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Thermal analysis

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  • 1. Thermal Analysis Terry A. RingChemical 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. TMAPolymer 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)

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