Thermogravimetric Analysis (TGA): Principles and Applications

What Is Thermogravimetric Analysis?

Thermogravimetric analysis (TGA) measures the change in a sample’s mass as a function of temperature or time while heated at a controlled rate in a defined atmosphere. ASTM E1131 is the primary standard governing compositional analysis by TGA, used to determine moisture and volatile content, polymer/organic content, filler content, and ash (inorganic residue) in a single continuous experiment.

Test Procedure

• Cut the sample into small, uniform pieces or pellets to ensure consistency across replicate runs
• Place the specimen in the TGA sample pan and set the initial weight reading to 100%
• Set the purge gas — nitrogen or another inert gas for the initial decomposition stages, switching to air or oxygen for the final oxidative stage
• Heat the sample at a controlled rate, typically 5-20°C/min, from ambient up to a maximum temperature (commonly as high as 1000°C)
• Record the continuous weight-loss curve throughout the heating program, identifying distinct mass-loss steps corresponding to different decomposition events

Interpreting the Weight-Loss Curve

Each stage of mass loss corresponds to a specific event: low-temperature loss typically reflects moisture or residual solvent, a mid-range loss reflects polymer or organic matrix decomposition, and a final high-temperature oxidative step (when the atmosphere is switched to air) burns off carbon black, leaving behind inorganic ash or filler content. The onset temperature of each weight-loss step also indicates the material’s thermal stability limit under that specific atmosphere.

Equipment Requirements

The furnace must maintain temperature within ±2°C of the set point, and the balance used for mass measurement requires a sensitivity of at least 0.1 mg to resolve the fine compositional detail TGA is meant to capture. Specimens must be representative and free from surface contamination that could distort the early-stage weight readings.

Applications, Techniques, and Industrial Relevance of Thermogravimetric Analysis

TGA examines the level of solvent residue, the degree of hydration, and the thermal decomposition temperature. Lattice and non-aqueous solvent water are distinguished from surface-adsorbed water. The gas composition (nitrogen or air) influences temperatures and degradation processes.

Thermogravimetric Analysis (TGA) (Conducted in a Nitrogen Environment) entails determining how much a sample’s mass changes depending on the temperature and heating period. At Infinita Labs, a Netzsch TG 209 F3 Tarsus is the TGA tool in use. This instrument can measure as little as a few milligrams or microliters of sample and has been certified for use from room temperature to 1000 °C.

In a TGA, the following analyses are most frequently requested:

Degree of hydration, level of solvent residue, and temperature at which a sample thermally decomposes. A non-aqueous solvent and water contained within a crystal lattice may usually be differentiated from surface adsorption.

The gas composition in the furnace is yet another crucial element of a TGA. A TGA is most frequently carried out in an inert nitrogen or highly oxidising atmosphere. In an inert environment, certain sample types may not exhibit the same degradation processes or mechanisms as they could in an oxidative one. As a result, the furnace environment can impact the number of degradation steps and the temperatures at which the steps take place.

Compositional analysis, decomposition kinetics, catalyst activity, hydration content, solvent content, polymer and filler content, and ash content are a few examples of research suited for a TGA. These studies have been used in the creation and development of pharmaceuticals and vaccines, food ingredients, electronics, catalysts and scrubbers, batteries and fuel cells, concrete and building materials, metals and alloys, plastics and polymers, and electronics, just to name a few industries that have used them.

Graphite, carbon black, graphene, carbon nanotubes, silica, alumina, titania, zinc oxide, and other microscopic particles have all been examined using a TGA in the mining industry.

Industry Specifications Referencing TGA

• ASTM E1131: primary compositional analysis method
• ISO 11358: international equivalent
• ASTM D6370: rubber-specific compositional analysis by TGA
• ASTM D7582: proximate analysis of fuels and coals by TGA

Conclusion

TGA’s real value is that it turns compositional analysis into a single automated experiment — moisture, polymer content, filler, and ash all resolve as distinct steps on one weight-loss curve, replacing what used to require several separate, time-consuming wet-chemistry procedures.

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