TGA/DTA

1

• Thermogravimetric analysis– The technique in which the mass change in a sample

is measured as a function of temperature, while subjected to a controlled temperature program.

– Sigmoidal curves

– Temperature range

– DTA

http://butterflyandbiotech.blogspot.com/2012/05/know-basics-about-dta-and-tga.htmlhttp://www.scielo.cl/scielo.php?pid=S0717-97072003000300010&script=sci_arttext

Thermal Methods

• Controlled temperature programs– dT/dt constant

– Isothermal

– Modulated

– Complex step

– Self regulating

2

T

T

t

t

TGA

3

• TGA instrumentation

http://www.tainstruments.com/product.aspx?id=21&n=1&siteid=11

Photodiodes

Infrared LED

Meter movement

Balance arm

Sample platform

Thermocouple

Sample pan Furnace assembly

Purge gas outlet

Heater

Elevator base

Purge gas inlet

Sample pan holder

Tare pan

Crucible & Thermobalance

4

• Crucible– Pt sample pans

– Ni, Al, Al2O3, SiO2, ceramic

• Thermobalance– Vertical rotating pivot

– Null deflection system

http://www.tainstruments.com/pdf/brochure/2011%20TGA%20Brochure.pdf

Furnace, Thermocouples & Atmosphere

5

• Furnace– Resistive alloy windings

• Thermocouples (B,R,S)– Pt-Pt/Rh

• Atmosphere– Inert– Removal of evolved gases– Vacuum

http://www.tainstruments.com/pdf/brochure/2011%20TGA%20Brochure.pdf

Degradation Curves

6

• Compositional Analysis– Wt.% loss

– Plateaus vs. shoulders

– Wt.% gain

a

b

c

Principles of Thermal Analysis and Calorimetry, P.J. Haines et al., Royal Society of Chemistry, 2002