DifferentialScanThermolyse

Differential Scanning Calorimetry (DSC) is a thermoanalytical technique used to measure the heat flow into or out of a sample as a function of time or temperature. By comparing the sample with an inert reference, DSC provides information about thermal transitions and reaction heats without requiring a chemical reaction to occur.

During testing, both the sample and reference pans are heated or cooled at a controlled rate in a DSC instrument. The instrument records the difference in heat flow between the two pans. Phase transitions such as melting, crystallization, and glass transitions appear as endothermic or exothermic events on a DSC curve, while baseline shifts reflect changes in heat capacity.

DSC instruments can operate in conventional or modulated modes. In standard DSC, a constant heating rate is applied. In modulated DSC, a small sinusoidal temperature modulation is added on top of the overall ramp, allowing separation of reversing and non-reversing heat effects and improved baseline resolution. Calibrations often use a known reference material such as indium.

Outputs include peak temperatures (Tm for melting, Tc for crystallization, Tg for glass transition) and associated enthalpies (ΔHf, ΔHc). From ΔHf, the crystallinity of a polymer can be estimated. Common sample sizes are in the milligram range, and data can be influenced by heating rate, sample preparation, and purge gas.

Applications span polymers, pharmaceuticals, foods, and metals to characterize thermal properties, purity, stability, and curing reactions. DSC is valued for speed, small sample requirements, and broad applicability, but interpretation requires care to account for baseline drift, overlapping transitions, and instrument calibration.