TGA of Chloroprene Rubber (CR)
Purpose
To perform thermogravimetric measurements on different types of CR
Sample
Three different types of unvulcanized CR
- Baypren 110
- Baypren 112
- Baypren 210
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 in nitrogen (50 ml/min), and then from 625 °C to 860 °C in air (50 ml/min) Heating rate 30 K/min
Atmosphere: Nitrogen then air, automatically switched
Interpretations
The TGA curves of chloroprene show several steps. The first effect is visible as a small step in the DTG curve at about 210 °C. This is due to the vaporization of oligomers of dichlorobutadiene, i.e. unpolymerized residues from the production process. The actual thermal decomposition of the polymer takes place in two steps. The largest weight loss step is about 52% and occurs in the first decomposition step at 380 °C. This is mainly due to the elimination of HCl and is seen as a large peak in the DTG curve.
The decomposition step of the residual polymer with a weight loss step of about 25% gives rise to the DTG peak at about 450 °C. The shoulder on the high temperature side of this peak indicates that several processes take place in this temperature range. The final step occurs on switching from nitrogen to air. This is due to the combustion of the carbon black formed during pyrolysis.
Evaluation
The evaluation of the individual steps in the TGA curves is summarized in the following table:
The maximum temperatures of the DTG peaks can be used as characteristic temperatures for the two degradation steps of the polymer
Conclusions
The CR samples contain about 1% oligomer. Pyrolysis takes place in two steps. About 19% carbon black is formed during pyrolysis. The proportion of carbon black formed depends on the type of CR. The residual ash is about 1%.
TGA of Chloroprene Rubber (CR) | Thermal Analysis Handbook No.HB430 | Application published in METTLER TOLEDO TA Application Handbook Elastomers, Volume 2