Polybutadiene

Butadiene rubber ( BR abbreviation from English Butadiene Rubber), and Buna ( butadiene polymer sodium ) is one of the elastomers. It is in relation to the global consumption second most important synthetic elastomer, in 2012 BR made ​​in about a quarter of the market volume.

Production

Butadiene rubber may be produced by anionic polymerization of 1,3- butadiene coordinative. Depending on the catalyst used arise polybutadiene with different proportions of polymers with 1,4 - linkage (cis and trans), or 1,2-linkage with the vinyl groups in the side chain. In practice, therefore macromolecules arise with different types of links in the chain ( see table).

Another method is the free-radical emulsion polymerization.

Succeeded in 1949 in a cold- polymer method (5 ° C) the preparation of polybutadiene with a useful rubber technological properties. As a redox catalyst ( Hyperperoxid, sodium formaldehyde sulfate and Fe ( II) complex ) is used. Fatty and resin acids are also suitable emulsifiers are used. In order to keep the low degree of branching, the reaction is stopped at 60 % conversion. The polybutadiene thus prepared has the following microstructure:

Properties

Polybutadiene is excellent in elasticity and is in the temperature range from - 80 ° C to 90 ° C can be used. Butadiene rubber also has a good strength without fillers (similar to natural rubber), excellent resistance to abrasion, when cured and filled and a high cracking resistance. To improve the properties and the processability of poly (butadiene) is mixed with natural rubber or styrene -butadiene rubber, SBR. It finds use in car tires and golf ball cores.