Advantages & Applications of TGA: What Thermogravimetric Analysis Reveals
What Is Thermogravimetric Analysis?
Thermogravimetric Analysis (TGA) is a thermal analysis technique that measures the mass of a sample as a function of temperature or time while the sample is subjected to a controlled temperature programme in a defined atmosphere. A TGA instrument consists of a precision balance (sensitivity typically ±0.1 µg) that measures the sample mass continuously as the furnace temperature increases (dynamic TGA) or holds it isothermally (isothermal TGA).
TGA provides fundamental information about thermal stability, composition, and degradation behaviour of materials — spanning polymers, elastomers, ceramics, inorganic compounds, and composite materials.
How TGA Works
A small sample (typically 5–20 mg) is placed in a platinum, alumina, or graphite crucible on the TGA balance. The furnace heats the sample at a defined rate (typically 5–20°C/min) from ambient to the maximum temperature (typically 600–1000°C). Mass is recorded continuously with temperature. The derivative of mass loss with respect to temperature (DTG — derivative thermogravimetry) is calculated and plotted to identify the temperatures at which the mass loss rate is maximum.
The TGA atmosphere controls the degradation chemistry:
- Nitrogen/argon (inert): Pure thermal decomposition without oxidation
- Air/oxygen: Thermal-oxidative degradation
- Reactive gas (H₂, CO₂, H₂O): Characterises gas-solid reactions
Key Advantages of TGA
Simultaneous Multi-Parameter Analysis
TGA measures mass changes throughout the temperature programme in a single experiment, detecting and quantifying multiple sequential mass-loss events (moisture, plasticiser evaporation, polymer decomposition, filler combustion, inorganic residue). Unlike single-temperature methods, TGA provides a complete thermal profile.
Atmospheric Flexibility
The ability to switch between inert and reactive atmospheres during a single TGA run enables the sequential characterization of both thermal decomposition (inert phase) and oxidation of the combustion residue (oxidative phase)
Quantitative Compositional Analysis
TGA directly quantifies: moisture content (mass loss below 120°C), organic content (mass loss during polymer decomposition, 300–600°C), carbon black content (mass loss during carbon oxidation in air, 400–700°C), and inorganic ash/filler residue (mass remaining after all combustion). This provides a non-extractive compositional analysis of complex multi-component materials.
High Sensitivity
Microgram-level mass resolution enables detection of very small mass losses — important for characterising low-moisture or low-additive-content materials.
Major Applications of TGA
Polymer and Rubber Characterisation
TGA in an inert atmosphere determines the polymer decomposition temperature and identifies the onset of degradation — enabling comparison of thermal stability across formulations or after ageing. In air, sequential mass losses quantify polymer matrix (by combustion), carbon black content (second combustion), and mineral filler/ash residue.
Composite Material Analysis
Carbon fibre content in CFRP composites is determined by burning off the polymer matrix in air and measuring the residual carbon fibre mass. The effectiveness of flame-retardant additives is assessed by comparing the decomposition profiles of stabilised and unstabilised compounds.
Moisture and Volatile Content
TGA at 105–120°C under nitrogen provides precise moisture determination — essential for hygroscopic polymers (nylon, polyurethane) and moisture-sensitive materials where Karl Fischer titration is impractical for solid samples.
Inorganic and Ceramic Materials
Dehydration of hydrated salts and minerals (loss of water of crystallisation), decomposition of carbonates (CaCO₃ → CaO + CO₂), and phase transformations in ceramics are characterised by their characteristic mass loss temperatures and profiles.
Oxidative Induction Time (OIT)
Isothermal TGA in oxygen at a defined temperature measures the time to initiate oxidative degradation — providing a rapid thermal stability index relevant to stabilised polyolefin and rubber quality control.
Conclusion
Thermogravimetric Analysis (TGA) — by measuring mass change as a function of temperature under controlled atmospheres — provides powerful insight into material composition, thermal stability, and degradation behaviour. It enables precise quantification of moisture, organic content, fillers, and residual ash, while revealing decomposition mechanisms across polymers, composites, and inorganic materials. The ability to tailor temperature programs and atmospheres makes TGA highly versatile for both research and quality control. Selecting appropriate test conditions and correctly interpreting mass loss profiles are essential to obtain meaningful results, making the analytical strategy as important as the measurement itself.
Why Choose Infinita Lab for TGA Analysis?
Infinita Lab provides comprehensive TGA analysis — compositional characterisation, decomposition temperature, OIT, moisture content, and carbon content — through our nationwide accredited thermal analysis laboratory network. Our specialists design and interpret TGA programmes for complex multi-component materials.
Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you.
Frequently Asked Questions (FAQs)
What information does TGA provide that DSC cannot? TGA provides quantitative mass loss data — enabling compositional analysis (filler content, moisture, carbon black) that DSC cannot provide. DSC measures heat flow without mass sensitivity, detecting phase transitions and enthalpy changes. Together, TGA and DSC provide complementary information on both thermal mass changes and energy changes in the same material.
What is the typical TGA temperature range for polymer analysis? Most polymers are analysed from ambient to 600–800°C. Moisture and solvents evaporate below 200°C; most organic polymers decompose between 300–500°C; carbon black burns at 400–700°C in air; mineral fillers and glass fibres remain as residue above 700°C.
Can TGA identify the type of polymer in a composite material? TGA alone provides decomposition temperature data that is indicative but not definitively identifying for most polymers. Coupling TGA with evolved gas analysis by FTIR or MS (TGA-FTIR or TGA-MS) identifies the decomposition products by their infrared or mass spectra, enabling unambiguous polymer identification.
What is derivative thermogravimetry (DTG) and why is it useful? DTG is the first derivative of the TGA mass loss curve with respect to temperature (or time). DTG peaks correspond to maximum mass loss rates and allow precise identification of decomposition temperatures and separation of overlapping mass loss events that appear as shoulders rather than distinct steps on the TGA curve.
How does sample mass affect TGA results? Larger sample masses increase the temperature gradient within the sample and can cause thermal lag — shifting apparent transition temperatures to higher values compared to smaller samples. Very small samples improve thermal equilibration but reduce signal-to-noise for minor mass loss events. Sample masses of 5–20 mg optimally balance sensitivity and thermal homogeneity for most TGA applications.
