“BR” stands for Butadiene Rubber, which is a synthetic rubber polymer primarily composed of butadiene. Polybutadiene rubber, often referred to as BR, is a type of synthetic rubber made by the polymerization of butadiene monomers. It is known for its excellent elasticity and low-temperature performance.

Polybutadiene rubber can be categorized into two main types based on its cis content: high cis and low cis polybutadiene. These classifications refer to the configuration of the butadiene monomers in the polymer chain, with cis and trans isomers being the two primary possibilities. The cis isomer has the methyl groups on the same side of the double bond, while the trans isomer has them on opposite sides.

High cis polybutadiene (Cis-BR):

High cis polybutadiene has a significant proportion of the cis isomer in its polymer structure, typically around 98% cis content or higher. This high cis content results in a highly elastic and resilient rubber with excellent properties, including:

High resilience:

High cis BR exhibits exceptional rebound and elasticity, making it suitable for applications where these properties are critical, such as in tire manufacturing.

Low-temperature flexibility:

It remains flexible at low temperatures, which is crucial for tires and other products used in cold environments.

Good abrasion resistance:

High cis BR is resistant to wear and abrasion, contributing to the durability of products like tire treads.

Low heat buildup:

It has low rolling resistance in tires, which helps improve fuel efficiency.

Low cis polybutadiene:

Low cis polybutadiene has a lower proportion of cis isomers and a higher proportion of trans isomers in its polymer structure. This results in different properties, including:

Reduced resilience:

Low cis BR has less elasticity and rebound compared to high cis BR, making it less suitable for applications that require high resilience.

Reduced low-temperature flexibility:

It may become stiffer at low temperatures compared to high cis BR.
The choice between high cis and low cis polybutadiene depends on the specific requirements of the end product. High cis BR is often preferred in tire manufacturing due to its outstanding resilience and low-temperature properties, while low cis BR may find use in applications where these properties are less critical or where different rubber characteristics are desired.

Common Uses
of Polybutadiene:

Tire Manufacturing
Belts and Conveyor Systems
Industrial Rubber Products
Sports Equipment
The properties of polybutadiene rubber can be modified by adjusting the polymerization conditions and blending it with other rubber types or additives to meet specific requirements for different applications.