Oriented Polymer Materials

Edited by Stoyko Fakirov

WILEY- VCH

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Oriented Polymer Materials

Edited by

Stoyko Fakirov

Oriented Polymer Materials

Edited by Stoyko Fakirov

WILEY- VCH

WILEY-VCH Verlag GmbH & Co. KGaA

This Page Intentionally Left Blank

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Contributors

Argon, A. S. Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Bahar, I. Bogazici University, Polymer Research Center, School of Engineering, and TUBITAK Advanced Polymeric Materials Research Center, Bebek 80815, Istanbul, Turkey

Bartczak, Z. Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Present address: Center of Molecular and Macromolecular Studies, Polish Academy of Sciences, 99-368 Lodz, Poland

Bonart, R. Universitat Regensburg, Institut fur Angewandte Physik, Postfach 10 10 42, 8401 Regensburg, Germany

Cohen, R. E. Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Erman, B. Bogazici University, Polymer Research Center, School of Engineering and TUBITAK Advanced Polymeric Materials Research Center, Bebek 80815, Istanbul, Turkey

V

Fakirov, S. Bogazici University, Polymer Research Center, School of Engineering, and TUBITAK Advanced Polymeric Materials Research Center, Bebek 80815, Istanbul, Turkey

Permanent address: Sofia University, Laboratory on Structure and Properties of Polymers, 1126 Sofia, Bulgaria

F'renkel, S. Institute of Macromolecular Compounds, Russian Academy of Sciences, 199004 St. Petersburg, Russia

F'riedrich, K. Institut fur Verbundwerkstoffe GmbH, University of Kaiserslautern, D-67663 Kaiserslautern, Germany

Galeski, A. Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Present address: Center of Molecular and Macromolecular Studies, Polish Academy of Sciences, 99-368 Lodz, Poland

Godovsky, Y. K. Karpov Institute of Physical Chemistry, 103064 Moscow K-64. Russia

Gupta, V. B. Indian Institute of Technology, Textile Technology Department, New Delhi 110016, India

Kunugi, T. Yamanashi University, Faculty of Engineering, Takeda-4, Kofu, 400 Japan

vi

Lee, B. J . Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Present address: University of California, Department of Applied Mechanics and Engineering Sciences, San Diego, LaJolla, CA 92093, USA

Marikhin, V. A. Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia

Matsuo, M. Department of Clothing Science, Nara Women’s University, Nara 630, Japan

Miiller, M. Faculteit der Chemische Technologie, Universiteit Twente, P. 0 .Box 2 17, 7500 AE Enschede, The Netherlands

Present address: Universitat Ulm, Abteilung Organische Chemie I11 89069 Ulm, Germany

Moneva, I. T. Institute of Polymers, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

Myasnikova, L. P. Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia

Parks, D. M. Massachusetts Insti t Ute of Technology, Cambridge, MA 02139, USA

Petermann, J . Universitat Dortmund, Fachbereich Chemietechnik, 44227 Dortmund 50, Germany

vii

Prevorsek, D. C. Allied-Signal Inc., Research & Technology P.O.Box 1021, Morristown, NJ 07962, USA

Schledjewski, R. Institut fur Verbundwerkstoffe GmbH, University of Kaiserslautern, D-67663 Kaiserslautern, Germany

Schultz, J . M. University of Delaware, Materials Science Program, Newark, DE 19716, USA

Sheiko, S. S. Faculteit der Chemische Technologie, Universiteit Twente, P.O.Box 217, 7500 AE Enschede, The Netherlands

Present address: Universitat Ulm, Abteilung Organische Chemie 111, 89069 Ulm, Germany

Siesler, H. W. Universitat GH Essen, Abteilung Physikalishe Chemie, 45117 Essen, Germany

... V l l l

CONTENTS

Chapter 1 Problems of the physics of the oriented state of polymers

S . Frenkel

1 . Introductory considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1. Interplay of fundamental and applied problems .

