Instant Notes: Analytical Chemistry

600 °C leaving carbon black. The atmosphere is now changed to air, when the

carbon black is oxidized away leaving a residue of ash.

The analysis of other materials such as pharmaceuticals, coal and minerals by

thermogravimetry has proved a valuable tool in the study of complex thermal

events.

The DTG curve permits the analyst to obtain additional information since:

● the magnitude of the DTG signal is directly proportional to the rate of

reaction, it allows the comparison of reaction rates; and

● the DTG curve separates overlapping reactions more clearly than the TG

curve.

310 Section G – Thermal methods

0

100

200 400 600 600

Temperature (°C)

700 800 900

Mass loss %

Oil

Polymer

N 2 atmosphere Air atmosphere

Carbon

black

Ash

Fig. 4. TG curve for carbon-black filled rubber.