Team members: Rampravesh, Nibedita, Balraj, Periyasamy, Durgakishore, M.S Dhar,
S.Chatterjee , V.G.Prabhu
Seminar by : Vijaykumar S Marakatti
Poornaprajna Institute of Scientific research, Bangalore
Change in physical properties of water with increase in temperature
Applied thermal analysis techniques
Change in physical property
Thermo gravimetric analysis (TGA)
It is an analysis, the mass of sample is recorded
continuously as its temperature is increased linearly from
ambient to high temperature.
Mass of material a functions of temperature.
Processes occurring without change in mass (e.g.- Physical
transitions ) cannot be studied by TG.
Reactant(s) Product(s) + Gas (a mass loss)
Gas + Reactant(s) Product(s) (a mass gain)
Thermal Gravimetric Instrument
Balance- hang down here
Best practices for Thermal Analysis
Removal of absorbed water by drying.
Use purge gas (N2or He) to remove corrosive off-gases
Use samples with narrow grain size distribution.
For measurement in vacuum, sample Grain size > 60
Calibration using the
- Curie Temperature.
Keep the constant heating rate, same gas atmosphere
and crucible for the analysis.
Decomposition of CaCO3 at different
Effect of gas atmosphere and crucible on TG
Decomposition of CaCO3 using
Three factors should be noted when you get a TG curve:
1. General shape.
2. The particular T at which changes in mass occur.
3. The magnitudes of the mass changes.
Differential Thermal Analysis(DTA)
Heat absorbed or emitted by sample is observed
by measuring the temperature difference between
that sample and reference compound as
temperature of both are increased.
ΔT =TS-Tr as function of Temperature.
Temperature of furnace
Differential Thermal Analysis (DTA)
Endothermic - heat flows into the sample.
Exothermic - heat flows out of the sample.
Interpretation of DTA
ΔH = K * Peak area
K - can be determined by measuring the ΔH and peak area of know metals
Limitations of Differential Thermal Analysis
ΔT determined by DTA is not so accurate (2-3 ̊C).
Small change in ΔT cannot be determined and
Due to heat variation between sample and reference
makes, it less sensitive.
To improve the above limitations change in the
methodology is required.
To determine Tg (glass transition temperature)
Application in Food Industry
Standard TGA results for Double mint chewing
TGA auto stepwise results for Double mint
chewing gum sample
The correct combination of the gum formulation.
Elastomers, glycerin, softening agents, and carbonates, flavoring agents, poly
Application in determination of phase
113 ̊ C
Rhombohedral to monoclinic
Liquid phase transistion
To find the melting and Boiling point of
OPEN FOR DISCUSSION
DSC ???ΔH ?
/DTA ???ΔT ?