Polymer Chemistry

Differential Scanning Calorimetry

A differential scanning calorimeter (DSC) measures the amount of energy (heat) absorbed or released by a sample as it is heated, cooled, or held at a constant temperature⁵⁶. DSC has become the method of choice for quantitative studies of thermal transitions in polymers⁵⁷.

Another good source of information about the DSC is the Macrogalleria Web site.

• The Calorimeter
  
  
• The Thermogram
  
  
• DSC Operation
  
  
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In a DSC a sample and a reference (often a piece of Indium metal) are contained in small aluminum pans with crimped tops. The pans are placed on individual heaters in a furnace in a nitrogen atmosphere. A diagram of a heat flux DSC furnace is shown at the right⁵⁸.

The furnace is heated and the temperature difference between the sample and reference is monitored so that the DSC can keep the temperatures the same. If an exothermic phase transition occurs, the temperature of the sample will tend to surge ahead of the reference. In this case the DSC doesn't need to furnish as much heat to the sample. If an endothermic transition occurs, the DSC must furnish more heat to the sample. The electrical power difference between the sample and reference measures the heat flow (dQ/dt) in the sample.