ASTM E698 Standard Test Method for Kinetic Parameters for Thermally Unstable Materials Using Differential Scanning Calorimetry and the Flynn/Wall/Ozawa Method

    ASTM E698 Introduction

    ASTM E698 offers a consistent method of determining the parameters of the kinetics, including activation energy, without a full comprehension of the reaction mechanism. Thermal characteristics of unstable materials are important to industries that handle chemicals, propellants, polymers, and explosives. The method of the test is based on non-isothermal DSC measurements at various heating rates using the model-free Flynn/Wall/Ozawa method to interpret energy changes when decomposing. The outcomes will be useful during safety analysis, risk assessment, and compliance with safety regulations during the storage, processing, and transportation of thermally non-stable materials.

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    ASTM E698 Test Method

    PrincipleSamples are heated in a differential scanning calorimeter (DSC) at multiple constant heating rates. The heat flow associated with decomposition or reaction is recorded. The Flynn/Wall/Ozawa method is applied to determine activation energy and other kinetic parameters from the shift in reaction temperature with different heating rates.
    ProcedureTest material is placed in the DSC pan and subjected to controlled heating under an inert or oxidizing atmosphere, depending on the study. Measurements are performed at different heating rates (commonly 2–20°C/min). Reaction onset, peak, and enthalpy are recorded. The FWO method is used to calculate activation energy based on conversion-dependent analysis.
    OutputActivation energy (Ea), thermal stability characteristics, and kinetic parameters that describe the decomposition or reaction process. Results aid in predicting behavior at different heating conditions.

    ASTM E698 Equipment and Sample Preparation

    Specimen DetailsSolid or liquid samples of thermally unstable materials, typically a few milligrams in mass.
    Specimen PreparationSamples must be finely divided (if solid), dried if necessary, and sealed in DSC pans to prevent sample loss during heating.
    Specimen DimensionsSmall sample sizes, usually 2–10 mg, are used to minimize thermal gradients and ensure uniform heating.

    ASTM E698 Results and Interpretation

    Test results give activation energy and kinetic data that define the thermal instability or decomposition of the material. The higher the activation energies, the more thermally stable, and vice versa. Data of this kind can be used to model rates of decomposition, time-to-explosion or ignition, and safe handling conditions. The use of these results is often applied to safety plans of dangerous chemicals, in degradation studies of polymers, or in testing explosives or propellants.

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    The ASTM E537 test method deals with thermal decomposition of chemicals by means of a differential scanning calorimeter, and the ASTM E1131 test method describes techniques to be used in the determination of thermal decomposition and loss of mass under thermogravimetric analysis (TGA).

    ASTM E698 Applications in Industry 

    One of the most popular industries to utilize this test method is hazmat, or hazardous materials, polymers, explosives, and energetic materials. It aids in the testing of chemical manufacturers to determine the safety of new chemicals, testing in the aerospace and defense industries in propellant safety testing and explosives, and polymer degradation research to select materials. Risk assessment, thermal hazard assessments, and transport safety certification are also carried out using this method in regulatory agencies and safety laboratories.

    ASTM E698 Materials Commonly Tested

    Examples of samples tested under this method are energetic propellants, explosives, reactive monomers, polymers that can be thermally degraded, pharmaceuticals, fine chemicals, and unstable intermediates. It also finds application in specialty chemicals, where the stability of chemicals during storage and transport is a critical issue.

    ASTM E698 Common Challenges and Troubleshooting

    Issues can be identified with baseline drift in DSC measurements, an inappropriate method of sealing samples, or overlapping reactions that make kinetic analysis intractable. The accuracy is improved by using small and similar samples and by ensuring adequate calibration of the DSC. That may necessitate deconvolution techniques or complementary TGA in the case of methods involving a sequence of decomposition steps.

    ASTM E698 Safety and Best Practices

    Smaller quantities of material should be tested under closely controlled circumstances, having due regard to shielding and ventilation. Laboratory safety rules must be observed, and protective equipment is required for the operators. Reactive residues are to be disposed of under the same guidelines as hazardous materials.

    Importance of ASTM E698 Test Method

    The importance of this method lies in its ability to provide a relatively easy and standardized procedure for obtaining kinetic parameters, requiring minimal information about the decomposition mechanism. This entails that it is an effective instrument in forecasting the thermal conduct of volatile material with safe processing, sturdy storage, and transportation. Its application reduces the risk of industries that deal with energetic compounds, avoids thermal accidents, and helps to follow the regulations.

    FAQ

    Where can I get the astm e698 tested?
    You can share your astm e698 testing requirements with MaTestLab. MaTestLab has a vast network of material testing laboratories, spread across the USA and Canada. We support your all material testing needs ranging from specific astm e698 test to various testing techniques.
    Please contact us for a detailed quote for your astm e698 testing needs. Cost incurred to carry out different astm e698 testing methodology depends on the type of raw material; number of samples, coupons, or specimens; test conditions, turn around time etc. Costs of some ASTM testing methods start from $100 and the final value depends upon the factors listed above. Please contact us for the best and latest prices.
    The required number of samples or specimens should comply with the procedure given in the astm e698 standard. However, the MaTestLab operations team can assist you for your special requirements once you share your testing details with us.
    MaTestLab has a vast testing laboratory network, hence we bring you the best testing facilities in a cost-effective way. We offer considerable discounts (15-20%) to our returning customers based on test volume and frequency.
    The turnaround time for astm e698 test methodology depends upon the test procedure mentioned in the standard test document. However, we at MaTestLab understand your research requirements and hence try to get your test completed within the least possible time.

    Updated on September 17, 2026

    Davis Scott
    About Author
    Davis Scott
    Davis Scott is an Electrical and Electronics Engineer specializing in multidisciplinary validation, quality assurance, and comprehensive electro-mechanical testing.
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