1. Thermal Analysis
Terry A. Ring
Chemical Engineering
University of Utah

2. Different Techniques
• Thermometric Titration (TT)
– Heat of mixing
• Thermal Mechanical Analysis (TMA)
– Thermal Expansion Coefficient
• Dynamic Mechanical Analysis (DMA)
– Viscoelastic Properties
• Differential Scanning Calorimetric (DSC)
– Heat flow during Transitions
• Thermal Gravimetric Analysis (TGA)
– Weight Loss due to decomposition
– Derivative Thermogravimetric Analysis (DTG)
• Differential Thermal Analysis (DTA)
– Heat of Transitions
• Temperature Programmed Desorption (TPD)
– Temperature at which gas is desorbed from (catalyst) surface
– Emission gas Thermoanalysis (EGT)

3. Basic Principle
• Sample is heated at a constant heating
rate
• Sample’s Property Measured
– Wt TGA
– Size TMA
– Heat Flow DSC
– Temp DTA
– Gas evolved TPD

4. TGA
• Constant Heating
Rate
– Initial Temp
– Final Temp
– Heating Rate (°C/min)
• Data
– Weight vs Time
– Weight vs Temp.
• Differential This Data
(DTG)

5. DSC

6. DSC
• Constant Heating Rate
– Initial Temp
– Final Temp
– Heating Rate (°C/min)
• Data
– Heat flow to sample minus
Heat flow to reference vs
Time (Temp.)
• Measures heat of
crystallization
Polymer without weight change in this temperature range

7. DTA
• Sample and Reference Placed in Heater
• Constant Heating Rate
– Initial Temp
– Final Temp
– Heating Rate (°C/min)
• Data
– Temp of Sample vs Time (or Temp)
– Temp of Reference vs Time (or Temp)
– Reference should be inert, e.g. nothing but latent heat
• Measures
– Heat of crystallization
– Glass Transition Temperature

8. DTA + DTG

9. TMA
• Constant Heating Rate
– Initial Temp
– Final Temp
– Heating Rate (°C/min)
• Data
– Size of Sample vs Time (or Temp.)
• Measures
– Thermal Expansion Coefficient
– Volume change on crystalization or crystal
transformations
– Sintering
– Glass Transitions in Polymers

10. TMA
Polymer with glass transition

11. DMA
• Constant Heating Rate
– Initial Temp
– Final Temp
– Heating Rate (°C/min)
• Data
– Force vs Time (or Temp.)
– Force delay vs Time (or
Temp.)
– Viscoelastic Properties
• Storage and Loss Modulus
• Measures
– Glass Transition
– Viscoelastic Properties Polymer with Glass Transition

12. We have TGA - only
• Heating a sample of Calcium oxalate
• Ca(C204)*xH2O  Ca(C204) *H2O + x-1 H2O
• Ca(C204)*H2O Ca(C204) + H2O
• Ca(C204)  CaCO3 + CO
• CaCO3  CaO + CO2

13. TGA
• Constant Heating
Rate
– Initial Temp
– Final Temp
– Heating Rate (°C/min)
• Data
– Weight vs Time
– Weight vs Temp.
• Differential This Data
(DTG)

14. TGA – Ca(C204)*xH2O

15. Different Heating Rates

16. Heating Rate
• Heating Too Fast
– Overlaps Transitions
• Interpretation Problems
• Kinetics of Decomposition
– Sample Size
– Mass Transfer
• Convective Mass Transfer
• Pore Diffusion
– Heat Transfer
• Convective Heat Transfer
• Thermal Conductivity
– Porous solid

17. Precipitated Zr5O8(SO4)2*15 H2O
This sample was dried fro 48 hrs at 110C before TGA analysis.
What is going on?

18. Analysis of Filtrate from
Precipitation
• Precipitation
• 5ZrOCl2 + 2H2SO4 + xH2O 
Zr5O8(SO4)2*15 H2O (s) + 10 HCl
• Decomposition
• Zr5O8(SO4)2*15 H2O (s) 
Zr5O8(SO4)2*14 H2O (s) + H2O (v)
• Zr5O8(SO4)2  5
ZrO2 (s) +2 SO2 (v)