Method for manufacturing fluoroelastomers

A method of making a fluoroelastomer (A), which is a (per)fluoroelastomer comprising Iodine and/or Bromine chain ends, said method comprising

• polymerizing vinylidene fluoride (VDF), in the presence of at least one second (per)fluorinated monomer (MF) different from VDF, in an aqueous emulsion in the presence of a chain transfer agent (CTA-X) having I and/or Br atoms and in the presence of a redox-initiating system (R) comprising at least one organic radical initiator (O) and at least one composition (CS) comprising at least one compound (S) bearing at least one sulfinic acid group,
• wherein:
• the amount of initiator (O) is of at least 1.50 and at most 15.00 mmol of O2 per kg of fluoroelastomer (A);
• the amount of compound(S) is of at least 0.20 and at most 2.00 g per kg of fluoroelastomer (A);
• and
• the ratio between agent (CTA-X) and composition (CS) is of at least 2.00 and of at most 8.00 g of X/g of composition (CS), whereas X is the amount of I and/or Br in the agent (CTA-X);
• and
• wherein said emulsion polymerization is carried out without addition of any fluorinated surfactant or hydrogenated surfactant.