TGA of Silicone Elastomers

Purpose

To investigate the behavior of silicone elastomers during pyrolysis.

Sample

A cross-linked, SiO₂–filled silicone elastomer (sample 1). For comparison, a pure uncross-linked polymer was measured (sample 2).  

Conditions

Measuring cell: TGA/SDTA851^e

Pan: Alumina 30 µl, with no lid

Sample preparation: Pieces of elastomer of approx. 7 mg

TGA measurement: Heating from 40 °C to 750 °C under nitrogen (80 ml/min), then from 750 °C to 900 °C under air (80 ml/min) Heating rate 30 K/min  

Atmosphere: Nitrogen then air, automatically switched  

Interpretation

Pyrolysis of the cross-linked elastomer occurred at relatively high temperatures. Decomposition begins above about 400 °C. The maximum of the DTG peak is at 600 °C. A smaller peak can be seen in the DTG curve at about 500 °C. Measurements performed on the pure uncross-linked polymer (sample 2) showed that this material exhibited a DTG peak just above 500 °C. We suspect that the small peak in the DTG curve in sample 1 is due to residual uncross-linked material. With silicone elastomers, no reaction occurs on switching from nitrogen to air because no carbon black is formed.

Conclusions

Silicone elastomers undergo pyrolysis at about 600 °C without the formation of carbon black

_{TGA of Silicone Elastomers | Thermal Analysis Application No.Hb461 | Application published in METTLER TOLEDO TA Application Handbook Elastomers, Volume 2.}