Flame Retardant Polymer Nanocomposites

by Alexander B. Morgan and Charles A.

Flame Retardant Polymer Nanocomposites Author Alexander B Morgan and Charles A Wilkie Isbn 9780471734260 File size 5MB Year 2007 Pages 429 Language English File format PDF Category Chemistry Flame Retardant Polymer Nanocomposites takes a comprehensive look at polymer nanocomposites for flame retardancy applications and includes nanocomposite fundamentals theory design synthesis characterization as well as polymer flammability fundamentals with emphasis on how nanocomposites affect flammability The book has practical exampl

Publisher :

Author : Alexander B. Morgan and Charles A. Wilkie

ISBN : 9780471734260

Year : 2007

Language: English

File Size : 5MB

Category : Chemistry



Edited by
Alexander B. Morgan
University of Dayton Research Institute
Dayton, Ohio

Charles A. Wilkie
Marquette University Department of Chemistry
Milwaukee, Wisconsin


Copyright  2007 by John Wiley & Sons, Inc. All rights reserved.
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Library of Congress Cataloging-in-Publication Data:
Morgan, Alexander B.
Flame retardant polymer nanocomposites / Alexander B. Morgan, Charles A.
p. cm.
Includes index.
ISBN 978-0-471-73426-0 (cloth)
1. Fire resistant polymers. 2. Nanostructured materials. 3. Polymeric
composites. I. Wilkie; C. A. (Charles A.) II. Title.
TH1074.5.M67 2007
628.9 223—dc22
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1


1 Introduction to Flame Retardancy and Polymer Flammability


Sergei V. Levchik

1.1 Introduction, 1
1.2 Polymer Combustion and Testing, 3
1.2.1 Laboratory Flammability Tests, 3
1.2.2 Polymer Combustion, 5
1.3 Flame Retardancy, 7
1.3.1 General Flame Retardant Mechanisms, 7
1.3.2 Specific Flame Retardant Mechanisms, 7
1.3.3 Criteria for Selection of Flame Retardants, 20
1.3.4 Highly Dispersed Flame Retardants, 20
1.4 Conclusions and Future Outlook, 22
References, 23
2 Fundamentals of Polymer Nanocomposite Technology


E. Manias, G. Polizos, H. Nakajima, and M. J. Heidecker

2.1 Introduction, 31
2.2 Fundamentals of Polymer Nanocomposites, 33
2.2.1 Thermodynamics of Nanoscale Filler
Dispersion, 33



2.2.2 Synthetic Routes for Nanocomposite
Formation, 36
2.2.3 Dispersion Characterization: Common Techniques
and Limitations, 42
2.3 Effects of Nanofillers on Material Properties, 45
2.3.1 Effects on Polymer Crystallization, 45
2.3.2 Effects on Mechanical Properties, 51
2.3.3 Effects on Barrier Properties, 56
2.4 Future Outlook, 60
References, 61
3 Flame Retardant Mechanism of Polymer–Clay


Jeffrey W. Gilman

3.1 Introduction, 67
3.1.1 Initial Discoveries, 68
3.2 Flame Retardant Mechanism, 69
3.2.1 Polystyrene Nanocomposites, 69
3.2.2 Polypropylene–Clay Nanocomposites, 75
3.2.3 Thermal Analysis of Polymer–Clay
Nanocomposites, 81
3.3 Conclusions and Future Outlook, 82
References, 83
4 Molecular Mechanics Calculations of the Thermodynamic
Stabilities of Polymer–Carbon Nanotube Composites


Stanislav I. Stoliarov and Marc R. Nyden


Introduction, 89
Background and Context, 90
Description of the Method, 93
Application to PS–CNT Composites, 96
Uncertainties and Limitations, 100
Summary and Conclusions, 104
References, 105

5 Considerations Regarding Specific Impacts of the Principal
Fire Retardancy Mechanisms in Nanocomposites
Bernhard Schartel

5.1 Introduction, 107
5.2 Influence of Nanostructured Morphology, 108
5.2.1 Intercalation, Delamination, Distribution, and
Exfoliation, 108
5.2.2 Orientation, 111




5.2.3 Morphology During Combustion or Barrier
Formation, 112
5.3 Fire Retardancy Effects and Their Impact on the Fire
Behavior of Nanocomposites, 113
5.3.1 Inert Filler and Char Formation, 113
5.3.2 Decomposition and Permeability, 115
5.3.3 Viscosity and Mechanical Reinforcement, 117
5.3.4 Barrier for Heat and Mass Transport, 118
5.4 Assessment of Fire Retardancy, 121
5.4.1 Differentiated Analysis with Regard to Different
Fire Properties, 121
5.4.2 Different Fire Scenarios Highlight Different Effects
of Nanocomposites, 123
5.5 Summary and Conclusions, 124
References, 125
6 Intumescence and Nanocomposites: a Novel Route for
Flame-Retarding Polymeric Materials


