2. Principle of DSC
The principle of DSc is “Heat flow to or from textile material is a function of time and temperature i.e. change in heat is directly proportional to the change in time(&T) as well as change in temperature(Tr-Ts).DSC) is a technique used to determine the difference of the heat flow rate between the tested sample and a reference, over a controlled temperature range. This analytical procedure is achieved in a closed system, which is isolated from the surroundings by some boundary, through which only heat and energy but not mass are able to flow. Calorimetry can be conducted at either constant pressure or constant volume, which allows the analysts to monitor the temperature changes induced by the investigated reaction.
DSC is often used to obtain the information about properties and composition of unknown materials, investigate sample purity and confirm composition analysis; meanwhile, DSC is also quite popular in the food and pharmaceutical industries to characterize and enable the fine-tuning of certain properties; the stability of macromolecules and folding/unfolding information can be measured with DSC experiments.Heating rate is 0.1 to 200°C and cooling rate is 1 to 50°C/min.
The glass transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs. It is always lower than the melting temperature Tm, of the crystalline state of the material, if one exists.he DSC measurements reported in this book are performed with the power-compensating DSC-2 and DSC-7 systems from perkin Elmer. The block surrounding the DSC sample holders is kept at −150°C ± 1°C.
3. Uses of DSC
- DSC is used for measuring thermal behaviour of block co-polymer,homo co-polymer and blends which are used.It is used to measure thermal history of the material.
- Measurement of Tg
- Specific heat capacity
- Thermal stability
- Chemical reactions
- Life of material(sonic modulus technique,X-ray diffraction,bi-fringes
If the crystallinity of the material is high so that there is high mobility of the molecule and higher glass transition temperature.). Level crystallinity means maximum crystallinity.
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