Hello everyone...
I have TGA test results for the same sample at four different heating rates (10, 20, 30 and 40 K/min). Now, how to proceed and illustrate the uncertainty analysis and repetitive test results?
I would be very much grateful if anyone can help me.
Dear Dipankar Saha ,
The document sent in the previous answer explains some parameters for uncertainty analysis.
You have 4 TGA results (with 4 different heating rate) on the same sample, you have then 4 different experiments. I don't know what kind of uncertainty that you want to calculate. Normally the uncertainty calculations are performed on the results obtained in the same conditions by repetition (for exemple you repeat TGA experiment 10 times on the same sample with the same heating rate of 10°/min). You can then study the uncertainty. After your results obtained with different parameters I am not sure that you can calculate the uncertainty.
Best regards
Atilla Atli Thanks for your reply.
May i know minimum how many repetition (TGA experiment at the same heating rate and for the same sample) is recommended and accepted for the study of uncertainty analysis?
And, repetition is recommended at lower heating rate (10 K/min) or higher heating rate (20 K/min)? Or i can choose any heating rate?
My experiment involves evaluation of kinetic parameters based on TGA data. So, do i have to show the final results of kinetic parameters (in regard to repetition experiment)? or showing the Mass loss vs Temperature profile will be enough?
Dear Dipankar Saha,
If the origin of the uncertainties is random, you can study the phenomenon as a classical statistics problem by using an appropriate distribution (normal distribution, student's law etc...). In such a case the more you have the experiments better the statistics.
A heating rate of 10°C/min is a usual value. But the heating rate plays on the kinetics, then the measured temperature. It is also important the thermal inertia phenomenon of the sample. If you heat the sample very fast, it is possible that the sample has not the same temperature as the temperature measured by thermocouple. In this subject, the sample size is also important. For example, if you perform two experiments in the same conditions (same heating rate, same atmosphere,...) on a same nature of sample but the sample size is different, the TGA curve will probably be different.
If you want to study the kinetic parameters by using different heating rate techniques (for exemple Ozawa method), it is better that you repeat the experiments a few times for each heating rate having the same sample size.
Hoping that these informations can help you.
Atilla Atli
I am really thankful to you for your reply. And, yes, the information really helped me. I will get back to you if i have further queries. Thanks again.
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