Polymer Science. Properties and Application

398 Pages·3.211 MB·398\398

by  Andrew J. Peacock and Allison Calhoun (Auth.)

Peacock(cid:1)/(cid:1)Calhoun
Polymer(cid:1)Chemistry
Andrew(cid:1)J.(cid:1)Peacock
Allison(cid:1)Calhoun
Polymer
Chemistry
Properties and Applications
Hanser Publishers, Munich • Hanser Gardner Publications, Cincinnati
TheAuthors:
Dr.AndrewJ.Peacock,TredegarFilmProducts,1100BouldresParkway,RichmondVA23225,USA
Dr.AllisonCalhoun,DepartmentofChemistry,WhitmanCollege,WallaWalla,WA99362,USA
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LibraryofCongressCataloging-in-PublicationData
Peacock,AndrewJ.,1959-
Polymerchemistry:propertiesandapplications/AndrewJ.Peacock,
AllisonCalhoun.--1sted.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN-13:978-1-56990-397-1
ISBN-10:1-56990-397-2
1.Polymers--Textbooks.2.Polymerization--Textbooks.I.Calhoun,Allison
R.II.Title.
QD381.P432006
668.9--dc22
2006008756
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ISBN-13:978-3-446-22283-0
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This book is dedicated to the memory of
William Lindsay Peacock
Preface
This book provides a comprehensive introduction to the field of polymer science, covering all
relevant topics in a single volume. It systematically develops the various branches of polymer
science, starting from basic chemical structures, working through the scientifi c principles
that describe polymer behavior and culminating with a description of their conversion to
usable products. The final section of the book is devoted to case studies that discuss the most
important classes of synthetic polymers. It is with regret that the authors decided to omit a
discussion of elastomeric materials. It was felt that a single volume could not do justice to
both plastics in the general sense and the wide ranging field of elastomers and rubbers.
The opening chapter of this book introduces the basic chemical features of synthetic polymers
that set them apart from the majority of compounds encountered in classic organic and
inorganic chemistry. The importance of the distribution of chemical structure is discussed in
detail, with particular relevance to how this influences properties and end uses. Subsequent
chapters enlarge upon this theme describing the relationships between molecular structure
and molten and solid state properties. The principal polymerization processes are surveyed
with respect to the range of molecular structures available therefrom.A chapter is devoted to
the rheological behavior of polymer melts, particular as it pertains to non-Newtonian fl ow
and how this affects processing. This theme continues with a discussion of the solidifi cation
of polymers from the molten state and the formation of the anisotropic structures that
characterize most polymer articles. The physical attributes of polymers in their solid state
are then described in terms of mechanical, thermal, optical, and electrical characteristics.
Analytical methods for characterizing polymers are briefly outlined as appropriate. Chemical
degradation and the importance of stabilization are briefly explored. Commercial processes
for converting raw polymers to useful products are described and their application to various
classes of polymer is discussed. The principle recycling processes as applied to polymers are
outlined. The final section of this book is dedicated to a series of case studies that describe
the most important classes of polymer. Each case study outlines the chemistry, properties
and applications of a particular polymer type in its own right and compared to competing
materials, both polymeric and non-polymeric. The book is illustrated throughout with fi gures
and tables that serve to further explain the principles under discussion.
This work is intended to introduce the field of polymer science to undergraduates in the areas
of physical sciences and engineering. It is also aimed at professionals who fi nd themselves
working with polymers for the first time and need to rapidly familiarize themselves with
guiding principles. In keeping with its role as a comprehensive text, this book assumes no
prior knowledge of the field of polymers.A bibliography is provided at the end of the book
for those wishing to delve further into a particular topic.
Andrew Peacockand Allison Calhoun
Acknowledgements
No work of this type could be written without the help, encouragement and support of many
practitioners in the field. The authors are indebted to their various teachers (both formal
and informal) over the years who instilled in them a love of knowledge, science in general,
and polymers in particular.
Dr. Peacock is grateful to his father Lindsay Peacock (who was also a chemist and did not live
to see the completion of this work) for starting him off on the right foot and encouraging
his scientific studies. Other memorable teachers include Dr. Pat Hendra, who inspired all
his graduate students to exercise their imagination to solve problems in creative ways, and
Dr. Leo Mandelkern who demanded rigorous scientific analyses and thorough experimental
programs. Last, but not least Dr. Peacock would like to thank his wife, Shavon, for allowing
him to devote a substantial portion of his “free” time to creating a work that he hopes will be
valuable to future generations of scientists and engineers.