1.2. Principal routes to the formation of uniaxially oriented Molecular cybernetics ..................................... 1

structures in olymers ..................................... 8

in synthetic polymers ........................................... 10 2 . Configurational in P ormation and orientation phenomena

2.1. Direct generation of orientational order from solutions and melts . Orientational hardening, orientational crystallization. and orientational catastrophes . . . . . . . . . . . . . . 10

2 . 2 . Assemblage; liquid crystalline polymers .................... 22 2 . 3 . Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

3 . Failure under load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 4 . Some specific properties of superoriented polymers . . . . . . . . . . . . . . 30 5 . Technological implications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 6 . General conclusions and summary .............................. 32

6.1. What is clear? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 6.2. What is incomprehensible? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 6 . 3 . What needs better understanding? ......................... 34 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Chapter 2 Structural basis of high-strength high-modulus polymers

V . A . Marikhin. L . P . Myasnikova

ix

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2 . Structural transformation in semicrystalline polymers

on stretching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

2.1. Deformation mechanisms at small strain . . . . . . . . . . . . . . . . . . . 39 2.2. Folded-extended chain solid phase transition in

2.3. Micro- and macrofibrillar structure in oriented

2.4. Drawing arrest and fracture of oriented polymers . . . . . . . . . . 57 2.5. Alternative mechanisms of drawing ........................ 59

polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

the neck region ............................................ 42

polymers and its plastic deformation ....................... 47

3 . Deformation-induced strengthening of semicrystalline

3.1. Structural kinetic approach to the enhancement

3.2. Physical criteria for the optimization of the

3.3. Optimal molecular weight and molecular weight

of polymer characteristics by deformation . . . . . . . . . . . . . . . . . . 62

drawing process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

distribution ............................................... 72 4 . Mechanical properties of highly oriented polymers . . . . . . . . . . . . . . 76 5 . Thermal properties of superstrong high-modulus

polymers ....................................................... 80 6 . Structural peculiarities of highly oriented polymers . . . . . . . . . . . . . 85

References ..................................................... 92

Chapter 3 X-ray diffraction by quasiperiodic polymer structures

R . Bonart

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 2 . Qualitative phenomenological aspects ........................... 102

2.1. Fibre diagrams ............................................ 102 2.2. Crystal density, chain cross section and chain conformation 107 2.3. Anisotropy perpendicular to the chain direction, planes of

plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 2.4. Position sphere ............................................ 109 2.5. Lattice distortions of the first and second kind . Distortion

parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

X

2.6 . Special lattice types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 2.7. Small-angle scattering, fibrils, layer lattices . . . . . . . . . . . . . . . . 117

3 . Basics of experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

3.1. X-ray spectrum and absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 4 . Theoretical relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

4.1. Structure factor ........................................... 122 4.2. The Ewald sphere ......................................... 125 4.3. Pair distribution .......................................... 126 4.4. A special application example ............................. 128

5 . Simple lattice models ........................................... 129

5.1. Ideal periodic lattices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 5.2. Distortions of the first kind ................................ 130 5.3. Distortions of the second kind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 5.4. Inhomogeneous coordination statistics . . . . . . . . . . . . . . . . . . . . . 133 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

Chapter 4 Characterization of polymer deformation by vibrational spectroscopy

H . W . Siesler

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 2 . Experimental and instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 3 . Orientational measurements by infrared dichroism . . . . . . . . . . . . . . 143 4 . Segmental mobility in liquid crystalline side-chain

5 . Rheo-optical FT-IR studies of the poly(ethy1ene polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

terephthalate) film forming process ............................. 148

5.1. Drawing of PET in the machine direction . . . . . . . . . . . . . . . . . . 153 5 .2 . Drawing of PET in the transverse direction . . . . . . . . . . . . . . . . 154 5 .3 . Rheo-optical FT-NIR spectroscopic light-fiber

..................... 157 6 . Rheo-optical FT-Raman spectroscopy of the stress-induced

conformational changes in poly(viny1idene fluoride) . . . . . . . . . . . . . 160 7 . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

investigations of the PET film process

xi

Chapter 5 Morphology in oriented semicrystalline polymers

J . Petermann

1 . General considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 2 . Morphologies in oriented polymers .............................. 168 3 . Formation of morphologies in oriented polymers . . . . . . . . . . . . . . . . 171

