polymers fkm copolymers of poly vinylidene fluoride and hexafluoropropylene vf2 hfp terpolymers of poly vinylidene fluoride hexafluoropropylene and tetrafluoroethylene vf2 hfp tfe terpolymers of poly vinylidene fluoride polyvinyl methyl ether and tetrafluoroethylene vf2 pvme tfe terpolymers of poly vinylidene fluoride hexafluoropropylene and tetrafluoroethylene vf2 hpf tfe terpolymers of poly vinylidene fluoride tetrafluoroethylene and propylene vf2 tfe p perfluoroelastomers such as tetrafluoroethylene perfluoroelastomers ffkm highly fluorinated elastomers fepm butadiene rubber br polychloroprene rubber cr polyisoprene rubber ir im polynorbornenes polysulfide rubbers ot and eot polyurethanes au and eu silicone rubbers mq vinyl silicone rubbers vmq fluoromethyl silicone rubber fmq fluorovinyl silicone rubbers fvmq phenylmethyl silicone rubbers pmq styrene butadiene rubbers sbr copolymers of isobutylene and isoprene known as butyl rubbers iir brominated copolymers of isobutylene and isoprene biir and chlorinated copolymers of isobutylene and isoprene ciir the expandable portions of the packers of the invention may include continuous strands of polymeric fibers cured within the matrix of the integral composite body comprising elastomeric members 2 and 6 strands of polymeric fibers may be bundled along a longitudinal axis of the expandable packer body parallel to longitudinal cuts in a laminar interior portion of the expandable body this can facilitate expansion of the expandable portion of the composite body yet provide sufficient strength to prevent catastrophic failure of the expandable packer upon complete expansion the expandable portions of the packers of the invention may also contain a plurality of overlapping reinforcement members these members may be constructed.