Biopolymer nanocomposites processing, properties, and applications

Tai Lieu Chat Luong


BIOPOLYMER
NANOCOMPOSITES


WILEY SERIES ON POLYMER ENGINEERING
AND TECHNOLOGY
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Hyperbranched Polymers: Synthesis, Properties, and Applications / Edited by
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Advanced Thermoforming: Methods, Machines and Materials, Applications
and Automation / Sven Engelmann
Biopolymer Nanocomposites: Processing, Properties, and Applications /
Edited by Alan Dufresne, Sabu Thomas, and Laly A. Pothan


BIOPOLYMER
NANOCOMPOSITES

PROCESSING, PROPERTIES,
AND APPLICATIONS

Edited By

Alain Dufresne
Grenoble Institute of Technology (Grenoble INP)
The International School of Paper
Print Media, and Biomaterials (Pagora)
Saint Martin d’Hères Cedex, France

Sabu Thomas
School of Chemical Sciences
Mahatma Gandhi University
Kottayam, Kerala, India

Laly A. Pothan
Department of Chemistry
Bishop Moore College
Mavelikara, Kerala, India


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Library of Congress Cataloging-In-Publication Data:
Biopolymer nanocomposites : processing, properties, and applications / edited by Alain
Dufresne, Sabu Thomas, Laly A. Pothan.
pages cm
Includes index.
ISBN 978-1-118-21835-8 (hardback)
1. Biopolymers. 2. Nanocomposites (Materials) I. Dufresne, Alain, 1962– editor of
compilation. II. Thomas, Sabu, editor of compilation. III. Pothan, Laly A, editor of
compilation.
TP248.65.P62B5457 2013
572–dc23
2013002843

Printed in the United States of America
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CONTENTS

Foreword

vii

Contributors

ix

1. Bionanocomposites: State of the Art, Challenges, and Opportunities

1

Alain Dufresne, Sabu Thomas, and Laly A. Pothan

2. Preparation of Chitin Nanofibers and Their Composites

11

Shinsuke Ifuku, Zameer Shervani, and Hiroyuki Saimoto

3. Chemical Modification of Chitosan and Its Biomedical Application

33

Deepa Thomas and Sabu Thomas

4. Biomimetic Lessons for Processing Chitin-Based Composites

53

Otto C. Wilson, Jr. and Tiffany Omokanwaye

5. Morphological and Thermal Investigations of Chitin-Based
Nanocomposites

83

Ming Zeng, Liyuan Lu, and Qingyu Xu

6. Mechanical Properties of Chitin-Based Nanocomposites

111

Merin Sara Thomas, Laly A. Pothan, and Sabu Thomas

7. Preparation and Applications of Chitin Nanofibers/Nanowhiskers

131

Jun-Ichi Kadokawa

8. Preparation of Starch Nanoparticles

153

Déborah Le Corre and Alain Dufresne

9. Chemical Modification of Starch Nanoparticles

181

Jin Huang, Qing Huang, Peter R. Chang, and Jiahui Yu

10. Starch-Based Bionanocomposite: Processing Techniques

203

Rekha Rose Koshy, Laly A. Pothan, and Sabu Thomas

11. Morphological and Thermal Investigations of
Starch-Based Nanocomposites

227

Peter R. Chang, Jin Huang, Qing Huang, and Debbie P. Anderson

12. Mechanical Properties of Starch-Based Nanocomposites

261

Hélène Angellier-Coussy and Alain Dufresne
v


vi

CONTENTS

13. Applications of Starch Nanoparticles and Starch-Based
Bionanocomposites

293

Siji K. Mary, Laly A. Pothan, and Sabu Thomas

14. Preparation of Nanofibrillated Cellulose and Cellulose Whiskers

309

David Plackett and Marco Iotti

15. Bacterial Cellulose

339

Eliane Trovatti

16. Chemical Modification of Nanocelluloses

367

Youssef Habibi

17. Cellulose-Based Nanocomposites: Processing Techniques

391

Robert A. Shanks

18. Morphological and Thermal Investigations of Cellulosic
Bionanocomposites

411

Anayancy Osorio-Madrazo and Marie-Pierre Laborie

19. Mechanical Properties of Cellulose-Based Bionanocomposites

437

B. Deepa, Saumya S. Pillai, Laly A. Pothan, and Sabu Thomas

20. Review of Nanocellulosic Products and Their Applications

461

Joe Aspler, Jean Bouchard, Wadood Hamad, Richard Berry, Stephanie Beck,
Franỗois Drolet, and Xuejun Zou

21. Spectroscopic Characterization of Renewable Nanoparticles
and Their Composites

509

Mirta I. Aranguren, Mirna A. Mosiewicki, and Norma E. Marcovich

22. Barrier Properties of Renewable Nanomaterials

541

Vikas Mittal

23. Biocomposites and Nanocomposites Containing Lignin

565

Cornelia Vasile and Georgeta Cazacu

24. Preparation, Processing and Applications of Protein Nanofibers

599

Megan Garvey, Madhusudan Vasudevamurthy, Shiva P. Rao,
Heath Ecroyd, Juliet A. Gerrard, and John A. Carver

25. Protein-Based Nanocomposites for Food Packaging

613

Hélène Angellier-Coussy, Pascale Chalier, Emmanuelle
Gastaldi, Valérie Guillard, Carole Guillaume, Nathalie Gontard,
and Stéphane Peyron

Index

655


FOREWORD

It is important to minimize the environmental impact of materials production
by decreasing the environmental footprint at every stage of their life cycle.
Therefore, composites where the matrix and reinforcing phase are based on
renewable resources have been the subject of extensive research. These efforts
have generated environmental friendly applications for many uses such as for
automotive, packaging, and household products to name some.

