Hello everyone,
I ran a TGA on a wood sample first using an inert gas all through the run. Then repeated the same but this time using the inert gas up to 400C and then switching to Oxygen from 400C to 800C. However on the DTG curve (Blue) I do not know the reason for the spike at 400C. I suspect its the Ignition of the material due to oxygen. Secondly another smaller spike can be seen at around 690C after the sample seems to have been completely decomposed. Please can anyone explain?
Thanks in advance!
The gas switching program is used for measuring Carbon content of a sample. So, it is normal to have a peak in DTG, where the gas is switched. The weight loss in the switching temperature gives the carbon content.
However, in the thermograms it is a bit weird that the residues under Argon and Air atmospheres looks almost the same!
It is expected to have more residue when an inert gas is used.
The sample is wood. The wood is formed with cellulose including organic and inorganic parts. I also agree with the suspection of its ignition of the material due to oxygen. The weight loss of the sample is due to burning or oxidation at 400C and weight loss is due to emission of volatile product from the wood. That's why there is a weight loss due to switching from nitrogen environment to oxygen. The secondary exothermic peak also correspondence to secondary volatization.
Thank you very much Sirs for sharing your knowledge with me. I am currently working on changing the parameters a bit to study differences in the curves. Warm regards
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