TGA thermogravimetric analysis helps you understand how materials behave under heat. It tracks changes in mass as temperature increases, helping you study decomposition, stability, or moisture content. This method is widely used in laboratories and industries that depend on material performance.
But what does the TGA curve really tell you? And how can this analysis improve product quality or research outcomes? This article gives you a clear and practical overview, written for anyone working with materials, from polymers to pharmaceuticals.
What Is TGA Thermogravimetric Analysis?
TGA stands for thermogravimetric analysis, a method used to measure mass loss during heating. It works by exposing a sample to controlled temperature changes while continuously tracking its weight. As temperature rises, volatile components, water, or gases leave the material, causing weight shifts.
You can use this method to detect moisture, fillers, decomposition stages, or oxidation behavior. It’s commonly used during R&D, quality control, or failure analysis in labs.
A typical TGA setup includes:
- Precision balance and furnace system
- Gas purge unit (nitrogen, oxygen, or argon)
- Real-time software for data acquisition
How Does TGA Work?
You begin by placing a small sample into a pan inside a precision furnace. This pan sits on a highly sensitive balance that records even the slightest change in weight. As the temperature follows a controlled program—usually heating—the sample undergoes physical or chemical changes.
The system purges the chamber with inert or reactive gas to create a stable testing environment. As heating progresses, the sample might lose mass from moisture, solvents, or decomposition. It can also gain mass if oxidation or gas absorption occurs.
Your results appear as a TGA curve, which plots mass against temperature or time. To analyze events more precisely, a DTG curve (first derivative) is often used. This highlights where rapid changes occur, ideal for detecting reactions like evaporation, degradation, or oxidation.
This process helps you uncover insights about material composition, stability, purity, and thermal behavior, all in one experiment.
Reading and Interpreting the TGA Curve
When you run a TGA thermogravimetric analysis, the curve is your guide. It tells you how your sample reacts as temperature changes. The x-axis shows temperature or time. The y-axis reflects how much mass your sample loses, usually as a percentage.
Each section of the curve represents a physical or chemical process. Here’s how to interpret it:
- Flat regions mean stability—your sample doesn’t lose weight in this range.
- Sloped drops show mass loss, often caused by moisture evaporation or decomposition.
- Multiple steps suggest that different components decompose at different temperatures.
At the end, the remaining mass is called residue. This could be inorganic fillers, char, or ash left behind after thermal breakdown.
To analyze events more precisely, use a DTG curve. It highlights the exact points where the sample loses mass most rapidly. Peaks on this curve indicate major transitions or decomposition phases.
You’ll also want to look at:
- Onset temperature (Ti): where mass loss starts
- Final temperature (Tf): where the mass loss ends
- Weight loss percentage: helps you estimate moisture, solvent, or filler content
- Number of steps: reveals single or multistage degradation
Sometimes, external factors like buoyancy or instrument drift can cause noise. Comparing with a blank curve helps correct these artifacts.
A real-time TGA system with DTG curve support allows you to pinpoint thermal events with greater precision.
Three Types of Thermogravimetric Analysis
TGA tests can follow different temperature programs, depending on your testing goals. You can select the right approach based on how your material behaves or what you need to investigate.
1. Dynamic TGA
This is the most commonly used method. You heat the sample at a steady, linear rate—typically a few degrees per minute. It’s useful when you want to study overall thermal stability or observe decomposition stages across a full temperature range.
2. Isothermal TGA
In this method, the temperature stays constant while the sample weight is tracked over time. It’s great for testing long-term thermal stability or slow reactions that occur at a specific temperature.
3. Quasistatic TGA
You apply heat in steps, holding the sample at each level until the weight stabilizes. Then the temperature increases again. This method helps when your sample has overlapping reactions
Each method gives different insights. You choose based on material type and expected behavior.
Where Is TGA Used?
TGA thermogravimetric analysis supports your work across industries. If you need to understand how heat affects your materials, TGA gives you real data to make smart decisions.
