Hexafluoropropylenevinylidenefluoride Copolymer ( FKM ) - Properties and Applications - Supplier Data by Goodfellow


Hexafluoropropylenevinylidenefluoride Copolymers ( FKM ) are a range of fluoropolymer elastomers whose formulation can be tailored to a reasonable extent to meet the needs of individual end-uses. They are normally black and have high heat, oil and chemical resistance but indifferent low temperature performance. With the exception of Kalrez® perfluorinated elastomer, Hexafluoropropylenevinylidenefluoride Copolymers ( FKM ) are about the most highly temperature resistant of all commercially available elastomers.


The main applications of Hexafluoropropylenevinylidenefluoride Copolymers ( FKM ) are seals, O-rings and linings.

Key Properties

The key properties of Hexafluoropropylenevinylidenefluoride Copolymer ( FKM ) are tabulated below.

Table 1. Key properties

Chemical Resistance
Acids - concentrated Good
Acids - dilute Good
Alcohols Good-Fair
Alkalis Good-Fair
Aromatic hydrocarbons Good-Fair
Greases and Oils Good
Halogens Good
Ketones Poor
Electrical Properties
Dielectric constant @ 1 kHz 10.5
Dielectric strength ( kV.mm-1 ) 20
Dissipation factor @ 1 kHz 0.034
Volume resistivity ( Ohm.cm ) 2 x 1013
Mechanical Properties
Compression set after 24 hr at 175 °C ( % ) 43
Elongation at break ( % ) 200
Hardness - Rockwell Shore A75
Tear strength ( N.mm-1 ) 10
Tensile strength ( MPa ) 9
Physical Properties
Density ( g.cm-3 ) 2.0
Flammability Self Extinguishing
Resistance to Ultra-violet Excellent
Thermal Properties
Coefficient of thermal expansion ( x10-6 K-1 ) 160
Lower working temperature (°C ) -10 to -50
Thermal conductivity ( W.m-1.K-1 ) 0.2 @ 23
Upper working temperature (°C ) 220 to 300

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