flexible , halogen - free films , both multilayer films and monolayer films , can replace polyvinyl chloride films in applications requiring high speed welding by high frequency radiation . the monolayer films result from a blend of a non - polar olefin polymer and a polar olefin polymer that contains carbon monoxide . the multilayer films have like that of the monolayer films , but located so as to promote high frequency sealing . products made from such films are particularly well suited for medical device applications .