Serge Bourbigot and Sophie Duquesne


Introduction, 131
Basics of Intumescence, 133
Zeolites as Synergistic Agents in Intumescent Systems, 138
Intumescents in Polymer Nanocomposites, 143
Nanofillers as Synergists in Intumescent Systems, 147
Critical Overview of Recent Advances, 153
Summary and Conclusion, 157
References, 157

7 Flame Retardant Properties of Organoclays and Carbon
Nanotubes and Their Combinations with Alumina Trihydrate
G¨unter Beyer

7.1 Introduction, 163
7.2 Experimental Process, 168
7.2.1 Materials, 168
7.2.2 Compounding, 169
7.2.3 Analyses, 169
7.3 Organoclay Nanocomposites, 169
7.3.1 Processing and Structure of
EVA/Organoclay-Based Nanocomposites, 169
7.3.2 Thermal Stability of EVA/Organoclay-Based
Nanocomposites, 170
7.3.3 Flammability Properties of EVA/Organoclay-Based
Nanocomposites, 171




7.3.4 NMR Investigation and Fire Retardant Mechanism
of EVA Nanocomposites, 173
7.3.5 Intercalation Versus Exfoliation of EVA
Nanocomposites, 174
7.3.6 Combination of the Classical Flame Retardant
Filler Alumina Trihydrate with Organoclays, 174
7.3.7 Coaxial Cable Passing the UL-1666 Fire Test with
an Organoclay/ATH-Based Outer Sheath, 176
7.4 Carbon Nanotube Nanocomposites, 177
7.4.1 General Properties of Carbon Nanotubes, 177
7.4.2 Synthesis and Purification of Carbon
Nanotubes, 177
7.4.3 Flammability of EVA–MWCNT and
EVA–MWCNT–Organoclay Compounds, 177
7.4.4 Crack Density and Surface Results of Charred
MWCNT Compounds, 179
7.4.5 Flammability of LDPE Carbon Nanotube
Compounds, 179
7.4.6 Cable with the New Fire Retardent System
MWCNTs–Organoclays–ATH, 182
7.5 Summary and Conclusions, 186
References, 186
8 Nanocomposites with Halogen and Nonintumescent
Phosphorus Flame Retardant Additives
Yuan Hu and Lei Song

8.1 Introduction, 191
8.1.1 Polymer–Organoclay Nanocomposites, 191
8.1.2 Conventional Halogen and Nonintumescent
Phosphorus-Containing Flame Retardants, 192
8.2 Preparation Methods and Morphological Study, 193
8.2.1 Melt Compounding and Solution Blending, 194
8.2.2 in situ Polymerization Method, 198
8.2.3 Summary of Synthetic Methods, 200
8.3 Thermal Stability, 201
8.4 Mechanical Properties, 204
8.5 Flammability Properties, 206
8.5.1 Cone Calorimetry, 208
8.5.2 LOI and UL-94 Tests, 216
8.6 Flame Retardant Mechanism, 222
8.6.1 Combination of Nanocomposites and Halogen
Flame Retardant Additives, 224




8.6.2 Combination of Nanocomposites and
Nonintumescent Phosphorus Flame Retardant
Additives, 225
8.7 Summary and Conclusions, 227
References, 228
9 Thermoset Fire Retardant Nanocomposites


Mauro Zammarano

9.1 Introduction, 235
9.2 Clays, 237
9.2.1 Cationic Clays, 237
9.2.2 Anionic Clays, 237
9.3 Thermoset Nanocomposites, 239
9.4 Epoxy Nanocomposites Based on Cationic Clays, 240
9.4.1 Preparation Procedures, 240
9.4.2 Characterization of the Composite, 244
9.4.3 Thermal Stability and Combustion Behavior, 247
9.5 Epoxy Nanocomposites Based on Anionic Clays, 255
9.5.1 Preparation Procedures, 256
9.5.2 Characterization of the Composite, 261
9.5.3 Thermal Stability and Combustion Behavior, 261
9.6 Polyurethane Nanocomposites, 271
9.6.1 Preparation Procedures, 271
9.6.2 Characterization of the Composite, 272
9.6.3 Thermal Stability and Combustion Behavior, 272
9.7 Vinyl Ester Nanocomposites, 274
9.7.1 Preparation Procedures, 274
9.7.2 Characterization of the Composite, 274
9.7.3 Thermal Stability and Combustion Behavior, 276
9.8 Summary and Conclusions, 277
References, 278
10 Progress in Flammability Studies of Nanocomposites with
New Types of Nanoparticles
Takashi Kashiwagi

