The invention relates to membranes formed from long chain branched fluoropolymers, and especially long chain branched homopolymers and copolymers of polyvinylidene fluoride such as KYNAR resins. The novel membranes retain all the advantages of a fluoropolymer membrane (excellent chemical resistance especially to strong acids and oxidizing agents, and good mechanical strength), and additionally offer improved permeability, improved strain hardening, and even better resistance to caustic attacks. The improvements are believed to be related to an improvement to the microstructure of the membranes, producing a more open structure due to the long chain branched fluoropolymers. Further improvements in the mechanical properties of the membranes can be induced by strain hardening.