Optimised polyolefin branch quantification by _1hn1_1hn3C NMR spectroscopy [Elektronische Ressource] / Katja Klimke
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Optimised polyolefin branch quantification by _1hn1_1hn3C NMR spectroscopy [Elektronische Ressource] / Katja Klimke

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OptimisedPolyolefinBranchQuantification13by CNMRSpectroscopyDissertationzurErlangungdesGradesDoktorderNaturwissenschaften“”amFachbereichChemie,PharmazieundGeowissenschaftenderJohannesGutenberg Universit at¨ MainzKatjaKlimkegeboreninMainzMainz,20062Die vorliegende Arbeit wurde in der Zeit von September 2001 bis April 2006 amMax Planck Institutf ur¨ PolymerforschunginMainzangefertigt.Tagdermundlichen¨ Prufung:¨ 07.07.2006Abstract13Quantitative branch determination in polyolefins by solid and melt state C NMRhas been investigated. Both methods were optimised toward sensitivity per unittime.Whilesolid stateNMRwasshowntogivequickalbeitonlyqualitativeresults,melt state NMR allowed highly time efficient accurate branch quantification. Com parison of spectra obtained using spectrometers operating at 300, 500 and 700 MHz1HLarmorfrequency,with4and7mmMASprobeheads,showedthatthebestsen 13 1–sitivity was achieved at 500 MHz using a 7 mm C H optimised high temperatureprobehead. For materials available in large quantities, static melt state NMR, usinglarge diameter detection coils and high coil filling at 300 MHz, was shown to pro duce comparable results to melt state MAS measurements in less time. While theuse of J coupling mediated polarisation transfer techniques was shown to be pos sible, direct polarisation via single pulse excitation proved to be more suitable forbranchquantificationinthemelt state.

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Publié par
Publié le 01 janvier 2006
Nombre de lectures 27
Langue English
Poids de l'ouvrage 17 Mo

Extrait

OptimisedPolyolefinBranchQuantification
13by CNMRSpectroscopy
Dissertation
zurErlangungdesGrades
DoktorderNaturwissenschaften“

