This document provides an overview of thermogravimetric analysis (TGA). TGA measures the mass of a substance as it is heated, allowing the determination of thermal stability and decomposition points. It describes key concepts like dynamic and isothermal TGA, and outlines the typical components of a TGA instrument including a furnace, balance, and temperature controller. Sample preparation and factors affecting analysis are also discussed. Applications include characterization of materials used in industries like pharmaceuticals and petrochemicals.

1. Presentation on
Thermal Analysis (TA):
THERMOGRAVIMETRIC ANALYSIS (TGA)

Prepared by: Mr. Franco John

2. Thermal Analysis (TA):
Contents:
Π - Concepts of thermal analysis (TA).
Π - Types of thermal analysis.
Π - Introduction to thermogravimetric analysis (TGA).
Π - Interests in studying Thermogravimetric analysis (TGA)
Π - Principles of Thermogravimetric analysis (TGA).
Π - Types of Thermogravimetric analysis (TGA).
Π - Sample preparation in TGA.
Π - Instrumentations.
Π - Factors affecting TGA.
Π - Advantages and disadvantages.
Π - Applications of TGA.
Π - References .

3. Thermal Analysis (TA):
concepts of TA:
Is a group of techniques that study
the properties of materials as they
change with temperature.
•In practice, thermal analysis gives
properties like; enthalpy, thermal
capacity, mass changes

4. and the coefficient of heat expansion
• Solid state chemistry uses thermal
analysis for studying reactions in
the solid state, thermal degradation
reactions, phase transitions and
phase diagrams.

5. Types of thermal analysis:
1- Thermogravimetric analysis (TGA): weight
or mass
2- Differential Thermal Analysis (DTA):
temperature difference .
3- Differential Scanning Calorimetry (DSC):
heat (energy)temperature.
4- Pressurized TGA (PTGA): mass changes as function
of pressure.

6. 5- Thermo mechanical analysis (TMA): deformations
and dimension
6- Dilatometry (DIL): volume.
7- Evolved gas analysis (EGA): gaseous decomposition
products.

7. 1- Thermogravimetric analysis (TGA):
Introduction:
TGA is an essential laboratory tool used for material
characterization in various environmental, food,
pharmaceutical, and petrochemical applications.
Definition: TGA is a technique in which the mass of a
substance is monitored as a function of temperature
or time as the sample specimen is subjected to a
controlled temperature program in a controlled
atmosphere.

8.  Interests in studying thermogravimetry Analysis (TGA):
TGA relies on a high degree of precision in three measurements: mass
change, temperature, and temperature change.
TGA has a wide variety of applications, it can provide information about
physical phenomena, such as second-order phase transitions,
including vaporization, sublimation, absorption and desorption.
TGA can provide information about chemical phenomena such
as chemisorptions, desolvation (especially dehydration),decomposition,
and solid-gas reactions (e.g., oxidation or reduction).
 It is an especially useful technique for the study of polymeric materials,
including thermoplastics, thermosets, elastomers, composites, plastic
films, fibers, coatings and paints.

9. Principles of TGA:
•TGA is a technique in which, upon heating a
material, its weight increases or decreases.
• This technique is used for those substances which
can exhibit weight loss or gain, loss of water, loss
of solvent, etc.
•TGA is a method of thermal analysis in which
changes in physical and chemical properties of
materials are measured as a function of increasing
temperature.

10. Cont.
• In TGA, the sample is heated in a given environment
(air, N2, CO2, He, Ar, etc.) at controlled rate.
• The temperature is increased at a constant rate for a
known initial weight of the substance and the changes
in weights are recorded as a function of temperature at
different time interval.
• This plot of weight change against temperature is called
thermogravimetric curve or thermogram.
• A TGA thermal curve is displayed from left to right.
• The descending TGA thermal curve indicates a weight
loss occurred.
these are the basic principles of TGA

11. Types of thermogravimetric analysis:
Dynamic TGA: in this type of analysis the sample
is subjected to conditions of continuous increase in
temperature usually linear with time.
Isothermal or static TGA: in this type of analysis
the sample is maintained at a constant temperature
for a period of time during which any change in
weight are noted.
Gravimetric analysis: concerned with the process
of producing and weighing a compound or element
in as pure form

12. Sample Preparation:
• The sample size should be between 2 and
50 mg.(sample characteristic)
• If you have minimum amount of sample,
run at least 1 mg.
• If possible, cover the bottom of the pan
with the sample material.
• The sample pans, ceramic or platinum, can
accommodate liquids, powders, solids or
crystals

