thermo gravimetric analysis

1. Thermo Gravimetric Analysis
(TGA)

2. Definition:
 Thermal Analysis is a branch of materials science by which the physical, chemical ,
and mechanical properties of materials are studied as a function of temperature.
This measurement provides information about physical phenomena, such as phase
transitions, absorption, adsorption and desorption; as well as chemical phenomena
including thermal decomposition, and solid-gas reaction

3. Methods of Thermal Analysis:

4. Thermo Gravimetric Analysis (TGA):
(TGA) Principle:
 Upon heating a certain material, its weight increases or decreases due to certain
reactions like decomposition, oxidation and dehydration.
 It measures the change in mass or weight in function with the temperature or
time with constant heating rate or constant time.
 TGA is based on that the sample is continuously weighted as temperature is
elevated using an instrument called “thermo balance”.
 Data is recorded in the form of curve called “thermo gram”.
 Instruments which can quantify loss of water, loss of solvent, loss of plasticizer are
used and comparing weight loss of material is being followed

5. Types of TGA:
 Dynamic (scanning mode) TGA:
This type of analysis the sample is subjected to conditions of continuous increase in
temperature usually linear with time.
 2) Static (Isothermal ) TGA:
This type of analysis the sample is maintained at a constant temperature for a period
of time during which any change in we

6. TGA Instruments:
Components of thermo balance:
 The balance (electronic micro balance)
 The furnace (heart)
 The programmer (brain)
 The recorder (data collector

8. Factors affecting TGA curve:
Instrumental factors:
 Furnace heating rate
 Furnace atmosphere
Sample characteristics:
 Weight of sample
 Sample particle size

9. TGA Applications:
 Materials characterization through analysis of characteristic decomposition
patterns.
 II. Can be used to evaluate the thermal stability of a material in a desired
temperature range.
 III. Can determine the inorganic or organic content in the sample

10. TGA provides a following useful
information:
 Decomposition temperatures
 Quantitative weight losses
 Compositional analysis
 Long term stabilities
 Flammability properties
 Rates of degradation
 Life time of a product
 Effect of reactive or corrosive atmospheres
 Oxidative stability of material

11. Dynamic Mechanical Analysis:
DMA Principle:
 A sinusoidal strain (oscillating force) is applied to the material at a given frequency,
while the temperature is ramped up or down over a range and deformation is
recorded.
 −50 and 220° C for polymers
 25 and 600° C for glasses and ceramics
 50 and 600° C for metals
 Sinusoidal motion is the repeated motion in which the dynamic clamp repeated the
same movement over and over with maximum and minimum values of forces

12. DMA Instrument:

13. DMA Information:
 Through DMA, some useful properties of materials can be measured, such as the
viscoelasticity, dynamic elastic modulus (E’) and the glass transition temperature
(Tg) in polymers , damping behavior , creep recovery behavior .

15. Glass transition temperature(Tg):
 The temperature at which the maximum in the tan delta peak is observed.
 It defines the point at which the material transitions from an elastic to a rubbery
state