3.1. Morphologies obtained by crystallization of oriented melts .......................................... 171

3.2. Orientation at interfaces ................................... 172 3.3. Orientation in thermal gradients ........................... 174 3.4. Orientation by plastic deformation ......................... 174 3.5. Polymerization induced orientations ....................... 175

5 . Outlook to morphology-property relationships . . . . . . . . . . . . . . . . . . 181 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

4 . Morphological changes during thermal treatments . . . . . . . . . . . . . . . 177

Chapter 6 Deformation calorimetry of oriented polymers

Y . K . Godovsky

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 2 . Deformation calorimetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

2.1. Gas calorimeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 2.2. Heat-conducted deformation calorimeters . . . . . . . . . . . . . . . . . . 187

3 . Thermodynamics of the stretching of oriented polymers . . . . . . . . . 189 4 . Thermophysical behaviour of oriented polymers

during deformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

4.1. Oriented amorphous polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 4.2. Oriented crystalline polymers .............................. 194 4.3. Superoriented crystalline polymers ......................... 199

polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 5 . Anisotropy of thermophysical behaviour of oriented

6 . Mechanisms of deformation of oriented polymers as revealed by deformation calorimetry and their relation to morphology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202

xii

7 . Thermophysical behaviour of oriented polymers under fracture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Chapter 7 on the orien- ultrahigh molec-

S . S . Sheiko. M . Moller

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 2 . On the structure of dried and solvent containing gels . . . . . . . . . . . . 211 3 . Gel necking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 4 . Fibrillar structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 5 . Gel blending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

Chapter 8 Polarized light scattering from polymer textures

I . T . Moneva

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 2 . Polarized light scattering: theory and instrumentation . . . . . . . . . . . 243

2.1. Fluctuations in density and fluctuations in optical anisotropy and orientation ................................. 243

2.2. Scattering considerations .................................. 244 2.3. Polarized light scattering technique ........................ 250

3 . Applications of the scattering analysis .......................... 251

3.1. Formation of shear bands during zone drawing . . . . . . . . . . . . . 252 3.2. Formation of macrofibrils in shear crystallization . . . . . . . . . . . 253 3.3. Determination of Poisson’s ratio by double exposure

4 . Polarized light scattering from textures of liquid crystalline speckle photography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255

polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

4.1. Polarized light scattering from schlieren textures . . . . . . . . . . . 257

xiii

4.2. Polarized light scattering from banded and other nematic textures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

5 . Concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

Chapter 9 Deformation induced texture develop- ment in polyethylene: computer simula- tion and experiments

A . S . Argon. Z . Bartczak. R . E . Cohen. A . Galeski. B . J . Lee. D . M . Parks

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 2 . Model description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269

2.1. Basic assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269 2.2. Constitutive relations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270 2.3. Composite inclusion ....................................... 275 2.4. Interaction law and solution procedure ..................... 276 2.5. Parameter selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

3 . Predicted results and comparison with experiments . . . . . . . . . . . . . 279

3.1. Modes of straining . . . . . . . . . . . . . . . . . . . . . . . 3.2. Uniaxial compression ..................... 3.3. Plane strain compression . . . . . . . . . . . . . . . . .

4 . Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 . Conclusions ...................................

References ....................................

. . . . . . . . . . . . . . . . . 279 . . . . . . . . . . . . . . . 280 . . . . . . . . . . . . . . . 289 . . . . . . . . . . . . . . . 298 . . . . . . . . . . . . . . . 299 . . . . . . . . . . . . . . . 300

Chapter 10 Intrinsic anisotropy of highly oriented polymeric systems in relation to molec- ular orientation and crystallinity

M . Matsuo

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 2 . Crystal lattice moduli of crystalline polymers . . . . . . . . . . . . . . . . . . . 303 3 . Theoretical approach to the estimation of

the crystal lattice modulus as measured by X-ray diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307

xi v

4 . Effect of crystallinity and molecular orientation on Young’s modulus in UHMWPE and LMWPE blend films . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310

5 . Temperature dependence of the crystal lattice modulus and Young’s modulus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

6 . Viscoelastic properties of ultradrawn polyethylene . . . . . . . . . . . . . . 318 7 . Morphological and mechanical properties of

