Patent ID: 6979699

Claim:
Supported or self-supported membranes obtained from sulphonic fluorinated ionomers crosslinked by radical crosslinking of: A) crosslinkable sulphonic fluorinated ionomers having equivalent weight 380-1300 g/eq and comprising: from 48% to 85% by moles of monomeric units of tetrafluoroethylene (TFE); from 15% to 47% by moles of fluorinated monomeric units containing sulphonyl groups —SO 2 F; from 0.01% to 5% by moles of monomeric units of a bis-olefin of formula: wherein: m=2-10; R 1 , R 2 , R 5 , R 6 , equal to or different from each other, are H or C 1 -C 5 alkyl groups; B) a fluorinated compound as crosslinking radical initiator; C) a fluorinated bis-olefin of structure (I) as cross-linking agent; the radical crosslinking being carried out at a temperature in the range of 250° C.-310° C.