Physical properties of novel polypropylenes [Elektronische Ressource] / vorgelegt von: Stefan Fischer

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• Physik

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• Publié par: universitat_ulm
• Publié le: 01 janvier 2009
• Nombre de lectures: 95
• Poids de l'ouvrage: 12 Mo

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Institut fu¨r Experimentelle Physik
Physical Properties of novel
Polypropylenes
Dissertation
zur Erlangung des Doktorgrades Dr. rer. nat.
der Fakulta¨t fu¨r Naturwissenschaften
der Universit¨at Ulm
vorgelegt von: Stefan Fischer
aus Augsburg
Jahr der Promotion: 2009Amtierender Dekan
1Prof. Dr. Peter B¨auerle
Gutachter
21. Prof. Dr. sc. nat. ETH Z¨urich Othmar Marti
32. Prof. Dr. Dr. h.c. Bernhard Rieger
Tag der Promotion
Datum: 01.12.2009
1Universit¨at Ulm, Institut fu¨r Organische Chemie II und neue Materialien
2Universita¨t Ulm, Institut fu¨r Experimentelle Physik
3Wacker-Lehrstuhl fu¨r Makromolekulare Chemie, Technische Universit¨at Mu¨nchen
2The important thing is not to stop questioning.
Albert Einstein4Contents
1. Introduction 15
I. Theoretical background 17
2. Polypropylene 19
2.1. Catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1.1. Ziegler-Natta catalysts . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1.2. Metallocene catalysts for propylene polymerization . . . . . . . . 19
2.2. Properties of polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.2.1. General properties . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.2.2. Thermal properties . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2.3. Morphology of iPP in α modification . . . . . . . . . . . . . . . . 25
2.3. Deformation behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.3.1. Typical mechanical behavior of isotactic polypropylene . . . . . . 27
2.3.2. Influence of strain rate, temperature and molecular weight . . . . 28
2.3.3. Deformation and failure mechanisms in polypropylene . . . . . . 30
2.3.4. Optimizing stress resistance and failure behavior . . . . . . . . . 31
2.4. Tie molecules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.4.1. Fischer’s solidification model . . . . . . . . . . . . . . . . . . . . 32
2.4.2. Model by Huang and Brown. . . . . . . . . . . . . . . . . . . . . 34
2.4.3. Increasing the probability for tie molecules . . . . . . . . . . . . 34
II. Experimental methods 37
3. Sample preparation 39
3.1. Blending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.2. Polymer preparation for mechanical tests and x-ray scattering . . . . . . 39
4. Chemical and physical analysis 41
4.1. Differential scanning calorimetry . . . . . . . . . . . . . . . . . . . . . . 41
4.2. Stress-strain tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5. X-ray scattering setup 45
5.1. Small-angle x-ray scattering . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.1.1. Setup beamline A2 at DESY, HASYLAB . . . . . . . . . . . . . 45
5.1.2. Stretcher with furnace . . . . . . . . . . . . . . . . . . . . . . . . 47
5.1.3. Setup Bruker ASX Nanostar . . . . . . . . . . . . . . . . . . . . 47
5.2. Wide-angle x-ray scattering . . . . . . . . . . . . . . . . . . . . . . . . . 47
6. Scanning probe microscopy 53
5Contents
6.1. Atomic force microscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6.2. Scanning electron microscopy . . . . . . . . . . . . . . . . . . . . . . . . 53
III. X-ray scattering data evaluation 55
7. Introduction to x-ray scattering 57
7.1. Laws of Bragg and von Laue . . . . . . . . . . . . . . . . . . . . . . . . 57
7.2. Generalized scattering theory . . . . . . . . . . . . . . . . . . . . . . . . 58
7.3. Scattering of cylindrical objects in a paracrystalline lattice . . . . . . . . 60
7.3.1. Amplitude factor . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7.3.2. Lattice factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
7.3.3. Total intensity in cylinder cluster model . . . . . . . . . . . . . . 65
8. Orientation of lamella clusters during stretching 67
8.1. Mathematical realization . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
8.1.1. Introducing an orientation function . . . . . . . . . . . . . . . . . 67
8.1.2. Model calculations . . . . . . . . . . . . . . . . . . . . . . . . . . 70
8.2. Simulation results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
8.2.1. Influence of the parameters . . . . . . . . . . . . . . . . . . . . . 73
8.2.2. Scattering at morphologies of special relevance . . . . . . . . . . 74
8.3. Limitations of the model and possible extensions . . . . . . . . . . . . . 75
9. Small-angle x-ray scattering of micro-voids 83
