Simultaneous Thermogravimetry and Differential Thermal Analysis (TG-DTA)

Simultaneous application of thermogravimetry (TG) and differential thermal analysis (DTA) to one and the same sample in a single instrument. The test conditions are perfectly identical for the TG analysis (mass evolution over time) and DTA (temperature difference between sample and reference) signals. A typical TG analyzer consists of a precision balance with a sample located inside a furnace with a programmable control temperature. The temperature is generally increased at constant rate (or for some applications the temperature is controlled for a constant mass loss) to incur a thermal reaction. The thermal reaction may occur under a variety of atmospheres including: ambient air, vacuum, inert gas, oxidizing/reducing gases, corrosive gases, carburizing gases, vapors of liquids or "self-generated atmosphere"; as well as a variety of pressures including: a high vacuum, high pressure, constant pressure, or a controlled pressure. The TG data is compiled into a plot of mass or percentage of initial mass on the y axis versus either temperature or time on the x-axis. This plot is referred to as a TG or TGA curve. The first derivative of the TG curve (the DTG curve) may be plotted to determine inflection points useful for in-depth interpretations. The DTA data is plotted against time, or against temperature (DTA curve). Changes in the sample, either exothermic or endothermic, can be detected relative to the inert reference. Thus, a DTA curve provides data on the transformations that have occurred, such as glass transitions, crystallization, melting and sublimation.