Cellulose is the most abundant biomass on the earth and its use in the
preparation of biobased nanomaterials has gained a growing interest during
the last ten years. This interest can be illustrated by how the number of scientific publications on the cellulose nanomaterial research has grown very rapidly
and reached more the 600 scientific publications during 2011. The research
topics have been extraction of cellulose nanofibers and nanocrystals from different raw material sources, their chemical modification, characterization of
their properties, their use as additive or reinforcement in different polymers,
composite preparation, as well as their ability to self-assemble.
Nanocelluloses, both fibers and crystals, have been shown to have promising
and interesting properties, and the abundance of cellulosic waste residues has
encouraged their utilization as a main raw material source. Cellulose nanofibers have high mechanical properties, which combined with their enormous
surface area, low density, biocompatibility, biodegradability, and renewability
make them interesting starting materials for many different uses, especially
when combined with biobased polymers. Since bionanocomposites are a relatively new research area, it is necessary to further develop processing methods
to make these nanomaterials available on a large scale, so that new applications based on them can be developed.
Information about this emerging research field could also prove to be a
catalyst and motivator not only for industries but also to a large number of
students and young scientists. A matrix of tools that could aid such work could
be developed through research enterprise. The book Biopolymer Nanocomposites: Processing, Properties, and Applications by Alain Dufresne, Sabu
Thomas, and Laly A. Pothan, as the authors themselves have pointed out
elsewhere, “is an attempt to introduce various biopolymers and bionanocomposites to a student of materials science. Going beyond mere introduction, the
book delves deep into the characteristics of various biopolymers and bionanocomposites and discusses the nuances of their preparation with a view to
vii


viii

FOREWORD

helping researchers find out newer and novel applications.” Students, researchers, and industrialists in the field of biocomposites will be greatly benefitted
by this book since its chapters are authored by an impressive array of prominent current researchers in this field. Sincere attempts like this at promoting

the use of green materials for sustainable growth of humanity should be
lauded indeed.
Kristiina Oksman
Luleå University of Technology


CONTRIBUTORS

Debbie P. Anderson, Bioproducts and Bioprocesses National Science
Program, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada
Hélène Angellier-Coussy, UnitéMixte de RechercheIngénierie des Agropolymères et Technologies Emergentes, INRA/ENSA.M/UMII/CIRAD, Université Montpellier II, Montpellier Cedex, France
Mirta I. Aranguren, INTEMA-CONICET, Facultad de Ingeniería-Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
Joe Aspler, FPInnovations, Pointe Claire, QC, Canada
Stephanie Beck, FPInnovations, Pointe Claire, QC, Canada
Richard Berry, FPInnovations, Pointe Claire, QC, Canada
Jean Bouchard, FPInnovations, Pointe Claire, QC, Canada
John A. Carver, School of Chemistry and Physics, The University of Adelaide,
Adelaide, SA, Australia; Research School of Chemistry, Australian National
University, ACT, Australia
Georgeta Cazacu, PetruPoni” Institute of Macromolecular Chemistry, Physical Chemistry of Polymers Department, Ghica Voda Alley, Iasi, Romania
Pascale Chalier, Unité Mixte de Recherche Ingénierie des Agropolymères
et Technologies Emergentes, INRA/ENSA.M/UMII/CIRAD, Université
Montpellier II, Montpellier Cedex, France
Peter R. Chang, Bioproducts and Bioprocesses National Science Program,
Agriculture and Agri-Food Canada, Saskatoon, SK, Canada; Department
of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, SK, Canada
B. Deepa, Department of Chemistry, Bishop Moore College, Mavelikara,
Kerala, India; Department of Chemistry, C.M.S. College, Kottayam, Kerala,
India
Franỗois Drolet, FPInnovations, Pointe Claire, QC, Canada

Alain Dufresne, Grenoble Institute of Technology (Grenoble INP), The International School of Paper, Print Media, and Biomaterials (Pagora), Saint
Martin d’Hères Cedex, France
ix


x

CONTRIBUTORS

Heath Ecroyd, School of Biological Sciences, University of Wollongong, NSW,
Australia
Megan Garvey, Institute of Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
Emmanuelle Gastaldi, Unité Mixte de Recherche Ingénierie des Agropolymères et Technologies Emergentes, INRA/ENSA.M/UMII/CIRAD, Université Montpellier II, Montpellier Cedex, France
Juliet A. Gerrard, Biomolecular Interaction Centre, University of Canterbury,
Christchurch, New Zealand; School of Biological Sciences, University of
Canterbury, Christchurch, New Zealand; MacDiarmid Institute, University
of Canterbury, Christchurch, New Zealand
Nathalie Gontard, Unité Mixte de Recherche Ingénierie des Agropolymères
et Technologies Emergentes, INRA/ENSA.M/UMII/CIRAD, Université
Montpellier II, Montpellier Cedex, France
Valérie Guillard, Unité Mixte de Recherche Ingénierie des Agropolymères et
Technologies Emergentes, INRA/ENSA.M/UMII/CIRAD, Université
Montpellier II, Montpellier Cedex, France
Carole Guillaume, Unité Mixte de Recherche Ingénierie des Agropolymères
et Technologies Emergentes, INRA/ENSA.M/UMII/CIRAD, Université
Montpellier II, Montpellier Cedex, France
Youssef Habibi, Center of Innovation and Research in Materials and Polymers, University of Mons, Belgium
Wadood Hamad, FPInnovations, Pointe Claire, QC, Canada
Jin Huang, College of Chemical Engineering, Wuhan University of Technology, Wuhan, China; and State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, China
Qing Huang, College of Chemical Engineering, Wuhan University of Technology, Wuhan, China

