Thermal analysis
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Thermal Analysis. Terry A. Ring Chemical Engineering University of Utah. Different Techniques. Thermometric Titration (TT) Heat of mixing Thermal Mechanical Analysis (TMA) Thermal Expansion Coefficient Dynamic Mechanical Analysis (DMA) Viscoelastic Properties

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Thermal Analysis

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Thermal Analysis

Terry A. Ring

Chemical Engineering

University of Utah


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)


Basic Principle

  • Sample is heated at a constant heating rate

  • Sample’s Property Measured

    • Wt TGA

    • SizeTMA

    • Heat FlowDSC

    • TempDTA

    • Gas evolvedTPD


TGA

  • Constant Heating Rate

    • Initial Temp

    • Final Temp

    • Heating Rate (°C/min)

  • Data

    • Weight vs Time

    • Weight vs Temp.

  • Differential This Data (DTG)


DSC


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


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


DTA + DTG


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


TMA

Polymer with glass transition


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


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


TGA

  • Constant Heating Rate

    • Initial Temp

    • Final Temp

    • Heating Rate (°C/min)

  • Data

    • Weight vs Time

    • Weight vs Temp.

  • Differential This Data (DTG)


TGA – Ca(C204)*xH2O


Different Heating Rates


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


Precipitated Zr5O8(SO4)2*15 H2O

This sample was dried fro 48 hrs at 110C before TGA analysis.

What is going on?


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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