13. • Once you have decided on the sample
form, then for best results, use
approximately the same sample weight
during each experiment. This will ensure
reproducibility.
• Many small pieces of sample are better
than one large chunk.Large particle may
result in apparent, very rapid weight loss
during heating.(sample characteristic)

14. Example: TGA Curve for AgNO3:
The horizontal portion of the
curve indicates that, there is
no change in weight (AB &CD)
and the portion BC indicates
that there is weight change.
The weight of the substance
(AgNO3) remains constant up
to a temperature of 473°C
indicating that AgNO3 is
thermally stable up to a
temperature of 473°C.
At this temperature it starts
losing its weight and this
indicates that the
decomposition starts at this
temperature. It decomposes to
NO2, O2 and Ag.
The diagram indicates the TGA
curve for AgNO3.
AgNO3 → Ag + NO2 + O2

15. • The loss in weight continues up to 608°C and
beyond this temperature the weight of the sample
remains constant, this is shown by the portion of
the curve CD.
• The portion between BC, represents the
decomposition of silver nitrate, the decomposition
is complete at 608°C leaving metallic silver as the
stable residue.
• BC indicates the point of greatest rate of change
on the weight loss curve. This is also known as the
inflection point.

16. Some times the level of temperature is indicated in the curve
Weight (%) in green, rate of weight loss (%°C) in blue.

17. What can we learn from TGA Thermal Curve?
• changes in sample composition.
• thermal stability.
• kinetic parameters for chemical
reactions in the sample.

18.  Instrumentation:
•The sample is continuously weighted by an instrument ,
called thermo balance.
•The instrument vary based on the sample needed to be
analyzed.
 Four general components of the TGA instrument:
 A recording balance
A furnace
Furnace programmer or controller
A recorder device

19. Instrumentation:

20. TEMPERATURE PROGRAMMER
BALANCE
CONTROLLER
POWER
FURNACE TEMP.
SAMPLE TEMP.
WEIGHT
GAS IN

21. How do I clean the TGA furnace?
A The furnace is easily cleaned by having the furnace open to
air and heating it up to 900 °C and actually “cooking” all
organic residue off the furnace.
Factors affecting the TGA:
(1) Instrumental factors
(a) Furnace heating rate
(b) Furnace atmosphere
(2) Sample characteristics
(a) Weight of the sample
(b) Sample particle size

22. Advantages of TGA:
The TGA provides the following useful information:
Decomposition temperatures
Quantitative weight losses
Compositional analysis
Long term stabilities
Flammability properties

23.  Disadvantages:
•Only provides meaningful data when a
change in mass occurs.
• Some liquids can be measured, but this is
generally very difficult to do.
• Very small samples are used, so non-
homogeneous materials generally cannot be
tested.

24.  Applications of TGA:
• TGA is used as a technique to characterize
materials used in various environmental,
food, pharmaceutical, and petrochemical
applications.
• TGA can be used to evaluate the thermal
stability of a material In a desired
temperature range.
• Can determine the purity of a mineral,
inorganic compound, or organic material.
• TGA is used to study the kinetics of the
reaction rate constant.

25. •Used in the study of catalyst.The change in
the chemical states of the catalyst.
•TGA is used in Carbon NanoTubes (CNT)
manufacturing process to characterize the
amount of metallic catalytic residue that
remains on the CNT.

26. Conclusion:
TGA analysis is widely used to characterize
and verify materials. TGA is applicable
to most industries. Environmental, food
science, pharmaceutical, and petrochemical
applications are the mainstay of
Thermogravimetric Analysis and Evolved Gas
Analysis. (to analyze the gas products from a TGA experiment.)

27. References
[1] Coats, A. W.; Redfern, J. P. (1963). "Thermogravimetric Analysis:
A Review". Analyst. 88 (1053): 906 - 924.
Bibcode:1963Ana....88..906C. doi:10.1039/AN9638800906.
[2] Pharmaceutical drug analysis Ashutosh Kar page no:
194
[3] C. M. Earnest (Ed.), Compostional Analysis by Thermogravimetry,
ASTM STP 97, American Society for Testing and Materials (1988).
[4]Thermogravimetric Analysis (TGA) A Beginner’s Guide
Page No: 7, 8 &18.
[5] Brown, Michael E. 1988. Introduction to Thermal Analysis:
Techniques and Applications. New York, NY: Chapman and Hall.