Shinsuke Ifuku, Department of Chemistry and Biotechnology, Graduate
School of Engineering, Tottori University, Koyama-cho Minami, Tottori,
Japan
Marco Iotti, Research Scientist, Paper and Fibre Research Institute, Trondheim, Norway
Jun-Ichi Kadokawa, Graduate School of Science and Engineering, Kagoshima
University, Korimoto, Kagoshima, Japan
Rekha Rose Koshy, Department of Chemistry, Bishop Moore College, Mavelikara, Kerala, India
Marie-Pierre Laborie, Institute of Forest Utilization and Work Sciences,
Albert-Ludwigs University of Freiburg, Freiburg, Germany, and Freiburg


CONTRIBUTORS

xi

Materials Research Centre—FMF, Albert-Ludwigs University of Freiburg,
Freiburg, Germany
Déborah Le Corre, University of Canterbury, New Zealand
Liyuan Lu, Engineering Research Center of Nano-Geomaterials of Ministry
of Education, China University of Geosciences, Wuhan, China
Norma E. Marcovich, INTEMA-CONICET, Facultad de Ingeniería-Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
Siji K. Mary, Bishop Moore College, Mavelikara, Kerala, India
Vikas Mittal, Chemical Engineering Department, The Petroleum Institute,
Abu Dhabi, United Arab Emirates
Mirna A. Mosiewicki, INTEMA-CONICET, Facultad de Ingeniería-Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
Tiffany Omokanwaye, Catholic University of America, BONE/CRAB Lab,
Department of Biomedical Engineering, Washington, DC
Anayancy Osorio-Madrazo, Institute of Forest Utilization and Work Sciences,
Albert-Ludwigs University of Freiburg, Freiburg, Germany, and Freiburg
Materials Research Centre—FMF, Albert-Ludwigs University of Freiburg,

Freiburg, Germany
Stéphane Peyron, Unité Mixte de Recherche Ingénierie des Agropolymères
et Technologies Emergentes, INRA/ENSA.M/UMII/CIRAD, Université
Montpellier II, Montpellier Cedex, France
Saumya S. Pillai, Department of Chemistry, Bishop Moore College, Mavelikara, Kerala, India
David Plackett, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark
Laly A. Pothan, Department of Chemistry, Bishop Moore College, Mavelikara, Kerala, India
Shiva P. Rao, New Zealand Institute of Plant and Food Research, Christchurch, New Zealand; Biomolecular Interaction Centre, University of Canterbury, Christchurch, New Zealand
Hiroyuki Saimoto, Department of Chemistry and Biotechnology, Graduate
School of Engineering, Tottori University, Koyama-cho Minami, Tottori,
Japan
Robert A. Shanks, School of Applied Sciences, RMIT University, Melbourne,
Vic., Australia
Zameer Shervani, Department of Chemistry and Biotechnology, Graduate
School of Engineering, Tottori University, Koyama-cho Minami, Tottori,
Japan


xii

CONTRIBUTORS

Deepa Thomas, Department of Chemistry, Bishop Moore College, Mavelikkara, Kerala India
Merin Sara Thomas, Centre for Nanoscience and Nanotechnology, M.G. University, Kottayam, Kerala, India
Sabu Thomas, Centre for Nanoscience and Nanotechnology, M.G. University,
Kottayam, Kerala, India
Eliane Trovatti, CICECO and Department of Chemistry, University of Aveiro,
Aveiro, Portugal
Cornelia Vasile, PetruPoni” Institute of Macromolecular Chemistry, Physical
Chemistry of Polymers Department, Ghica Voda Alley, Iasi, Romania

Madhusudan Vasudevamurthy, New Zealand Institute of Plant and Food
Research, Christchurch, New Zealand; Biomolecular Interaction Centre,
University of Canterbury, Christchurch, New Zealand
Otto C. Wilson, Jr., Catholic University of America, BONE/CRAB Lab,
Department of Biomedical Engineering, Washington, DC
Qingyu Xu, Hubei Research Institute of Chemistry, Wuhan, China, and Haiso
Technology Co., Ltd, Wuhan, China
Jiahui Yu, Institute of Biofunctional Materials and Devices, East China
Normal University, Shanghai, China
Ming Zeng, Engineering Research Center of Nano-Geomaterials of Ministry
of Education,China University of Geosciences, Wuhan, China, and State
Key Laboratory of Polymer Materials Engineering, Sichuan University,
Chengdu, China
Xuejun Zou, FPInnovations, Pointe Claire, QC, Canada