amFachbereichChemie,PharmazieundGeowissenschaften
derJohannesGutenberg Universit at¨ Mainz
KatjaKlimke
geboreninMainz
Mainz,20062
Die vorliegende Arbeit wurde in der Zeit von September 2001 bis April 2006 am
Max Planck Institutf ur¨ PolymerforschunginMainzangefertigt.
Tagdermundlichen¨ Prufung:¨ 07.07.2006Abstract
13Quantitative branch determination in polyolefins by solid and melt state C NMR
has been investigated. Both methods were optimised toward sensitivity per unit
time.Whilesolid stateNMRwasshowntogivequickalbeitonlyqualitativeresults,
melt state NMR allowed highly time efficient accurate branch quantification. Com
parison of spectra obtained using spectrometers operating at 300, 500 and 700 MHz
1HLarmorfrequency,with4and7mmMASprobeheads,showedthatthebestsen
13 1–sitivity was achieved at 500 MHz using a 7 mm C H optimised high temperature
probehead. For materials available in large quantities, static melt state NMR, using
large diameter detection coils and high coil filling at 300 MHz, was shown to pro
duce comparable results to melt state MAS measurements in less time. While the
use of J coupling mediated polarisation transfer techniques was shown to be pos
sible, direct polarisation via single pulse excitation proved to be more suitable for
branchquantificationinthemelt state.Artificiallinebroadening,introducedbyFID
truncation,wasabletobereducedbytheuseof pulse trainheteronucleardipolar
decoupling.Thisdecouplingmethod,whencombinedwithanextendedduty cycle,
allowed for significant improvement in resolution. Standard setup, processing and
analysis techniques were developed to minimise systematic errors contributing to
the measured branch contents. The final optimised melt state MAS NMR method
was shown to allow time efficient quantification of comonomer content and distri
bution in both polyethylene and polypropylene co olefins. The sensitivity of the
technique was demonstrated by quantifying branch concentrations of 8 branches
per 100,000 CH for an industrial linear polyethylene in only 13 hours. Even lower2
degreesof3–8long chainbranchesper100,000carbonswereabletobeestimatedin
just24hoursforaseriesof irradiatedpolypropylenehomopolymers.
3Contents
1 Introduction 9
1.1 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2 BranchinginPolyolefins 14
2.1 Polyethylenesynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.1.1 1930s:Low densitypolyethylene(LDPE) . . . . . . . . . . . . . 16
2.1.2 1950s:High densityp(HDPE) . . . . . . . . . . . . 18
2.1.3 1970s:linearlow densitypolyethylene(LLDPE) . . . . . . . . . 19
2.1.4 1980s:ultra highmolecularweightpolyethylene(UHMWPE) . 19
2.2 Polypropylenesynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2.1 Stereo regularpolypropylene(iPP/sPP) . . . . . . . . . . . . . . 20
2.2.2 Highmeltstrengthpolypropylene(HMS PP) . . . . . . . . . . . 21
2.2.3 Polypropylene co olefins . . . . . . . . . . . . . . . . . . . . . 21
2.3 Catalystsforpolyolefinsynthesis . . . . . . . . . . . . . . . . . . . . . . 22
2.3.1 Multiple sitecatalysts:Ziegler Natta/Phillips . . . . . . . . . . 22
2.3.2 Single sitecatalysts:Metallocenes . . . . . . . . . . . . . . . . . 23
2.4 Polyolefinbranchdetermination . . . . . . . . . . . . . . . . . . . . . . 27
2.4.1 Transmissioninfraredspectroscopy . . . . . . . . . . . . . . . . 27
2.4.2 Thermalfractionationmethods . . . . . . . . . . . . . . . . . . . 28
2.4.3 Multipledetectionsizeexclusionchromatography(SEC) . . . . 32
2.4.4 Rheology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.4.5 Nuclearmagneticresonance(NMR) . . . . . . . . . . . . . . . . 40
2.5 Polyolefinsstudied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3 GeneralNMRTheory 46
3.1 NMRinteractions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4CONTENTS 5
3.1.1 Zeeman interaction . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.1.2 Theeffectofradiofrequencypulses . . . . . . . . . . . . . . . . 51
3.1.3 Quadrupolarcoupling . . . . . . . . . . . . . . . . . . . . . . . . 53
3.1.4 Chemicalshift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.1.5 Dipole dipolecoupling . . . . . . . . . . . . . . . . . . . . . . . 56
3.1.6 J coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.2 Motionalinteractionaveraging . . . . . . . . . . . . . . . . . . . . . . . 59
3.2.1 Isotropicmolecularmotion . . . . . . . . . . . . . . . . . . . . . 59
3.2.2 Semi isotropicmolecularmotion . . . . . . . . . . . . . . . . . . 61
