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July/August 2011
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Kinetic Parameters

Users of standards involving kinetic parameters need reference materials to qualify individual laboratories and to validate procedures and software. A new ASTM International standard will provide such parameters to accommodate apparatus configurations and kinetic models.

E2781, Practice for Evaluation of Methods for Determination of Kinetic Parameters by Thermal Analysis, was developed by Subcommittee E27.02 on Thermal Stability and Condensed Phases, part of ASTM International Committee E27 on Hazard Potential of Chemicals.

“By definition, materials with kinetic properties change with temperature and time, so the development of a suitable standard reference material is not practical,” says Roger Blaine, retired from TA Instruments and a longtime ASTM member. “The best that can be done is the selection, for fresh materials, of known kinetic parameters. The user may then compare the results obtained on their instrument or with their procedure to those accepted values.”

Kinetic parameters (for example, activation energy, pre-exponential factor, reaction order) are used to estimate the lifetime of products (E1877, Practice for Calculating Thermal Endurance of Materials from Thermogravimetric Decomposition Data) and to assess the thermal safety of high energy chemicals (E1213, Test Method for Minimum Resolvable Temperature Difference for Thermal Imaging Systems). Other ASTM standards for the determination of kinetic parameters include the following (committee jurisdiction for each standard is shown in parentheses):

  • E698, Test Method for Arrhenius Kinetic Constants for Thermally Unstable Materials Using Differential Scanning Calorimetry and the Flynn/Wall/Ozawa Method (E27);
  • E1641, Test Method for Decomposition Kinetics by Thermogravimetry (E37 on Thermal Measurements);
  • E2041, Method for Estimating Kinetic Parameters by Differential Scanning Calorimeter Using the Borchardt and Daniels Method (E37); and
  • E2070, Test Method for Kinetic Parameters by Differential Scanning Calorimetry Using Isothermal Methods (E37).

Blaine says that E2781 can be used to select from the literature and to standardize the kinetic parameters for a series of materials that might be used for the evaluation of kinetic parameters. Developers of standards, procedures and tools for the measurement of kinetic parameters will be the primary users of the standard. Users will include regulatory agencies, safety specialists interested in the storage and transportation of high energy materials, safety testing instrument manufacturers and safety software developers.

CONTACT

Technical Information: Roger Blaine, Corvallis, Ore.

Phone: 302-559-6827

ASTM Staff: Scott Orthey

Phone: 610-832-9730