CHAPTER 1

Bionanocomposites: State of the Art,
Challenges, and Opportunities
ALAIN DUFRESNE, SABU THOMAS, and LALY A. POTHAN

1.1  INTRODUCTION
Researchers are currently developing and modifying biobased materials that
have various applications in different fields. Ecological concerns are the main
reasons behind this renewed interest in natural and compostable materials.
Tailoring new products with the perspective of sustainable development is a
philosophy that is applied to more and more materials now. The importance
gained by natural polymers recently should be viewed from this perspective.
Compared with their synthetic counterparts, natural polymers are renewable,

biocompatible, and biodegradable. Production of nanocomposites from natural
polymers, such as starch, chitin, and cellulose, and specific research in this field
aimed at increasing the properties of the products and developing newer techniques are the order of the day. Polysaccharide polymers that are abundant in
nature are increasingly being used for the preparation of nanocomposites.
Biopolymers are polymers that are biodegradable. They are designed to
degrade through the action of living organisms. They are the best alternatives
to traditional nonbiodegradable polymers whose recycling is unpractical or
not economical. The input materials for the production of such biodegradable
polymers may be either renewable (based on agricultural plant or animal
products) or synthetic. Biopolymers from renewable resources are more
important than others for obvious reasons [1]. Biopolymers are said to be
from renewable sources because they are made from materials that can be
grown each year, indefinitely. Plant-based biopolymers usually come from
agricultural nonfood crops. Therefore, the use of biopolymers would create a

Biopolymer Nanocomposites: Processing, Properties, and Applications, First Edition. Edited by
Alain Dufresne, Sabu Thomas, and Laly A. Pothan.
© 2013 John Wiley & Sons, Inc. Published 2013 by John Wiley & Sons, Inc.

1


2  

Bionanocomposites: State of the Art, Challenges, and Opportunities

sustainable industry. In contrast, the feedstock of synthetic polymers derived
from petrochemicals will eventually run out. Biopolymers have also been
reported to be close to carbon-neutral. When a biodegradable material (neat
polymer, blended product, or composite) is obtained completely from renewable resources, we may call it a green polymeric material.

Nature provides an impressive array of polymers that are generally biodegradable and that have the potential to replace many current polymers, as
biodegradation is part of the natural biogeochemical cycle. Natural polymers,
such as proteins, starch, and cellulose, are examples of such polymers. Polymer
nanocomposites represent a new alternative to conventional polymers. Polymer
nanocomposites are materials in which nanoscopic inorganic or organic particles, typically 10–1000 Å in at least one dimension, are dispersed in an organic
polymer matrix in order to improve the properties of the polymer dramatically.
Owing to the nanometer length scale, which minimizes scattering of light,
nanocomposites are usually transparent and exhibit properties that are markedly improved over those of pure polymers or their traditional composites.
They have increased modulus and strength, outstanding barrier properties,
improved solvency, heat resistance, and generally lower flammability, and they
do not have detrimental effects on ductility.
1.2  NANOCRYSTALLINE CELLULOSE
The hierarchical structure and semicrystalline nature of polysaccharides (cellulose, starch, and chitin) allow nanoparticles to be extracted from naturally
occurring polymers. Native cellulose and chitin fibers are composed of smaller
and mechanically stronger long thin filaments, called microfibrils, consisting of
alternating crystalline and noncrystalline domains. Multiple mechanical shearing actions can be used to release these microfibrils individually.
The extraction of crystalline cellulosic regions, in the form of nanowhiskers,
can be accomplished by a simple process based on acid hydrolysis. Samir et al.
have described cellulose whiskers as nanofibers that have been grown under
controlled conditions that lead to the formation of high purity single crystals
[2]. Many different terms have been used in the literature to designate these
rod-like nanoparticles. They are mainly referred to as whiskers or cellulose
nanocrystals. A recent review from Habibi et al. gives a clear overview of such
cellulosic nanomaterials [3].
Nanocrystalline cellulose (NCC) derived from acid hydrolysis of native
cellulose possesses different morphologies depending on the origin and hydrolysis conditions. NCCs are rigid rod-like crystals with a diameter in the range
of 10–20 nm and lengths of a few hundred nanometers (Figure 1.1). Acid treatment (acid hydrolysis) is the main process used to produce NCC, which are
smaller building blocks released from the original cellulose fibers. Native cellulose consists of amorphous and crystalline regions. The amorphous regions
have lower density than the crystalline regions. Therefore, when cellulose

Nanocrystalline Cellulose  

(a)

(b)

(c)

(d)

3

(e)

Figure 1.1  NCCs are rigid rod-like crystals with diameter in the range of 10–20 nm
and lengths of a few hundred nanometers Reproduced with the permission from Reference [5].

