TGA of Styrene-Butadiene Rubber (SBR)
Purpose
To perform thermogravimetric measurements on SBR that had been produced under different conditions
Sample
Two types of unvulcanized SBR:
- Krylene 1500 made by emulsion polymerization, with a wide molecular weight distribution
- VSL5025-0 polymerized from solution, with a narrow molecular weight distribution
Conditions
Measuring cell: TGA/SDTA851e
Pan: Alumina 30 µl
Sample preparation: Pieces of rubber of approx. 15 mg
TGA measurement: Heating from 50 °C to 625 °C under nitrogen (50 ml/min), and then from 625 °C to 860 °C under air (50 ml/min) Heating rate 30 K/min
Atmosphere: Nitrogen then air, automatically switched
Interpretation
The measurement curves show that the thermal degradation of SBR depends on the polymerization conditions. Emulsion polymerized SBR contains more volatile components than SBR polymerized in solution. In the Krylene1500 DTG curve, a peak appears just before the actual pyrolysis at about 400 °C. SBR polymerized in solution does not show this step. With both materials, the main step of the pyrolysis causes a peak in the DTG curve with a maximum at about 470 °C. The pyrolysis of SBR produces only a small amount of carbon black (approx. 0.3%). The ash content is also low (approx. 0.2%).
Evaluation
The evaluation of the individual steps is summarized in the following table:
Conclusions
SBR pyrolyzes at about 470 °C. The amount of carbon black formed during pyrolysis and the residual ash is negligible. With emulsion polymerized SBR, the loss of mass due to vaporization of the emulsifying agent before pyrolysis can be measured.
TGA of Styrene-Butadiene Rubber | Thermal Analysis Handbook No.HB428 | Application published in METTLER TOLEDO TA Application Handbook Elastomers, Volume 2
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