Butadiene rubber (BR), formally known as cis-1,4-polybutadiene rubber, is a high-cis synthetic rubber polymerised from butadiene monomers. It possesses extremely high elasticity, excellent cold resistance and outstanding wear resistance.
BR possesses the highest resilience of all general-purpose rubbers, with elasticity reaching over 80%, and remains soft and elastic even at temperatures as low as -50°C, offering superior cold resistance to natural rubber and styrene-butadiene rubber. With a glass transition temperature as low as -105°C, it is highly suitable for dynamic sealing in extremely cold environments.
Butadiene rubber possesses excellent wear resistance, which is 30% to 50% higher than that of natural rubber, second only to polyurethane rubber. At the same time, BR generates low dynamic heat and exhibits excellent fatigue resistance, making it suitable for sealing applications subject to frequent bending and dynamic loads.
BR exhibits good resistance to dilute acids, dilute alkalis, water, alcohols and polar solvents, but is not resistant to mineral oils, fuels, non-polar solvents (such as benzene, toluene and petrol) or strongly oxidising media. Consequently, BR seals are primarily used in non-oil-contact dynamic sealing and vibration damping applications.
BR has moderate tensile strength, typically ranging from 15 to 20 MPa, and its tear strength is lower than that of natural rubber. Its operating temperature range is generally from -70°C to +100°C, though specially formulated grades can withstand short-term exposure up to +120°C. Above 100°C, its resistance to ageing and thermal oxidation deteriorates significantly, necessitating the use of anti-ageing agents or compounding modifications.
Furthermore, butadiene rubber possesses good water resistance and electrical insulation properties; however, its resistance to ozone and UV ageing is poor. Prolonged outdoor use can lead to cracking, making it unsuitable for direct exposure to the atmosphere. It is usually required to be used in combination with natural rubber or styrene-butadiene rubber, or to have ozone inhibitors added to improve performance.
BR seals, i.e. sealing rings made from butadiene rubber, play a unique role in low-temperature environments, dynamic vibration damping and certain non-contact oil-based sealing systems due to their ultra-high elasticity, excellent cold resistance and outstanding wear resistance.
Sealing in Low-Temperature and Extreme Cold Environments: In pneumatic pipe joints in cold regions, outdoor instrument seals, valve gaskets for refrigeration equipment, and the air systems of snow vehicles, BR seals can maintain their flexibility and sealing performance below -50°C, preventing leaks caused by low-temperature hardening. Their low-temperature flexibility is unmatched by many general-purpose rubbers.
Vibration Damping and Cushioning Seals: In washing machine shock absorber seals, industrial equipment cushioning washers, vibrating screen sealing strips and audio equipment suspension edges, BR’s high resilience and low heat generation effectively absorb vibration energy whilst providing auxiliary sealing and dust protection. It is widely used in applications requiring both sealing and vibration damping.
Tyre and Roller Seals: BR is one of the primary raw materials used in the manufacture of tyre sidewalls and treads. In the sealing structures of off-road tyres, solid tyres and industrial rollers, BR sealing rings are used at the junction between the hub and the roller end cap. By utilising its high wear resistance and resistance to flex cracking, it extends maintenance intervals.
Rubber Rollers and Conveying Components: In textile rollers, printing rollers, conveyor belt idlers and doctor blade seals for papermaking machinery, BR material is utilised to manufacture components that combine sealing and transmission functions, owing to its low rolling resistance and high elasticity. It effectively reduces frictional heat generation and maintains dimensional stability.
Food and pharmaceutical packaging: BR formulations compliant with FDA standards are suitable for non-oil-contact seals in food processing machinery, such as anti-drip sealing lips in beverage filling machines and gaskets for quick-connect fittings in pharmaceutical powder conveyance pipelines. However, care must be taken to avoid contact with oils or acidic foods.
Sports Equipment and General Sealing: In applications such as inner wheel seals for roller skates, cushioning pads for fitness equipment, check valves in toy air pumps, and certain water pump impeller seals, BR O-rings provide cost-effective sealing solutions thanks to their low-temperature flexibility and wear resistance.
Furthermore, BR is rarely used alone for static oil-resistant seals; it is typically blended with natural rubber, styrene-butadiene rubber (SBR) or nitrile rubber (NBR) to balance oil resistance, ageing resistance and elasticity. In applications where contact with mineral oils is avoided and where resilience and cold resistance are paramount, BR seals are the ideal choice.
In summary, butadiene rubber and its BR seals, owing to their unrivalled high elasticity, exceptional cold resistance and good wear resistance, possess unique application value in low-temperature sealing, vibration damping and cushioning, rubber roller drives and non-oil-resistant dynamic seals. They are reliable sealing materials for cold environments and applications where elasticity is a priority.