Hello medhat,

With the help of origin you can only interpret the data, The weight loss occurs in 3 stages with respect to temperature.

Hope you can calculate the the activation energy in excel sheet using below formula.

In order to perform the calculations in excel you will need to export the raw data as text files. You will then need to firstly calculate α (which is the degree or conversion or fraction converted) and convert temperature to K (if it is in °C) in excel for the TGA data obtained at each heating rate.

α = (W0-WT) / (W0-W∞)

W0 is the initial sample weight, WT is the weight at temperature (T) and W∞ is the weight at the reaction end point.

It is typically a good idea to plot α against Temperature (K) to see how α shifts with heating rate. All you need to do from here is to calculate and plot the left hand side of your chosen isoconversional method against 1/K for a given α.

Helpful