Dr. Derek Patton Techniques PSC341L/720
Electronic Handout
2008 D.L. Patton
Thermogravimetric Analysis (TGA)
Thermogravimetric Analysis (TGA) is an analytical technique that measures the amount
and rate of change in the weight of a material as a function of temperature or time in a
controlled atmosphere. TGA was developed in the early 1900’s,
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but has only been
applied to polymeric materials since 1960s.
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Measurements are used primarily to
determine the composition of materials and to predict their thermal stability at
temperatures up to 1000°C. TGA is commonly employed in research and testing to
determine characteristics of materials such as polymers, to determine degradation
temperatures, absorbed moisture content of materials, the level of inorganic and organic
components in materials, decomposition points of explosives, and solvent residues.
Mechanisms of Weight Change
At low temperatures, weight loss may originate from evaporation of residual moisture or
solvent, but at higher temperatures weight loss can arise from a various processes
including:
Decomposition: The breaking apart of chemical bonds
Evaporation: The loss of volatiles with elevated temperature
Reduction: Interaction of sample to a reducing atmosphere (hydrogen, ammonia,
etc).
Desorption
Weight gain processes may also be observed and measured with TGA. For example:
Oxidation: Interaction of the sample with an oxidizing atmosphere
Absorption
Polymer Characterization
Polymers have different thermal stabilities depending on polymer structure, composition,
etc. TGA is advantageous in that it provides a rapid method to differentiate various
polymers on the basis of temperature range, extent, rate, and activation energy of
decomposition. Figure X shows the TGA curves of several polymers illustrating the
different decomposition profiles.
Figure X. Thermograms for common polymers
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