Flynn-Wall equation

In this method (Ozawa, 1965 Augis Bennett, 1978 Boswell, 1980 Flynn Wall, 1966) the temperature integral in Eq. (4) is simplified by using the Doyle s appa-oximation (Doyle, 1%1,1%2,1%5) and hence we obtain the following equation ... 

The Flynn-Wall-Ozawa method [142, 143] has been used to determine the activation energy from dynamic tests by plotting the logarithm of heating rate as a function of the inverse of the temperature, at different conversions. Being integrated with the initial condition of a = 0 at r= To, the equation (24) can be arranged as follows ... 

Where a is the extent of decomposition, Z is a pre-exponential factor, E is the activation energy, R the universal gas constant (8.3154 Jmol K 0> and f(a) depends on the decomposition mechanisms. E, Z, and a) are commonly called the kinetic triplet [28]. There are different kinds of methods to obtain the kinetic triplet reported in the scientific literatme among which are those reported by Flynn-Wall-Ozawa [29], Friedman [30], Kissinger [21], or Coats-Redfem [31], with different proposed equations presented to solve Eq. (7.1). 

To calculate the activation energy (Eact), Flynn and Wall [60] adapted the classic Arrhenius equation into Eq. (4.3) to reflect the... 

The Flynn and Wall method [3-21,3-22] uses the thermogravimetric curves to calculate the activation energy E and the frequency (pre-exponential) factor A of the Arrhenius equation. In this approach the TGA curve of the analysed material is recorded from at least three test runs at heating rates P between 1 and 20 K/min. The corresponding temperatures of selected constant conversion levels are determined for each test run (Fig. 3-51). The measured values of temperature and heating rate are then used to compute the activation energy E using the method of successive approximations ... 

Doyle, C.D. (1962). Estimating Isothermal Life from Thermogravimetric Data, Journal of Applied Polymer Science, Vol. 6, pp. 693-642 ISSN 1097-4628 Doyle, C.D. (1965). Series Approximations to the Equation of Thermogravimetric Data, Nature (London), Vol. 207, pp. 290-291 ISSN 0028-0836 (Print), EISSN 1476-4687 Flynn, J.H. Wall, L. A. (1966). General Treatment of the Thermogravimetiy of Polymers,... 

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