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A VF2/PMVE/TFE copolymer fluoroelastomer was prepared by a continuous emulsion polymerization process, carried out at 105° C. in a well-stirred 2.0-liter stainless steel liquid full reaction vessel. An aqueous solution, consisting of 1.98 g/hour (g/h) ammonium persulfate initiator and 0.79 g/h sodium hydroxide, was fed to the reactor at a rate of 4 L/hour. The reactor was maintained at a liquid-full level at a pressure of 6.2 MPa by means of a backpressure control valve in the effluent line. After 30 minutes, polymerization was initiated by introduction of a gaseous monomer mixture consisting of 569 g/h vinylidene fluoride (VF2), 393 g/h perfluoro(methyl vinyl ether) (PMVE), and 101 g/h tetrafluoroethylene (TFE), fed through a diaphragm compressor. Fifteen minutes after polymerization commenced, 4-bromo-3,3,4,4-tetrafluoro-1-butene (BTFB) was fed into the reactor at a rate of 10.0 g/h. After a further 1.75 hours, collection of effluent dispersion was begun and collection continued for 5 hours. The effluent polymer latex, which had a pH of 8.64 and contained 20.7 wt. % solids, was separated from residual monomers in a degassing vessel at atmospheric pressure.

1. customcarried out at 105° C. in a well-stirred 2.0-liter stainless steel liquid full reaction vessel
2. temperatureThe reactor was maintained at a liquid-full level at a pressure of 6.2 MPa by means of a backpressure control valve in the effluent line
3. custompolymerization
4. customFifteen minutes after polymerization
5. waitAfter a further 1.75 hours
6. customcollection of effluent dispersion
7. customcollection
8. waitcontinued for 5 hours
9. customwas separated from residual monomers in a degassing vessel at atmospheric pressure