UHMWPE-UHMWPP blend gel films .......................... 324 8 . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

References ..................................................... 329

Chapter 11 Nature of the crystalline and amorphous phases in oriented polymers and their in- fluence on physical properties

V . B . Gupta

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331 2 . Nature and role of molecular architecture . . . . . . . . . . . . . . . . . . . . . . . 334

2.1. Axial modulus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334

2.3. Thermal expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339 2.4. Melting point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339

3 . Nature and role of defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

2.2. Axial strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338

3.1. Nature of defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341 3.2. Effect on thermal properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 3.3. Effect on optical properties ................................ 342 3.4. Effect on crystallization ................................... 344

4 . Coupling effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344

4.1. Nature of coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344 4.2. Effect on mechanical properties of fib 4.3. Effect on deformation mechanisms . . . . . . . . . . . . . . . . . . 4.4. Effect on thermal behaviour . . . . . . . . . . . . . . . . . .

5 . Content and size of the phase . . . . . . . . . . . . . . . . . . . . . . 6 . Crystal and amorphous orientation 7 . Structure formation 8 . Concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . 346

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357

xv

Chapter 12 Structure development in highly oriented PET

J . M . Schultz

.................................................... 1 . Background 361

1.1. Post mortem studies ....................................... 363 1.2. In situ studies: spinline observations ....................... 366 1.3. Models of structure development ........................... 367

2 . Interrupted transformation experiments ......................... 369 3 . Transmission electron microscopy ............................... 371 4 . Property isotherms ............................................. 374

4.1. Structure ............................. . . . . . . . . . . . . . . . 374 4.2. Kinetics .......................... . . . . . . . . . . . . . . . . 378

5 . Low temperature transformation: radial distribution function studies . . . . . . ....................... 379

6 . Thermal dendrite model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383 7 . Concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391 References . . . . . .

Chapter 13 Preparation of highly oriented fibres or films with excellent mechanical proper- ties by the zone-drawing/zone-annealing met hod

T . Kunugi

1 . Basics of the zone-drawinglzone-annealing method . . . . . . . . . . . . . 394

1 .1 . Original zone-drawingfzone-annealing method ............. 394 1.2. Multistep zone-drawinglzone-annealing method . . . . . . . . . . . 395 1.3. High-temperature zone-drawing method . . . . . . . . . . . . . . . . . . . 396 1.4. Vertical two-step zone-drawing method .................... 396

2 . Application to polymer fibres or films . . . . . . . . . . . . . . . . . . . . . . . . . . . 398

2.1. Polyethylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 2.2. Polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401 2.3. Polyvinyl alcohol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404 2.4. Poly(ethy1ene terephthalate) ............................... 406

xvi

2 . 5 . Nylon 6 and 66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410 2.6. Pol y (et her-et her- ketone) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 13 2.7. Polyimide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417

3. A recent development of the zone-drawing/zone

4. Conclusion . . . . . . . . . . . . . . . . . . . . . . . method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419

References . . . . . . . . . . . . . . . . . . . .

Chapter 14 Alternative approaches to highly ori- ented polyesters and polyamides with im- proved mechanical properties

S. Fakirov

1. General considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422 2. Improvement of the mechanical properties of

polycondensates by ultraquenching of their melts . . . . . . . . . . . . . . . 425

2.1. Creation of optimal initial structure for preparing highly oriented polycondensates . . . . . . . . . . . . . . . . . 425

2.2. Ultraquenching with previous melt annealing . . . . . . . . . . . . . . 428 2.3. Ultraquenching of polymer blends . . . . . . . . . . . . . . . . . . . . . . . . . 429

polycondensates by drawing and thermal treatment . . . . . . . . . . . . . 430 3. Improvement of the mechanical properties of oriented

3.1. Contribution of solid state reactions to the improvement of the mechanical properties of polyesthers and polyamides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430

polyesters and polyamides by zone annealing under stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435

3.2. Improvement of mechanical properties of

4. Attempts to overcome the mechanical anisotropy of highly drawn polymer films . . . . . . . . . . . . . . . . . . .

4.1. Cross-plied laminates bonded through physical

4.2. Laminates bonded through chemical healing

4.3. Laminates bonded through chemical healing

healing of highly drawn polyolefin films . . . . . . . . . . . . . . . . . .

of highly drawn polycondensate films ....................

with coupling agent of highly drawn polycondensate films . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. .

