General Properties
Short Name:
Name:
BR
Butadiene rubber
BR stands for “butadiene rubber” and designates, along with SBR (styrene butadiene rubber), the most commonly used synthetic rubber. BR is produced from 1,3-butadiene. The monomers can be connected on both ends (1,4 bonding) or only on one end (1,2 bonding, vinyl group in the side chain) producing diff erent BR types with different properties. The 1,4 bonding can further be classified into 1,4 cis and 1,4 trans, where “cis“ means that the substituents are on the same side of the double bond; “trans” means they are on the opposite side of the double bond.
Structural Formula
Properties
| Glass Transition Temperature | -106 to -95 (1.4 cis), -107 to -83 (1,4 trans), -15 (1,2)°C |
|---|---|
| Melting Temperature | -25 to 12 (1,4 cis), 97 / 145 (1,4 trans), 126 (1,2)°C |
| Melting Enthalpy | 46/170 (1,4 cis), 70 to 140 (1,4 trans) J/g |
| Decomposition Temperature | 370 to 385 / 460 to 475°C |
| Young's Modulus | - |
| Coefficient of Linear Thermal Expansion | - |
| Specific Heat Capacity | 1.76 to 1.96 J/(g*K) |
| Thermal Conductivity | 0.25 W/(m*K) |
| Density | 0.9 to 1.0 g/cm³ |
| Morphology | Elastomer with hard and soft segments |
| General properties | High elasticity. High stability. High abrasion resistance |
| Processing | Extrusion, calendering, injection molding, vulcanization |
| Applications | Tire industry (blends with NR or SBR). Mechanical engineering. Technical rubber goods (e.g., band conveyors). Golf balls, shoe soles |
NETZSCH Measurement
| Instrument | DSC 204 F1 Phoenix® |
| Sample Mass | 12.29 mg |
| Isothermal Phase | 8 min / 3 min / 8 min |
| Heating/Colling Rates | 10 K/min |
| Crucible | Al, pierced lid |
| Atmosphere | N2 (40 ml/min) |
Evaluation
Polybutadiene or butadiene rubber has both soft and hard segments. For this reason, the above graphic shows a glass transition at -101°C (midpoint) in both heatings with a step height (Δcp) of approx. 0.27 J/(g.K) from the soft segments and a melting EndothermEin Phasenübergang oder eine Reaktion ist endotherm, wenn für die Umwandlung Wärme benötigt wird.endotherm with a peak temperature of -5°C from the hard segments. It can be concluded that the sample is mainly a 1,4 cis type.