General Properties
Short Name:
Name:
SBR
Styrene-butadiene rubber
Styrene butadiene rubber (SBR), manufactured from 1,3-butadiene and styrene, is the most widely used synthetic rubber. It usually contains 23.5% styrene and 76.5% butadiene. The rubber shows increasing thermoplastic properties with increasing styrene content, yet remains curable. With 1,3-butadiene as a co-monomer, cis-trans-isomerism also occurs.
Structural Formula
Properties
| Glass Transition Temperature | -55 to -35°C |
|---|---|
| Melting Temperature | (-20)°C |
| Melting Enthalpy | (170 (cis)) J/g |
| Decomposition Temperature | 435 to 470°C |
| Young's Modulus | 2 to 10 MPa |
| Coefficient of Linear Thermal Expansion | 180 *10-6/K |
| Specific Heat Capacity | 1.88 to 2.00 J/(g*K) |
| Thermal Conductivity | 0.20 to 0.25 W/(m*K) |
| Density | 0.94 g/cm³ |
| Morphology | Rubber with hard and soft segments |
| General properties | Good aging and abrasion resistance |
| Processing | Cross-linking by means of sulfur accelerating systems or peroxides |
| Applications | Tire industry (cap of tires). Technical rubber goods (conveyor bands, seals). Mechanical engineering. Household articles (e.g., shoe soles) |
NETZSCH Measurement
| Instrument | DSC 204 F1 Phoenix® |
| Sample Mass | 13.10 mg |
| Isothermal Phase | 8 min |
| Heating/Colling Rates | 10 K/min |
| Crucible | Al, pierced lid |
| Atmosphere | N2 (40 ml/min) |
Evaluation
In the DSC curve from the 1st heating (blue), SBR shows a glass transition at -45°C (midpoint), a broad, complex melting transi- tion (with peak temperatures at 19°C and 58°C and a melting enthalpy of approx. 6 J/g), caused by the melting of additives and an exothermal eff ect (peak temperature: 168°C, enthalpy: approx. 10 J/g) that can be attributed to post-vulcanization. This exothermal effect is absent in the 2nd heating (red) after controlled cooling, indicating that vulcanization was completed in the 1st heating. As a result, the Tg in the 2nd heating is shifted to a slightly higher temperature (midpoint of -44°C compared to -45°C in the 1st heating). The step height (Δcp) of approx. 0.5 J/(g·K) remained almost unchanged. This small effect of post-cross-linking on temperature and height of the glass transition step is typical for elastomers. A melting transition due to additives with peak temperatures of 23°C and 34°C and an enthalpy of approx. 4 J/g is also seen in the DSC curve of the 2nd heating.