3: Thermogravimetry

Thermogravimetry is the study of the relationship between a sample's mass and its temperature. Thus it is possible to study physical or chemical processes that cause a material to lose volatile gases. These include sublimation, evaporation, and thermal degradation. Experiments are most commonly carried out under conditions where the temperature is increased in a linear fashion with time or the sample is held isothermally at an elevated temperature. More sophisticated temperature profiles are occasionally employed for compositional and kinetic analysis. Processes that do not result in a change in sample mass are not detected by this technique. Therefore, simultaneous measurements by differential scanning calorimetry are useful. Volatile decomposition products may be detected and identified (e.g. by infrared spectrometry or mass spectrometry) in order to elucidate the mechanism of mass changes. Thermogravimetry is used for quantitative compositional analysis of many substances, lifetime prediction and kinetic studies making the technique invaluable in many areas of materials characterisation.