Table Of ContentStructural Biomaterials
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Structural Biomaterials
T h i r d E d i T i o n
• Ju lian Vinc ent •
PrincETon UnivErSiTy PrESS
PrincETon and oxford
Copyright © 2012 by Princeton University Press
Published by Princeton University Press, 41 William Street,
Princeton, New Jersey 08540
In the United Kingdom: Princeton University Press, 6 Oxford Street,
Woodstock, Oxfordshire OX20 1TW
press.princeton.edu
All Rights Reserved
Library of Congress Cataloging-in-Publication Data
Vincent, Julian F. V.
Structural biomaterials / Julian Vincent. — 3rd ed.
p. cm.
Includes bibliographical references and index.
ISBN-13: 978-0-691-15400-8 (pbk. : acid-free paper)
ISBN-10: 0-691-15400-7 (pbk. : acid-free paper) 1. Biopolymers—Mechanical
properties. 2. Biomedical materials—Mechanical properties. I. Title.
QP801.B69V56 2012
610.28—dc23
2011045733
British Library Cataloging- in-P ublication Data is available
This book has been composed in Times and Helvetica
Printed on acid- free paper. ∞
Printed in the United States of America
1 3 5 7 9 10 8 6 4 2
• contents •
Preface vii
chaPTEr onE
Basic Elasticity and viscoelasticity 1
1.1 Hookean Materials and short- Range Forces 1
1.2 non- Hookean Materials and High strains 4
1.3 the energy approach 6
1.4 Yield and Fracture 21
1.5 adhesion 28
chaPTEr Two
Proteins 29
2.1 amino acids and their Polymerization—Primary structure 29
2.2 conformation—secondary structure 33
2.3 structural Proteins 35
2.4 coping with strain energy 57
chaPTEr ThrEE
Sugars and fillers 61
3.1 Fibers 65
3.2 structural Polysaccharides in Plants 68
3.3 Water, the invisible support 72
3.4 Mucus 82
chaPTEr foUr
Soggy Skeletons and Shock absorbers 84
4.1 composite Materials 84
4.2 stress–strain Behavior 88
4.3 Poisson’s Ratio and auxeticism 89
4.4 the skeleton of the sea anemone 95
4.5 stretching the Pregnant locust 99
4.6 Fracture—chance and choice 101
4.7 stiffness—a Biological Variable 108
chaPTEr fivE
Stiff Materials from Polymers 116
5.1 crystals and order 116
5.2 composite Materials 118
5.3 to stiffen the Matrix 129
5.4 Hardness and indentation 133
5.5 cellular Materials 135
vi
• Contents •
chaPTEr Six
Biological ceramics 143
6.1 calcium salts or silica? 144
6.2 Problems with Mechanical tests 147
6.3 Mollusc shells 151
6.4 the Functional Design of Bone 159
6.5 teeth 169
6.6 eggshell 171
6.7 echinoderms 175
chaPTEr SEvEn
implementing ideas Gleaned from Biology 178
7.1 Biomimetic Products 179
7.2 Quasi- Biomimetic Products 185
7.3 techniques for Biomimetics 187
7.4 instead of energy . . . 193
7.5 . . . use space . . . 195
7.6 . . . or use information . . . 197
7.7 . . . and structure . . . 199
7.8 Well, that’s it 204
References 205
index 223
• PReFace •
It’s been twenty years since this book was last revised, by someone who resembled
me in many respects. In the present edition I have tried to retain that author’s chal-
lenge and enthusiasm tempered (I hope) by knowledge and hard- edged simplicity.
Those twenty years have seen major advances that impinge on the study of struc-
tural biomaterials. Knowledge of the molecular structure and properties of biological
polymers has expanded, initially under the guise of molecular biochemistry, which
developed into “structural biology.” Nanotechnology, in which materials scientists
have burrowed down from millimeters to micrometers to nanometers, is meeting
biologists (as many biochemists like to call themselves) coming up. This marriage is
starting to produce a new class of materials, including biomimetic and “intelligent”
ones, as the roots of the complexity and adaptiveness of biological materials become
better known. This understanding will inevitably feed back to biology.
New models, such as cellular materials, are being developed for complex materials
(or are they structures?), which, in turn, further the understanding of the mechanics
of plants. The principles of biological design—function, shape, and structure—are
being applied to architecture. Biomechanics is increasingly being used by paleon-
tologists to expand their understanding of the lifestyle of extinct animals and plants.
They can calculate the physical limits of performance implied by a particular mor-
phology, and hence its behavioral possibilities.
This wide- ranging use of the study of engineering design of biological materi-
als and structures is a product of the many disciplines it encompasses. Generally,
no single person has the knowledge and intuition to appreciate all the aspects of a
particular problem. In a viable research group, engineering, materials science, poly-
mer physics, mathematics, zoology, physical chemistry, ecology, and botany may
all be more or less equally represented and equally important. Such a diversity of
approach is stimulating to all those involved. And just as biomechanics cuts across
wide boundaries of science, so it cuts across phylogenetic boundaries within biology.
Biomechanics is about functions and mechanisms. Thus the ideas involved in study-
ing fracture or composite materials or plasticizers or ceramics can be applied equally
to animals and plants, since all organisms are limited to a relatively small range of
materials and structures. They are also subject to similar ranges of forces within the
environment, dependent on such generalities as size. Different phyla will be found to
have come to terms with these forces in different ways, but since they are all subject
to the same mechanical and engineering limitations (which is why pigs can’t fly), the
general principles remain the same. Thus biomechanics combines with comparative
functional morphology and becomes the refinement and redefinition of one of the
most traditional approaches to biology. Biomechanics is neomorphology. It is mor-
phology plus numbers and so is “hard” science. And in the stressful environment,
viii
• prefaCe •
mechanical functions and properties are as important as the developmental and phys-
iological functions that generate the structures and materials. A subject area that, to
the traditionalist, is so diverse cries out for a novel form of categorization. The last
chapter includes an account of the development of biomimetics, biology’s challenge
to engineering. Is technology the best way to run the Earth, or can biology (and biolo-
gists) teach us how better to live and survive?
In this book I have combined several approaches but tried throughout to maintain
a viewpoint that the biologist (and I am first and foremost a lover of animals and
plants) can appreciate and understand. It seems necessary to provide a framework of
theory, so the first chapter explains and expounds some of the basic concepts, but it
is as much an appendix as an introduction. There follow five chapters in which the
molecular rather than the mathematical approach is developed, from proteins and
polysaccharides through ceramics. One of the outcomes of this approach is explored
in a chapter on biomimetic materials and comparisons between biology and the ideas
of materials science and engineering that have been used to describe it.
I have, unashamedly, included only those ideas and topics I find interesting and
feel I can understand. I apologize profoundly to those whose work I appear to find,
by implication of omission, boring or obscure! Thus this book is a statement, as well
as a product, of my enthusiasm. It is therefore bound to be bitty and unbalanced but
with odd thoughts and asides that I hope will stimulate and perhaps even amuse.
My thanks are due to many friends and colleagues, some of them past students. I
was going to list them, but their names all appear somewhere in this volume. Even
so, I must particularly mention the late Jim Gordon, who was the first person to make
this all seem possible for me.
Structural Biomaterials
