Pervaporation method for separating liquids in mixture

A pervaporation method for the separation of ethyl alcohol from or enrichment of ethyl alcohol in a liquid mixture of water and ethyl alcohol which comprises the steps of:

• (a) partitioning the liquid phase from the adjacent vapor phase with a membrane;
• and
• (b) producing a pressure difference between the liquid mixture and the vapor phase, the pressure being higher in the liquid mixture than in the vapor phase, in which the membrane is made of a polymeric composition comprising from 50 to 95 percent by weight of an organosilyl-substituted polyenic polymer composed of the monomeric moieties represented by the general formula ##STR3## the group denoted by R.sup.1 being a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms and the groups denoted by R each being a hydrogen atom, a monovalent hydrocarbon group having 1 to 8 carbon atoms or a silicon-containing organic group represented by the general formula
• --CH.sub.2 --SiMe.sub.2 R.sup.2,
• in which Me is a methyl group and R.sup.2 is a lower alkyl group having 1 to 4 carbon atoms, and from 50 to 5 percent by weight of a poly(trimethyl vinyl silane).