber composition being comprised of a highly crosslinked nitrile rubber having repeat units which are derived from 1 , 3 - butadiene , acrylonitrile , and a crosslinking agent , wherein said highly crosslinked nitrile rubber has a mooney viscosity of about 50 to about 120 , a swelling index of less than about 10 percent , a mill shrinkage of less than 10 percent , and a gel content of greater than 90 percent ; and from about 1 to about 30 phr of a plasticizer .