| abstract |
A composite ionomeric membrane comprising a layer or film of a porous inert material on which a (per) fluorinated sulphonic ionomer is deposited wherein the sulphonic groups are at the end of short side chains (SSC), said ionomer having:n equivalent weight comprised between 280 and 1,700 g/eq; side chains of formula: —O—CF 2 —CF 2 —SO 3 —M + , wherein M is hydrogen or an alkaline metal;n nsaid membrane having in each of the two orthogonal directions xy of the plane, after dipping in demineralized water at 100° C. for 30 minutes and preliminary drying at 105° C. under vacuum for one hour, the following size variations:n in one direction, size variation lower than 25%; in the other direction, size variation lower than 20%. |