Thermal AnalysisBy: Andrew Paul, Martin Antensteiner,

Maddie Boyer, Ahmad Alraddadi, Dave Walkling

Introduction

• Dilatometry:CTE (coefficient of thermal expansion) of titanium.

• TGA (Thermogravimetric analysis)the amount of water in zirconyl nitrate hydrate.

• DSC (Differential scanning calorimetry) :percent crystallinity of PET (polyethylene terephthalate)

Procedure: Dilatometry of Ti

• Theta Industries Dilatronico Initial Temperature 0oCo 6oC/min to 1100oC

• Ambient Nitrogen Gaso 0.5SCFH

• Initial Length 25.42mm

Procedure: Dilatometry of Ti

• Polycrystalline Ti (assumed to be isotropic)• Assume sample is homogenous

• Calibrated Equipment

• Rod composed of aluminao To limit the oxidation of Ti to TiO2

Dilatometry of Ti Results

CTE = 10.614 ppm/K

Dilatometry of Ti Results

860oC used as the cutoff between cool and hot CTEs.

Dilatometry of Ti Results

CTEcool = 10.594 ppm/K CTEhot = 11.692 ppm/K

Dilatometry of Ti Discussion

• The distinct change of CTE was due to a phase change in Ti

• Phase Change at 882oC which is similar

to the 860oC used in the data

Dilatometry of Ti Discussion

• CTEcool = 10.594 ppm/K

• CTEhot = 11.692 ppm/K

• Accepted values based on MatWeb o 8.9 ppm/K at temperatures from 20oC to 100oCo 10.1 ppm/K at temperatures above 1000oC

• CTE of TiO2 mineralso Rutile - 7.14 ppm/Ko Anatase - 10.2 ppm/Ko Brookite - 11.0 ppm/K

Dilatometry of Ti Discussion

• CTE data predicts that there was some oxidation of the titanium sample with higher CTEs

Procedure: TGA of zirconyl nitrate hydrate

• SDT Q600 from TA Instruments Inc.• Initial mass of zirconyl nitrate hydrate

o = 10.905mg

• Gas used; Nitrogen at 100.0mL/min

• Calibrated with Al2O3 sample for referenceo Identical mass to test sampleo DTA and TGA run simultaneously

• Increase of 5 °C/min to 500.00°C

TGA Results

Mass of zirconium dioxide = 4.154mg

Water

Nitrogen

Oxygen

Determination of water content in zirconyl nitrate hydrate

• Balanced Stoichiometric Equation=> ZrO(NO3)2*xH2O

ZrO2+2NO2+1/2O2+xH2O

• Finding "x"o Ratio of end to starting mass o Ratio of ending to starting molecular weight (MW)o Set ratios equal to each othero Solve for "x"

Determination of water content in zirconyl nitrate hydrate

• Finding "x"o Ratio of end to starting mass = 0.381o Ratio of end to starting MW in g/molo ZrO2/(ZrO(NO3)2 + xH2O)

• 123.218/(231.233 +x*18.001) = 0.381o x = 5.333 ~ 5 total water molecules

• ZrO(NO3)2*5H2O ZrO2+2NO2+1/2O2+5H2O

TGA Discussion

• Effects of testing conditionso Heating Rate

• 5°C/min standard• Faster rates lead to poor resolution

o Result of increased reaction rates at higher temperature

TGA Discussion

• Effect of Testing Conditionso Sample Size

Smaller grain size reduces temperature gradient across sample• Results in more gradual mass reduction during testing

o Atmosphere Altering the atmosphere can give rise to the

origin of the thermal reaction• Different gasses can dictate at what temperature a

compound decomposes Alters precision of the test

Procedure: DSC of PET

• DSC Q100 from TA Instruments Inc.o heat-flux type DSC

• Inert Gas used; Nitrogen 20 ml/min

• Calibrated with air sample for reference

• 7.1 mg of sample used

Figure: Schematic of the Q100 DSC by TA Instruments.

Procedure: DSC of PET

1st heating

2nd heating

DSC of PET Results

Cooling

2nd Melting

1st Melting

DSC of PET Results

DSC of PET Results cont.Estimated Hf= 27.4J/g

Delta Hm of pure PET: 140.1 J/g

%Percent Crystalization:27.4/140.1*100=19.5

DSC of PET Discussion

• Explanation of Calculations• Differences in heating cycle

o First heating cycleo Second heating cycle

Conclusion

• Dilatometry: different CTEs - different phases of Ti.

• TGA: heated the sample to produce Zirconia, find water amount.

• DSC: enthalpy of formation relates to % crystallinity.