fibers are subjected to harsh acid treatment, the amorphous regions break up,
releasing the individual crystallites. The properties of NCC depend on various
factors, such as cellulose sources, reaction time and temperature, and types of
acid used for hydrolysis.
Polysaccharide nanoparticles are obtained as aqueous suspensions, and
most investigations have focused on hydrosoluble (or at least hydrodispersible) or latex-form polymers. However, these nanocrystals can also be dispersed in nonaqueous media using surfactants or chemical grafting. The
hydroxyl groups present on the surface of the nanocrystals make extensive
chemical modification possible. Even though this improves the adhesion of
nanocrystals with nonpolar polymer matrices, it has been reported that this
strategy has a negative impact on the mechanical performance of the composites. This unusual behavior is ascribed to the reinforcing phenomenon of polysaccharide nanocrystals resulting from the formation of a percolating network
due to hydrogen bonding forces.
As a result of its distinctive properties, NCC has become an important class

of renewable nanomaterials, which has many useful applications, the most


4  

Bionanocomposites: State of the Art, Challenges, and Opportunities

important of which is the reinforcement of polymeric matrices in nanocomposite materials. Favier et al. were the first to report the use of NCC as reinforcing fillers in poly(styrene co-butyl acrylate) (poly(S-co-BuA))-based
nanocomposites [4]. Since then, numerous nanocomposite materials have been
developed by incorporating NCC into a wide range of polymeric matrices.
Owing to their abundance, high strength and stiffness, low weight, and biodegradability, nanoscale polysaccharide materials can be used widely for the
preparation of bionanocomposites. In fact, a broad range of applications of
these nanoparticles exists. Many studies show its potential, though most focus
on their mechanical properties and their liquid crystal self-ordering properties.
The homogeneous dispersion of cellulosic nanoparticles in a polymer matrix
is challenging. In addition, there are many safety concerns about nanomaterials, as their size allows them to penetrate into cells of humans and to remain
in the system. However, finding newer applications for nanocellulose will have
a very positive impact on organic waste management. To date, there is no
consensus about categorizing nanocellulosic materials as new materials.
NCC is an environmentally friendly material that could serve as a valuable
renewable resource for rejuvenating the beleaguered forest industry. New and
emerging industrial extraction processes need to be optimized to achieve more
efficient operations, and this will require active research participation from the
academic and industrial sectors. The application of nanotechnology in developing NCC from the forest industry to more valuable products is required
because the availability of materials based on NCC is still limited. Increasing
attention is devoted to producing NCC in larger quantities and to exploring
various modification processes that enhance the properties of NCC, making it
attractive for use in a wide range of industrial sectors [5]. As the second most
abundant biopolymer after cellulose, chitin is mainly synthesized via a biosynthetic process by an enormous number of living organisms such as shrimp,
crab, tortoise, and insects and can also be synthesized by a nonbiosynthetic

pathway through chitinase-catalyzed polymerization of a chitobiose oxazoline
derivative [6, 7].
Chitosan, as the most important derivative of chitin, can be prepared by
deacetylation of chitin. Chitin and chitosan have many excellent properties
including biocompatibility, biodegradability, nontoxicity, and absorption, and
thus they can be widely used in a variety of areas such as biomedical applications, agriculture, water treatment, and cosmetics. Chitin has been known to
form microfibrillar arrangements in living organisms. These fibrils with diameters from 2.5 to 25 nm, depending on their biological origins, are usually
embedded in a protein matrix [8]. Therefore, they intrinsically have the potential to be converted to crystalline nanoparticles and nanofibers and to find
application in nanocomposite fields. The structure of chitin is very analogous
to cellulose. Chitin and cellulose are both supporting materials for living
bodies and are found in living plants or animals with sizes increasing from
simple molecules and highly crystalline fibrils on the nanometer level to composites on the micrometer level upward [9]. Therefore, they intrinsically have


Nanocrystalline Cellulose  

5

the potential to be converted to crystalline nanoparticles and nanofibers and
to find application in nanocomposite fields. Chitin has been known to form
microfibrillar arrangements in living organisms [10, 11].
Chitin whiskers (CHW) can be prepared from chitins isolated from chitincontaining living organisms by a method similar to the preparation of cellulose
whisker through hydrolysis in a strong acid aqueous medium. On the basis of
preparation of cellulose crystallite suspension, Marchessault et al. [11] for the
first time reported a route for preparing suspension of chitin crystallite particles in 1959. In this method, purified chitin was first treated within 2.5 N
hydrochloric acid (HCl) solutions under reflux for 1 hour; the excess acid was
decanted; and then distilled water was added to obtain the suspension. Acidhydrolyzed chitin was found to be spontaneously dispersed into rod-like particles that could be concentrated to a liquid crystalline phase and self-assemble
to a cholesteric liquid crystalline phase above a certain concentration [12].
CHWs are attracting attention from both the academic field and industry
since it is a renewable and biodegradable nanoparticle. CHWs have numerous

