What is the Composition of NBR Rubber Compound?

NBR is a synthetic rubber compound widely used for its resistance to oils, fuels, and other chemicals. The composition of an NBR rubber compound typically includes a variety of ingredients designed to enhance its properties, such as flexibility, durability, and chemical resistance. Here's a breakdown of the key components:

1. Nitrile Butadiene Rubber (NBR) Polymer:

  - Base Material: NBR is a copolymer made from butadiene and acrylonitrile. The ratio of these two monomers affects the rubber's properties:

    - Butadiene: Provides flexibility and elasticity.

    - Acrylonitrile: Improves chemical and oil resistance.

  - The acrylonitrile content usually ranges from 15% to 50%. Higher acrylonitrile content offers better oil resistance, while lower content provides better flexibility at low temperatures.

2. Fillers:

  - Carbon Black: Commonly used as a reinforcing filler to improve tensile strength, abrasion resistance, and overall durability.

  - Silica: Another reinforcing filler, sometimes used to enhance mechanical properties and improve heat and chemical resistance.

  - Calcium Carbonate: A cost-effective filler that increases the volume of the compound without significantly affecting its mechanical properties.

3. Plasticizers:

  - Processing Oils: Used to improve the processability of the rubber, making it easier to mold and shape during manufacturing. Examples include paraffinic oil or phthalate esters.

  - Phthalates or Esters: These can be used as plasticizers to soften the material and increase flexibility.

4. Curing Agents (Vulcanizing Agents):

  - Sulfur or Peroxides: NBR rubber is vulcanized (cured) to improve elasticity, strength, and temperature resistance. Sulfur is the most common curing agent, but organic peroxides are sometimes used for better heat resistance.

5. Accelerators:

  - Thiazoles, Sulfenamides, or Guanidines: These chemicals speed up the vulcanization process, ensuring that the rubber cures properly and in a shorter amount of time.

6. Activators:

  - Zinc Oxide and Stearic Acid: These activators improve the efficiency of the curing process by interacting with the accelerators and sulfur to form strong cross-links in the rubber matrix.

7. Antioxidants and Antiozonants:

  - Antioxidants: Protect the rubber from oxidative degradation caused by heat and exposure to oxygen. Examples include amines and phenolic antioxidants.

  - Antiozonants: Protect the rubber from degradation caused by ozone in the atmosphere, which can lead to cracking. Wax coatings or chemical antiozonants are often used.

8. Stabilizers:

  - Stabilizers, such as UV stabilizers or thermal stabilizers, are added to enhance the rubber’s resistance to aging from exposure to sunlight or high temperatures.

9. Other Additives:

  - Color Pigments: Depending on the application, NBR compounds can be colored using pigments.

  - Flame Retardants: In some applications, halogenated compounds or phosphates may be added to improve fire resistance.

  - Processing Aids: Substances like stearates or waxes are included to improve the flow properties of the rubber during manufacturing.

Composition Summary:

1. NBR Polymer (Butadiene and Acrylonitrile)

2. Fillers (Carbon Black, Silica, Calcium Carbonate)

3. Plasticizers (Oils, Phthalates)

4. Curing Agents (Sulfur or Peroxides)

5. Accelerators (Thiazoles, Sulfenamides)

6. Activators (Zinc Oxide, Stearic Acid)

7. Antioxidants and Antiozonants

8. Stabilizers

9. Other Additives (Pigments, Flame Retardants)

Final Properties of NBR Rubber:

- Oil and Chemical Resistance: Due to the acrylonitrile content, NBR is highly resistant to oils, fuels, and chemicals, making it suitable for gaskets, seals, and hoses.

- Temperature Range: NBR performs well in a temperature range of -40°C to 120°C, depending on the formulation.

- Mechanical Strength: NBR has good tensile strength, abrasion resistance, and elasticity.

The exact formulation of an NBR compound can vary based on the specific application requirements, but these components provide the foundation for its desirable properties in a wide range of industries.

Xiamen Sanlongda Rubber Industry Co., Ltd. was established in 1986 and specializes in the formula development and manufacturing of various high-precision and high-quality rubber compounds. The company has independent import and export rights, and has established and improved a complete quality management system. It is a large private rubber compound production enterprise in Fujian.

Visit our website at https://www.sldrubbersolutions.com/ to learn more about our products. For inquiries, you can reach us at DYLAN@TEC-RUBBER.COM.