Nitrile Butadiene Rubber (NBR) is a synthetic rubber produced by copolymerizing butadiene and acrylonitrile. Thanks to its unique molecular structure, it holds an irreplaceable position across a wide range of industrial applications. The following is a systematic overview of its strengths and limitations, based on its performance characteristics.
I. Key Advantages
1. Outstanding Oil Resistance
This is NBR’s most defining characteristic. It exhibits exceptional resistance to mineral oils, animal and vegetable oils, fuel oils, and various greases. As a result, NBR is often the material of choice whenever rubber components are expected to come into contact with oils.
2. Excellent Abrasion Resistance
At equivalent hardness levels, NBR’s wear resistance significantly outperforms common alternatives such as natural rubber and SBR (styrene-butadiene rubber). This makes it particularly well-suited for environments involving prolonged friction or compression.
3. Reliable Heat Resistance
Standard NBR grades perform stably within a temperature range of 100°C–120°C, with some specialized formulations capable of withstanding even higher temperatures. This explains its widespread use near heat sources such as engine compartments and industrial machinery.
4. Strong Adhesion Properties
NBR demonstrates good bonding performance with various metal, fabric, and plastic substrates. It is frequently used as the base material in adhesives and composite structures.
5. Superior Gas Barrier Performance
Its densely packed molecular chains result in an extremely low gas permeability rate, giving NBR excellent airtightness. This makes it ideal for inflatable products, sealing diaphragms, and other components requiring effective gas containment.
6. Inherent Antistatic Properties
With a moderate volume resistivity, NBR naturally possesses antistatic capabilities. This enhances safety in explosive or flammable environments, as well as in electronically sensitive settings.
II. Main Limitations
1. Lower Elasticity Compared to Natural Rubber
The introduction of polar nitrile groups into the molecular chain reduces NBR’s rebound resilience relative to natural rubber. As a result, it is not the optimal choice for applications requiring high elastic cushioning.
2. Poor Low-Temperature Performance
This is NBR’s most notable weakness—when temperatures drop below freezing, the material gradually hardens and loses flexibility. Conventional grades are prone to embrittlement and cracking at temperatures below –20°C.
3. Vulnerability to Ozone Aging
NBR’s molecular structure lacks protective groups against ozone attack. Prolonged exposure to ozone-rich environments leads to surface cracking, significantly shortening service life when used outdoors without protection.
4. Unsuitable for Electrical Insulation
Due to the presence of polar nitrile groups, NBR’s electrical insulation properties are only average. It should not be used in applications with strict dielectric requirements.
5. Poor Low-Temperature Flexibility
Under cold conditions, NBR’s relatively high glass transition temperature causes a sharp drop in flexibility. Dynamic seals operating at low temperatures are therefore at risk of failure.
III. Typical Application Scenarios
Given the properties outlined above, NBR’s primary application areas are clearly defined:
Sealing — O-rings, oil seals, gaskets, shaft seals
Power Transmission — timing belts, V-belts, conveyor belts
Fluid Transfer — oil-resistant hoses, hydraulic hoses
Industrial Rollers — dyeing rollers, paper-making rollers, coating rollers
Wire & Cable — jacketing materials, inner insulation layers
Specialty Products — oil-resistant soles, antistatic flooring, gloves
NBR is a critical, high-volume material in industries such as automotive manufacturing (engine seals, fuel systems), aerospace (hydraulic seals), petrochemicals (pipeline gaskets, valve seals), and office equipment (copier rollers).