advantages over conventional inorganic particles such as low density, nontoxicity, biodegradability, biocompatibility, easy surface modification, and functionalization. Figure 1.2 shows the transmission electron microscopy (TEM) and
atomic force microscopy (AFM) images of CHWs obtained by the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) mediated oxidation method. CHWs,
with or without modification, are hoped to have extensive application in many
areas such as reinforcing nanocomposites, the food and cosmetics industries,
drug delivery, and tissue engineering. However, recent studies have focused
mainly on the preparation and nanocomposite application of CHWs, and less
attention has been paid to other application areas. It is hoped that in the future,
more attention will be focused on developing novel applications of CHWs. Even
for the CHW-reinforced nanocomposites there will still be much valuable work
to be done, for example, developing new simple and effective processing
methods so as to commercialize high performance polymer/CHWs composites,
producing polymer nanocomposites filled with individual CHWs that would
create higher reinforcing efficiency than the conventional CHW due to the high
aspect ratio of individual CHWs. Thus, there are abundant opportunities combined with challenges in CHW-related scientific and industrial fields [13].
Starch is the second most studied organic material for producing nanocrystals. Starch nanocrystals are the nanoscale biofillers derived from native starch
granules and are a suitable candidate for the preparation of semicrystalline
polymers for preparing renewable and potentially biodegradable nanoparticles. As a natural biopolymer, starch is abundant, renewable, inexpensive,
biodegradable, environmentally friendly, and easy to chemically modify,
making it one of the most attractive and promising bioresource materials.
Several techniques for preparing starch nanoparticles (SNP) have been developed over the years and render different kinds of SNP, which are described in
this book. Acid hydrolysis and precipitation methods are the two main methods
employed for the preparation of SNPs. Starch nanocrystals obtained by acid


6  

Bionanocomposites: State of the Art, Challenges, and Opportunities

(a)

(b)

(c)

(d)

Figure 1.2  TEM (a) and AFM (b) images of a dilute suspension of chitin whiskers
and TEM images of individual chitin whiskers obtained by the TEMPO method (c)
and surface cationization (d). Reproduced with permissions from Reference [9].

hydrolysis of starch have been used as fillers in natural and synthetic polymeric
matrices and appear to be an interesting reinforcing agent. Figure 1.3 shows
the TEM image of starch nanocrystals [14]. Nanoreinforced starch-based
nanocomposites generally exhibit enhanced mechanical and thermal properties when nanofillers are well dispersed, while the nature of the matrix and/or
nanofiller contributes to its biological properties.
Nanocellulose produced by the bacterium Gluconacetobacter xylinus (bacterial cellulose, BC), is an another emerging biomaterial with great potential
as a biological implant, wound and burn dressing material, and scaffold for
tissue regeneration. This BC is quite different from plant celluloses and is
defined by high purity (free of hemicelluloses, lignin, and alien functionalities


Nanocrystalline Cellulose  

7

Figure 1.3  TEM observations of starch nanocrystals: longitudinal view and planar
view. Reproduced with permission from Reference [14]. Copyright 2003 American
Chemical Society.

such as carbonyl or carboxyl groups) and a high degree of polymerization (up

to 8000) [15]. BC has remarkable mechanical properties despite the fact that
it contains up to 99% water. The water-holding ability is the most probable
reason why BC implants do not elicit any foreign body reaction. Fibrosis,
capsule formation, or giant cells were not detected around the implants, and
connective tissue was well integrated with the BNC structures. Moreover, the
nanostructure and morphological similarities with collagen make BC attractive for cell immobilization, cell migration, and the production of extracellular
matrices [16, 17]. Figure 1.4 shows BNC fleeces formed by different Gluconacetobacter strains and their network structure.
The advanced natural fiber-reinforced polymer composite contributes to
enhancing the development of bionanocomposites with regard to performance
and sustainability. In the future, these biocomposites will see increased use in
optical, biological, and engineering applications. But there are still a number
of problems that have to be solved before biocomposites become fully competitive with synthetic fiber composites. These include extreme sensitivity to
moisture and temperature, expensive recycling processes, high variability in
properties, nonlinear mechanical behavior, poor long-term performance, and
low impact strength. As of now, the methods for extracting nanocrystals of
these various biomaterials are expensive, and more economical methods will
have to be sorted out in future.
The poor interfacial adhesion between natural fibers and polymeric matrix
is the key issue that dictates the overall performance of the composites. Interaction of two or more different materials with each other depends on the
nature and strengths of the intermolecular forces of the components involved.
The mechanical performance of composites is dependent on the degree of


8  

Bionanocomposites: State of the Art, Challenges, and Opportunities

Figure 1.4  Fleeces of bacterial nanocellulose produced by two different Gluconacetobacter strains and their network structure. Reproduced with permissions from Reference [17].

dispersion of the fibers in the matrix polymer and the nature and intensity of

fiber–polymer adhesion interactions. Therefore, the selection of appropriate
matrices and filler with good interfacial interaction is of great importance. The
irreversible aggregation of the nanofiller (hornification) in the matrix, which
prevents its redispersion in the matrix, is another hurdle to be overcome. This
irreversible aggregation results in a material with ivory-like properties that
can neither be used in rheological applications nor be dispersed for composite
applications. Therefore, it is necessary to continue research in this area to
obtain a better understanding of the adhesion interactions including mechanical interlocking, interpenetrating networks, and covalent linkages on a fundamental level to improve interfacial properties with thermoplastics, thermosets,
and biopolymers.
This book is an attempt to introduce various biopolymers and bionanocomposites to students of material sciences. Going beyond a mere introduction,


