UNIVERSITY OF CALIFORNIA SAN DIEGO Impact resistant and energy absorbent natural keratin ...

213 Pages·2017·10.5 MB·English

by  Vincent Sherman

UC San Diego
UC San Diego Electronic Theses and Dissertations
Title
Impact resistant and energy absorbent natural keratin materials: horns and hooves
Permalink
https://escholarship.org/uc/item/4kn4z9dp
Author
Huang, Wei
Publication Date
2018

Peer reviewed|Thesis/dissertation
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University of California
UNIVERSITY OF CALIFORNIA SAN DIEGO

Impact resistant and energy absorbent natural keratin materials: horns and hooves

A dissertation submitted in partial satisfaction of the
requirements for the degree of Doctor of Philosophy

in

Materials Science and Engineering

by

Wei Huang

Committee in charge:

Professor Joanna McKittrick, Chair
Professor Shengqiang Cai
Professor Yu Qiao
Professor Jan Talbot
Professor Michael Tolley

2018
Copyright
Wei Huang, 2018
All rights reserved
The Dissertation of Wei Huang is approved, and is acceptable in quality and form for publication
on microfilm and electronically:

____________________________________________________________

____________________________________________________________

____________________________________________________________

____________________________________________________________

____________________________________________________________
Chair

University of California San Diego
2018

iii
TABLE OF CONTENTS
TABLE OF CONTENTS ............................................................................................................... iv
LIST OF FIGURES ....................................................................................................................... ix
LIST OF TABLES ....................................................................................................................... xxi
ACKNOWLEDGEMENTS ........................................................................................................ xxii
VITA .......................................................................................................................................... xxiv
ABSTRACT OF DISSERTATION .......................................................................................... xxvii
CHAPTER 1: INTRODUCTION ....................................................................................................1
1.1 Introduction to biological materials science......................................................................1
1.2 Impact resistance and energy absorption in biological materials ......................................3
1.2.1 Bone and antler ..........................................................................................................6
1.2.2 Nacre ........................................................................................................................12
1.2.3 Mantis shrimp dactyl club ........................................................................................14
1.3 Bioinspired designs .........................................................................................................16
1.3.1 Freeze casting...........................................................................................................16
1.3.2 Additive Manufacturing ...........................................................................................19
1.3.3 Bottom-up synthesis of nanocomposites .................................................................22
CHAPTER 2: BACKGROUND OF KERATIN ...........................................................................25
2.1 Natural keratin materials .................................................................................................25
2.2 Classification of keratin materials ...................................................................................26
2.2.1 Soft vs. hard .............................................................................................................26
2.2.2 Mineralized vs. non-mineralized .............................................................................27
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2.2.3 Offensive vs. defensive ............................................................................................28
2.3 Structure and properties of keratin ..................................................................................29
2.3.1 Multi-phase compositions ........................................................................................29
2.3.2 Multi-scale hierarchical structure ............................................................................31
2.3.3 Multi-mechanical properties ....................................................................................33
CHAPTER 3: STRUCTURE AND PROPERTIES OF BIGHORN SHEEP HORN ....................37
3.1 Introduction to bighorn sheep horn .................................................................................37
3.2 Experiments and methods ...............................................................................................40
3.2.1 High resolution X-ray micro-computed tomography (HR µ-CT) ...........................41
3.2.2 Optical and scanning electron microscopy imaging ................................................42
3.2.3 Transmission electron microscopy imaging ............................................................43
3.2.4 Compression tests ....................................................................................................43
3.2.5 Hopkinson bar impact recovery tests and failure surface imaging ..........................45
3.2.6 Statistical analysis ....................................................................................................46
3.3 Results and discussions ...................................................................................................46
3.3.1 Hierarchical structure of horn ..................................................................................46
3.3.2 Strain rate, anisotropy and water dependency of mechanical properties .................52
3.3.3 Hopkinson bar impact recovery test results and failure mechanisms ......................58
3.4 Conclusions .....................................................................................................................65
CHAPTER 4: STRUCTURE AND PROPERTIES OF DIFFERENT HORNS ...........................69
4.1 Introduction .....................................................................................................................69
4.2 Experiments and methods ...............................................................................................74
v
4.2.1 Materials preparation ...............................................................................................74
4.2.2 Structural characterization .......................................................................................74
4.2.3 Water absorption and FTIR .....................................................................................75
4.2.4 Compression and tensile tests ..................................................................................75
4.2.5 Impact tests ..............................................................................................................77
4.2.6 Statistical analysis ....................................................................................................78
4.3 Results and discussions ...................................................................................................78
4.3.1 Microstructures of the different horns .....................................................................78
4.3.2 Compression tests ....................................................................................................81
4.3.3 Tensile tests ..............................................................................................................88
4.3.4 Drop tower impact tests ...........................................................................................92
4.4 Conclusions .....................................................................................................................95
4.5 Supplementary information .............................................................................................97
CHAPTER 5: WATER EFFECTS ON HORN KERATIN .........................................................101
5.1 Introduction ...................................................................................................................101
5.2 Materials and methods ..................................................................................................102
5.2.1 Acquisition and preservation of horn samples .......................................................102
5.2.2 Synchrotron wide angle X-ray diffraction (WAXD) .............................................102
5.2.3 Fourier transform infrared spectroscopy (ATR-FTIR) ..........................................103
5.2.4 Tensile tests and fracture surface imaging .............................................................103
5.2.5 Viscoelastic behavior: Creep tests .........................................................................104
5.2.6 Compression recovery tests ...................................................................................105
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5.3 Results and discussions .................................................................................................106
5.3.1 Water effects on the structure of horn keratin .......................................................106
5.3.2 Water effects on tensile and creep properties ........................................................109
5.3.3 Water assisted recoverable behaviors ....................................................................113
5.4 Conclusions ...................................................................................................................117
5.5 Supplementary information ...........................................................................................119
CHAPTER 6: STRUCTURE AND PROPERTIES OF EQUINE HOOF ...................................122
6.1 Introduction ...................................................................................................................122
6.2 Experiments and methods .............................................................................................123
6.2.1 Micro- and nanoscale structural characterization ..................................................123
6.2.2 Compression tests and failure surface imaging .....................................................126
6.2.3 Modulus and hardness mapping through nanoindentation ....................................126
6.2.4 In-situ synchrotron X-ray computed tomography compression ............................127
6.3 Results and discussions .................................................................................................127
6.3.1 Hierarchical structure of equine hoof wall .............................................................127
6.3.2 Multi-scale mechanical behavior of equine hoof wall ...........................................132
6.3.3 Failure and energy absorption mechanisms ...........................................................136
6.4 Conclusions ...................................................................................................................140
CHAPTER 7: BIOINSPIRED DESIGNS BASED ON 3D PRINTING .....................................142
7.1 Introduction ...................................................................................................................142
7.2 Experiments and methods .............................................................................................143
7.2.1 3D printing of bioinspired horn and hoof structures ..............................................143
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7.2.2 Synchrotron X-ray micro-computed tomography ..................................................145
7.2.3 Drop-tower impact tests of 3D printed models ......................................................146
7.3 Results and discussions .................................................................................................146
7.3.1 Energy absorption properties of bioinspired designs .............................................146
7.3.2 Failure mechanisms in horns and bioinspired materials ........................................149
7.3.3 Impact resistance of bioinspired designs ...............................................................154
7.4 Conclusions ...................................................................................................................156
CHAPTER 8: SUMMARY AND FUTURE WORK ..................................................................158
8.1 Summary .......................................................................................................................158
8.2 Future work ...................................................................................................................164
REFERENCES ............................................................................................................................166

