DSC measures thermal events in a material. TGA, being a gravimetric technique, shows weight loss (if any) associated with the thermal event. For e.g., sorbed water is evaporated in a material during heating. This water evaporation is seen as an endotherm in DSC and a step change in TGA in similar temperature zone.

Yes. For chemical reaction with a change in weight, there will be a exo/endothermic peak in DSC thermogram with a corresponding changes in TGA thermogram. If you take derivative of TGA, you can compare weight change rate and heat evolution rate. In general they may be look similar but in some reaction they not look so. On the other hand, meting will not be detected in TGA unless the sample has high vapor pressure at that temperature.

Though both TGA (Thermogravimetric Analysis) and DSC (Differential Scanning Calorimetry) are thermal analyses, yet the major difference between TGA and DSC. There is no relationship between the TG and DSC curves, because the first is the integral curve and the second differential curve.

The information from DSC is over as it starts decomposing and TGA information starts from that temperature. The TG is obtained with a thermobalance where the weight of samples is continuously plotted as a function of increasing temperature but DSC is a measure of the heat flowing to the sample compared to reference material.

I hope this helps.

DSC measures thermal events in a material. TGA, being a gravimetric technique, shows weight loss (if any) associated with the thermal event. For e.g., sorbed water is evaporated in a material during heating. This water evaporation is seen as an endotherm in DSC and a step change in TGA in similar temperature zone.

Additional notes to others reply: The heat treatment of your sample reflects in both TGA and DSC curves shows a common story. However the curves are not the same. i) the DSC measures the heat flow or heat absorbed/released by the sample crucible/pan compared to the reference crucible in mW or uV. ii) the TGA show you instantaneous weight change of the sample crucible compared to the reference crucible in mg or ug inside the furnace.

Examples : i) When sample dehydrates, usually shows weight change in TGA curve but almost no/negligible heat flow curve variation in DSC/DTA, if there is no transition events (endothermic or exothermic) with that temperature range. ii) If the sample show melting heat flow peak at the same time decomposition peaks as observed in DSC as you have described, the TGA curve will also show weight variations.

As Ganesh Shete mentioned, DSC and TGA measure different properties of a material. DSC can be used to measure phase changes in a material (melt point, crystallization point, etc) whereas TGA measurement characterizes changes in masss (decomposition primarily).

Yes

Yes, there definitely is a relationship. In certain materials, a phase change results in the production of a volatile component, which can decompose and affect the mass of the resultant material.

Different aspects of the same degradation process may be observed through the different analyses. It is possible that the detected DSC peaks can be accounted to the detected TGA peaks but it is not always the case.

A possible method to decide which is the case, you can try heating the sample with two or three different heating rates with both DSC and TGA, and check the changes in peak positions.

Dear all

Thank you all for your valuable comments.

Here, I am attaching the DSC and TGA curve for same flour. DSC curve shows the 1st peak at 71.45oC while TGA displays the 1st peak at 79.26oC. I want to know: Is there any similarity between the 1 st peak observed in both cases?

Thank you in advance.

To me, the first peak around 70 °C on the TGA trace seems to be some evaporation of residual water content (or degradation) which is continued in a major decomposition process, peak around 215 °C. The peak on the DSC trace should be the same evaporation (or degradation) process, with the main decomposition around 200-230 somewhat delayed and not on the graph.

What are the heating rates, measured sample amount and atmosphere for a) TGA and b) DSC? These parameters can have a huge effect on the comparability of the two measurements.

DSC provides thermodynamic information about the material, while TGA provides physical information about the nature of the material. To correlate information between the two methods, the same temperature ramp should be used. This allows a determination of an observed thermodynamic event in the DSC with a corresponding weight loss (or no weight loss) in the TGA. One can observe a thermodynamic event with no significant weight loss, or a thermodynamic event with a corresponding weight loss. Example: a glass transition may have no associated weight loss, but an endotherm or exotherm could yield a weight loss.

I doubt that these peaks are not the same. It would probably be a complete coincidence, if they were.