May 19 2003
Background
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.
Applications
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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