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What is Nitrile Butadiene Rubber (NBR)?
What is Nitrile Butadiene Rubber (NBR)?
Nitrile butadiene rubber (NBR, also known as Buna-N) is a synthetic rubber copolymerized from acrylonitrile (ACN) and butadiene. The core performance of its sealing components is directly related to the ratio of acrylonitrile to butadiene: NBR with low acrylonitrile (ACN) content has a lower glass transition temperature and better low-temperature flexibility; NBR with high acrylonitrile (ACN) content significantly improves its resistance to non-polar solvents. Due to its excellent overall performance and high cost-effectiveness, nitrile butadiene rubber elastomers have been widely used in the sealing field.
Main advantages of nitrile rubber
Nitrile butadiene rubber (NBR) O-rings, gaskets, and various seals possess numerous superior performance advantages, with the following core characteristics:
Excellent media resistance: Resistant to petroleum-based oils, fuels, silicone grease, hydraulic oil, water, and alcohols.
Excellent low-temperature adaptability: Maintains good flexibility even at low temperatures, resisting hardening and cracking.
Low compression set: Excellent resilience after long-term compression, ensuring a stable and long-lasting seal.
High tensile strength + high abrasion resistance: Tear-resistant and abrasion-resistant, suitable for high-frequency reciprocating or rotary motion conditions.
Compliance: Custom formulations can be made according to FDA standards to meet the needs of special applications such as food contact applications.
Temperature tolerance range: Standard NBR seals can operate stably in the range of -40°F to +257°F; specially customized products can withstand temperatures ranging from -67°F to +275°F in dry, high-temperature environments.
Commonly used fields
Nitrile rubber is widely used in numerous industries, including automotive, aerospace, marine, and military. Common applications of nitrile rubber in these industries include:
Off-road equipment
Aircraft, automotive, and marine fuel systems
Automotive drive belts
O-rings
Oil seals
Static and dynamic hydraulic seals
Disposable non-latex gloves
limitation
Nitrile butadiene rubber (NBR) has become a widely used high-quality elastomer in the sealing field due to its many outstanding advantages. However, it also has some limitations that require attention:
Insufficient ozone resistance: NBR materials are susceptible to corrosion from low concentrations of ozone. Long-term exposure to outdoor environments will significantly reduce their compatibility and service life.
Plasticizer migration risk: Conventional NBR products often contain phthalate plasticizers. These substances may migrate and leach from the rubber matrix, thereby damaging some plastic components.
Furthermore, caution should be exercised regarding the risks of commercially available NBR products: These products are often blends of NBR and styrene-butadiene rubber (SBR) modified materials, designed to reduce production costs. However, the acrylonitrile (ACN) content of these products is usually less than 10%, making it difficult to achieve the performance standards of pure NBR materials. Therefore, it is recommended to consult a professional engineer before purchasing and using the product to confirm that the content of each component meets the requirements of the actual operating conditions.