Properties of FFKM O-rings

Properties of FFKM O-rings

FFKM O-rings offer exceptional chemical and thermal resistance. They combine the sealing force, resistance and recovery characteristics of a regular elastomer O-ring with the chemical resistance of PTFE. The Carbon-Fluorine bonds of FFKM, regarded as the strongest single bond in organic chemistry, guarantee the high chemical, thermal and oxidation resistance of our moulded FFKM O-rings.

An increase in fluorine content raises the chemical resistance of hydrocarbons. As such, FFKM contains 72.5% fluorine with a fully fluorinated backbone chain, which is the maximum fluorination possible whilst still retaining the elastomeric properties required for effective sealing. FFKM’s ether group (R-O-R) gives it its elastomeric properties and elasticity, without which perfluoroelastomers would behave in much the same way as PTFE.

A third monomer is also included within the FFKM polymer chain, which is known as a cure site monomer (CSM). This allows the formation of a three-dimensional network when processed under the correct conditions. This three-dimensional network not only greatly increases the elasticity of the material, but also increases the maximum operating temperature of FFKM to above the melting point of PTFE, giving FFKM the highest thermal stability and chemical resistance of any elastomer.

There are 3 types of cure systems used within perfluoroelastomers which gives FFKM O-Rings a wide range of high performance properties. These are:

Peroxide Curing 

This gives an FFKM the highest level of chemical resistance whilst providing high-temperature resistance. This curing system was successfully implemented in around 90% of applications.

Modified Peroxide curing – This method of curing increases the operating temperature of FFKM without sacrificing chemical resistance. This grade is typically implemented where high-temperature steam resistance is required.

Nitrilic Cure (Triazine)

This method of curing provides the maximum operating temperature for FFKM. However, these grades cannot be used with hot water, steam or amines at elevated temperatures.

Variations in FFKM’s ether group can provide FFKM with an even greater low-temperature performance. TRP have two low-temperature FFKMs with static sealing capability down to -45oC.

A full list of TRP’s FFKMs can be found in the datasheet section.

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