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FEPM Dipolymers of tetrafluoroethylene (TFE) and propylene (P) are known to exhibit excellent resistance to nucleophilic attack by basic chemicals. FEPM polymers, however, are difficult to process, and exhibit relatively poor resistance to many hydrocarbon lubricants, particularly compared to conventional fluoroelastomers (FKM): e.g., copolymers of vinylidene fluoride (VF2), hexafluoropropylene (HFP), and, incorporated in some FKM types, tetrafluoroethylene (TFE). Terpolymers of TFE, propylene, and VF2 are available which contain higher levels of fluorine than FEPM dipolymers, due to the incorporation of VF2 monomer, and these polymers exhibit some improvement in resistance to hydrocarbon fluids. TFE/P/VF2 terpolymers, however, are not as resistant to base attack as dipolymers of TFE/P. This paper introduces a new polymer that exhibits excellent processing characteristics, including mold release.

Prevailing trends in automotive powertrain applications are pushing current elastomeric seal materials to their limits. These trends include the push towards higher temperatures under the hood; longer warranties up to 100,000 - 150,000 miles and 10 - 15 years; and increasingly more stringent environmental regulations. These trends are combined with an expanded use of fluids containing additives that are more aggressive towards elastomeric materials, and the use of low viscosity fluids for improved low temperature performance in automatic transmission and hydraulic fluids. In this presentation traditional fluoroelastomer compounds used in automotive powertrain sealing applications will be compared to several new specialty types of fluoroelastomers that are designed to help both the end user and rubber part manufacturers solve difficult sealing problems. Specifically, fluoroelastomer polymers, with both improved low temperature properties and fluid resistance will be reviewed.