10.1 Introduction, 285
10.2 Nanoscale Oxide-Based Nanocomposites, 286
10.2.1 Nanoscale Silica Particles, 286
10.2.2 Metal Oxides, 288
10.2.3 Polyhedral Oligomeric Silsequioxanes, 289
10.3 Carbon-Based Nanocomposites, 295
10.3.1 Graphite Oxide, 295




10.3.2 Carbon Nanotubes, 299
10.4 Discussion of Results, 315
10.4.1 Flame Retardant Mechanism, 315
10.4.2 Morphology, 316
10.4.3 Thermal Gravimetric Analysis, 318
10.5 Summary and Conclusions, 318
References, 319
11 Potential Applications of Nanocomposites for Flame


A. Richard Horrocks and Baljinder K. Kandola

11.1 Introduction, 325
11.2 Requirements for Nanocomposite System Applications, 326
11.3 Potential Application Areas, 331
11.3.1 Bulk Polymeric Components, 331
11.3.2 Films, Fibers, and Textiles, 334
11.3.3 Coatings, 343
11.3.4 Composites, 344
11.3.5 Foams, 347
11.4 Future Outlook, 348
References, 349
12 Practical Issues and Future Trends in Polymer Nanocomposite
Flammability Research


Alexander B. Morgan and Charles A. Wilkie

12.1 Introduction, 355
12.2 Polymer Nanocomposite Structure and Dispersion, 356
12.2.1 Synthesis Procedures, 356
12.3 Polymer Nanocomposite Analysis, 365
12.3.1 Nanoscale Analysis Techniques, 366
12.3.2 Microscale Analysis Techniques, 371
12.3.3 Macroscale Analysis Techniques, 372
12.4 Changing Fire and Environmental Regulations, 373
12.5 Current Environmental Health and Safety Status for
Nanoparticles, 376
12.6 Commercialization Hurdles, 377
12.7 Fundamentals of Polymer Nanocomposite
Flammability, 379
12.8 Future Outlook, 383
References, 388



Beyer, Kabelwerk Eupen AG, Malmedyer Strasse 9, B-4700 Eupen,
Serge Bourbigot, Laboratoire Proc´ed´es d’Elaboration
des Revˆetements
Fonctionnels, LSPES UMR/CNRS 8008, Ecole
Nationale Sup´erieure de
Chimie de Lille, F-59652 Villeneuve d’Ascq Cedex, France
Sophie Duquesne, Laboratoire Proc´ed´es d’Elaboration
des Revˆetements
Fonctionnels, LSPES UMR/CNRS 8008, Ecole
Nationale Sup´erieure de
Chimie de Lille, F-59652 Villeneuve d’Ascq Cedex, France
Jeffrey W. Gilman, National Institute of Standards and Technology, Gaithersburg, MD 20899-8665
M. J. Heidecker, Materials Science and Engineering Department, Pennsylvania
State University, University Park, PA 16802
A. Richard Horrocks, Fire Materials Laboratory, Centre for Materials Research
and Innovation, University of Bolton, BL3 5AB Bolton, UK
Yuan Hu, State Key Lab of Fire Science, University of Science and Technology
of China, Hefei, 230026 Anhui, China
Baljinder K. Kandola, Fire Materials Laboratory, Centre for Materials Research
and Innovation, University of Bolton, BL3 5AB Bolton, UK
Takashi Kashiwagi, Fire Research Division, National Institute of Standards and
Technology, Gaithersburg, MD 20878-8665
Sergei V. Levchik, Supresta U.S. LLC, 430 Saw Mill River Road, Ardsley, NY



E. Manias, Materials Science and Engineering Department, Pennsylvania State
University, University Park, PA 16802
Alexander B. Morgan, University of Dayton Research Institute, Nonmetallic
Materials Division, 300 College Park, Dayton, OH 45429
H. Nakajima, Materials Science and Engineering Department, Pennsylvania
State University, University Park, PA 16802
Marc R. Nyden, National Institute of Standards and Technology, Gaithersburg,
MD 20899-8665
G. Polizos, Materials Science and Engineering Department, Pennsylvania State
University, University Park, PA 16802
Bernhard Schartel, Federal Institute for Materials Research and Testing, BAM
Unter den Eichen 87, 12205 Berlin, Germany
Lei Song, State Key Lab of Fire Science, University of Science and Technology
of China, Hefei, 230026 Anhui, China
Stanislav I. Stoliarov, SRA International, Egg Harbor Township, NJ 08234
Charles A. Wilkie, Marquette University, Department of Chemistry, Milwaukee,
WI 53201
Mauro Zammarano, Building and Fire Research Laboratory, National Institute
of Standards and Technology, Gaithersburg, MD 20899-8665; NIST Guest
Researcher from CimTecLab, Area Science Park, 34012 Trieste, Italy