437

437

438

439 440

xvii

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 1

Chapter 15 Structural aspects of the damage toler- ance of Spectra fibres and composites

D . C . Prevorsek

1 . Introduction ................................................... 444

1.1. Theoretical limits in modulus and strength . . . . . . . . . . . . . . . . 445 1.2. The ultrastrong polyethylene fibres ........................ 446

2 . Creep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 448

2.1. Structural parameters affecting creep ...................... 448 2.2. Deformation in creep versus plastic

deformation in drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451

polyethylene fibres and composites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451 3 . Strain rate effects in ultrastrong

3.1. Ballistic impact on fibres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452 3.2. Ballistic impact on Spectra composites ..................... 453

4 . Damage tolerance in penetration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455

4.1. Mechanisms of penetration and analysis of penetration resistance ................................... 456

4.2. Repeated impact and additional energy absorption mechanism of PE fibre ......................... 459

5 . Morphology of ultrastrong PE fibres ............................ 462 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465

Chapter 16 Segmental orientation in deformed rub- bery networks

I . Bahar. B . Erman

1 . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467 2 . Relationships between macroscopic and molecular

deformation and network structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469 3 . Segmental orientation in network chains . . . . . . . . . . . . . . . . . . . . . . . . 470 4 . Higher order approximation for segmental orientation . . . . . . . . . . . 473

xviii

5. Experimental determination of segmental orientation

6. Theoretical interpretation of infrared dichroism in rubbery networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474

measurements of segmental orientation in rubbery networks . . . . . 476 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480

Chapter 17 Orientation effects on the thermal me- chanical and tribological performance of neat, reinforced and blended liquid crys- talline polymers

R. Schledjewski, K. Friedrich

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483 2. Liquid crystalline polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 484

2.1. Liquid crystals and their history . . . . . . . . . . . . . . . . . . . . . . . . . . . 484 2.2. Structure of LCPs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 485

3. Thermotropic liquid crystalline polymers and their properties . . . 486

3.1. Neat, filled or reinforced LCP ...................... 487 3.2. LCP blends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500

. . . . . . . . . . . . . 503 References . . . . . . . . . . . . . . . . . 505

. . . . . . . . . . . . . . . . . . . 507 Author Index . . . . . . . . . . . . . . . . . . . . . . . . Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510

xix

Preface

The orientation phenomenon is a basic inherent peculiarity of polymers, arising from the chain character of macromolecules and their ability to adopt different conformations - from a coil to an extended chain. The realization of these two extreme conformations or some intermediate ones determines to the greatest extent the mechanical properties of polymers as materials. In addition to the synthesis of new polymers, orientation is a basic approach to the obtaining of polymeric materials with superior properties. Incidentally, the outstanding mechanical properties of liquid crystalline polymers do not stem directly from their chemical composition, but are related to their unique ability of perfect orientation due to the peculiarities of their chemical composition.

The driving forces for the preparation of this book were the clear un- derstanding of the importance of orientation itself and of the oriented poly- meric materials, I met everywhere, as well as the fact that the last book related to this important topic appeared more then ten years ago. This situ- ation was recognized somewhat earlier by other polymer scientists, too, and I am pleased to note here that this project was started, although in another form, by Dr. I. Moneva and some colleagues of ours from St. Petersburg, but the turbulent changes in the former Soviet Union and in the contries of Central and Eastern Europe affected it badly. Owing to the generous en- couragement and support of Dr. R. E. Bareiss from Die Makromolekulare Chemie, the project was modified and could be materialized.

Although the chapters are not formally organized in larger units, an attempt is made to start the book with an overview of the orientation phenomenon, followed by chapters dealing with basic techniques for the study and characterization of orientation and oriented polymers. Another goal was to include as much as possible different representatives of oriented polymer materials, as well as approaches to the improvement of their me- chanical properties. These two fields are by far not completely covered and many more contributions are required for doing so.

