Jump to content

User:N-DevCore/sandbox

From Wikipedia, the free encyclopedia

Determination of Activation Energy by Means of ASTM E2070

[edit]

ASTM E2070 in Section 5.8.[1] describes an integral Model-Free (isoconversional) method of calculation of activation energy in kinetics analysis in chemical kinetics for isothermal data curves. The method is applicable for a group of isothermal measurements including isothermal crystallization[2]

Description

[edit]
Example of ASTM E2070 Analysis of LDPE Measurements. Analysis shows a chart of Log(Time to conversion) vs. inverse temperatures of the points at the same conversions. Linear fit curves are shown for each conversion value specified:

The method descriped in ASTM E2070, Section 5.8 determines the calculation of activation energy without assumption of reaction type by using points with the same conversion (0.01, 0.02, …, 0.99, 1.00) from the isothermal measurements performed at different temperatures.

At least two measurements at different isothermal temperatures are required, four measurements are recommended.

Analysis in ASTM E2070 method shows a chart Log of time-to-conversion vs inverse temperature for the points with the same conversion from the different measurements. The chart is shown as the straight line for each conversion value.

Activation energy and pre-exponential factor are determined from the slope and intersect of these lines.

Advantages

[edit]
  • Each reaction point is evaluated.

Disadvantages

[edit]
  • Applicable only for low n-th order[1] one-step reactions. It can't be used for more complex reactions because the points are not on the straight line.
  • Applicable for the set of several isothermal measurements only.

References

[edit]
  1. ^ a b "ASTM E2027 Standard Test Methods for Kinetic Parameters by Differential Scanning Calorimetry Using Isothermal Methods". October 5, 2023.
  2. ^ "Short descriptopn of ASTM E2027 method". June 24, 2025.
[edit]

Description of using ASTM E2070