1. Polymers and Plastics
You can use TGA to analyze thermoplastics, thermosets, elastomers, films, and composites. It helps detect plasticizers, fillers, or additives and reveals the temperature ranges where decomposition starts. This is useful for improving processing, molding, and product reliability.
2. Pharmaceuticals
TGA is widely used to measure moisture in drug powders and confirm solvent removal. You’ll also find it helpful for studying drug-polymer interactions and estimating shelf-life based on thermal exposure.
3. Metals, Ceramics, and Inorganics
In materials science, TGA helps evaluate oxidation behavior, especially for reactive metals like copper alloys. You can quantify residue, test stability, and assess thermal resistance in challenging environments.
4. Food Industry
Use TGA to study shelf life, moisture levels, and decomposition temperatures. It helps you verify product consistency, detect contaminants, and support quality control in food processing and packaging.
5. Environmental and Fuel Analysis
TGA helps analyze soil, sludge, or air particle samples for thermal stability. It’s also used to study combustion and pyrolysis behavior in fuels, which supports cleaner energy research and emission reduction.
6. Manufacturing and Quality Assurance
In manufacturing, you rely on TGA to confirm product stability under heat. It’s valuable for screening raw materials, detecting defects in thermoplastics, or evaluating thermal tolerance before product launch.
Calibration and Standards for TGA
If you rely on TGA thermogravimetric analysis for accurate results, proper calibration is non-negotiable. It keeps your measurements consistent and reliable, whether you’re testing moisture loss or decomposition temperatures.
Temperature Calibration
Temperature calibration ensures that what your instrument reads matches actual thermal behavior. This can be done using:
- Melting point standards: Materials with known melting points are tested, and the instrument’s temperature scale is adjusted accordingly.
- Curie point standards: These use magnetic materials like nickel or alumunium that lose their magnetic properties at a specific temperature. The sudden apparent weight change at this transition point is used for calibration.
For magnetic calibration, place a Curie standard in the pan near a magnet, then heat through the expected transition temperature. The change in signal indicates the Curie point, which you compare to its certified value.
ASTM E1582 outlines detailed procedures for this process, ensuring accuracy across a temperature range from 25 °C to 1500 °C. To avoid drift, perform calibration under the same gas, flow rate, and heating rate you plan to use in your experiments.
Weight Calibration
Weight calibration ensures your balance measures accurately—even at small mass changes. It’s done using certified calibration weights (like 100 mg or 1000 mg) traceable to NIST or similar standards.
You start by zeroing the balance, adding the standard weight, and letting the value stabilize. Enter that into the calibration function, and the system adjusts its readings. ASTM E2040 covers this process in detail.
Recalibrate if you move the instrument, change the pan or hang-down wire, or notice unexpected results during analysis.
Baseline Calibration and Correction
Baseline drift can skew your data, especially in low mass-loss applications. Run an empty pan under your test conditions to establish a clean, stable baseline. If needed, apply corrections to subtract instrument or environmental influences.
Key International Standards for TGA
- ASTM E1131 – For compositional and thermal analysis by TGA
- ASTM E1582 – Temperature calibration using melting point or magnetic standards
- ASTM E2040 – Mass scale calibration for accurate weight readings
- ISO 11358 – Global standard for conducting thermogravimetric analysis of polymers and other materials
These standards guide everything from setup to data interpretation. Following them helps you produce consistent results that meet industry or regulatory expectations.
If you’re working under ASTM or ISO methods, using a TGA system designed for accuracy and compliance helps ensure your results meet global standards.
Final Thoughts
TGA thermogravimetric analysis gives you more than just numbers. It helps you see how materials behave, how stable they are, and what changes during heat exposure.
Whether you’re running QA tests or developing new products, TGA gives clear, usable insights. Looking to add this capability to your lab?
Explore the ToronTGA Analyzer to bring reliable thermal analysis into your workflow.
