Processes for preparing low molecular weight hexafluoropropylene-olefin cotelomers

A process comprising:

• 1) forming a reaction mixture by combining reactants comprising from 80 to 99 weight % of hexafluoropropylene, from 1 to 20 weight % of an olefinically unsaturated co-monomer, from 0.05 to 2 weight % of a free-radical initiator, and from 0.25 to 5 weight-% of a non-monomeric chain transfer agent, based on the total weight of the reaction mixture;
• 2) causing the free-radical initiator to initiate a free-radical polymerization;
• and
• 3) causing the reaction mixture to undergo free radical polymerization at a temperature in the range of 225 to 400° C. and a pressure of 40-700 MPa, for a period of 10 seconds to 1 minute, to form an amorphous hexafluoropropylene liquid telomer comprising from 30 mole % to 95 mole % of monomer units derived from hexafluoropropylene, said liquid telomer being characterized by a viscosity in the range of 1 to 10,000 centistokes at 40° C.;
• whereby the amorphous hexafluoropropylene liquid telomer is formed at a rate of 31-198 pounds per gallon per hour;
• wherein the olefinically unsaturated co-monomer is selected from the group consisting of tetrafluoroethylene, vinylidene fluoride;
• ethylene, perfluoroalkylvinyl ether of the structure RfOCF═CF2 wherein Rf is a C1-C4 perfluoralkyl radical;
• hexafluoroisobutylene;
• perfluoroalkylethylenes of the structure R′fCH═CH2 wherein R′f is a linear C1 to C8 perfluoroalkyl radical;
• vinyl fluoride (VF);
• trifluoroethylene, and chlorotrifluoroethylene, and the concentration of ethylene is 3 weight % or less, provided that when the olefinically unsaturated co monomer is vinylidene fluoride, perfluoropropylvinyl ether, ethylene, or tetrafluoroethylene, the total of the concentrations of vinylidene fluoride, ethylene, and tetrafluoroethylene is 10 weight % or less.