References  

9

the book delves deep into the characteristics of various biopolymers and
bionanocomposites and discusses the nuances of their preparation with a view
to helping researchers discover newer and novel applications. Chapter 2, for
instance, describes the preparation of chitin nanofibers and their composites
and discusses the basics, such as isolation of chitin nanofibersfrom different
sources. Chapter 3 discusses chemical modification of chitosan and its biomedical application. While biometric lessons for processing chitin-based composites
are provided in Chapter 4, Chapter 5 deals with morphological and thermal
investigations of chitin-based nanocomposites. Mechanical properties of
chitin-based nanocomposites are discussed in Chapter 6, and preparation and
applications of chitin nanofibers/nanowhiskers is the topic of Chapter 7. Thus,
Chapters 2 to 7 are allotted to chitin and related topics.
Various aspects of starch-based composites, such as preparation of SNPs
(Chapter 8), chemical modification of SNPs (Chapter 9), processing techniques
of starch-based bionanocomposites (Chapter 10), morphological and thermal

investigations of starch-based nanocomposites (Chapter 11), mechanical properties of starch-based nanocomposites (Chapter 12), and applications of SNPs
and starch-based bionanocomposites (Chapter 13), are the subject matter of
Chapters 8 to 13.
Preparation of nanofibrillated cellulose and cellulose whiskers are dealt
with in Chapter 14. Chapter 15 is exclusively set apart for BC. It examines
the details of production of microorganisms, production of BC, production of
BC from food and agro-forestry residues, and the structure of BC. Chemical
modification of nanocelluloses is discussed in Chapter 16, and processing
techniques of cellulose-based nanocomposites are dealt with in Chapter 17.
Chapter 18 is on morphological and thermal investigations of cellulosic bionanocomposites, and Chapter 19 discusses mechanical properties of cellulosebased bionanocomposites. A review of nanocellulosic products and their
applications is provided in Chapter 20. In Chapter 21 spectroscopic characterization of renewable nanoparticles and their composites are dealt with.
Chapter 22 deals with barrier properties of renewable nanomaterials. Chapter
23 is set apart for biocomposites and nanocomposites containing lignin. While
Chapter 24 deals with preparation, processing, and applications of protein
nanofibers, Chapter 25 deals with protein-based nanocomposites for food
packaging. Thus, this book is a sincere attempt at promoting the use of green
materials for sustainable growth of humanity.

REFERENCES
  [1]  Kaplan, D.L., ed. (1998) Biopolymers from Renewable Resources; Macromolecular
Systems—Materials Approach. Berlin, Heidelberg: Springer-Verlag.
  [2]  Samir, M.A.S.A., Alloin, F., and Dufresne, A. (2005) Review of recent research
into cellulosic whiskers, their properties and their application in nanocomposite
field. Biomacromolecules, 6, 612–626.


10  

Bionanocomposites: State of the Art, Challenges, and Opportunities

  [3]  Habibi, Y., Lucia, L.A., and Rojas, O.J. (2010) Cellulose Nanocrystals: Chemistry,
self assembly, and applications. Chemical Reviews, 110(6), 3479–3500.
  [4]  Favier, V., Chanzy, H., and Cavaille, J.Y. (1995) Polymer nanocomposites reinforced by cellulose whiskers. Macromolecules, 28, 6365–6367.
  [5]  Peng, B.L., Dhar, N., Liu, H.L., and Tam, K.C. (2011) Chemistry and applications
of nanocrystalline cellulose and its derivatives: A nanotechnology perspective.
Canadian Journal of Chemical Engineering, 89(5), 1191–1206.
  [6]  Kobayashi, S., Kiyosada, T., and Shoda, S.I. (1996) Synthesis of artificial chitin:
Irreversible catalytic behavior of a glycosyl hydrolase through a transition state
analogue substrate. Journal of American Chemical Society, 118, 13113–13114.
  [7]  Kadokawa, J. (2011) Precision polysaccharide synthesis catalyzed by enzymes.
Chemical Reviews, 111, 4308–4345.
  [8]  Revol, J.F., Marchessault, R.H. (1993) In vitro chiral nematic ordering of chitin
crystallites. International Journal of Biological Macromolecules, 15, 329–335.
  [9]  Fan, Y., Saito, T., and Isogai, A. (2008) Preparation of chitin nanofibers from squid
pen β-chitin by simple mechanical treatment under acid conditions. Biomacromolecules, 9, 1919–1923.
[10]  Carlstrom, D. (1957) The crystal structure of α-chitin (poly-n-acetyl-d-glucosamine).
The Journal of Biophysical and Biochemical Cytology, 3, 669–683.
[11]  Marchessault, R.H., Morehead, F.F., and Walter, N.M. (1959) Liquid crystal systems
from fibrillar polysaccharides. Nature, 184, 632–633.
[12]  Li, J., Revol, J.F., Naranjo, E., and Marchessault, R.H. (1996) Effect of electrostatic
interaction on phase separation behaviour of chitin crystallite suspensions. International Journal of Biological Macromolecules, 18, 177–187.
[13]  Zeng, J.B., He, Y.S., Li, S.L., and Wang, Y.Z. (2012) Chitin whiskers: An overview.
Biomacromolecules, 13, 1–11.
[14]  Putaux, J.L., Molina-Boisseau, S., Momaur, T., and Dufresne, A. (2003) Platelet
nanocrystals resulting from the disruption of waxy maize starch granules by acid
hydrolysis. Biomacromolecules, 4(5), 1198–1202.
[15]  Kramer, F., Klemm, D., Schumann, D., Heßler, N., Wesarg, F., Fried, W., and Stadermann, D. (2006) Nanocellulose polymer composites as innovative pool for (Bio)
material development. Macromolecular Symposia, 244, 136–148.
[16]  Gatenholm, P., Klemm, D. (2010) Bacterial nanocellulose as a renewable material
for biomedical applications. MRS Bulletin, 35, 208–213.

