Difference Between FKM and FFKM

The key difference between FKM and FFKM is that FKM offers a less degree of versatility compared to FFKM.

FKM stands for fluoroelastomer whereas FFKM stands for perfluoroelastomer. FKM and FFKM are two types of elastomer materials. Therefore, these are two types of polymers having elastic properties.

1. Overview and Key Difference
2. What is FKM
3. What is FFKM
4. Side by Side Comparison – FKM vs FFKM in Tabular Form
5. Summary

What is FKM?

The term FKM stands for fluoroelastomer. This type of material was developed during world war II as an antidote to the leaking nitrile seals that plagued the aircraft of the era. Fluorinated polymers that were developed as a solution for this matter contained chemically inert fluorine-carbon bonds that deliver a combination of temperature performance and a high chemical resistance. There are two major types of FKM as FKM type 1 and type 2. These grades were commercialized in the 1950s. The fluorine content, which ranges around 26.7% to 67%, of this material, offers increased chemical resistance.

There are different important advantages of using FKM material, and they include a wide temperature range it can withstand, excellent chemical resistance, excellent weather ability and ozone resistance, more resistance to burning than non-fluorinated hydrocarbons, high density and high-quality feel, good mechanical properties, etc.

However, there are some disadvantages of using this FKM material as well. These include the tendency to swell in fluorinated solvents, inability to use with molten or gaseous alkali metals, higher price compared to other non-fluorinated hydrocarbons, rapid failure to choosing the wrong grade, etc. The applications of FKM material include the automotive industry, chemical processing, oil and gas production, heavy-duty machinery, and aerospace applications.

What is FFKM?

The term FFKM stands for perfluoroelastomer. This material was developed around the 1960s after the discovery of FKM materials. The need for producing this material came due to the requirement of more chemically resistant and processed high-temperature capabilities. This material has become a regular fixture in the aerospace and automotive industries in the present.

Figure 01: Structure of a Perfluorocarbon Compound

There are some important advantages of using FKM material; this includes the wide temperature range that it can withstand, excellent chemical resistance, excellent gas and liquid performance, excellent weather ability and ozone resistance, high density, self-extinguishing nature and non-flammability in air, etc.

There are some disadvantages as well; it can swell significantly in fluorinated solvents, cannot be used with molten or gaseous alkali metals, it has a large thermal coefficient compared to other elastomers, expense, etc.

What is the Difference Between FKM and FFKM?

The term FKM stands for fluoroelastomer whereas the term FFKM stands for perfluoroelastomer. The key difference between FKM and FFKM is that FKM offers a less degree of versatility compared to that of FFKM. FFKM can withstand comparatively high temperatures than FKM. Moreover, FKM is more resistant to burning than non-fluorinated hydrocarbon compounds while FFKM is self-extinguishing and non-flammable in air. Besides, application-wise, FKM is used in automotive, chemical processing, oil and gas production, heavy-duty machinery, aerospace applications, etc. while FFKM is useful as a regular fixture in aerospace and automotive industries.

The following infographic presents the differences between FKM and FFKM in tabular form.

Summary – FKM vs FFKM

FKM and FFKM are elastomer materials containing fluorocarbon structures. they have slightly different chemical and physical properties. The key difference between FKM and FFKM is that FKM offers a less degree of versatility compared to that of FFKM.