Properties and Applications
Polybutadiene (BR) is the second largest volume of synthetic rubber produced, next to styrene-butadiene rubber (SBR).
Polybutadiene in Tyres
The major use of polybutadiene is in tyres with over 70% of the polymer produced going into treads and sidewalls. Cured BR imparts excellent abrasion resistance (good tread wear), and low rolling resistance (good fuel economy) due to its low glass transition temperature (Tg).
so polybutadiene is usually blended with other elastomers like natural rubber or styrene-butadiene rubber for tread compounds.
Polybutadiene as an Impact Modifier in Other Polymers
Polybutadiene also has a major application as an impact modifier for polystyrene and acrylonitrile-butadiene-styrene resin (ABS) with about 25% of the total volume going into these applications.
Polybutadiene in Golf Balls
Also, about 20,000 metric tons worldwide of "high cis" polybutadiene is used each year in golf ball cores due to its outstanding resiliency. This application is growing since the golf ball industry seems to be moving away from the traditional wound ball technology to the two-piece, solid core construction.
High cis polybutadiene
This type is characterized by a high proportion of cis (typically over 92%)[17] and a small proportion of vinyl (less than 4%).
It is manufactured using Ziegler–Natta catalysts based on transition metals. Depending on the metal used, the properties vary slightly.
Using cobalt gives branched molecules, resulting in a low-viscosity material that is easy to use, but its mechanical strength is relatively low. Neodymium gives the most linear structure (and therefore higher mechanical strength) and a higher percentage of 98% cis. Other less-used catalysts include nickel and titanium.
Low cis polybutadiene
Using an alkyllithium (e.g. butyllithium) as the catalyst produces a polybutadiene called "low cis" which typically contains 36% cis, 54% trans, and 10% vinyl.
Despite its high liquid-glass transition, low cis polybutadiene is used in tire manufacturing and is blended with other tire polymers, also it can be advantageously used as an additive in plastics due to its low contents of gels.
High vinyl polybutadiene
In 1980, researchers from the Japanese company, Zeon, discovered that high-vinyl polybutadiene (over 70%), despite having a high liquid-glass transition, could be advantageously used in combination with high cis in tires. This material is produced with an alkyllithium catalyst.
High trans polybutadiene
Polybutadiene can be produced with more than 90% trans using catalysts similar to those of high cis: neodymium, lanthanum, and nickel. This material is a plastic crystal (i.e. not an elastomer) that melts at about 80 °C. It was formerly used for the outer layer of golf balls. Today it is only used industrially, but companies like Ube are investigating other possible applications.
