scanningcalorimetrie

Scanning calorimetry is a thermal analysis technique used to measure heat flow to or from a sample as a function of time or temperature under a controlled program. The most widely used form, differential scanning calorimetry (DSC), compares the sample with an inert reference. By heating or cooling at a programmed rate, DSC detects phase transitions and reaction events as changes in heat flow.

In a DSC instrument, the sample and reference are placed in separate pans with a shared temperature sensor. The instrument records endothermic and exothermic events from heat flow differences, such as melting, crystallization, glass transition, and curing. From the curves, one can determine transformation temperatures (Tm, Tc, Tg) and enthalpies (ΔH).

Modulated DSC (MDSC) adds a small periodic temperature modulation to the base heating program, allowing separation of reversing and nonreversing heat flows. This improves baseline stability and resolution. Scanning calorimetry is widely used in polymers, pharmaceuticals, foods, and materials science for characterizing crystallinity, polymorphism, thermal stability, and cure kinetics.

Practical notes: typical sample masses are milligrams. Calibration uses standards (e.g., indium) for temperature and enthalpy. Experiments are often conducted under nitrogen, with heating/cooling rates of 1–20 °C/min. Baseline drift and instrument history require careful conditioning and correction.

Limitations include overlapping transitions, sensitivity to sample history, and dependence on heating rate. DSC provides information on transitions but may be limited for kinetic details; results are often complemented by other methods such as thermogravimetric analysis or dynamic mechanical analysis.