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EPDM vs NBR: what's the difference?

Synthetic rubber comes in nearly a dozen major types with different properties for different applications. Two common synthetic rubber compounds are known as EPDM and nitrile rubber. The main differences between these two rubber products are their resistance to petroleum-based fuels and lubricants and their resistance to weathering.

The main difference between NBR and EPDM is that NBR is a non-aromatic polymer compound while EPDM is an aromatic polymer.

NBR and EPDM are two types of rubber materials. Rubber is a material that can stretch when subjected to an external force and then return to its original shape when the force is removed. Natural rubber, derived from the latex of the rubber tree, is the most common way to make rubber-like materials; however, there are also synthetic routes.

What is NBR?

The term NBR stands for nitrile butadiene rubber. It is also known as nitrile rubber, Buna-N and acrylonitrile butadiene rubber. It is a synthetic form of rubber made from the monomers acrylonitrile and butadiene. The most common trade names for this rubber are Perbunan, Nipol, Krynac and Europrene.

NBR material is exceptionally resistant to oil, fuel and most chemicals. Therefore, it is used in the automotive and aerospace industries to make hoses, gaskets, grommets, and fuel tanks for fuel and oil.

NBR is also used in the nuclear industry to make protective gloves. This material has a very high stability in the temperature range from minus 40 degrees Celsius to 108 degrees Celsius. This makes it an ideal material for aerospace applications. In addition, NBR is important in the manufacture of molded articles, shoes, adhesives, sealants, sponges, foams and floor mats.

The exceptional elasticity of NBR also makes it important for the manufacture of disposable laboratory items, cleaning purposes and examination gloves. Compared to natural rubber (NR), NBR is more resistant to oils and acids. NBR also has higher strength and does not cause allergic reactions (natural rubber can cause allergic reactions on the skin).

Advantages of NBR

  •  excellent compression set
  • good tear strength
  • good abrasion resistance
  • good resistance to mineral oil based oils
  • good resistance to hydraulic fluids based on mineral oil
  • good resistance to solvents, water and alcohols

Disadvantages of NBR

  • poor weather resistance
  • moderate heat resistance
  • not suitable for use in brake fluids
  • not suitable for use in highly polar solvents

What is EPDM

The term EPDM stands for ethylene propylene diene monomer rubber. It is a type of synthetic material that belongs to the group of elastomers and is made up of saturated polyethylene chains. EPDM is an aromatic compound. The monomers used to make this polymeric material are ethylene, propylene and a diene comonomer. Its structure allows cross-linking by sulfur vulcanization.
Due to the presence of a saturated component, EPDM is significantly more resistant to heat, light and ozone compared to the other unsaturated rubber materials such as natural rubber, SBR and neoprene. In addition, EPDM can be formulated in a temperature-resistant form of the polymer that can withstand up to about 150 degrees Celsius. It can be used outdoors for many years without the material deteriorating. In addition, this material has good low-temperature properties such as elasticity.

Advantages of EPDM

  • excellent weather and ozone resistance
  • excellent water and chemical resistance
  • excellent resistance to gas permeability and aging from exposure to steam
  • good in ketones and alcohols
  • good heat resistance
  • good cold flexibility

Disadvantages of EPDM

  • poor resistance to fuels and solvents
  • not recommended for food applications
  • not recommended for contact with aromatic hydrocarbons

What is the difference between NBR and EPDM?

NBR and EPDM are two types of rubber materials. NBR stands for Nitrile Butadiene Rubber while EPDM stands for Ethylene Propylene Diene Monomer Rubber. The main difference between NBR and EPDM is that NBR is a non-aromatic polymer compound while EPDM is an aromatic polymer. Also, NBR is made from the monomers acrylonitrile and butadiene, while EPDM is made from ethylene, propylene, and a diene comonomer.

Summary – NBR vs. EPDM

EPDM, or ethylene propylene diene monomer, is widely used to make O-rings, washers and other seals in water and steam lines, as well as in the cooling and braking systems of cars and trucks. EPDM seals are resistant to mild acids, detergents, silicones, glycols, ketones and alcohols and can withstand temperatures from -30C to +150C. They are resistant to ozone. The greatest weakness of EPDM rubber seals and other seals is that they fail and have poor sealing performance in systems that work with petroleum based fuels, oils and solvents.

Nitrile rubber, also known as Buna-N, Perbunan, Nipol, Krynac and Europrene, is made by combining the polymers butadiene and acrylonitrile. It offers excellent resistance to gasoline, diesel fuel, motor oil and other petroleum based products.

Because of this, it is commonly used for washers and O-rings that seal fuel systems in cars, boats, airplanes, and stationary engines.

It can be formulated for temperatures from -55C to 135C. The main disadvantage of nitrile rubber is that it can be affected by exposure to the sun, general weather conditions or ozone from electrical equipment unless it is specifically manufactured for these purposes.

Stamped parts made of EPDM and NBR

The Dr. Dietrich Mueller GmbH manufactures stamped parts, strips and blanks from both materials. The processes that can be used are water jet cutting, punching and roll cutting.

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