1.
Thermogravimetric analyser
By
Dr. S. PUGALENDHI, Emeritus Professor
Dr. P. VIJAYAKUMARY, Assistant Professor
Er. T. AYISHA NAZIBA, II-M.Tech.(REE)

2.
 Thermal Gravimetric Analysis (TGA) is a type of testing that is performed on samples to determine
changes in weight in relation to change in temperature. Such analysis relies on a high degree of
precision in three measurements; Weight, Temperature and Temperature Change.
 A derivative weight loss curve can be used to predict the point at which weight loss is more
apparent. The analyzer usually consists of a high-precision balance with a pan (generally Platinum)
loaded with the sample.
 The pan is placed in a small electrically heated oven with a thermocouple to accurately measure the
temperature. The atmosphere may be purged with an inert gas to prevent oxidation or other
undesired reactions.

3.
 A computer is used to control the instrument. Analysis is carried out by raising the temperature
gradually and plotting weight (Percentage) against temperature.
 The temperature in many testing methods routinely reaches 1000°C or greater, but the oven is so
greatly insulated that an operator would not be aware of any change in temperature even if
standing directly in front of the device.
 After the data are obtained, curve smoothing and other operations may be done such as to find the
exact points of inflection.

4.
Procedure
 Switch on the thermo-gravimetric analyzer setup and also the computer system connected to it.
 Double click on the TA instruments icon available in the desktop. A window with the Q50 TGA
programme appears. Enter the appropriate input which is given in the following steps.
 Open the nitrogen gas valve and the TGA release valve.
 Check the sample pan for its cleanliness and carefully use tweezers to place the empty pan on the
sample platform, making sure the pan is correctly oriented on the platform.
 Press the TARE button located on the console on the bottom of the instrument. The instrument will
perform an automated tare, which may take a couple of minutes.
 Take a small quantity of biomass sample and measure its mass using a weighing balance. The
sample should be in the range of 20 mg.

5.
 Once the sample is weighed, it is transferred into the pan carefully. Then again the pan is placed on the platform. The
external residues on the platform are wiped off to avoid disturbances to the pan.
 Now enter the appropriate inputs into the Q50 TGA program
 Summary tab
Mode : TGA 1000C
Test : Ramp
Sample Name : Biomass materials (Name it accordingly)
Pan type : Platinum
Comments : None
Data file Name : (Specifies where the data from the experiment to be stored)
 Procedure tab
Test : Ramp
Heating rate : 20C /min (Select based on the requirement)
Final temperature : 900C

6.
 Click apply to save changes
 Press the green button on the top-left corner of the software to start the run. The TGA instrument
will automatically perform the experiment. Once the experiment is finished, the instrument will
automatically unload the sample on to the sample platform and begin an air cooling sequence.
 If there is any residue left on the sample pan, carefully hold the pan using long tweezers and clean
the pan by using tissue paper.
 Raise the furnace to check the internal furnace temperature (Control – furnace up).
 Once the furnace has fully scaled, check the temperature reading on software. If the temperature
has turned to room temperature, proceed with the next sample. If not, repeat the air cooling
sequence.

7.
Results