Since the early 1990s, the subject of polymer nanocomposites has expanded
greatly, to its current status as a major field of polymer materials research. It is
now realized that polymer nanocomposites, as a class of materials, were in use
long before this field of research was officially named in the early 1990s. Indeed,
work published as early as 1961, and patents going back to the 1940s, have
shown that layered silicates (or clays) can be combined with polymers in low
amounts to produce new materials with greatly improved properties. However, it
was the work in the 1990s that properly identified these clay-containing materials
as polymer nanocomposites and kindled today’s interest in these materials. One
could argue that polymer nanocomposites are just part of the nanotechnology
boom, but there is more to it. The fundamental understanding of how two dissimilar materials interface at the nanometer scale has tremendous implications for
performance and properties at the macro scale. Therefore, the study of polymer
nanocomposites is not just about capturing the buzz from nanotechnology; it is
about understanding structure–property relationships and interfacial science at
the molecular and macromolecular scale.
With the recent understanding that the addition of clays or other nanoparticles to a polymer forms a polymer nanocomposite, these materials have been
investigated for many potential applications. One of the first well-publicized
commercial uses was in polyamide-6 [poly(hexamethylamide) or nylon-6] for
automotive applications developed by Toyota. Specifically, the improved heat
distortion temperature of the nanocomposite allowed it to be used as part of the
engine, resulting in a weight savings in a car. Additional early applications for
nanocomposite technology have included improved gas barrier properties (beverage and food packaging), electrical conductivity for electromagnetic applications,



and improved mechanical strength and toughness for engineering use. Flammability applications for polymer clay nanocomposites were discovered a little later,
and only recently has the material found its way into commercial use. Polymer
nanocomposites for flammability applications are attractive because the formation
of a nanocomposite not only improves the fire properties but can also improve
other properties (e.g., mechanical properties), and it has the potential to bring
true multifunctionality to materials.
Multifunctionality has the great potential to simplify materials science and
engineering by having one material do the work of several. For example, a plastic case for an electronic device can have several requirements. It will require
particular mechanical properties (e.g., modulus, impact strength), thermal properties (not melt or sag under normal use conditions), flammability properties (meet
regulations depending on the fire risk scenario), and electromagnetic properties
(frequency shielding). Also, cost, density, color, and recyclability will need to be
considered if it is a commercial product. With such a long list of requirements,
it can be very difficult to find one material that can meet all needs. For example,
polycarbonate can be used to achieve the desired mechanical and thermal properties, and with the right additives, flammability, density, and color can be obtained
as well. For cost-effectiveness, polycarbonate is usually mixed with acrylonitrile–butadiene–styrene terpolymer in consumer electronics. Another feature not
often obtained in the casing for electronic devices is electromagnetic shielding.
To obtain this shielding requirement, such as in the use of a laptop case, special
paints are used, and not surprisingly, this solution increases cost, limits color
choices, and can make recycling difficult. An acceptable combination of materials can be difficult to find during typical research and development operations,
and frequently, the choice made by the engineer is a compromise that can lead
to other problems. If just one material could meet all requirements, fabrication
of parts and goods would become easier, costs might decrease, and innovation
could be enabled. The class of materials that has the greatest chance of obtaining
true multifunctionality is that of polymer nanocomposites.
Polymer nanocomposites have shown great improvements over traditional
composites in mechanical, thermal, gas barrier, conductivity, flammability, electromagnetic shielding, and other properties, and this has spawned a huge amount
of research. There are already several key references and books that look at the
polymer nanocomposite field as a whole, and even focus on particular areas,
but no book to date has focused on the improvements in materials flammability. As indicated previously, it has only recently been understood that the
nanocomposite structure is responsible for the improvements in material properties, especially flammability, and so only now is there enough research to warrant
a book focused on polymer nanocomposite flammability. Significant changes in
fire safety regulations and perceptions of existing flame retardant additives have
served as catalysts for increased emphasis on polymeric material flammability
reduction. This increased emphasis demands not only lowered flammability but
also improvements in environmental impact for the final flame-retarded part,
as well as maintaining the difficult balance of properties discussed previously.



