NBR vs. SBR

Attribute	NBR	SBR
Material	Nitrile Butadiene Rubber	Styrene Butadiene Rubber
Chemical Structure	Polymer of butadiene and acrylonitrile	Polymer of butadiene and styrene
Oil Resistance	Excellent	Good
Temperature Range	-40°C to +120°C	-40°C to +100°C
Hardness	50-90 Shore A	40-90 Shore A
Tensile Strength	High	Medium
Elongation at Break	Good	Good
Abrasion Resistance	Good	Good

Introduction

Nitrile Butadiene Rubber (NBR) and Styrene Butadiene Rubber (SBR) are two widely used synthetic rubbers with distinct attributes and applications. Understanding the differences between these materials is crucial for selecting the right rubber for specific applications. In this article, we will compare the attributes of NBR and SBR, including their chemical composition, physical properties, applications, and advantages.

Chemical Composition

NBR is a copolymer of butadiene and acrylonitrile, while SBR is a copolymer of styrene and butadiene. The acrylonitrile content in NBR can vary, affecting its oil resistance and low-temperature flexibility. Generally, higher acrylonitrile content results in improved oil resistance but reduced low-temperature flexibility. SBR, on the other hand, has a higher styrene content, which enhances its hardness and abrasion resistance.

Physical Properties

NBR exhibits excellent resistance to oil, fuel, and chemicals, making it suitable for applications in the automotive, oil and gas, and industrial sectors. It also has good tensile strength, tear resistance, and compression set properties. Additionally, NBR offers good resistance to heat and aging, allowing it to withstand harsh environmental conditions. However, NBR has relatively poor ozone and weathering resistance compared to SBR.

SBR, on the other hand, has excellent abrasion resistance, making it ideal for applications such as tires, conveyor belts, and footwear. It also offers good resilience, low-temperature flexibility, and electrical insulation properties. SBR is less resistant to oil and chemicals compared to NBR, but it has superior ozone and weathering resistance. These properties make SBR suitable for outdoor applications where exposure to sunlight and environmental elements is a concern.

Applications

Due to its excellent oil resistance, NBR is commonly used in automotive seals, gaskets, O-rings, hoses, and fuel system components. It is also utilized in industrial machinery, hydraulic seals, and oil-resistant gloves. NBR's resistance to chemicals and heat makes it suitable for applications in the oil and gas industry, such as seals for drilling equipment and pipelines.

SBR, with its superior abrasion resistance, is extensively used in the manufacturing of tires, both for vehicles and bicycles. It provides excellent traction, durability, and resistance to wear and tear. SBR is also employed in conveyor belts, shoe soles, rubber mats, and various molded rubber products. Its electrical insulation properties make it suitable for cable insulation and electrical components.

Advantages

NBR offers several advantages, including its excellent oil resistance, good tensile strength, and resistance to heat and aging. Its ability to withstand harsh environments and chemicals makes it a reliable choice for many industrial applications. NBR's flexibility and sealing properties also contribute to its widespread use in automotive and oil-related industries.

SBR, on the other hand, excels in its abrasion resistance, ozone resistance, and weathering resistance. Its durability and resilience make it a preferred choice for tire manufacturing, where it can withstand the demanding conditions of road surfaces. SBR's electrical insulation properties and low-temperature flexibility further enhance its versatility in various applications.

Conclusion

In conclusion, NBR and SBR are two distinct synthetic rubbers with different chemical compositions, physical properties, applications, and advantages. NBR's excellent oil resistance and resistance to heat and aging make it suitable for automotive and industrial applications. SBR, on the other hand, offers superior abrasion resistance, ozone resistance, and weathering resistance, making it ideal for tire manufacturing and outdoor applications. Understanding the attributes of NBR and SBR is crucial for selecting the appropriate rubber for specific applications, ensuring optimal performance and durability.