[17]  Klemm, D., Kramer, F., Moritz, S., Lindstrom, T., Ankerfors, M., Gray, D., and
Dorris, A. (2011) Nanocelluloses: A new family of nature-based materials. Angew.
Chem. Int. Ed., 50, 5438–5466.


CHAPTER 2

Preparation of Chitin Nanofibers and
Their Composites
SHINSUKE IFUKU, ZAMEER SHERVANI, and HIROYUKI SAIMOTO

2.1  INTRODUCTION
Biodegradable chitin nanofibers (CNFs) have attracted the attention of
researchers worldwide in recent years, as they constitute an important part of
the rapidly growing field of nanotechnology, which deals with nanometer-sized
(1–100 nm) composites. Bionanofibers have superiority over their synthetic
counterparts because of their biocompatible nature. They have applications in
the medical, cosmetics, pharmaceutical, and chemical industries. If doped with
inorganic metals, the hybrid organic–inorganic composites can have vast applications in electronics, electrical, and optical fields, and, most important, in
much needed renewable energy production. Nanofibers (NFs) have a large
surface-to-mass ratio, making them promising candidates for advanced material devices. A number of methods are employed to spin NFs. Electrospinning
is one of the methods that use electrical charge to draw nanoscale fibers from
polymer liquid solutions. As synthetic NFs are environmentally toxic, natural
NFs are preferred products over synthetic fibers. Natural NFs are known to
exist in nature in various forms: collagen fibrils, silk fibroin, double helical
deoxyribonucleic acid, and so on. Apart from natural chitin NFs, there are
cellulose microfibrills, which are more abundant natural NFs.
Abe et al. [1] achieved efficient extraction of wood cellulose NFs, which
existed in a cell wall, of a uniform width of 15 nm, using a simple mechanical
treatment. Wood powder of size <60 mesh from the Radiata pine tree was

used. First, organic solvent extraction was conducted to remove wax and other
small organic components. The larger complex lignin moiety was separated by

Biopolymer Nanocomposites: Processing, Properties, and Applications, First Edition. Edited by
Alain Dufresne, Sabu Thomas, and Laly A. Pothan.
© 2013 John Wiley & Sons, Inc. Published 2013 by John Wiley & Sons, Inc.

11


12  

Preparation of Chitin Nanofibers and Their Composites

acidified sodium chlorite solution. A number of extraction cycles were used
until the product turned white. Hemicellulose was leached by the treatment
of 6 wt% potassium hydroxide. Cellulose thus obtained as α-cellulose constituted 85% of whole cellulose. Finally, 1 wt% slurry of cellulose was passed
through a grinder at a speed of 1500 rpm. Field emission scanning electron
microscopy (FE-SEM) measurement confirmed the formation of 15 nm width
cellulose NFs.
All cellulose composites of consisting fibers and matrix were studied [2, 3]
for structural, mechanical, and thermal properties. The elastic modulus, in the
direction parallel to the polymer molecule chain axis, was found to be 138 GPa
for the crystalline regions. This value is comparable to that of high performance synthetic fibers. The tensile strength of cellulose is 17.8 GPa, which is
seven times higher than that of steel. The linear thermal expansion coefficient
is about 10−7/K. Due to their high elastic modulus and tensile strength and low
thermal expansion, fibers are promising candidates as reinforcement agent for
a number of composites.
Chitin is the second most abundant biopolymer after cellulose that occurs
in nature [4]. Its annual production worldwide is 1010 to 1011 tons, mostly

produced from external skeletons of shellfish, crabs, shrimp, insects, mushrooms, and algae. The fibrous material of cellular walls of mushrooms and
algae and external skeletons in shellfish and insects are composed of chitin.
Chitin content is in the range of 8–33%, which is disposed of as industrial
waste in shellfish canning industries. Chitin and chitin compounds find application in various fields, including cosmetics and chemical industries, engaging
researchers from around the world. Chitin and their hybrid inorganic composites are also expected to have applications in electrical, electronics, and
optical devices. Natural chitin is highly crystalline (mostly α-chitin), though
the distribution among α- and -β-chitin depends on the source. Among the
applications discovered so far, chitin serves as an effective reinforcement for
the preparation of composites; there are reports in the literature on chitin
whisker-reinforced nanocomposites [4]. The chitin structure comprises the
repeating units along the N-acetylglucosamine structure. It has two hydroxyl
and an acetamide groups per unit [5], which make the molecule reactive for
a number of applications. A dominant feature of arthropod exoskeletons is
that they are well organized, arranged in different structural levels. Considering molecular levels, there are long chain polysaccharide chitin fibrils with
dimensions of 3 nm in width and 300 nm in length. The fibrils are wrapped in
proteins and aggregated into bundles of fibers of about 60 nm in diameter.
Step-by-step breakup of these assemblies has been shown by Chen et al. [6],
who have described the structural and mechanical properties of crab exoskeleton in detail. Chitin whiskers were prepared from crab shells by using chemical treatment followed by mechanical treatment [4]. The proteins were
removed with 5% KOH; NaClO2 and a small amount of sodium acetate buffer
were used as bleaching agents. The residual proteins were again removed by
using 5% KOH.