. . . "Examples of the types of polymers that can be used as pervaporation membranes are nitrile rubber, neoprene, silicone rubber (such as for example polydimethylsiloxane), chlorosulfonated polyethylene, polysilicone-carbonate copolymers, fluoroelastomers, plasticized polyvinylchloride, polyurethane, cis-polybutadiene, cis-polyisoprene, poly(butene-1), polystyrene-butadiene copolymers, styrene/butadien" .