Dr. Calhoun is grateful to Dr.Allen King, Jr. and Dr. Darwin Smith – mentors who act as
a source of inspiration by their own joy for learning, their expertise in physical chemistry
and their exceptional skills at communicating their extensive knowledge with others. Their
patience, high expectations, academic rigor and faith were, undoubtedly, the greatest infl uences
in her career choices. Dr. Calhoun offers her sincerest gratitude to the three most important
people in her life – her husband,William, and two daughters, Kaitlyn and Jordan, for their
love and support. Finally, she thanks her colleagues at Whitman College, her family and
friends for their encouragement.
Both authors thank Dr. Christine Strohm, the publisher and editor of this text, for her hard
work and unfailing kindness.
Contents
Preface ........................................................................ VII
Acknowledgements ........................................................... VIII
1 Introduction to Synthetic Polymers .......................................... 1
1.1 Definition of Polymers ................................................ 1
1.2 Chemical Categories of Polymers ....................................... 3
1.2.1 Addition Polymers ............................................. 5
1.2.2 Condensation Polymers ........................................ 7
1.2.3 Thermoplastic Polymers ........................................ 8
1.2.4 Thermoset Polymers ........................................... 9
1.3 Physical Categories of Polymers ....................................... 10
1.3.1 Amorphous State ............................................. 10
1.3.2 Semicrystalline State .......................................... 12
1.4 Statistical Distributions ............................................... 13
1.4.1 Molecular Weight Distribution ................................. 13
1.4.2 Short Chain Branching Distribution ............................ 15
1.4.3 Long Chain Branching Distribution ............................. 15
1.4.4 Shape Distributions ........................................... 16
1.4.5 Orientation Distribution....................................... 16
1.5 Properties and Applications ........................................... 17
1.5.1 Mechanical Properties ......................................... 17
1.5.2 Barrier Properties ............................................. 18
1.5.3 Surface Contact Properties ..................................... 18
1.5.4 Optical Properties ............................................. 18
1.5.5 Electrical Properties ........................................... 19
1.6 Conclusions ......................................................... 19
Review Questions for Chapter 1 .............................................. 19
2 Polymer Chemistry ........................................................ 21
2.1 Introduction ........................................................ 21
2.2 Thermoplastics and Thermosets ....................................... 21
2.3 Chain Growth Polymerization of Thermoplastics ........................ 22
2.3.1 Free Radical Polymerization .................................... 26
2.3.2 Anionic Polymerization ....................................... 27
2.3.3 Cationic Polymerization ....................................... 28
2.3.4 Coordination Polymerization of Thermoplastics ................. 30
2.4 Step Growth Thermoplastic Polymers .................................. 32
2.4.1 Mechanisms of Step Growth Polymerization ..................... 32
X Contents
2.5 Comparison of Chain Growth and Step Growth Polymers ................ 35
2.6 Commercial Methods of Thermoplastic Polymerization .................. 36
2.6.1 Bulk Polymerization........................................... 36
2.6.2 Solution Polymerization ....................................... 37
2.6.3 Types of Interfacial Polymerization ............................. 37
2.6.4 Synthesis of Copolymers ....................................... 40
2.7 Polymerization of Thermosets ......................................... 41
2.8 Conclusions ......................................................... 43
Review Questions for Chapter 2 .............................................. 43
3 Thermodynamics, Statistical Thermodynamics, and Heat Transfer ............. 45
3.1 Introduction ........................................................ 45
3.1.1 Energy ....................................................... 46
3.1.2 Internal Energy ............................................... 47
3.1.3 Enthalpy ..................................................... 48
3.1.4 Entropy and Spontaneity ...................................... 50
3.1.5 Equilibrium .................................................. 52
3.2 Energy of Polymerization Reactions .................................... 53
3.3 Energies of Interactions ............................................... 54
3.3.1 Bonding ..................................................... 55
3.3.2 Intermolecular Interactions .................................... 57
3.4 Statistical Thermodynamics ........................................... 59
3.5 Heat Transfer ........................................................ 60
3.6 Summary ........................................................... 60
Review Questions for Chapter 3 .............................................. 61
4 Kinetics ................................................................... 63
4.1 Introduction ........................................................ 63
4.1.1 Defi ning Rates ................................................ 63
4.2 The Rate Law: Orders, Rate Constants, and Their Use .................... 64
4.2.1 The Mechanistic Meaning of Order ............................. 65
4.2.2 The Meaning of the Rate Constant .............................. 66
4.2.3 The Role of Catalysts .......................................... 68
4.3 Kinetics of Step Growth Polymerization Processes ....................... 69
4.3.1 Kinetic Experiments ........................................... 70
4.4 Kinetics of Chain Growth Polymerization .............................. 70
4.4.1 Initiation ..................................................... 71
4.4.2 Propagation and Chain Branching .............................. 71
4.4.3 Termination .................................................. 72
4.4.4 The Steady State Approximation ................................ 73
4.4.5 Measuring the Kinetics of Chain Growth Polymerization .......... 73