9.1. Scattering of statistically distributed particles . . . . . . . . . . . . . . . 83
9.2. Void model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
9.3. Comparison with other models . . . . . . . . . . . . . . . . . . . . . . . 87
9.4. Approach to data evaluation . . . . . . . . . . . . . . . . . . . . . . . . . 88
9.4.1. Quality of the model . . . . . . . . . . . . . . . . . . . . . . . . . 88
9.4.2. Influence of noisy data . . . . . . . . . . . . . . . . . . . . . . . . 88
9.4.3. Suitable areas in scattering images for data evaluation . . . . . . 89
IV. Results 93
10.Bulk properties of polypropylene blends 95
10.1.Mechanical properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
10.2.SEM images of fracture sites . . . . . . . . . . . . . . . . . . . . . . . . 100
10.3.Evaluation of micro-voids in polypropylenes during stretching . . . . . . 103
10.4.Evaluation of orientation in polypropylenes during stretching . . . . . . 109
11.Properties of melt-spun polypropylene blends 115
11.1.Sample dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
11.2.Mechanical properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
11.3.SAXS orientation in melt-spun polypropylenes . . . . . . . . . . . . . . 123
11.4.WAXS orientation in melt-spun polypropylenes . . . . . . . . . . . . . . 129
12.Summary 133
6Contents
13.Zusammenfassung 135
V. Appendix 139
A. Supplemental information 141
A.1. Fourier transformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
A.2. Maximum of the lattice function . . . . . . . . . . . . . . . . . . . . . . 142
A.3. Overview over the orientation simulations . . . . . . . . . . . . . . . . . 143
A.4. Data evaluation with Matlab: from scattering data to model parameters 148
A.5. Evaluation of SAXS on melt-spun fibers . . . . . . . . . . . . . . . . . . 163
A.6. Protocol for tensile tests and data evaluation . . . . . . . . . . . . . . . 168
Bibliography 173
B. Acknowledgments 183
C. Curriculum Vitae 185
D. Publikationen und Prasentationen 187¨
E. Issue of statement 189
7Contents
8List of Figures
1.1. Chemical structure of polypropylene. . . . . . . . . . . . . . . . . . . . . . 15
2.1. Catalyst structures and resulting polymers . . . . . . . . . . . . . . . . . . 20
2.2. 3 helix of polypropylene; side-view and top-view . . . . . . . . . . . . . . 211
2.3. Schematic depiction of lamellas and spherulites. . . . . . . . . . . . . . . . 22
2.4. Lamellas and spherulites analyzed by AFM. . . . . . . . . . . . . . . . . . 23
2.5. WAXS profile of semicrystalline and amorphous polypropylene. . . . . . . 23
2.6. Polymer structure, morphology and end-use properties. . . . . . . . . . . . 24
2.7. Shish-kebab and fibril structure with SAXS images. . . . . . . . . . . . . . 26
2.8. Typical stress-strain curve for ductile polymers. . . . . . . . . . . . . . . . 27
2.9. Strain rate dependence of yielding stress in polypropylene. . . . . . . . . . 28
2.10. Tensile behavior at different temperatures. . . . . . . . . . . . . . . . . . . 29
2.11. Yield stress depending on the temperature of the sample. . . . . . . . . . . 30
2.12. Transition from lamellar to fibril morphology. . . . . . . . . . . . . . . . . 31
2.13. Schematic diagram of tie molecules. . . . . . . . . . . . . . . . . . . . . . . 33
2.14. Probability for tie molecules in utilized polymers. . . . . . . . . . . . . . . 35
2.15. Probability for tie molecules over n lamellas. . . . . . . . . . . . . . . . . . 35
3.1. Extruder used in experiments . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.2. Utilized press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.1. DSC crystallinity X for standard prepared samples. . . . . . . . . . . . . 42C
4.2. Melting temperature T for standard prepared samples. . . . . . . . . . . 43M
4.3. Zwick tensile tester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.1. Schematic depiction of beamline A2 at HASYLAB, DESY . . . . . . . . . 46
5.2. Status of DORIS storage ring. . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.3. Stretcher and video of sample . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.4. Bruker ASX Nanostar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.5. Guinier camera and two dimensional setup for WAXS measurements. . . . 49
5.6. WAXS crystallinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
5.7. Flat film WAXS measurements. . . . . . . . . . . . . . . . . . . . . . . . . 51
7.1. Bragg model and von Laue construction. . . . . . . . . . . . . . . . . . . . 57
7.2. Magic square of x-ray scattering. . . . . . . . . . . . . . . . . . . . . . . . 59
7.3. Cylindrical scattering objects and utilized coordinate system. . . . . . . . 61
7.4