Principle of Differential Scanning Calorimetry (DSC) Testing

When a sample is heated or cooled, it absorbs or releases energy that can be measured using the differential scanning calorimetry (DSC) method in analytical chemistry and material science. It offers details on the physical and chemical alterations caused by exothermic processes like crystallization and endothermic processes like melting as a function of time or temperature.

Differential Scanning Calorimetry (DSC) Testing

The DSC testing process measures the difference in energy required to raise a sample’s temperature based on temperature or time. The sample and reference are kept in close thermal contact and heated or cooled in the same chamber. The information collected includes phase transitions, reaction kinetics, purity, enthalpy, heat capacity, and curing reactions. The process involves preparing a sample, placing it in a specialized pan, initiating a temperature program, monitoring heat flow, and recording the resulting DSC curve. Peaks in the curve represent transitions in the sample, and the area under a peak can be used to determine the enthalpy change. Applications include polymer science, pharmaceuticals, food science, and metallurgy. Advantages include fast analysis, a small sample size, and both qualitative and quantitative information.

Differential Scanning Calorimetry (DSC) is a thermal analysis technique used by Westmoreland Mechanical Testing & Research to evaluate various qualities in specimens. It allows monitoring of glass transition temperatures, fusion and crystallization occurrences, and other chemical reactions. The end product of a DSC experiment is a heat flux versus temperature or versus time curve. The ASTM D3418 standard test method is widely used for determining the melting and crystallization temperatures and enthalpies of polymers using DSC. The testing procedure involves heating or cooling the sample under a specified purge gas and monitoring the resulting temperature difference between the sample and a reference material using a suitable sensing device. The glass transition temperature can reveal a material’s processing requirements, stability, chemical reactions, and mechanical and electrical properties. The standard test method for DSC to determine specific heat capacity is ASTM E1269.

Working Principle

• A typical DSC apparatus includes two pans: one for the sample and one for the reference. Typically, the reference is an inert substance or an empty pan. The thermally protected container contains both pans.

• Regulated Heating/Cooling: The reference and sample pans are simultaneously heated (or cooled) at a regulated rate. Making sure they are in an environment with the same temperature is the goal.

• Heat Flow Detection: The sample will either absorb or release heat as it passes through a thermal transition (such as melting, crystallization, or a chemical reaction). The sample and reference pans’ temperatures will differ as a result of this heat exchange. This temperature difference is picked up by the DSC device.

• Feedback Mechanism: The device will regulate the heating or cooling to the pans to maintain the same temperature in both pans. The heat flow curve is produced by adjusting or compensating the sample pan’s energy consumption to maintain the reference pan’s temperature. Plotting the heat flow (usually expressed in mW or W/g) vs temperature (or time) yields the DSC curve.

• The Differential Scanning Calorimetry curve can be analyzed to learn more about the sample’s endothermic (heat-absorbing) and exothermic (heat-releasing) activities. Peaks that point upward or downward denote endothermic processes (such as melting) or exothermic processes (such as crystallization).