Fundamentals of Polymer Engineering, Third Edition

Anil Kumar, Rakesh K. Gupta

• Publisher: CRC Press
• Year: 2018
• Print ISBN: 9781498759502
• eBook ISBN: 9780429676307
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Exploring the chemistry of synthesis, mechanisms of polymerization, reaction engineering of step-growth and chain-growth polymerization, polymer characterization, thermodynamics and structural, mechanical, thermal and transport behavior of polymers as melts, solutions and solids, Fundamentals of Polymer Engineering, Third Edition covers essential concepts and breakthroughs in reactor design and polymer production and processing. It contains modern theories and real-world examples for a clear understanding of polymer function and development. This fully updated edition addresses new materials, applications, processing techniques, and interpretations of data in the field of polymer science. It discusses the conversion of biomass and coal to plastics and fuels, the use of porous polymers and membranes for water purification, and the use of polymeric membranes in fuel cells. Recent developments are brought to light in detail, and there are new sections on the improvement of barrier properties of polymers, constitutive equations for polymer melts, additive manufacturing and polymer recycling.

This textbook is aimed at senior undergraduate students and first year graduate students in polymer engineering and science courses, as well as professional engineers, scientists, and chemists. Examples and problems are included at the end of each chapter for concept reinforcement.

1	Introduction

1.1 DEFINING POLYMERS

Polymers are materials of very high molecular weight that are found to have multifarious applications in our modern society. They usually consist of several structural units bound together by covalent bonds [1,2]. For example, polyethylene is a long-chain polymer and is represented by

$-{\text{CH}}_2{\text{CH}}_2{\text{CH}}_2-\text{or}{{\text{[-CH}}_2{\text{CH}}_2-\text{]}}_{\text{n}}$

(1.1.1)

where the structural (or repeat) unit is −CH₂−CH₂− and n represents the chain length of the polymer.

Polymers are obtained through the chemical reaction of small molecular compounds called monomers. For example, polyethylene in Eq. (1.1.1) is formed from the monomer ethylene. In order to form polymers, monomers either have reactive functional groups or double (or triple) bonds whose reaction provides the necessary linkages between repeat units. Polymeric materials usually have high strength, possess a glass transition temperature, exhibit rubber elasticity, and have high viscosity as melts and solutions.

In fact, exploitation of many of these unique properties has made polymers extremely useful to mankind. They are used extensively in food packaging, clothing, home furnishings, transportation, medical devices, information technology, and so forth. Natural fibers such as silk, wool, and cotton are polymers and have been used for thousands of years. Within the last 75 years, they have been supplemented and, in some instances, replaced by synthetic fibers such as rayon, nylon, and acrylics. Indeed, rayon itself is a modification of a naturally occurring polymer, cellulose, which in other modified forms has served for years as commercial plastics and films. Synthetic polymers (some common ones are listed in Table 1.1), such as polyolefins, polyesters, acrylics, nylons, and epoxy resins, find extensive applications as plastics, films, adhesives, and protective coatings. Depending upon the specific usage, the properties of polymers are modified by adding additive chemicals to them, and there is a multibillion-dollar industry dedicated to manufacturing them. These different chemicals could serve as plasticisers, flame retardant, heat stabilizers, impact modifiers, lubricants, antioxidants, UV light stabilizers, and blowing agents [3]. It may be added that biological materials, such as proteins, deoxyribonucleic acid (DNA), and mucopolysaccharides, are also polymers. Polymers are worth studying because their behavior as materials is different from that of metals and other low molecular weight materials. As a result, a large percentage of chemists, physicists, and engineers are engaged in works involving polymers, which necessitates one or more than one formal course in polymer science.

Biomaterials [4] are defined as materials used within human bodies either as artificial organs, bone cements, dental cements, ligaments, pacemakers, or contact lenses. The human body consists of biological tissues (e.g., blood, cells, proteins, etc.), and they have the ability to reject materials that are ‘‘incompatible’’ either with the blood or with the tissues. For such applications, polymeric materials, which are derived from animals or plants, are natural candidates, and lately, polyacrylamide, polyester, and polyethylene oxides have been commonly employed because they are inert within the body. Sometimes, due to the requirements of mechanical strength, selective permeation, adhesion, and/or degradation, even noncompatible polymeric materials have been put to use, but before they are utilized, they are surface modified by biological molecules (such as heparin, biological receptors, enzymes, and so forth). Some of these concepts will be developed in this and subsequent chapters.

TABLE 1.1
Some Common Polymers

Commodity Thermoplastics
Polyethylene	$\sout{[}{\text{CH}}_2{\text{CH}}_2\sout{]}$
Polystyrene
Polypropylene	$\sout{[}{\text{CH}}_2\underset{\stackrel{|}{{\text{CH}}_3}}{\text{CH}}\sout{]}$
Polyvinyl chloride	$\sout{[}{\text{CH}}_2\underset{\stackrel{|}{\text{Cl}}}{\text{CH}}\sout{]}$
Polymers in electronic applications Polyacetylene	$\sout{[}\stackrel{\underset{|}{\text{H}}}{\text{C}}=\underset{\stackrel{|}{\text{H}}}{\text{C}}{\sout{]}}_n$
Poly(p-phenylene vinylene)
Polythiophene
Polyphenylene sulfide
Polyanilines	$\sout{[}{\text{CH}}_2\underset{\stackrel{|}{{\text{NH}}_2}}{\text{CH}}{\sout{]}}_n$
Biomedical applications
Polycarbonate (diphenyl carbonate)
Polymethyl methacrylate	$\sout{[}{\text{CH}}_2\stackrel{\underset{|}{{\text{CH}}_3}}{\underset{\stackrel{|}{{\text{COOCH}}_3}}{\text{C}}}{\sout{]}}_n$
Silicone polymers	$\sout{[}\stackrel{\underset{|}{{\text{CH}}_3}}{\underset{\stackrel{|}{{\text{CH}}_3}}{\text{Si}-}}\text{O}{\sout{]}}_n$
Specialty polymers Polyvinylidene chloride	$\sout{[}{\text{CH}}_2\underset{\stackrel{|}{\text{Cl}}}{\stackrel{\underset{|}{\text{Cl}}}{\text{C}}}\sout{]}$
Polyindene
Polyvinyl pyrrolidone
Coumarone polymer

In all civilized societies, industrial activities are carried out, which more often produces pollution, leading to environmental issues. In the separation of pollutants, polymers play a major role in membrane separation. The material of construction of these membranes is mostly polymeric and has the potential of replacing considerably more expensive methods of separation, such as distillation, solvent extraction, crystallization, etc. In view of the recent energy cri...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Preface to the Third Edition
• Authors
• Chapter 1 Introduction
• Chapter 2 Effect of Chemical Structure on Polymer Properties
• Chapter 3 Step-Growth Polymerization
• Chapter 4 Reaction Engineering of Step-Growth Polymerization
• Chapter 5 Chain-Growth Polymerization
• Chapter 6 Reaction Engineering of Chain-Growth Polymerization
• Chapter 7 Emulsion Polymerization
• Chapter 8 Measurement of Molecular Weight and Its Distribution
• Chapter 9 Thermodynamics of Polymer Mixtures
• Chapter 10 Theory of Rubber Elasticity
• Chapter 11 Polymer Crystallization
• Chapter 12 Mechanical Properties
• Chapter 13 Polymer Diffusion
• Chapter 14 Flow Behavior of Polymeric Fluids
• Chapter 15 Polymer Processing
• Index