Polybutadiene rubber: Characteristics
Why a glass transition near -100 C matters for wear
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.BR grades are chosen by cis content, branching, Mooney viscosity and gel content. Tyre makers want high-cis, linear Nd-BR for wear and rolling resistance; HIPS makers want low-gel Li-BR with controlled solution viscosity.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Cis-1,4 content | Nd-BR over 97%; Ni/Co-BR 96-97%; Li-BR about 35-40% (indicative) | Higher cis gives better wear and elasticity | typical (indicative) |
| Glass transition temperature | about -100 to -110 C for high-cis BR (indicative) | Low-temperature flexibility and low heat build-up | typical (indicative) |
| Mooney viscosity ML1+4 at 100 C | about 40-60 (indicative) | Mixing and extrusion behaviour | typical datasheet (indicative) |
| Solution viscosity (5% in styrene) | about 30-200 mPa s (indicative) | Controls rubber particle size in HIPS | typical (indicative) |
Commercial grades
- Nd-BR (high-cis, tyres)
- Ni-BR and Co-BR (high-cis, general)
- BR9000 (China standard high-cis)
- Li-BR low-cis (HIPS, ABS)
- oil-extended BR
- functionalised Nd-BR