Patent ID: 8247505

Claim:
A peroxide vulcanizable fluorine-containing elastomer comprising 20 to 90% by mole of vinylidene fluoride repeating units and 10 to 80% by mole of hexafluoropropylene repeating units; (a) which contains 0.01 to 10% by weight of an iodine atom in the elastomer, (b) which has a number average molecular weight of from 1,000 to 300,000, (c) which has a VDF branch ratio of at most 200 ppm, the ratio being calculated from the following formula: an ⁢ ⁢ area ⁢ ⁢ from ⁢ ⁢ δ ⁢ ⁢ F - 96.5 ⁢ ⁢ to ⁢ - 99.5 ⁢ ⁢ ppm 3 ⨯ ( an ⁢ ⁢ area ⁢ ⁢ from ⁢ ⁢ δ ⁢ ⁢ F - 88.0 ⁢ ⁢ to ⁢ - 124.0 ⁢ ⁢ ppm ) in which an acetone solution having a polymer concentration of about 20% is subjected to measurement on high-resolution 19 F-NMR.