3. Differential thermal analysis
In Differential Thermal Analysis, the
temperature difference that develops between a
sample and an in reference material is
measured, when both are subjected to identical
heat treatments.
7. APPARATUS
1.Sample holder comprising thermocouples,
sample containers and a ceramic or metallic
block.
2.Furnace.
3.Temperature programmer
4.Recording system
8. Procedure
• Heart of the analysis – heating block
• Identical pair of cavities for the sample, ref.
material
• Whole unit is set in an oven- control pressure
• Thermocouple is place directly in contact with
the sample and another in contact with the
reference
9. • Temperature of the block is raised, the
temperature of the sample & reference follow
• Zero temp. difference – no physical or
chemical change
• If any reaction – difference in ∆T
12. NOTE..
• Sharp Endothermic–changes in crystallinity or
fusion Broad endotherms-dehydration
reaction Physical changes usually result in
endothermic curves Chemical reactions are
exothermic
14. Advantage of DTA
• Instruments can be used at very high
temperatures
• instruments are highly sensitive
•characteristic transition or reaction
temperatures can be accurately determined.