Like many books of this type, the present one suffers from the diversity of styles and ways of presentation of the chapters, but we hope that this disadvantage is compensated by the high professionalism of the co-authors and by the updated results they have offered. Here it should be mentioned that the chapters differ also in their volume, the contributions from the

Russian co-authors being the longest. The reason is that for many decades there were no equal opportunities for worldwide exchange of information, therefore research in the former Soviet Union did not have access to West- ern scientists. The review character of the two introductory chapters is an attempt to overcome partially this situation.

As editor, I wish to express my sincere gratitude to the individual con- tributors, because this type of publication requires perseverance and a great deal of patience. I am greatly indebted to my co-worker Mrs. S. Petrovich - without her everyday help this project could not have been undertaken. A special note of thanks to Dr. Z . Denchev for preparing the Author and Subject Indices as well as appreciation to the Bosphorus University in Is- tanbul for the hospitality offered to me during my sabbatical year when the book was finalized.

Sofia 1991 - Istanbul 1994 S. Fakirov Editor

xxi

The book is dedicated to

Professor Anton Peterlin in recognition of his essential contribution to the understanding of orientation phenomena and oriented polymers.

Professor Peterlin was one of the most enthusiastic co- authors at the beginning of this project but, to our deep sorrow, he passed away before completing the chapter he had started on the influence of amorphous layers.

Chapter 1

Problems of the physics of the oriented state of polymers

S. F’renkel

1. Introductory considerations

I preferred this subtitle to “Introductory notes” for the following reasons. Quite a lot is already written on orientation phenomena and physical prop- erties of oriented polymers, and it would be difficult and even senseless to present something substantionally new on this subject using common terms and formalism. An additional difficulty arises from the fact that a similar contribution [l] is supposed to appear.

Therefore, to avoid autoplagiary, I have to discuss most of the problems considered in the preceding paper in a quite different manner, paying spe- cial attention to molecular cybernetics and to systemic analysis connected with a special formulation of Bohr’s complementarity principle, resulting from the recent difficulty (if not impossibility) to treat in comprehensible and/or graphic terms the multidimensional state trajectories, attractors, fractals and transitions of fractional order appearing in modern physics and particularly unavoidable when dealing with polymers.

1.1. Interplay of fundamental and applied problems. Molecular cybernetics

Starting from 1973 [2], in a series of papers dealing with general or spe- cial problems of polymer science. I frequently used the term “para.doxes” in an explicit or implicit form. Most of those paradoxes are not of a real

Oriented Polymer Material> Stoyko Fakirov

Copyright 0 2002 Wiley-VCH Verlag GmbH & Co. KGaP

2 S. Frenkel

physical nature, but are due to the fact that, in contrast to the normal evolution of science and practical applications in the case of polymers (in- cluding plastics, synthetic rubber, synthetic fibres, etc.), most industrial processings rapidly developed when practically nothing was known about their molecular structure, not to mention ecological implications.

Chemistry and physics were needed jr,t to explain rather than to con- trol technological results; the situation being changed only before World War 11. In certain technological circles such mistreatments (though in a new form) still exist, despite that some new trends in polymer science offer special technologies (for instance connected with plasma treatment or reactions to produce non-conventional coatings, thin films for non-linear optics, etc.) preceding full knowledge of the resulting chemical and physical structure. In these cases, the situation is quite different, and these rapidly developing technologies do not contradict or ignore fundamentals.

Coming back to our main topic, we must introduce the notion of pre - destinatzon of special polymers for special uses; it is connected with such a fundamental property of macromolecules as linear memory [3] and, for bet- ter understanding, we should consider molecular biology as a main source of information for molecular cybernetics [4]. Since the latter book is, unfortu- nately, very difficult to obtain, some details connected with the applications of the theory of information to polymer science and technology should be given here. In the case of oriented polymers, such an approach is especially advantageous since it deals with linear coding, and uncoiling of chains on orientation has a lot in common with habitual uncoding procedures.

