thermal analysis 462 pres
TRANSCRIPT
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.