DSC curves often exhibit effects that cannot immediately be understood. In such cases, it would be very helpful to actually see what is going on in the sample. This would enable us to identify solid-solid transitions, differentiate between overlapping effects such as melting and decomposition, observe the shrinkage of fibers or films, or simply identify the cause of an artifact in a DSC curve.
- Imaging possibilities – microscopy yields information on processes that generate little or no enthalpy and cannot be detected by DSC
- MultiSTAR® DSC sensor capability – very weak effects can be measured with excellent sensitivity and temperature resolution
- Simultaneous image analysis and DSC measurements – provide a complete thermal picture of the sample
- Possibility to upgrade from a conventional DSC to a DSC-Microscopy System within minutes – a DSC 1, DSC 2, DSC 3, DSC 3+ or DSC82xe can be easily upgraded to include reflected-light microscopy measurement capability
|Paints, lacquers, adhesives, coatings|
(organic and inorganic materials),
| ||DSC-microscopy analysis of an active pharmaceutical ingredient|
The melting point is an important characteristic property of a substance. The DSC measurement of an active pharmaceutical substance (API) yielded a curve with two main peaks – an endothermic peak with a maximum at 210.8 °C and an exothermic peak at about 228 °C. A smaller peak was also apparent between these two peaks at about 214 °C. The initial interpretation was that the endothermic peak at 210.8 °C is due to melting. The DSC-microscopy results, however, told a different story. No melting was observed at 211 °C – the first signs were detected at about 214 °C. Clearly, the endothermic DSC peak is not caused by a melting process. The color change of the molten substance leads one to conclude that it decomposes immediately on melting. The small DSC peak observed at about 214 °C is therefore the sum of two simultaneously occurring effects – endothermic melting and exothermic decomposition. Separate TGA-MS measurements showed that the endothermic DSC peak at 210.8 °C is caused by the evaporation of water of crystallization.
|Dehydration of CoCl2 hexahydrate|
The images illustrate the dehydration process of cobalt (II) chloride hexahydrate when it is heated from 30 °C at 1.5 K/min. The initial ruby-red color becomes lighter and lighter until it suddenly changes at about 55 °C. Further color changes are observed between 100 °C and 120 °C and at 160 °C. The differences can be quantified by calculating a curve showing image brightness as a function of temperature. The DSC curve shows a broad endothermic peak up to 80 °C with a sharp peak at about 55 °C superimposed on it. Two further endothermic peaks follow at about 104 and 130 °C. The brightness first increases and then suddenly decreases at about 55 °C. Afterward, it increases again in several steps. The peak at about 55 °C is due to a change in crystalline structure. The images around 55 °C show small droplets of water on the surface of the crystals. This indicates that part of the water of crystallization eliminated from the crystal lattice during the solid- solid transition collects on the surface of the crystals and then evaporates. This is completed by about 80 °C. The two broad endothermic peaks on the DSC curve and the step-like changes in the brightness are due to further loss of water of crystallization.