The basic concept for interpretaton of TGA Analysis are determination of the fiber content of composite materials (by thermogravimeter) and investigation of segregation behavior of different mortar constituents (with TGA/SDTA) [example application for characterization of composite, mortar, or more objects]. The main specific of DSC measurement is focused to determine of Polimer Crystalinity [in case, problem] .
I think artifacs are effects observed on the measurement curve that are not directly caused by the sample (properties measure).
TGA Artifact are Buoyancy effect (density of gas decreasing on heating), Fluctuations of purge gas flow rate, sudden loss of mass arising from injection of sample element, and apparent weight gains caused by samples (contact with furnace).
The part of interpetation TGA curves:
In additional several other different curves are used to aid interpretation:
- The first derivative (DTG curve - rate of change of mass).
- The SDTA curve: measure exothermic or endothermic effect (simmilar to DSC).
- EGA (Evolved Gas Analysis): FTIR or MS Measurements (Gas & Vapors).
Occasionally a gain in weight is observed from TGA curves (display weight losses): Chemical reactions (decomposition and loss of water of crystallization, combustion, reduction of metal oxides) and Physical transitions (vaporization, evaporation, sublimation, desorption, drying).
The specific purpose of TGA curves from chemical reactions can be viewed in below Image link (from ref. Mettler Toledo).
Gravimeter effect on melting are explained:
- sample with low vapor pressure (low TGA effect) with no fluctution curve (stable curve).
- Volatile melt with the liquid sample evaporates (declined sharply curve).
- Moisture escapes on melting (decrease and then stable curve).
- Sample melts with decomposition (stable curve and the decrease curve).
If you need full explanation reference about this topic. I can send it via email.
I guess, you can be read the the full paper to support your problem (in the below of link).
http://www.sciencedirect.com/science/article/pii/S0008884607001044
http://www.sciencedirect.com/science/article/pii/S0958946506001685
Thanks, Best regards.
If your doubt is related to experimental detail, you can submited your sample at atmosphere of air or nitrogen form room temperature until the maximun temperature that equipment allows and you can observed in the thermograms the weight loss and obtain the decomposition temperature of the all components (curve of weight vs temperature) and the curve of derivated weight vs temperature.
Aman,
If you do TGA with concrete powder instead of cement paste, there will always be an unknown component of your aggregate in it. You can still identify the phases/group of phases but their relative fraction wouldn't be a true representation of the cement hydration, as cement and aggregates may be present in unknown proportion.
It is best to do it on cement paste only. Do it in a nitrogen environment as if you do in air some of the products can get oxidised. Moreover, it is best to remove the free and physically bound water by one of the solvent replacement methods using, acetone/isopropanol/ethanol etc. and dry at 40 degree temperature, though you can use other drying methods as well. When you conduct your TGA do it upto atleast 900 deg, that will cover the breakdown of majority of phases.
Once, you have got your TGA data, you can create plot temperature vs slope of TGA to obtain your DTG.
Sometime, you find lot of noise in your data, i found sigma plot's data smoothening option the best, which you can use at the stage of the presentation of your results.
Hope this assists in your query, but if you have any further queries feel free to ask
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