FPM fluorinated rubber

FPM, fluorinated rubber (Viton®, Fluorel®, Tecnoflon®) is used for mixed polymers composed of heavily fluorinated hydrocarbons.
The first such type was developed by DU PONT® and appeared on the market in 1958 under the name of VITON® (and is still being sold). It was a product of the copolymerization of vinyldene fluoride and hexafluoropropylene. A similar product, called Fluorel® was later introduced by 3M®. Apart from Viton® and Fluorel®, other kinds of fluorinated rubber types are being produced by other companies.

For most applications, FPM mixtures undergo cross-linking in two stages:

1. A pre-vulcanization stage, under pressure
(using either a press or pressurized steam) until a sufficient stability is attained.

2. A post-vulcanization stage
where pre-vulcanized products are hot-cured in unpressurized containers using hot air circulation to bring the cross-linking process to completion (this treatment is vital if the end product is to display the typical properties of this elastomer).

Properties

Fluorinated elastomer are fireproof and very resistant to high temperatures, ozone, oxygen, mineral oil, synthetic hydraulic fluids, fuels, aromatic compounds, as well as to many solvents and organic chemicals. As long as the mixture has the proper composition, they can also be water-resistant and withstand the action of steam and a number of acids. Drawbacks are represented by a HIGH price and sometimes unsatisfactory elastic properties at lower temperatures.

As an indication we provide here some values that can be achieved using different rubber mixtures:

  • Hardness: Shore rating: 65 to 90
  • Fireproof properties: excellent
  • Impact strength: very limited, 5 to 8%
  • Extensibility: 100 to 300%
  • Heat resistance: excellent up to 200°C (and even more for a limited time only).
  • Resistance to low temperatures: FPM vulcanized products can usually withstand dynamic stress up to -20°C.
  • Resistence to ozone, aging and weathering: excellent
  • Resistance to irradiation: unexpectedly lower than that of conventional elastomers such as SBR, EMPD and NBR.
  • Resistence to chemicals:
    • Good resistance to:
      Mineral oil and grease
      Poorly flammable hydraulic fluids of the HFD group
      Silicone-based oil and grease
      Oils and fats of animal or vegetable origin
      Aliphatic hydrocarbons (e.g. gasoline, butane, propane, methane, etc.)
      Aromatic hydrocarbons (e.g. benzol and toluol)
      Chlorinated hydrocarbons (e.g. trichloroethylene and carbon tetrachloride)
      Fuels containing methanol (special rubber mixtures only)
    • Does not resist to:
      Polar solvents like acetone, ethylene acetate, diethyl ether and dioxan
      Schirolo 500
      Glycol-based brake fluid
      Ammonia gas, amines, alkalis
      Superheated steam (because it breaks up the elastomer links)
      Organic acids with low molecular weight such as the formic and acetic acids
      Chlorosulfonic acid.


Applications

Fluorinated rubber is used above all for gaskets, hose and molded products that must withstand temepratures as high as 200°C. and that may come into contact with lubricants, poorly flammable hydraulic fluids and aggressive chemicals.
Used in PLANT ENGINEERING, special mechanical applications, etc.



   

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