Table Of ContentSPRINGER BRIEFS IN MATERIALS
Nikhil Gupta
Dinesh Pinisetty
Vasanth Chakravarthy Shunmugasamy
Reinforced
Polymer Matrix
Syntactic Foams
Effect of Nano
and Micro-Scale
Reinforcement
SpringerBriefs in Materials
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Nikhil Gupta · Dinesh Pinisetty
Vasanth Chakravarthy Shunmugasamy
Reinforced Polymer Matrix
Syntactic Foams
Effect of Nano and Micro-Scale
Reinforcement
1 3
Nikhil Gupta Dinesh Pinisetty
Mechanical Engineering Department The California Maritime Academy
Polytechnic Institute of NYU Vallejo, CA
Brooklyn, NY USA
USA
Vasanth Chakravarthy Shunmugasamy
Mechanical Engineering Department
Polytechnic Institute of NYU
Brooklyn, NY
USA
ISSN 2192-1091 ISSN 2192-1105 (electronic)
ISBN 978-3-319-01242-1 ISBN 978-3-319-01243-8 (eBook)
DOI 10.1007/978-3-319-01243-8
Springer Cham Heidelberg New York Dordrecht London
Library of Congress Control Number: 2013946314
© The Author(s) 2013
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Preface
Hollow particle-filled composites, called syntactic foams, are also classified as
closed-cell foams. Enclosing porosity inside thin stiff shells of particles provides
reinforcing effect to every void present in the materials microstructure. Such
composites can be tailored to have higher specific modulus than the matrix resin
and a high level of energy absorption under compression. Increasing interest of
marine and aerospace structures in lightweight composites has generated con-
siderable interest in finding new methods to enhance the properties of syntactic
foams, including exploring micro and nanosized reinforcements. Higher gas mile-
age requirements for automobiles have also pushed them to look for lighter weight
materials, where syntactic foams are expected to be useful in some components.
In reinforced syntactic foams, the presence of hollow particles and one or
more additional reinforcing phases can generate complex deformation and failure
mechanisms. The interaction between the mechanisms contributed by micro- and
nano-scale materials can also be complex. Only systematic large-scale experimen-
tal studies followed by modeling and simulation efforts can help in decoupling
such effects and help in designing effective material microstructures. Often, the
incorporation of additional phase may be directed by the desire of obtaining a spe-
cific set of properties, which may not be limited to mechanical properties. Carbon
nanotube and nanofibers affect mechanical, electrical, and thermal properties of
syntactic foams. Such reinforced syntactic foams may be developed in the form of
multifunctional materials.
This work summarizes and critically analyzes the progress made in the design
and analysis of reinforced syntactic foams. Nanofibers, nanoclay, and microfib-
ers provide different strengthening mechanisms in reinforced syntactic foams.
Comparative studies conducted in this book have shown some surprising trends.
For example, irrespective of the reinforcement type, the tensile and compressive
properties of most reinforced syntactic foams vary linearly with respect to the
composite density. It is also shown that the existing theoretical models can be
extended to predict the elastic properties of nanoscale reinforced syntactic foams
and the results are validated with the experimental data. Discovery of common-
ality in the experimental trends and applicability of theoretical models can guide
future studies and help in understanding the potential for developing syntactic
foams for transportation and structural applications.
v
vi Preface
From a vast body of literature on reinforced syntactic foams, it is possible to
miss some contributions in the references. We have primarily covered the informa-
tion available in journal publications. The field continues to evolve at a rapid pace.
Advancements in the understanding of nanomaterials and nanocomposites directly
impact the reinforced syntactic foams field. We hope that this brief book will pro-
vide a starting point for the interested readers to gain basic understanding about
the major material parameters and mechanical properties of reinforced syntactic
foams.
Brooklyn, New York, USA Nikhil Gupta
Vallejo, California, USA Dinesh Pinisetty
Brooklyn, New York, USA Vasanth Chakravarthy Shunmugasamy
Acknowledgments
The authors wish to thank a number of people who contributed to the research
related to reinforced syntactic foams in their group over the past decade. These
individuals include Dr. Nguyen Q. Nguyen, Dr. Dung D. Luong, Dr. Gabriele
Tagliavia, Ronald L. Poveda, Tien Chih Lin, Momchil Dimchev, Anton Talalayev,
Ryan Caeti, Dennis John, and Gleb Dorogokupets. Diligent work by these current
and past students resulted in several publications that became the basis for devel-
oping this book. We also wish to thank William Ricci and Dr. Gary Gladysz of
Trelleborg Offshore, Boston for information related to applications of syntactic
foams and technical discussions.
