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Thermogravimetric Analysis (TGA) Testing of Materials

Significance and Purpose

Thermogravimetric Analysis (TGA) is a thermal analysis technique that measures the mass change of a material as a function of temperature, time, or atmosphere. TGA provides essential information about a material’s thermal stability, composition and decomposition behavior. The TGA technique can be critical for identification, selection and optimization of materials suitable for high-temperature or oxidative environments. This technique is widely used in material development, quality control, and failure analysis across industries such as polymers, composites, pharmaceuticals, and energy systems.

Relevant ASTM and ISO Standards

TGA testing is governed by various standards to ensure uniformity and reproducibility. Key standards include:

  • ASTM E1131: Standard Test Method for Compositional Analysis by Thermogravimetry.
    • Focuses on using TGA for analyzing the composition of a material by quantifying mass loss at various temperature ranges.
  • ISO 11358 (Parts 1–3): Plastics — Thermogravimetry (TGA)
    • Outlines general principles, procedures, and specific methods for materials such as polymers.

These standards provide guidance on procedures, calibration, and data interpretation for TGA experiments.

DatapointLabs Tests for Thermogravimetric Analysis Testing

Tests in the DatapointLabs test catalog that reference thermogravimetric analysis testing are as follows:

General Thermogravimetric Analysis Testing (inquire regarding material suitability)

Test Test Description Standards
T-201 Thermogravimetric Analysis (TGA) ASTM E1131
T-203 Carbon Black Content by TGA ASTM E1131

Principle of Operation

The thermogravimetric analysis technique measures the mass change of a sample while it is subjected to controlled heating or cooling under a specific atmosphere. The key principles include:

  1. Sample Heating: A small sample (typically 5–20 mg) is placed in a crucible within a thermogravimetric analyzer.
  2. Temperature Program: The sample is heated (or cooled) at a controlled rate (e.g., 10 °C/min) to a target temperature.
  3. Mass Monitoring: A precision microbalance continuously measures the sample's mass during the test.
  4. Controlled Atmosphere: The test can be conducted under various atmospheres (e.g., nitrogen, air, oxygen, or inert gases) to study specific thermal behaviors such as oxidative degradation.

The resulting mass loss or gain is recorded as a function of temperature or time, providing insights into thermal and chemical properties.

Typical Procedure

  1. Sample Preparation:
    • A small, representative sample is weighed (typically 5–20 mg) and placed in a microbalance pan.
    • The sample should be dry, homogeneous, and free of contaminants.
  2. Instrument Calibration:
    • Calibrate the TGA instrument using standard reference materials to ensure accuracy in temperature, mass, and baseline stability.
  3. Test Setup:
    • Place the sample pan in the TGA furnace and select the desired test conditions:
      1. Heating rate (e.g., 10 °C/min).
      2. Maximum temperature (e.g., 800–1000 °C).
      3. Atmosphere (e.g., nitrogen for inert conditions or air for oxidative conditions).
  4. Run the Test:
    • Start the test, and the thermogravimetric analysis continuously measures mass changes as the temperature increases.
    • If necessary, switch atmospheres during the test (e.g., from nitrogen to air) to simulate oxidative environments.
  5. Data Analysis:
    • Analyze the mass vs. temperature (or time) curve to identify thermal events such as decomposition, evaporation, or oxidation.
  6. Repeat for Reproducibility:
    • Conduct additional tests to confirm the reliability and repeatability of results.

Specimen Types

Specimens used by DatapointLabs in thermogravimetric analysis testing are as follows:

Specimen Type DatapointLabs Test IDs
Pellets [Details] T-201, T-203

Characterization Measurements

TGA provides a wealth of thermal and compositional data, including:

  • Thermal Stability: Onset temperature of decomposition or mass loss.
  • Decomposition Temperature: The temperature range over which significant mass loss occurs.
  • Volatile Content: The percentage of material lost due to the evaporation of moisture, solvents, or other volatiles.
  • Filler or Residual Content: The percentage of inorganic or non-volatile residue remaining after complete thermal degradation.
  • Oxidation Behavior: Mass gain due to oxidation under air or oxygen atmospheres.
  • Kinetic Data: Thermal degradation kinetics and activation energy.

Typical Data Reported (see test descriptions for exact details)

  • Thermogram (Mass vs. Temperature/Time Curve): The primary output, showing the material’s mass changes over the temperature or time range.
  • Onset Decomposition Temperature: The temperature where significant mass loss begins.
  • Peak Decomposition Temperature: The temperature at which the highest rate of mass loss occurs.
  • Percent Mass Loss: The proportion of the sample’s mass lost at specific temperature intervals, often used to quantify volatile content, polymer decomposition, or residue.
  • Residual Mass (%): The remaining mass after heating to the maximum test temperature (e.g., ash or fillers).

Suitable Material Types

The TGA technique is versatile and can analyze a wide range of materials, including:

  • Polymers and Plastics: For studying decomposition, additives, and fillers.
  • Composites: For determining the thermal stability of matrix and reinforcement materials.
  • Elastomers and Rubbers: For assessing thermal degradation and volatile content.
  • Inorganic Materials: Such as ceramics, glasses, and metals, for analyzing oxidation or mass stability.
  • Pharmaceuticals: For moisture content, thermal stability, and decomposition behavior.
  • Food and Biomaterials: For water content, volatiles, and residue analysis.

Suitable Applications

The TGA technique is widely applied across various industries and research fields, including:

  • Polymer and Plastic Industries: Assessing thermal stability, decomposition temperature, and filler content (including carbon) in thermoplastics and thermosets.
  • Pharmaceuticals: Analyzing drug formulations for moisture content, solvent evaporation, and thermal degradation.
  • Composites and Advanced Materials: Determining the thermal behavior of composite materials and their components.
  • Energy Storage: Evaluating the thermal properties of batteries, fuel cells, and energy materials.
  • Food and Agriculture: Analyzing moisture and volatile content in food products.
  • Environmental Studies: Quantifying organic and inorganic content in soil, waste, and other samples.
  • Quality Control: Verifying material consistency and performance in production environments.

Conclusion

Thermogravimetric analysis (TGA) is a versatile and reliable method for measuring thermal stability, composition, and decomposition behavior of a wide range of materials. By analyzing mass changes as a function of temperature and time, TGA provides critical insights for material characterization, quality control, and research & development. With applications spanning polymers, composites, pharmaceuticals, and beyond, the technique is an essential tool for industries requiring precise thermal property data. By following ASTM E1131 and ISO 11358 standards, this technique ensures high-quality, reproducible results for such thermal property measurements.

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