Principle of Thermogravimetry (TG)
Definitions of Thermogravimetry (TG)
A technique in which the mass of the sample is monitored against time or temperature while the temperature of the sample, in a specified atmosphere, is programmed.
* This is definition of TG by ICTAC.
Definitions of Simultaneous Thermogravimetry and Differential Thermal Analysis (TG/DTA, TGA/DTA)
A method in which thermogravimetry and differential thermal analysis are combined and measured simultaneously by a single apparatus.
* This is definition of TG-DTA by JIS (Japanese Industrial Standard)
As defined above, TG is a technique that measures mass change in a sample, and it is used to detect evaporation, decomposition, oxidation and other effects of temperature change that cause mass changes.
Description of TG/DTA
Figure 1 shows the The balance beams for the sample and the reference are located in the furnace. The masses of the sample and the reference are measured by the sensitivity-calibrated drive coils separately. The mass difference is sent as TG signal. By the differential mass measurement, the effects of the beam expansion, the convection flow, and buoyant force are cancelled. Thus the highly sensitive thermogravimetry measurement is achieved. The mass measurement of the sample and the reference by the independent drive coils enables the easy adjustment of the TG baseline drift electrically.
Also, thermocouple is located in each holder which enables the simultaneous DTA signal output.
TG can be utilized for the analysis of the thermal decomposition, the oxidization, the dehydration, the heat resistance, and kinetics analysis. By combining with the other measurement technique, variety of information can be achieved from one sample. In particular, TG/DTA simultaneous measurement instrument is most common.