properties and methods for their preparation are more fully discussed in u s pat no 3 218 373 which patent is hereby incorporated herein by reference the ethylene copolymer rubber may be cross linked or non crosslinked if a cross linked ethylene copolymer rubber is used it may be cross linked by contacting the ethylene copolymer rubber with a peroxide catalyst and heating by radiation or by any other known method the rubbery copolymers which may be useful include copolymers comprising ethylene vinyl acetate and alkyl acrylate or methacrylate 1 allyl methallyl crotyl 1 chloroallyl 2 chlorallyl vinyl methvinyl 1 phenylallyl butenyl etc esters of saturated and unsaturated aliphatic and aromatic monobasic and polybasic acids such for instance as acetic propionic butyric valeric caproic crotonic malonic succinic glutaric adipic pimelic suberic azelaic maleic fumaric citraconic mesaconic itaconic benzoic phenylacetic phthalic terephthalic benzoylphthalic etc acids 2 saturated monohydric alcohol esters e g the methyl ethyl propyl isopropyl butyl sec butyl amyl etc esters of ethylenically unsaturated aliphatic monobasic and polybasic acids illustrative examples of which appear above 4 vinyl compounds including monovinyl aromatic hydrocarbons e g styrene o m and p chlorostyrenes bromostyrenes fluorostyrenes methylstyrenes ethylstyrenes cyanostyrenes 5 various poly substituted styrenes such for example as the various di tri and tetra chlorostyrenes bromostyrenes flourostyrenes methylstyrenes ethylstyrenes cyanostyrene etc vinyl naphthalene divinyl benzene trivinyl benzene allyl benzene diallyl benzene the various allyl cyanostyrenes 6 various alpha substituted styrenes and alpha substituted ring substituted styrenes e g alpha methyl styrene alpha methyl para methyl styrene etc 8 unsaturated amides for instance acrylamide and n substituted acrylamides e g n methylol acrylamide n allyl acrylamide n methylacrylamide n phenyl.