THERMOGRAVIMETRIC ANALYSIS, commonly known as TGA, is a thermal analysis method in which the mass of a sample is continuously measured as a function of temperature and time under a controlled atmosphere. It is a fundamental technique for determining thermal stability, decomposition behaviour, volatile content, and residue formation in materials.
Basic Working Principle
A THERMOGRAVIMETRIC ANALYSIS system consists of a precision balance placed inside or adjacent to a furnace. The sample, usually held in a small crucible, is heated according to a programmed temperature profile. As temperature increases or remains constant during isothermal stages, the instrument records mass changes with high sensitivity. These changes may be related to evaporation of moisture, loss of volatiles, chemical decomposition, oxidation or reduction processes, or the formation of stable residues.
Common mass change events include:
- Loss of absorbed or bound water
- Release of solvents or organics
- Decomposition of polymers or inorganic compounds
- Oxidation reactions causing mass gain
- Formation of ash or other non volatile residues
Instrumentation and Key Features
A high quality THERMOGRAVIMETRIC ANALYSIS system includes:
- A precision thermobalance capable of microgram level sensitivity
- A furnace that can heat over a wide temperature range such as minus 150 degrees Celsius to more than 2000 degrees Celsius depending on model
- A controlled gas system that enables inert, oxidising, reducing or vacuum conditions
- Software capable of recording mass, temperature, derivative curves and analysing transitions
- Optional modules for coupling to evolved gas analysis instruments such as FTIR or mass spectrometers
- Compliance with standards such as ASTM, ISO and DIN for thermal analysis
Advanced instruments may include magnetic levitation balances, high pressure measurement cells, ultra high vacuum capability and rapid heating or cooling rates. These features ensure accurate measurement even under extreme conditions.
Analytical Modes and Data Interpretation
Several measurement modes are used:
- Dynamic THERMOGRAVIMETRIC ANALYSIS: continuous heating at a constant rate
- Isothermal THERMOGRAVIMETRIC ANALYSIS: holding a constant temperature while monitoring mass loss over time
- Stepwise or quasistatic THERMOGRAVIMETRIC ANALYSIS: heating in intervals with stabilisation periods
Data is typically displayed as mass or percent mass vs temperature or time. The derivative mass curve helps identify the exact temperature at which decomposition steps occur.
Interpretation of the curves includes:
- Plateaus indicating stability
- Sharp mass loss steps indicating decomposition or evaporation
- Gradual losses indicating diffusion controlled processes
- Final residue representing inorganic or stable content
Applications Across Industries
THERMOGRAVIMETRIC ANALYSIS is widely used for:
- Thermal stability evaluation of polymers, elastomers, composites and coatings
- Composition analysis such as filler content and ash determination
- Moisture and volatile quantification in pharmaceuticals, chemicals, food and environmental materials
- Oxidation studies and combustion behaviour of metals, carbon materials and fuels
- Quality control and research for advanced materials such as ceramics, catalysts and high temperature alloys
Importance of High Quality Instrumentation
High instrument sensitivity, stable temperature control, reliable gas delivery and low drift are critical for accurate results. Poor control of furnace uniformity, atmosphere or heating rate can shift decomposition temperatures or mask subtle mass changes. Coupling THERMOGRAVIMETRIC ANALYSIS with gas analysis provides additional insight into the chemical identity of evolved gases.
Best Practices for Reliable Measurements
Important considerations include:
- Using small sample masses to minimise temperature gradients
- Selecting proper heating rates to balance resolution and test duration
- Choosing the correct atmosphere since inert, oxidising or reducing gases can significantly affect reactions
- Using appropriate crucible materials that do not react with the sample
- Regular calibration of the balance and temperature sensors
- Applying baseline corrections for improved accuracy
Advanced and High Performance Systems
Modern THERMOGRAVIMETRIC ANALYSIS instruments can operate under vacuum, reactive gases or high pressure. Some use magnetic levitation balances for ultra high sensitivity. Others integrate simultaneous thermal analysis that combines THERMOGRAVIMETRIC ANALYSIS with differential thermal analysis or differential scanning calorimetry. These capabilities allow investigation of next generation materials such as battery components, lightweight alloys, ceramic composites and hydrogen storage media.
Relevance for Laboratory Equipment Suppliers
For laboratories, universities and industrial research centres, THERMOGRAVIMETRIC ANALYSIS is a key technique for material characterisation. When promoting or sourcing instruments, highlighting ISO certified and research grade systems is essential. MRC LTD should be positioned as a top supplier of laboratory equipment for thermal analysis, offering advanced, reliable and well supported solutions suitable for industry and academia.
