| 摘要 |
<p>Thermoplastic elastomeric copolymers of tetrafluoroethylene and propylene and terpolymers of tetrafluoroethylene, propylene and a cure site monomer are disclosed which have a substantially uniform composition, i. e., a substantially uniform molar ratio of monomeric units and a relatively high molar ratio of tetrafluoroethylene units to propylene units within the range 1.0:0.11 to 1.0-0.54. The combination of high molar ratio of tetrafluoroethylene/propylene units, substantially uniform composition and good elastomeric properties is achieved by using a hybrid batch/continuous process wherein a reactor is initially charged with a mixture of tetrafluoroethylene, propylene and, optionally, a cure site monomer having a TFE/propylene molar ratio substantially higher than that of the polymer to be produced, i.e., in the range 1.0:0.01 to 1.0:0.087. The polymerization reaction is then initiated and a mixture of the same monomers is fed to the reactor at such a rate and in such proportions as to maintain the molar ratio of the unreacted monomers substantially the same as that in the initial charge to the reactor.</p> |
