Fundamentals of Polymer Science

An Introductory Text, Second Edition

Michael M. Coleman, Paul C. Painter

• Publisher: CRC Press
• Year: 2019
• ISBN:
  9781351446389
• Edition: 2
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Now in its second edition, this widely used text provides a unique presentation of today's polymer science. It is both comprehensive and readable. The authors are leading educators in this field with extensive background in industrial and academic polymer research. The text starts with a description of the types of microstructures found in polymer

CHAPTER 1

The Nature of Polymeric Materials

“He fixed thee mid this dance of plastic circumstance”

—Robert Browning

A. WHAT ARE POLYMERS—WHAT IS POLYMER SCIENCE?

Simply stated, polymers are very large molecules (macromolecules) that are comprised or built up of smaller units or monomers. The arrangements of these units, the various types of chains that can be synthesized and the shapes that these chains can bend themselves into, result in a class of materials that are characterized by an enormous and intriguing range of properties. Some of these are unique to polymers (e.g., rubber elasticity) and, as we shall see, are simply a consequence of their size and chain-like structure.

Polymer science is also a relatively new discipline and one that is characterized by extraordinary breadth. It involves aspects of organic chemistry, physical chemistry, analytical chemistry, physics (particularly theories of the solid state and solutions), chemical and mechanical engineering and, for some special types of polymers, electrical engineering. Clearly, no one person has an in-depth knowledge of all these fields. Most polymer scientists seek a broad overview of the subject that is then usually supplemented by a more detailed knowledge of a particular area. This book is a first step towards the former and to give a flavor for the diversity of this subject matter we will commence with an outline of some of the areas we will cover.

Polymer Synthesis

Many polymer scientists think that it is unlikely that we will ever again see any new thermoplastic take the world by storm (i.e., achieve levels of production comparable to polyethylene or polystyrene), but it should be kept in mind that similar things were being said round about 1950, just before high density polyethylene and isotactic polypropylene made their debut (some of this terminology will be defined shortly). Today, there are two good reasons to think they may be right, however. First, all the monomers that can be readily polymerized already have been; second, commercializing a new commodity plastic would probably cost more than $1 billion (The Economist, May 1980). This is not promising in an industry that has become infected by MBA’s with a six month time-horizon. Fortunately, this does not mean that polymer synthetic chemists are out of business. There is considerable interest in using new catalysts (for example) to produce commodity plastics more cheaply, or in producing better defined chain structures to give controlled properties; synthesizing “specialty” polymers such as those with stiff chains and strong intermolecular attractions to give thermal resistance and high strength; or chains with the types of delocalized electronic structures that result in unusual electrical and optical properties. These materials would be produced in smaller quantities than “bulk” plastics, but can be sold at a much higher price. Our intention is only to give you a start in this area, however, so you won’t find any discussion of advanced synthetic methods in this book. In chapter 2 we simply cover the basics of polymer synthesis, but this is enough for you to grasp the essentials of how the majority of commercial polymers are produced.

Polymer Characterization

What a chemist thinks he or she has made is not always the stuff that is lying around the bottom of his or her test tube. Accordingly, there is an enormous field based on characterization. This is now a particularly exciting area because of recent advances in instrumentation, particularly those interfaced with high-powered yet small and relatively cheap dedicated computers. These novel analytical techniques are not only useful in studying new materials, but answering questions that have intrigued polymer scientists for decades. For example, spectroscopic techniques are used to examine “local” chemical structure and interactions in polymer systems. Electron and other microscopies and the scattering of electromagnetic radiation are used to characterize overall structure or morphology; i.e., how components of a system phase separate into various types of structures; how chains fold into crystals; and the shape of an individual chain in a particular environment. Some techniques are so expensive that national facilities are required, e.g., synchotron radiation and neutron scattering. Our focus in this book will be on the basics, and in particular we will discuss the measurement of molecular weight and the use of molecular spectroscopy to characterize chain structure.

Polymer Physical Chemistry

Paul Flory was awarded the Nobel Prize in Chemistry for his work in this area and we will mention his name often in this book. Polymer physical chemistry is a subject that demands a knowledge of theory and the ability to perform carefully controlled experiments, often using the types of instruments mentioned above. (The areas of characterization and polymer physical chemistry overlap considerably and they are artificially separated here merely to illustrate the different types of things polymer scientists do.) The simplest way to get a “feel” for this subject is get a copy of Flory’s book Principles of Polymer Chemistry, still a classic after forty years, and scan the chapters on, for example, the theories of rubber elasticity, solution thermodynamics, phase behavior, etc. This subject is still attracting enormous interest, and there has been much recent emphasis on polymer blends or alloys and polymer liquid crystals.

Polymer Physics

Polymer physics and polymer physical chemistry are overlapping disciplines that are not, in many cases, easily delineated. Historically, however, it is possible to point to an enormous impact by theoretical physicists starting in the late 1960’s and early 1970’s. Until then most theory was based on almost classical physical chemistry, but a number of leading physicists (notably de Gennes and Edwards) started to apply modern theories of statistical physics to the description of long chain molecules. The result has been a revolution in polymer theory, one that is not easily assimilated by “traditional” polymer scientists and is still ongoing.

Polymer physics is not confined to theory, however. Experimental polymer physics continues to focus on areas such as chain conformation, viscoelastic and relaxation properties, phenomena at interfaces, kinetics of phase changes and electrical and piezoelectric properties. In our discussions of polyme...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Preface to the Second Edition
• Preface to the First Edition
• 1. The Nature of Polymeric Materials
• 2. Polymer Synthesis
• 3. Kinetics of Step-Growth and Addition Polymerization
• 4. Statistics of Step-Growth Polymerizations
• 5. Copolymerization
• 6. Spectroscopy and the Characterization of Chain Structure
• 7. Structure
• 8. Crystallization, Melting and the Glass Transition
• 9. Thermodynamics of Polymer Solutions and Blends
• 10. Molecular Weight and Branching
• 11. Mechanical and Rheological Properties
• Index