I have doubts regarding finding the glass transition temperature for neat epoxy and epoxy composites reinforced with bamboo fibers. Anyone having knowledge about it, kindly help.
For a glass transition, there will be a small change in the baseline of the DSC curve. you have colour coded the samples, however, on a blind note it could be the purple curve showing this feature at around 65.
Dear Hrishikesh Dutta,
Thank you for sharing this question!
I will refrain from doing some interpretation on the DSC graphs because the experimental information is missing, and I can’t see some modifications at different loadings of bamboo (NB: regarding the modification of peaks on the DSC traces; difficult to understand).
Please look at this paper, for sure you will find some more answers:
Yang, M., Wang, F., Zhou, S., Lu, Z., Ran, S., Li, L. and Shao, J. (2019), Thermal and mechanical performance of unidirectional composites from bamboo fibers with varying volume fractions. Polym. Compos., 40: 3929-3937. https://doi.org/10.1002/pc.25253.
Moreover, don’t hesitate to correlate DSC measurements with those of DMA!
Good luck with your R&D project and best regards,
Marius
Hello Hrishikesh Dutta,
are your DSC graphs showing the first or a subsequent heating run? Often DSC graphs show a different development for the first and subsequent heating runs. This may be a result of synthesis leftovers (i.e. solvent or monomer traces) or thermal history (i.e. you can see a relaxation if the polymer was streched and then 'frozen' in this state before the analysis).
Is the resin the same as in the publication? Like Venkataraman Abbaraju mentioned, glass transition temperatures are normally a change in the baseline, but no peak. Peaks are normally related to melting and your signal may be a melting peak. I often observe a dip in the baseline directly next to the glass transition temperature, but these are much less pronounced than in your case.
I would suggest to start the measurement from lower temperatures. When doing this, you have more data for a baseline at lower temperatures than the possible glass transition. In the current graph, the baseline is heavily influenced by the heat flow at the start of the experriment (or the heat flow between a previous step in the experiment and the shown heating run). If the step/peak is something else than a Tg, you may find your Tg at the lower temperature.
With best regards
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