A method of insert molding comprises placing in a first mold a curable rubber composition comprising a reactive species; placing on a surface of the rubber composition a first thermoplastic material in a film or layer comprising a group reactive with the reactive species of the rubber composition; curing the rubber composition in the mold to form a first molded article of cured rubber having a first thermoplastic material layer covalently bonded through reactive of the reactive species and the group; placing the first molded article as an insert into a second mold, the cured rubber contacting an inside surface of the second mold and the thermoplastic layer facing into the second mold cavity; closing the second mold and injecting into the second mold a second thermoplastic material that to form a second molded article comprising the first molded article thermally welded and/or covalently bonded to the second thermoplastic material.