4.5 Other Kinetic Processes Studied in Polymeric Systems .................... 74
4.6 Conclusions ......................................................... 74
Review Questions for Chapter 4 .............................................. 74
Contents XI
5 Molecular Characterization of Polymers ..................................... 77
5.1 Introduction ........................................................ 77
5.2 Molecular Weight .................................................... 78
5.2.1 Molecular Weight versus Molecular Length and Molecular
Volume ...................................................... 78
5.2.2 Molecular Weight Distribution ................................. 80
5.2.3 Molecular Weight Determination ............................... 82
5.3 Homopolymer Chemical Composition ................................. 86
5.3.1 Regiodefects .................................................. 86
5.3.2 Tacticity ..................................................... 87
5.3.3 Composition Analysis ......................................... 89
5.4 Copolymer Chemical Composition .................................... 89
5.4.1 Comonomer Distribution ...................................... 90
5.4.2 Spectroscopic Analysis ......................................... 92
5.5 Branching ........................................................... 93
5.5.1 ShortChain Branches ......................................... 93
5.5.2 Long Chain Branches .......................................... 95
5.5.3 Long Chain Branching Analysis ................................. 98
5.6 Crosslinking ......................................................... 98
5.6.1 Types of Crosslink ............................................ 98
5.6.2 Statistics of Network Formation ................................ 99
5.6.3 Crosslinking Analyses ........................................100
5.7 Conclusions ........................................................102
Review Questions for Chapter 5 .............................................102
6 Rheological Properties of Polymeric Materials ..............................103
6.1 Introduction .......................................................103
6.2 Flow, Stresses, Strains and Deformations ...............................103
6.2.1 Normal Stresses and Strains ...................................103
6.2.2 Shear Stresses ................................................104
6.2.3 Viscosity ....................................................106
6.3 The Molecular Origin of Rheological Properties ........................107
6.3.1 Molecular Structure Effects on Melt Viscosity ...................108
6.4 Temperature Effects on Rheological Properties .........................110
6.5 Measurement Techniques ............................................111
6.6 Implications of Rheology and Conclusions.............................112
Review Questions for Chapter 6 .............................................113
7 Development and Characterization of Solid State Molecular and
Supermolecular Structure .................................................115
7.1 Introduction .......................................................115
7.2 Solid State Morphology..............................................116
7.2.1 Amorphous States ...........................................116
7.2.2 Polymer Crystallites ..........................................118
XII Contents
7.3 Crystallization ......................................................122
7.3.1 Nucleation ..................................................122
7.3.2 Primary Crystallization .......................................123
7.3.3 Secondary Crystallization .....................................124
7.3.4 Crystallization Rate ..........................................124
7.4 Characterization of Solid State Molecular and Supermolecular
Structure ...........................................................126
7.4.1 Scattering Measurements .....................................126
7.4.2 Microscopy ..................................................129
7.4.3 Differential Scanning Calorimetry .............................132
7.4.4 Density .....................................................133
7.5 Conclusions ........................................................134
Review Questions for Chapter 7 .............................................135
8 Solid State Properties of Polymers ..........................................137
8.1 Introduction .......................................................137
8.2 Mechanical Properties ...............................................137
8.2.1 Force versus Deformation Properties ...........................138
8.2.2 Toughness Measurement ......................................146
8.2.3 Creep .......................................................151
8.3 Optical Properties ...................................................152
8.3.1 Haze........................................................153
8.3.2 Transparency ................................................154
8.3.3 Gloss .......................................................155
8.4 Surface Contact Properties ...........................................156
8.4.1 Friction .....................................................156
8.4.2 Cling .......................................................157
8.4.3 Wear Resistance ..............................................158
8.5 Barrier Properties ...................................................160
8.5.1 Permeation Through Polymers ................................160
8.5.2 Barrier PropertyAnalysis .....................................162
8.6 Electrical Properties .................................................163
8.6.1 Electrical Resistance ..........................................163
8.6.2 Capacitive Properties .........................................164
8.6.3 Dielectric Strength ...........................................166
8.6.4 Arc Resistance ...............................................166
8.6.5 Corona Treatment ...........................................167
8.6.6 Factors Influencing Polymers in Electrical Applications ..........167
8.7 Weather Resistance ..................................................168
8.7.1 Natural Outdoor Weathering ..................................168
8.7.2 Accelerated Outdoor Weathering ..............................168
8.7.3 Artifi cial Weathering .........................................169
8.8 Conclusions ........................................................169
Review Questions for Chapter 8 .............................................169