ASTM E1641-13 Method for Decomposition Kinetics by Thermogravimetry using the Ozawa/Flynn/Wall Method

Scope:

ASTM E1641-13 test method determines the kinetic parameters, Arrhenius activation energy, and pre exponential factor by thermogravimetry. ASTM E1641-13 test method is based on the assumption that the decomposition obeys first-order kinetics by using the Ozawa/Flynn/Wall conversational method. ASTM E1641-13 test method is generally applicable to materials with well-defined decomposition profiles occurring in the range from 400 to 1300K (nominally 100 to 1000°C).

Test Procedure:

ASTM E1641-13 test method consists of heating a series of four or more test specimens, taken from the original sample, each at a different heating rate between 1 and 10 K/min, through their decomposition region. The specimen mass is recorded continuously as a function of temperature. The temperatures for constant conversion are determined from the resultant mass loss curves. The Arrhenius activation energy is then determined from a plot of the logarithm of heating rate versus the reciprocal of the absolute temperature at constant conversion level. This activation energy may then be used to calculate thermal endurance.

Test Specimen:

Powdered or granular specimens, which have a high surface-to-volume ratio, are preferred in ASTM E1641-13 test method.

Data:

In ASTM E1641-13 test method, the glass transition temperature is calculated using the following equation:-

Where:

y =  ∆ log β,

x = 1/T,

δm = uncertainty in the value of m, 

m = n∆ (log β)/∆ (1/T),

n = number of individual sets of x and y data,

xi = an individual x data point,

yi = an individual y data point,

∑ = mathematical function equivalent to “sum of all,”

δyi = the uncertainty in an individual y value and is given

by, and δyi = yi − (m × xi − b)

Conclusion:

ASTM E1641-13 provides details about the test method for measurement of the Decomposition Kinetics by Thermogravimetry.