DSC vs DTA
DSC and DTA are thermoanalytical techniques, where the studies are carried on using temperature changes. When temperature is changed, materials undergo different changes such as phase transitions. Both these techniques use an inert reference in order to compare the results of the sample. They are carried under temperature controlled environments. So the temperature differences of material and reference can be used to derive important information. These methods provide specific and important details about the chemical and physical properties of material.
Differential scanning calorimetry is known as DSC. A calorimeter measures the heat that enters (endothermic) a sample or which exists (exothermic) from a sample. Differential calorimeter does this same thing with a reference. DTA is a combination of a normal calorimeter and differential calorimetry. Therefore, it measures the heat with reference to another sample and meanwhile heats the sample to maintain a linear temperature. Therefore, the heat required for the sample to increase the temperature and the reference is measured as a function of temperature. Sometimes this can be measured as a function of time. When the measurements are taking, normally the temperature is controlled in the atmosphere. Usually, sample and the reference are kept at the same temperature. DSC is important because it provides qualitative and quantitative data about the material. It can give information about physical and chemical changes taking place in the material, melting and boiling points, heat capacity, crystallization time and temperature, heats of fusion, reaction kinetics, purity, etc. This can be also used to study the polymers upon heating. It is hard to measure the heat absorbed or released during a phase transition (e.g. glass transition), since those are latent heat. Another obstacle for this is there is no temperature variation at this point. So with the help of DSC, we can overcome this problem. A reference is used in this technique. Therefore, when the sample undergoes phase transitions, the relevant amount of heat should be supplied to reference, as well, in order to keep its temperature same as the sample. By observing this different heat flow of the sample and the reference, differential scanning calorimeters are able to give the amount of heat released or absorbed during a phase transition.
Differential thermal analysis is a similar technique as differential scanning calorimetry. In DTA, an inter reference is used. The heating or the cooling of both the sample and the reference is carried under the same conditions. While doing this, the changes between the sample and the reference are recorded. As in DSC, the differential temperature is plotted against temperature or time. Since the two materials do not response to temperature changes in a similar way, differential temperatures arise. DTA can be used to thermal properties and phase changes which are not related with an enthalpy change.
What is the difference between DSC and DTA?
• DTA is an older technique than DSC. So DSC is more sophisticated and improved than DTA.
• DTA instrument can be used at very high temperatures and in aggressive environments where DSC instrument may not work.
• In DSC, influence of sample properties on the area of the peak is comparatively lower than in DTA.