Some possible reasons for weight gain detection in TGA have been discussed at this forum; see:

https://www.researchgate.net/post/Why_my_TGA_graph_shows_a_weight_gain https://www.researchgate.net/post/What_is_the_process_to_get_a_weight_Gain_in_TGA https://www.researchgate.net/post/What_are_the_reasons_for_weight_gain_in_TG_curve_My_sample_is_Cement_and_the_weight_gain_is_in_the_temp_range_of_400_to_650_degree

Nitrogen can react with your sample at elevated temperatures and it forms SIALON if your glass contains aluminosilicate materials which will show up as weight gain in your sample. To avoid that, run TGA under Argon atmosphere.

Thank you Hamed Salimkhani Sir ,

Dear Sanjay Kumar,

For sure you react with the nitrogen gas.

If your glass sample, by any means, has porous, it would happen to a large extent, as you have even at some high temperature trapped gas molecules.

However, the interpretation of your data needs a better knowledge of the start materials, if some of it is trapped inside your final glass the reaction may occur not with the final product.

Check the purity of your glass, before trying to interpreter the final product under a gas atmosphere.

regards

WNM

I may be able to help having worked in the area of thermal analysis for the past 40 years.

In order to intelligently answer your question, I need to exactly what your feed stock is for your DTG and TGA. You mentioned 'glasses', but that is broad an area. Please narrow it down for me. Thanks

But I need