The purely physical notion of linear memory can be enriched by treating it as configurational anformataon [2,4,5], and the latter can be best understood by the example of globular proteins. All proteins are formed by polypeptide chains consisting of 20 different aminoacid residues. In each individual protein the number and sequence of these residues R1, Ra, RS . . . R20 are coded by simple combinations of four purine and pyrimidine bases in DNA responsible for the direct storage of genetic in- formation, and RNA, being a kind of messenger, transfers this information to the cell loci where the synthesis of protein chains proceeds. These over- simplifications of the well known subject allow us to come faster to our less common considerations.

Again omitting details, the so-called primary structure of proteins, be- ing just configurational information, or the strict sequence of Ri, predes- tinates local ordered @-helical or folded p-conformations (secondary struc- ture) and the overall globular conformation (tertiary structure) resulting as interchain repacking and bonding necessary to attain, under given con- ditions, the lowest possible level of free energy. These “given conditions” in aqueous solutions are pH, ionic strength, temperature, water thermo- dynamic activity (that can be affected by the addition of other liquids), etc. The resulting conformation is unique for the given individual protein and also allows the formation of the centres of activity (enzymatic, redox,

Problems of the physics of the oriented s t a t e of polymers 3

charge transfer, e tc . ) , rnaking the molecules of globular proteins “molecular machines” responsible for all events of energy and information exchange or production, tha t we call “Life” [4,6,7]. These centres are usually formed - also in a predestinated way ~ by 3 or 4 residues R; separated along the initial chain by sequences corresponding (as pointed by de Gennes in his Nobel lecture) to a “magic number” 13 (this number will reappear in connection with quite different considerations).

Such a binding in one specifically active site of several distant (along the chain) residues Ri is not a statistical event, but a necessity contained in the configurational information. Moreover, there is no need of external forces to achieve this local configuration and the overall globular conformation; the configurational information being realized by means of “autoscanning” leading to the mentioned repacking of an initially extended chain into the tertiary structure .

The type of configurational information considered and connected with selfscanning can be called the discrete configurational information since it encompasses not only the overall behaviour on molecular and higher structural levels, but in particular the details of dynamically active unique conformations.

However ~ and with synthetic polymers it becomes a necessity - one should also consider a second ~ statist ical ~ type of configurational infor- mation, prescribing (or allowing to predict, which is particularly important in technology) the overall behaviour of a protein molecule and its overall conformation in aqueous or non-aqueous media. This type of configura- tional information can be given in different terms but the most obvious expression would be the fraction FH of the hydrophobic residues in the primary chain or the ratio of the number of non-polar to polar residues

The first more or less intuitive model of the molecular structure of globular proteins and their interaction with surrounding media proposed by Talmud and Bresler in pre-cybernetic times (1944; see [2],[27]) was based on the assumption tha t - just as in micellar colloid systems - the polypeptide chain forms a close-packed coil containing a lipidic “drop” in the inside, built-up by non-polar side groups enveloped by polar groups sustaining the whole molecule in aqueous solution. This model supposes inverted structures in non-aqueous media. The very meager information on protein structure was, in principle, sufficient enough to avoid the first orientational catastrophe in the fibre and textile industry tha t occurred during the It,alo-Abyssinian war in the mid-thirties. I t is irnportant even loday for the better understanding of orientation phenomena in polymers in general, as well as for explaining how the neglect of configurational informa- tion turns apparently sanely designed technologies into “antitechnologies” , which I shall describe in some detail.

In the beginning of the thirties it was known that all proteins are al- most identical in their chemical structure, the industry of synthetic fibres

(m).

4 S. Frenkel

already existed, and the composition of the natural protein fibres - silk and wool - was also known. Therefore it seemed quite logical to use some convenient ( “technologically” and “economically”) proteins for developing a spinning and textile process to obtain an artificial wool fabric. The pro- cess was patented by a certain Commodore Ferretti, and a battalion of the Italian army was equipped with a uniform made from this artificial wool. Now it is time to name the chosen protein: it was casein, the main pro- tein constituent of cheese or curd. At present it is well known that the FH and m values for casein are unfavourable for attaining extended conforma- tions in aqueous media or simply at high humidities. Therefore, one can easily understand what happened when the battalion got under a tropical shower. The uniform simply ravelled out. A deeper insight in this appar- ently anecdotic episode is however not only instructive; one should correlate information with free energy and other common physical parameters.