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LIST OF FIGURES
Figure 1.1 The materials development timeline from ancient to modern times. Images taken from:
newsletter.echa.eu; dailymail.co.uk; shutterstock.com. .................................................................. 1
Figure 1.2 Common characteristics of biological materials [4]. ..................................................... 3
Figure 1.3 Young’s modulus as a function of density for biological and synthetic materials. Taken
from [4]. .......................................................................................................................................... 4
Figure 1.4 The Wegst-Ashby map of toughness and Young’s modulus in natural materials.
Fracture toughness is also shown in the map. Taken from [6]. ...................................................... 6
Figure 1.5 Hierarchical structures of human compact bone. From the left to the right, the collagen
fibers comprise several mineralized collagen fibrils, which is formed by collagen molecule chain
helices in nanoscale. Osteons have a lamellar structure and individual lamella consists of fibers
arranged in geometrical patterns. Finally, the osteons and Haversian canals form compact bone
structure. Taken from [24]. ............................................................................................................. 7
Figure 1.6 Crack-resistance curves (R-curves) and fracture behaviors of human cortical bones in
different orientations. (a) R-curves for crack length less than 500 µm; (b) R-curves for longer crack
length at 7000 µm. (c, d) In-situ SEM images and schematic showing crack propagation along
transverse and longitudinal directions respectively [26]. ............................................................... 8
Figure 1.7 Intrinsic and extrinsic toughening mechanisms in human cortical bone. (a) Intrinsic
toughening mechanisms exist at the front of the crack tip including microvoid coalescence,
promotion of plasticity zone and cleavage fracture, whereas extrinsic toughening mechanisms, act
as shielding local stresses or strains from promoting fracture, existing behind the crack tip. (b)
Extrinsic mechanisms on the left side at the micro- to macro-level; intrinsic toughening
mechanisms including microcracking and fibrillar sliding at sub-micron and nanoscale level [24].
......................................................................................................................................................... 9
Figure 1.8 Compressive stress strain curves of antler in different loading orientations: (a)
longitudinally and (b) transversely in both wet and dry conditions at different strain rates: 10−3,
100 and 103 s−1. Taken from [32]. ................................................................................................. 10
Figure 1.9 Failure mechanisms of antlers after compression in different orientations: left:
transverse direction, which is perpendicular to the osteons; right: longitudinal direction, which is
parallel with the osteons. The central arrow shows the changing of the length scale of the features
taken by scanning electron microscopy. Taken from [32]. ........................................................... 12
Figure 1.10 The hierarchical structure of nacre. (a) Single mineral platelet as “brick” in nacre. The
platelet is composed of millions of ~30 nm nanograins glued together by protein and chitins. (b)
The microscale platelets stacked layer by layer. The interface between platelets provides several
toughening mechanisms, including breakage of mineral bridges, organic glues in the interface,
surface roughness due to the nano-asperities and interlocking sliding due to the uneven surface of
platelets. (c) SEM image of the lamellar structure in nacre. Taken from [24]. ............................ 13
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