Analysis Of Kissinger's Equation

According to Kissinger’s Equation, a plot of ln [(Tg)2/α] versus 1/Tg should be a straight line as shown in figure 4, and from its slope, the value of Eg can be calculated. And it is equal to 328.82 kJ/mol.

The crystallization process can be explained by the DSC results which obtained at different heating rates. The kinetic parameters (activation energy for crystallization, Ec, and Avrami exponent, n) for the crystallization peaks determined. Kissinger method used to determine the activation energy for crystallization (Ep) considering the heating rate (α) dependence of the peak crystallization temperature (Tp) as shown in figure 5.

The value of Ep can be determined from the slope of a plot of ln [(Tp)2/α] vs 1/Tp according to the following equation: [ 19, 20]

1/Tp for the sample as shown in Figures 6 and 7. According to the slopes of the lines, the values of Ec1 and Ec2 can be calculated they are equal to 164.37 and 128.37 kJ/mol, respectively.

The fraction of crystallization (X) can be calculated from the DSC curves, according to the following ratio:

X =AT/A where AT is the area between Ti and T, while A is the total area of the exothermic peak between Ti and Tf, as shown in previous work [21].

Figure 8 shows the fraction of crystallization (x)

This figure shows the presence of two exothermic peaks that represent the crystallization temperature.

The as the prepared sample was heat-treated at a temperature around this value and measured each time at DTA.

In addition, Figure 11 shows that the first exothermic peak disappeared when the sample heat treated at and higher than 530 OC and second exothermic peak appeared. And the two exothermic peaks disappeared when sample heat treated at 620 OC.

XRD