Differential scanning calorimetry DSC

1. Differential scanning
calorimetry (DSC)
Haneen
Abukatab
Murad Abu hasan

2. Differential Scanning Calorimetry, or DSC:
 is a thermal analysis technique that looks at how a material’s
heat capacity (Cp) is changed by temperature. A sample of
known mass is heated or cooled and the changes in its heat
capacity are tracked as changes in the heat flow.
 Quantitative measure heat absorbed or release.
 This allows the detection of transitions such as melts, glass
transitions, phase changes.
 DSC is used in many industries, including pharmaceuticals,
polymers, food, paper, printing, manufacturing, agriculture,
semiconductors, and electronics.
Heat capacity (Cp) is the amount of energy a unit of
matter can hold.

4. sample undergoes a physical transformation
such as phase transitions, more or less heat
will need to flow to it than the reference to
maintain both at the same temperature.
These transitions involve energy changes or
heat capacity changes that can be detected by
DSC with great sensitivity.

5. DSC curve

7. Heat Flux DSC
 in Heat-Flux DSC, the difference in heat flow into the
sample and the reference is measured while the
sample temperature is changed at a constant rate.
 Both sample and reference are heated by a single
heating units.
 Use of disc thermocouple (TC) to measure the
temperature difference between sample and reference

8. • These are most fundamental types of heat flux DSC:
The disk-type measuring system, where the heat
exchange takes place via a disk which serves as solid
sample support.
The turret-type measuring system, where the heat
exchange takes place via small hollow cylinders which
serve as elevated sample support.
The cylinder-type measuring system, where the heat
exchange between the (big) cylindrical sample cavities
and the furnace takes place via a path with low thermal
conductivity (often a thermopile).

9. Fig.2.1. a Heat flux DSC with disk-
type measuring system.
1 disk,
2 furnace (‫فرن‬)
3 lid
4 differentia thermocouple(s)
5 programmer and controller,
S sample substance,
R reference sample substance,
ɸps heat flow rate from furnace
to sample.
ɸpR heat flow rate from furnace
to reference sample.
(

10. Fig.2.2. Heat flux DSC with turret-
type measuring system (TA
Instruments).
1 -elevated constantan
platform for sample and
reference sample,
2- chromel area thermocouple,
3 constantan
body,
4- chromel - constantan
thermocouple,
5- silver furnace, S sample
substance,
R reference sample substance,~T
platform temperature difference,
To body (furnace) temperature

11. Fig.2.3. Heat flux DSC with
cylinder-type measuring
system
(
1- containers to take up sample
and reference sample,
2- thermopiles,
3- furnace (with programmable
temperature controller),
4- lid
S- sample substance
R- reference sample substance,
∆ T temperature difference
between the containers

12.  Power Compensation DSC
 A technique in which difference of thermal energy that is applied to the
sample and the reference material per unit of.
 In a power compensation DSC, the sample and reference pans are placed in
separate furnaces heated by separate heaters. The sample and reference
are maintained at the same temperature, and the difference in thermal
power required to maintain them at the same temperature is measured and
plotted as a function of temperature or time.

13. Fig.2.S. Power compensation DSC
S sample measuring system with sample crucible,
microfurnace and lid, R reference sample
system (analogous to S), 1 heating wire, 2
resistance thermometer. Both measuring systems
-
separated from each other - are positioned in a
surrounding (block) at constant temperature

14. DIFFERENTIAL SCANNING
CALORIMETRIC SAMPLE TEST
DSC Thermal Analysis is used primarily for :
• Polymers
• Plastics
• Monomers
• Elastomers
• Organic materials
• Chemicals
• Biological samples

15. ADVANTAGES
• Wide range of temperatures
• Any material in any form may be tested
• Small amount of material is needed (1-10mg)
• Does not take much time (10-30 minutes)
• Auto sampler and auto analysis

16. DISADVANTAGES
• Interpretation of results is often difficult.
• Quantitative analysis of the individual processes is impossible.
• Cannot optimize both sensitivity and resolution in a single experiment.
• Very sensitive to any changes.