Discovery TGA™ Getting Started Guide
Page 19
Modulated TGA™ (MTGA™)
TA Instruments Modulated TGA (MTGA) is an innovative option that is used with Thermogravimetric
Analyzers. This option is used to study the same decomposition or volatilization properties as conventional
TGA. However, MTGA provides unique capabilities that increase the amount of information obtained
from a single TGA experiment, thereby improving the quality of interpretation.
These unique capabilities include:
•
continuous determination of activation energy
•
verification of single kinetic mechanism
•
verification of first-order kinetic model.
MTGA is an enhancement of TGA that provides the same information as traditional TGA, plus new infor-
mation that permits unique insights into the behavior of the weight loss reaction.
Specifically, MTGA provides an alternative way to obtain kinetic information about one or more weight
losses, in a shorter period of time than the multiple heating rate approach.
In addition, MTGA provides continuous determined values for activation energy throughout the weight
loss reaction, not just at specific reaction levels. The ability to obtain activation energy continuously allows
you to follow changes in the activation energy during the reaction, as a function of temperature or
conversion. The calculation of activation energy is “model free” – no knowledge about the form of the
kinetic equation is required.
The assumption of a first-order kinetic model (a reasonable assumption for many decomposition
reactions), permits the calculation of natural logarithm of the pre-exponential factor in the same manner as
the continuous determination of activation energy.
Other Discovery TGA Accessories
The TGA can be interfaced with many standard analytical accessories offered by various manufacturers
such as FTIR spectrometers, mass spectrometers, gas chromatographs, and evolved gas analyzers.
For the TGA 5500, to assist in the performance of mass spectrometer analysis and to prevent condensation
between the IR furnace and the transfer line to the other coupled instrument, the standard connector at the
outlet can be replaced by an optional heated connector. Purge gas, exiting the balance chamber above the
furnace, exits by the same route.
If desired, a vacuum pump can be connected to the standard 1/4-inch Swagelok connector of the IR furnace
or the 1/8-inch Swagelok connector of the EGA furnace at the furnace gas outlet.
Consult the appropriate local instrument manufacturer for further information.