Parts of this work are supported by the Ofcfi e of Naval Research grant N00014-
10-1-0988, Army Research Laboratory cooperative agreement W911NF-11-2-0096,
and the previous National Science Foundation grants. The views expressed in this
text are those of authors, not of funding agencies.
vii
Contents
1 Introduction ................................................ 1
1.1 Porosity in Foams ........................................ 2
1.2 Syntactic Foams ......................................... 3
1.3 Reinforced Syntactic Foams ................................ 4
1.4 Applications of Syntactic Foams ............................ 4
2 Fillers and Reinforcements .................................... 9
2.1 Type of Particles ......................................... 9
2.2 Hollow Particle Parameters ................................ 12
2.3 Reinforcements .......................................... 13
2.3.1 Fibers ........................................... 14
2.3.2 Nanoclay ......................................... 14
2.3.3 Carbon Nanotubes and Nanofibers ..................... 15
2.3.4 Rubber Particles ................................... 16
3 Processing and Microstructure of Syntactic Foams ................ 19
3.1 Processing Methods and Challenges ......................... 19
3.2 Microstructure and Porosity Issues .......................... 21
4 Tensile Properties ........................................... 25
4.1 Micro-Fiber Reinforced Syntactic Foams ..................... 26
4.2 Nanoscale Reinforced Syntactic Foams ....................... 27
4.2.1 CNT and CNF Reinforced Syntactic Foams ............. 28
4.2.2 Nanoclay Reinforced Syntactic Foams ................. 29
4.3 Remarks ............................................... 30
5 Modeling and Simulation ..................................... 31
5.1 Microscale Reinforced Syntactic Foams ...................... 32
5.2 Nanoscale Reinforced Syntactic Foams ....................... 33
5.2.1 Porfiri–Gupta Model ............................... 33
5.2.2 Bardella–Genna model .............................. 36
5.2.3 Parametric Study .................................. 37
5.2.4 Molecular Simulation Methods ....................... 39
5.3 Relation Between Density and Tensile Properties ............... 41
ix
x Contents
6 Compressive Properties ...................................... 43
6.1 Compressive Stress–Strain Behavior ......................... 44
6.2 Compressive Properties of Fiber Reinforced Syntactic Foams ..... 46
6.3 Compressive Properties of Rubber Reinforced Syntactic Foams .... 47
6.4 Compressive Properties of Nanoscale Reinforced Syntactic
Foams ................................................. 48
6.5 Environmental Effects on Compressive Properties .............. 49
6.6 Relation Between Density and Compressive Properties .......... 50
7 Flexural Properties .......................................... 53
7.1 Fiber Reinforced Syntactic Foam ............................ 54
7.2 Silica Particle Reinforced Syntactic Foam ..................... 55
7.3 Nanoclay Reinforced Syntactic Foam ........................ 55
7.4 Relations Between Density and Flexural Properties of
Syntactic Foams ......................................... 57
8 Fracture Toughness .......................................... 59
8.1 Nanoscale Reinforced Syntactic Foams ....................... 60
8.2 Fiber Reinforced Syntactic Foams ........................... 61
8.3 Comparison of Nano and Microscale Toughening ............... 61
9 Dynamic Mechanical Properties ............................... 63
9.1 Nanoscale Reinforced Syntactic Foams ....................... 66
9.2 Microscale Reinforced Syntactic Foams ...................... 67
9.3 Remarks ............................................... 68
10 Summary and Future Challenges .............................. 69
References .................................................... 73
Chapter 1
Introduction
Abstract Lightweight materials are of great interest to transportation applications.
Structural weight reduction directly translates into fuel saving and increased payload
capacity. Porous materials can provide signicfi ant weight saving but their applications
are limited by their low strength and modulus. This chapter provides an introduc-
tion to porous materials, which includes open- and closed-cell foams. The closed-
cell foams can be further divided into foams containing gas porosity and the foams
containing hollow particles. The hollow particle lfiled porous materials are called syn-
tactic foams. These foams are also classiefi d as particulate composites. Enclosure of
porosity within a thin but stiff shell helps in obtaining low density in syntactic foams
without a severe penalty on the mechanical properties. Syntactic foams possess supe-
rior properties under compression compared to foams comprising gas porosity in the
matrix. Several micro- and nano-scale reinforcements have been used to improve
the tensile and efl xural strengths of syntactic foams. Nanoclay, carbon nanobfi ers,
carbon nanotubes, glass bfi ers, and ceramic particles have been used as reinforce-
ments in syntactic foams. Establishing structure-property correlations of reinforced
syntactic foams will pave way to design effective lightweight composites for engi-
neering structures. The chapter also discusses some of the present day applications of
syntactic foams.
Keywords Foam • Open-cell foam • Closed-cell foam • Syntactic foam • Porosity •
Hollow particle • Marine structures • Thermal insulation • Polymer foam •
Porous material
Use of lightweight materials can result in significant saving of energy and
resources in a number of fields. For example, weight reduction of automobiles,
marine vessels, and aircraft can save fuel, increase payload capacity, and contrib-
ute to reducing pollution [1, 2]. Reduction in structural weight is possible by using
lightweight porous materials. However, conventionally porosity is viewed as an
N. Gupta et al., Reinforced Polymer Matrix Syntactic Foams, SpringerBriefs in Materials, 1
DOI: 10.1007/978-3-319-01243-8_1, © The Author(s) 2013
