peroxide containing olefin polymer has a peroxide concentration typically ranging from about 10 to about 100 milli equivalent per kilogram of the polymer meq kg and preferably ranging from about 20 to about 50 the reactive peroxide containing olefin polymer may be prepared by using a method described in wo 2005 116091 or wo 2005 063376 the content of which is incorporated herein by reference preferably the reactive peroxide containing olefin polymer may be prepared via an irradiation and oxidation process by exposing the polyolefin starting material to high energy ionizing radiation in an essentially oxygen free environment i e an environment in which the active oxygen concentration is established and maintained at 0 004 by volume or less the olefin polymer starting material is exposed to high energy ionizing radiation under a blanket of inert gas preferably nitrogen the ionizing radiation should have sufficient energy to penetrate the mass of polymer material being irradiated to the extent desired the ionizing radiation can be of any kind but preferably includes electrons and gamma rays more preferred are electrons beamed from an electron generator having an accelerating potential of 500 4 000 kilovolts satisfactory results are obtained at a dose of ionizing radiation of about 0 1 to about 15 megarads u201c mrad u201d preferably about 0 5 to about 9 0 mrad the term u201c rad u201d is usually defined as that quantity of.