This can be attained by considering the so-called Fisher diagram which is a plot of molecular size and/or shape vs. FH or m (Figure 1).

For modern molecular biologists and biophysicists the Fisher diagram appears oversimplified and obsolete, but for polymer physics and especially for molecular cybernetics it still has an important position, giving a key for decoding the statistical configurational information and for its direct use both in fundamental research and in technology.

As shown in Figure 1, the Fisher diagram is an isoenergetic curve corre- sponding to equilibrium, i.e. to minimal (for given conditions) Gibbs’ free energy. The upper left part of the diagram corresponding to extended con-

m or F,

Figure 1. The Fisher diagram. The most probable conformations for some iden- tical “reduced molecular weight” are shown near the extremes and in the middle part of the curve

Problems of the physics of the oriented state of polymers 5

formations is occupied by fibrillar proteins (fibroin, keratin, collagen) and the right lower part , to very compact globular proteins. Casein occupies just an intermediate position. Well, fibrillar proteins are just “predestinated” t o form fibres, and t o discuss the predestination of properly said globular proteins, one should consider in more detail the discrete configurational information.

Casein has a smooth conformation, and its chain can be easily attacked by proteolytic enzymes. However, i t is still sufficiently compact (due to relatively high FH or m values) to resist complete uncoiling, and retains extended chain conformation in contact with water. Since after the failure with casein, new, even more ill-attempted ventures to spin fibres from sev- eral plant globulins occupying the lower right part of the Fisher diagram were made, it seems instructive to present the diagram as an isoconforma- tional plot (the conformation being very extended) of free energy vs. FH or m in aqueous media (Figure 2) .

It is readily seen that not only the fibres will be unstable, the high free energy stored leading to a development of internal stresses tearing the fibres “from inside”, but spinning by itself will be very energy-consuming since globular molecules will strongly resist uncoiling for the same reasons.

Figures 1 and 2 explain the origin of many “antitechnologies” connected with orientation of polymers. However, i t is instructive to consider briefly the opposite case, when the protein is predestined to form fibres or webs.

Figure 3 shows schematically (for more details see [a] or [4]) the spinning of silk or webs by silkworms or spiders. Though oversimplified, this scheme

1 m or FH

Figure 2. The inverted Fisher diagram for identical extended conformations in aqueous media corresponding to the left upper part of Figure 1. In general, such diagrams explain the second type orientational catastrophes in fibres

6 S. Frenkel

a b

Figure 3. Schematic representation of stream-thread transition during “spinning” of natural silk or cobwebs. (a) the initial solution (in glands). Only a part of the molecules is shown, containing two crystallizable peptides in a-helical form; (b) under the influence of elongational flow (gradient +) the molecules uncoil and align in parallel; (c) due to further draw and flow a helix-to-coil transition oc- curs, followed by slip controlled by charged groups; (d) the last step: a coil-to-p- structure (shown by thick lines) transition occurs, the crystallizable polypeptides now assembled into crystallites by hydrogen bonding. The resulting microfibril- lar structure with alternating crystalline and amorphous regions is optimal for “natural” or textile needs, since it combines high tenacities (the number of the tie chains is high) and flexibilities

gives a further insight in the role played by the configurational information in orientation and jixzng of the oriented state.

In the case of fibroin 18 [a ] , it is sufficient to know that the fibroin chain consists of four “crystallizable peptides” containing only four out of 20 possible aminoacid residues. Just this “quartet” - glycine, alanine, tyrosine and serine - is coded genetically and has a special significance for the rheology of “spinning” p e r se and for the subsequent fixing of an optimal fibrillar order. Such polypeptide can form both a-helical conformation and the “pleated sheet” P-structure with a cooperative system of interchain hydrogen bonds, making this structure practically insoluble in water [6].

The remaining 12 amino-acids forming the “non-crystallizable” pep- tides are also “chosen” specifically to play their role in the second stage of “spinning” and to provide flexible amorphous segments between crystal- lites, containing practically 100 percent of tie chains (in ordinary synthetic