Since a polymeric material can reduce flammability and improve mechanical
and thermal properties and possibly other properties as well, there is a great
deal of promise that polymeric nanocomposites will not just meet this need for
flammability reduction, but also exceed it, thus providing fire safety and improved
properties for a wide range of consumer goods.
This book focuses on polymer nanocomposites for flammability applications
and includes supporting information important to this subject. The information
is divided into sections for specific topic searching, and the book is divided into
three parts to help those new to the fields of materials flammability research
and polymer nanocomposites: theory and fundamentals, specific flame retardant
systems, and current applications and future work.
On the subject of theory and fundamentals, there are five chapters: flammability fundamentals, nanocomposite fundamentals, the impact of nanocomposite
formation on flammability, modeling of thermal degradation by fire, and the
flammability of specific polymers.
The chapters on specific flame retardant systems are meant to serve as detailed
sources of information, allowing the reader to gather essential facts on very specific flame retardant and polymer systems. Since flame retardant solutions can
vary greatly depending on polymer chemistry and intended application or regulatory test, it can be difficult to organize all available knowledge on flame retardant
nanocomposites. This information is organized by flame retardant classes; within
each classification there is extensive discussion of the various combinations of
nanocomposites with flame retardants as solutions. The chapters are devoted to
the combination of nanocomposite formation with intumescent systems, mineral
additives, and halogen- and phosphorus-based fire retardants. The last chapter
dealing with specific flame retardant systems focuses on thermoset flame retardant
nanocomposites. This chapter is separated from the others because thermosets are
prepared much differently than thermoplastics and behave quite differently under
fire conditions.
The final chapters of the book are designed to show the newest advances in the
field as well as to show practical uses for polymer nanocomposites in flammability application and to provide insight into the future direction of the field. Since
the field of polymer nanocomposite research is rather new, new results are published regularly, including work with new types of nano-dimensional materials.
The majority of work in this book refers specifically to polymer layered-silicate
(clay) nanocomposites, but as shown in Chapter 10, results with carbon nanotubes, nanofibers, and colloidal inorganic particles that have shown reductions
in flammability are reviewed. Chapter 11 focuses on the use of polymer nanocomposites for specific applications and their successes and pitfalls to date. In the
last chapter what is known today is summarized and where the field is heading
is indicated. This chapter can perhaps be viewed as a forward-looking statement concerning the types of work that must be carried out in the future. Some
of the fundamental unknowns behind this technology are addressed in detail,
showing the researcher ways to proceed for nanocomposite solutions to flammability issues.



We appreciate all of the efforts that the chapter authors have made to provide an up-to-date account of activities regarding the use of nanocomposites in
flame retardancy. We trust that the book will be useful and that it will advance
worldwide knowledge on this topic. We would like to thank Don Klosterman
and Lynn Bowman of UDRI for their assistance in obtaining references on nanoreinforced composites and nanoparticle health and safety, respectively, and Dr.
Anteneh Worku of the Dow Chemical Company for his assistance in obtaining
references and reviewing. Finally, we thank our wives, Julie Ann Morgan and
Nancy Wilkie, for their tireless support.
Dayton, Ohio
Milwaukee, Wisconsin
16 November 2006




Acrylonitrile–butadiene–styrene copolymer
Poly(ethylene-co-vinyl acetate)
Diglycidyl ether of bisphenol A
High-density polyethylene
Low-density polyethylene
Poly(butylene terephthalate)
Poly(dimethyl siloxane)
Polyethylene-graft-maleic anhydride
Poly(ethylene terephthalate)
Poly(lactic acid)
Poly(methyl methacrylate)
Polypropylene-graft-maleic anhydride




Poly(vinyl chloride)
Styrene–acrylonitrile copolymer
Styrene–butadiene–styrene copolymer
Thermoplastic polyurethane


Antimony oxide
Ammonium polyphosphate
Aluminum hydroxide (also known as alumina trihydrate)
Bromine-containing flame retardant
Chlorinated paraffin wax
Decabromodiphenyl oxide
Melamine cyanurate
Magnesium hydroxide
Melamine polyphosphate
Nitrogen-containing flame retardant
Phosphorus-containing flame retardant
Resorcinol diphosphate

tign /TTI/tig

Fire growth rate
Heat release rate/rate of heat release
Limiting oxygen index
Mass loss rate
Specific extinction area
Total heat release/total heat evolved
Time to ignition
Underwriter’s Laboratory Test #94
Volume of smoke production


Atomic force microscopy
Cross-polarization–magic angle spinning–nuclear
magnetic resonance
Dynamic mechanical analysis
Differential scanning calorimetry
Derivative of TGA curve

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