EPDM vs. NBR

Attribute	EPDM	NBR
Chemical Resistance	Excellent	Good
Temperature Range	-50°C to +150°C	-30°C to +120°C
Hardness	40-90 Shore A	40-100 Shore A
Tensile Strength	10-20 MPa	10-25 MPa
Elongation at Break	200-600%	200-500%
Oil Resistance	Good	Excellent
Abrasion Resistance	Good	Excellent

Introduction

When it comes to choosing the right material for various applications, it is essential to consider the specific attributes and characteristics of each option. In this article, we will compare two commonly used elastomers: EPDM (Ethylene Propylene Diene Monomer) and NBR (Nitrile Butadiene Rubber). Both materials have unique properties that make them suitable for different applications. By understanding their attributes, you can make an informed decision about which material is best suited for your specific needs.

Chemical Composition

EPDM is a synthetic rubber made from the copolymerization of ethylene, propylene, and a diene monomer. The diene monomer introduces unsaturated carbon-carbon double bonds into the polymer chain, providing EPDM with excellent resistance to ozone, weathering, and aging. On the other hand, NBR is a synthetic rubber made from the copolymerization of butadiene and acrylonitrile. The acrylonitrile content in NBR determines its oil resistance, while the butadiene content contributes to its flexibility and low-temperature performance.

Physical Properties

EPDM exhibits excellent resistance to heat, ozone, and weathering, making it an ideal choice for outdoor applications. It can withstand temperatures ranging from -50°C to 150°C (-58°F to 302°F) without significant degradation. EPDM also has good electrical insulation properties and is resistant to polar solvents, acids, alkalis, and many chemicals. On the other hand, NBR offers superior resistance to oils, fuels, and greases, making it commonly used in automotive and industrial applications. It has a temperature range of -40°C to 120°C (-40°F to 248°F) and provides good resistance to compression set, abrasion, and tear.

Mechanical Properties

EPDM has excellent elasticity and flexibility, allowing it to withstand repeated stretching and compression without permanent deformation. It has a low compression set, meaning it can return to its original shape after being compressed. EPDM also has good tensile strength and tear resistance, making it suitable for applications that require durability and resilience. On the other hand, NBR has moderate elasticity and flexibility. It offers good tensile strength and tear resistance, but not as high as EPDM. NBR is known for its excellent resistance to compression set, making it suitable for sealing applications.

Compatibility with Fluids

EPDM exhibits excellent resistance to water, steam, and polar solvents. It is not recommended for applications involving oils, hydrocarbons, and non-polar solvents as it may swell or degrade. On the other hand, NBR is highly resistant to oils, fuels, and hydrocarbons. It can withstand exposure to petroleum-based fluids, making it widely used in automotive and oil industry applications. However, NBR is not recommended for applications involving polar solvents and strong acids.

Applications

EPDM's excellent weathering resistance and electrical insulation properties make it suitable for outdoor applications such as roofing membranes, window seals, and automotive weatherstripping. It is also used in the construction industry for gaskets, seals, and expansion joints. NBR's superior oil resistance makes it ideal for applications such as oil seals, fuel hoses, gaskets, and O-rings in automotive, aerospace, and industrial equipment. It is also commonly used in hydraulic systems, oil refineries, and chemical processing plants.

Conclusion

EPDM and NBR are both versatile elastomers with unique attributes that make them suitable for different applications. EPDM excels in outdoor environments, offering excellent weathering resistance and electrical insulation properties. NBR, on the other hand, is known for its superior oil resistance, making it a popular choice in automotive and industrial applications. By considering the specific requirements of your application, you can determine which material will provide the best performance and longevity. Whether you need a material that can withstand harsh weather conditions or one that can resist oils and fuels, EPDM and NBR offer reliable solutions for a wide range of industries.