Low field NMR for analysis of rubbery polymers [Elektronische Ressource] / vorgelegt von Alexandra Elena Voda

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Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2006
• Nombre de lectures: 26
• Langue: Deutsch
• Poids de l'ouvrage: 1 Mo

Extrait

Low Field NMR for
Analysis of Rubbery Polymers


Von der Fakultät für Mathematik, Informatik und Naturwissenschaften der Rheinisch-
Westfälischen Technischen Hochschule Aachen zur Erlangung des akademischen Grades
einer Doktorin der Ingenieurwissenschaften genehmigte Dissertation

vorgelegt von

Master of Science
Alexandra Elena Voda (geb. Stroescu)
aus Rm. Vilcea, Rumänien







Berichter: Universitätsprofessor Dr. Dr. h.c. Bernhard Blümich
Universitätsprofessor Dr.-Ing. Edmund Haberstroh

Tag der mündlichen Prüfung: der 1 Februar 2006
Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar.





Content

List of Tables ...............................................................................................................................I
List of Figures...........................................................................................................................III
List of Abbreviations and Symbols ..........................................................................................IX
1 Introduction ........................................................................................................................1
2 Basics of NMR ...................................................................................................................5
2.1 Definition....................................................................................................................5
2.2 Equipment...................................................................................................................6
2.3 General Considerations...............................................................................................6
2.4 Classical Approach .....................................................................................................9
2.4.1 Bulk Magnetization ............................................................................................9
2.4.2 Rotating Frame .................................................................................................10
2.4.3 Relaxation.........................................................................................................12
2.5 Quantum Mechanics Approach ................................................................................19
2.5.1 Quick Overview of Quantum Mechanics .........................................................19
2.5.2 Anisotropic Nuclear Spin Interactions .............................................................20
2.5.3 Excitation and Detection of Nuclear Transitions .............................................23
2.6 NMR for Elastomers.................................................................................................29
2.6.1 BWR Theory.....................................................................................................31
2.6.2 Autocorrelation and Spectral Density...............................................................32
2.6.3 Anderson/Weiss Formalism .............................................................................34
2.6.4 NMR Models for Polymer Investigation ..........................................................36
3 Thermoplastic Polyurethanes ...........................................................................................43
3.1 Introduction ..............................................................................................................43
3.1.1 Polyurethane chemistry, structure and property relationship ...........................43
3.2 Experimental.............................................................................................................47
3.3 Results and Discussion .............................................................................................51
3.3.1 DSC Measurements ..........................................................................................51
3.3.2 Rebound Resilience Measurements ................................................................. 55
3.3.3 Hardness Measurements .................................................................................. 57
3.3.4 Tensile Test Measurements.............................................................................. 58
3.3.5 NMR Measurements ........................................................................................ 62
3.4 Microscopic-Macroscopic Properties Correlations.................................................. 75
3.5 Conclusions.............................................................................................................. 83
4 Segmental Dynamics and Orientation in EPDM Elastomers: Influence of Fillers.......... 87
4.1 Introduction.............................................................................................................. 87
4.2 Experimental............................................................................................................ 89
4.2.1 NMR Measurements ........................................................................................ 91
4.3 Results and Discussion ............................................................................................ 92
4.4 Conclusions............................................................................................................ 102
5 Summary and Outlook ................................................................................................... 103
References.............................................................................................................................. 107
Appendix.............................................................................................................................. A - 1


I



List of Tables

All Tables are given in the Appendix.

Table Page
2.3.1 Nuclear isotopes and their spin quantum number. A - 2
2.5.1 Spin interactions, corresponding Hamilton operators and the size of A - 3
the interactions at 7.4T [2].
3.2.1 Composition of the TPU materials. A - 4
3.3.1 Thermal transitions of the TPU materials in Table 3.2.1 (Appendix) as A - 5
determined by DSC.
3.3.2 Rebound resilience angles for the TPU materials in Table 3.2.1 A - 6
(Appendix).
3.3.3 Mechanical properties of TPU materials in Table 3.2.1 (Appendix) as A – 7
determined by hardness.
3.3.4 Mechanical properties of TPU materials in Table 3.2.1 (Appendix) as A - 8
determined by tensile tests.
3.3.5 Amount of the hard and soft segments and their effective relaxation A - 9
rates for the TPU materials in Table 3.2.1 (Appendix) as determined
by transverse magnetization relaxation measurements at 40° C and at
150° C.
4.2.1 Physical properties of carbon black and their amount in the studied A - 10
samples.
4.2.2 Preparation process of filled EPDM. A - 11
4.3.1 Molecular mobility of the carbon black filled EPDM samples as seen A - 12
from the two NMR models.


II
4.3.2 The slope of a fitted linear dependence of the molecular mobility as A - 14
seen from the two NMR models as a function of the amount of filler.
Residuum R gives the accuracy of the fit.
2 24.3.3 A - 15 Table 4.3.3: Average residual dipolar coupling M ?(2p ) [kHz ] as 2
determined by NMR.

III



List of Figures

Figure Page
2.3.1 The motion of a magnetic moment in a magnetic field: it executes a 7
precessional motion in which the vector sweeps out a cone at a constant
angle of the magnetic field direction.
2.3.2 8 Quantum-mechanical energies of a magnetic moment in a magnetic
field B [6]. 0
2.4.1 The motion of the magnetic moment in a magnetic field of two 10
components: a static magnetic field B and an oscillatory magnetic 0
field B perpendicular to each other. 1
2.4.2 11 In the rotating frame the effective filed B is the vectorial sum of the eff
reduced field DB and the B field (left). The effective field is also 1
expressed in terms of frequencies (right). The tilt angle q is defined as
the angle between DB and B . eff
2.4.3 (a) Hahn echo decay pulse sequence; (b) the vector model of nuclear 17
magnetization illustrating the refocusing of the isochromats in a spin –
echo experiment; (c) the evolution of the transverse magnetization M xy
as a function of the time t .
2.4.4 (a) The inversion recovery pulse sequence; (b) the vector model of the 18
nuclear magnetization illustrating the recovery of the magnetization in
the z-axis; (c) the evolution of the longitudinal magnetization M as a z
function of t .




IV
2.5.1 Energy levels and possible transitions in a two coupled half spin system 25
[10].
2.5.2 Pulse sequence for a double-quantum experiment. 27
2.6.1 Schematic representation of the polymer components (a) and details of 37
the molecular chain between the cross-link points (b).
3.1.1 Key reaction in the polyurethane materials: the reaction of the 44
isocyanate and hydroxyl group which leads to the formation of the
urethane.
3.1.2 Schematic representation of the structure of segmented polyurethane (a) 45
and the di