3.2.3 Magic anglespinning(MAS) . . . . . . . . . . . . . . . . . . . . 62
3.3 Nuclearrelaxation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.3.1 Spin latticerelaxation . . . . . . . . . . . . . . . . . . . . . . . . 64
3.3.2 Spin spinrelaxation . . . . . . . . . . . . . . . . . . . . . . . . . 66
3.3.3 Crossrelaxation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3.4 GeneralNMRtechniques . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3.4.1 Single pulseexcitation(SPE) . . . . . . . . . . . . . . . . . . . . 72
3.4.2 Heteronuclearspindecoupling . . . . . . . . . . . . . . . . . . . 73
3.4.3 Cross polarisation(CP) . . . . . . . . . . . . . . . . . . . . . . . 75
3.4.4 INEPT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.4.5 DEPT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.4.6 INADEQUATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.4.7 Inversion recovery . . . . . . . . . . . . . . . . . . . . . . . . . . 80
3.4.8 Saturation recovery . . . . . . . . . . . . . . . . . . . . . . . . . 80
3.5 GeneralNMRprocessingtechniques . . . . . . . . . . . . . . . . . . . . 81
3.5.1 FIDtruncationandapodisation . . . . . . . . . . . . . . . . . . . 81
3.5.2 Zerofilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4 Solid stateMASNMR 85
4.1 CPMASofPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
4.1.1 Comparisonwithsolution stateNMR . . . . . . . . . . . . . . . 87
4.1.2 PotentialoffastMAS . . . . . . . . . . . . . . . . . . . . . . . . . 88
4.1.3 VariabletemperatureCPMAS . . . . . . . . . . . . . . . . . . . 90
4.1.4 Effectsofshortrecycledelays . . . . . . . . . . . . . . . . . . . . 91
4.2 ApplicationsofoptimisedCPMAS . . . . . . . . . . . . . . . . . . . . . 926 CONTENTS
4.2.1 Branchquantification . . . . . . . . . . . . . . . . . . . . . . . . 92
4.2.2 Endgroupquantification . . . . . . . . . . . . . . . . . . . . . . 93
4.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5 Melt statestaticNMR 96
5.1 Comparisonofmelt statestaticandMASNMR . . . . . . . . . . . . . . 97
5.2 Thepotentialoflargedetectioncoils . . . . . . . . . . . . . . . . . . . . 99
5.3 Exploitationofstray B field . . . . . . . . . . . . . . . . . . . . . . . . . 1021
5.4 Highfieldstaticmelt stateNMR . . . . . . . . . . . . . . . . . . . . . . 104
5.5 Theeffectofsampletemperatureonresolution . . . . . . . . . . . . . . 107
5.6 ThePotentialofanorthogonal coilssetup . . . . . . . . . . . . . . . . . 108
5.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
6 Melt stateMASNMR 112
6.1 Comparisonwithsolution stateNMR . . . . . . . . . . . . . . . . . . . 112
6.2 Hardwaresetup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
6.2.1 Effectsofexternalmagneticfieldandrotorsize . . . . . . . . . 114
13 16.2.2 Theadvantageof C– Hoptimisedprobeheads . . . . . . . . . 116
6.2.3 OptimummeasurementtemperatureforunstabilisedPEs . . . 118
6.2.4 SamplepreparationandMASrotorpacking . . . . . . . . . . . 119
6.3 Alternativemethodsofspinpolarisation . . . . . . . . . . . . . . . . . . 122
6.3.1 Directpolarisationviasinglepulseexcitation . . . . . . . . . . . 123
6.3.2 J mediatedpolarisationtransfermethods . . . . . . . . . . . . . 130
6.4 Decouplingschemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
6.4.1 Decouplinglimitationsonacquisitiontime . . . . . . . . . . . . 135
6.4.2 Lowpowerdecoupling:WALTZ 16 . . . . . . . . . . . . . . . . 136
6.4.3 Stroboscopicdecoupling: pulse train . . . . . . . . . . . . . . 137
6.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
7 Quantitativeanalysis 141
7.1 Measuredpropertiesandacceptancecriteria . . . . . . . . . . . . . . . 141
7.2 Standardisedset upandprocessingofNMRdata . . . . . . . . . . . . 142
7.2.1 Shimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
7.2.2 Power leveldetermination . . . . . . . . . . . . . . . . . . . . . 143
7.2.3 Digitisedsignalcropping . . . . . . . . . . . . . . . . . . . . . . 144CONTENTS 7
7.2.4 Zero filling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
7.2.5 Apodisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
7.2.6 Phasecorrection . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
7.2.7 Baselinecorrection . . . . . . . . . . . . . . . . . . . . . . . . . . 147
7.2.8 Spectralintegration . . . . . . . . . . . . . . . . . . . . . . . . . . 148
7.2.9 Branchsitesusedforquantification . . . .

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