Macro Thermogravimetric Analyzers: Versatile and Underutilized Analytical Instruments

Thermogravimetric analysis (TGA) is an analytical technique in which changes in physical and chemical properties of materials are measured as a function of temperature or time or both. TGA is commonly used to determine selected characteristics of materials that exhibit either mass loss, or gain, because of decomposition, oxidation, reduction, or loss of volatile material, such as moisture. Common applications of TGA are materials characterization through analysis of characteristic decomposition patterns and determination of combustible materials and combustion residues from a sample. Macro thermogravimetric analyzer (macro TGA) systems that use gram-size samples have been used for almost four decades for routine laboratory measurements, especially those measurements that monitor industrial processes. The larger sample sizes allow more accurate mass measurements for characterization of materials. Larger sample sizes also reduce the effects of uneven particle sizes and uneven distribution of properties between particles. Macro TGAs are automatic multi-sample analyzers with a multi-position sample carousel. Widespread use of these systems has led to the development of at least four ASTM International standard test methods that use macro TGAs. Other standard test methods using macro TGAs are in the process of being developed by ASTM International. Some other countries have developed, or are in the process of developing, standard test methods that use macro TGA instrumentation.