it is a technique in which the energy necessary to establish a zero temp. difference between the sample & reference material is measured as a function of temp. The technique was developed by E. S. Watson and M. J. O'Neill in 1962 and introduced commercially in 1963 at Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy. In this method, sample & reference material are heated by separate heaters in such a way that their temp is kept equal while this temp. are increased or decreased linearly. These measurements provide quantitative and qualitative information about physical and chemical changes that involve endothermic or exothermic processes, or changes in heat capacity. DSC Is widely used to measure glass transition temp & characterization of polymer.

In this course, students will understand the different types of DSC instruments available. There are five different types of DSC instruments as-1. Heat flux DSC, 2. Power compensated DSC, 3. Modulated DSC, 4. Hyper DSC, 5.Pressure DSC. Commonly used DSC instruments are Heat Flux DSC and Power Compensated DSC. The heat flux DSC is based on the Change in Temperature ΔT between the sample and reference. In power compensation DSC, the temperatures of the sample and reference are kept equal to each other while both temperatures are increased or decreased linearly. Power compensated DSC has lower sensitivity than heat flux DSC, but its response time is more rapid. This makes power-compensated DSC well suited for kinetics studies in which fast equilibrations to new temperature settings are needed. it is also capable of higher resolution than heat flux DSC.

Here, students will be able to learn about the different factors that affect the DSC curve such as 1. Instrumental factors: Furnace heating rate, Recording or chart speed, Furnace atmosphere, Geometry of sample holder/location of sensors, Sensitivity of the recording system, Composition of sample containers. 2. Sample characteristics: Amount of sample, Nature of sample, Sample packing, Solubility of evolved gases in the sample, Particle size, Heat of reaction, Thermal conductivity.

Students will understand the advantages, disadvantages, and applications of the DSC method for analysis. Advantages of DSC- Instruments can be used at very high temperatures. Instruments are highly sensitive. Flexibility in sample volume/form. Characteristic transition or reaction temperatures can be determined. A high resolution was obtained. High sensitivity. Stability of the material.

Limitations of DSC- DSC is generally unsuitable for two-phase mixtures. Difficulties in test cell preparation in avoiding the evaporation of volatile Solvents. DSC is generally only used for thermal screening of isolated intermediates and products. Does not detect gas generation. Uncertainty of heat of fusion and transition temperatures.

Applications- Determine the melting behavior of complex organic materials, both temperatures and enthalpies of melting can be used to determine the purity of a material. Measurement of plastic or glassy material glass transition temperatures or softening temperatures, which change depending upon the temperature history of the polymer or the amount and type of fill material, among other effects. Determines crystalline to amorphous transition temperatures in polymers and plastics and the energy associated with the transition. Determine the thermal stability of a material. Determine the reaction kinetics of a material.

In this lecture the video of demonstration of DSC instrument was shared. With the help of this, the students will understand the working of the DSC cell and how it work when materials will undergo the heating with varying temperature. The content includes the example of polypropylene and polystyrene.