Experimental methods in chemical engineering: Differential scanning calorimetry-DSC

Differential calorimetry assesses energy flow between a sample and its environment. The sample may be heated at a known heating rate (either constant or temperature modulated), or held in an isothermal environment or adiabatic environment depending on instrument and experimental design. The subset of differential calorimetry that deals with known heating or cooling rates is termed differential scanning calorimetry (DSC) and is a foundational technique to modern thermodynamics. It reports the heat flow versus temperature or time from which we calculate specific heat capacity at constant pressure, cP, enthalpy of fusion, and the heat of reaction. Moreover, it identifies how microstuctural properties evolve and thermal arrests-a characteristic of phase transitions. Heat-flux DSCs measure the temperature difference between a reference and a sample that sit on a thin two-dimensional plate. Power compensated DSCs heat reference material and the sample in independent furnaces while maintaining each at the same temperature. The Tian-Calvet DSC is similar to the heat-flux DSC, but minimizes error induced at high temperature with ring shaped thermopiles that surround the reference and the sample and in most designs incorporate the independent furnaces characteristic of heat flux DSC (three-dimensional heat flow probe). Convection and radiation energy leaks compromise accuracy above 600 circle C, particularly for pan-style heat flux and power-compensated DSC, which are sensitive to heat transfer by conduction only. The Tian-Calvet DSC maximizes the signal-to-noise ratio by enveloping the sample and reference in the thermopile. Web of Science indexed 11 800 articles in 2016 and 2017 that mentioned DSC and assigned 789 to chemical engineering, which ranks it 5th after polymer science, material science, physical chemistry, and multi-disciplinary chemistry. A bibliometric analysis recognizes four research clusters: polymers and nano-composites, alloys and kinetics, nano-particles and drug delivery, and fibres.