EPDM vs. FKM

Attribute	EPDM	FKM
Chemical Resistance	Excellent	Excellent
Temperature Range	-50°C to 150°C	-20°C to 200°C
Cost	Lower	Higher
Compression Set Resistance	Good	Excellent
Weather Resistance	Good	Excellent

Introduction

EPDM (ethylene propylene diene monomer) and FKM (fluoroelastomer) are two popular elastomers used in a variety of industries for their unique properties and characteristics. While both materials are known for their excellent resistance to heat, chemicals, and weathering, they have distinct differences that make them suitable for different applications. In this article, we will compare the attributes of EPDM and FKM to help you understand their strengths and weaknesses.

Chemical Composition

EPDM is a synthetic rubber made from ethylene, propylene, and a diene monomer. This composition gives EPDM its excellent resistance to heat, ozone, and weathering, making it a popular choice for outdoor applications. On the other hand, FKM is a type of fluoroelastomer that contains fluorine atoms, which provide exceptional resistance to chemicals, oils, and high temperatures. This makes FKM ideal for applications where exposure to harsh chemicals is a concern.

Temperature Resistance

EPDM has a temperature range of -50°C to 150°C, making it suitable for a wide range of applications where moderate heat resistance is required. FKM, on the other hand, has a higher temperature range of -20°C to 200°C, making it more suitable for applications where extreme heat resistance is needed. This makes FKM a preferred choice for industries such as automotive, aerospace, and oil and gas, where exposure to high temperatures is common.

Chemical Resistance

EPDM is known for its excellent resistance to water, steam, and polar solvents, making it a popular choice for sealing applications in the automotive and construction industries. FKM, on the other hand, has superior resistance to oils, fuels, acids, and bases, making it ideal for applications in the chemical processing and oil and gas industries. The fluorine atoms in FKM provide a barrier against harsh chemicals, ensuring long-term durability and performance.

Weathering Resistance

EPDM is highly resistant to ozone, UV radiation, and weathering, making it a preferred choice for outdoor applications such as roofing, seals, and gaskets. FKM, on the other hand, has good resistance to weathering but may degrade over time when exposed to high levels of ozone and UV radiation. This makes EPDM a better choice for applications where long-term exposure to the elements is a concern.

Compression Set

EPDM has a low compression set, meaning it can maintain its shape and sealing properties over time, even under high pressure or temperature conditions. FKM, on the other hand, has a higher compression set, which may result in permanent deformation or loss of sealing properties over time. This makes EPDM a preferred choice for applications where long-term performance and reliability are critical.

Cost

EPDM is generally more cost-effective than FKM, making it a popular choice for applications where budget constraints are a concern. FKM, on the other hand, is more expensive due to its superior chemical resistance and high-temperature capabilities. While the initial cost of FKM may be higher, its long-term durability and performance may justify the investment in certain applications.

Conclusion

In conclusion, EPDM and FKM are two versatile elastomers with unique properties that make them suitable for a wide range of applications. While EPDM is known for its excellent weathering resistance and cost-effectiveness, FKM stands out for its superior chemical resistance and high-temperature capabilities. By understanding the differences between EPDM and FKM, you can choose the right material for your specific application needs.