Differential Scanning Calorimetry (DSC)

Differential scanning calorimetry (DSC) is a thermal analysis technique used to characterize a variety of temperature-dependent physical and chemical changes in a material.

Strengths

• Direct method of measuring heat capacity and detecting thermal transitions in the material
• Straightforward data collection
• 3 sample pan types available to accomodate different material types

Limitations

• Oxidation analysis, volatile material characterization, thermal degradation experiments, and solvent loss measurements are not supported as they can permanently damage the instrument
• Upper temperature limit must be lower than material decomposition temperature

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Example Outputs Instruments Used How DSC Works

• Solid samples only
• No volatile samples
• Sample material must have no chemical incompatibility with pan material (pan options: aluminum and gold)
• Only samples with known decomposition temperature can be tested
  (TGA recommended as a preliminary test / screening method to validate sample viability for DSC)
• For non-powder samples, must be able to trim sample to fit into DSC pan
• Safety data sheets for sample materials are required

DSC instruments measure the amount heat transferred (exothermic (heat produced) and endothermic (heat required) between a sample and its environment as the overall temperature of the system is modulated / ramped.

The sample is placed in a small pan and sealed. To increase the precision of the measurement, the system simultaneously measures heat flux in both the sample of interest, and an adjacent reference (a “blank,” or empty) pan.

After the energy transfer in the reference is subtracted from the specimen signal, one is left with a DSC curve that quantitatively reflects the temperature dependence of numerous thermal events. Characteristic features in a DSC curve correspond to certain thermodynamic processes, as well as exothermic and endothermic chemical and physical transitions. These transitions can include include: recrystallization, softening and phase changes.

By identifying these, it is possible to quantify the temperatures at which they occur, often allowing identification of the material (s) and to calculate additional, correlated thermal properties.