Materials Chapter 3:
Carbon Nanotube Properties
Table of Contents
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Introduction
Potential Applications
Properties
Functionalized CNTs
Property Data for Specific Themoplastics
Micrographs of Carbon Nanotubes
Introduction
Introduction
• Scientists have been trying to use the
phenomenal mechanical properties of
multiwalled carbon nanotubes (MWNT) to
create high performance nanocomposites,
since their discovery in 1991.
• The properties of the MWNT’s suggest that
significant improvements should be added to
the mechanical and other properties of the
polymer matrix, which they reinforce.
Introduction
• To alter the properties, strength, stiffness,
permeability, optical clarity and electrical
conductivity of the nanocomposites
consistently, two things need to occur:
– the MWNT’s need to be dispersed homogeneously
throughout the matrix material, and there needs
to be good interfacial bonding between the
MWNT’s and the polymer matrix material.
Introduction
• Strong bonding at the interface is required to
transfer the load from the polymer material to
the reinforcing MWNT .
• This can be achieved if the surface energy of
the carbon nanotubes (CNT) exceeds the
cohesive energy of the polymer matrix.
• Weak interfacial bonding will result in delamination giving instant mechanical failure.
Introduction
• Weak interfacial bonding is a result of a nonwetting phenomenon between the CNT and
polymer matrix, which is caused by the lack of
functional groups on the CNT’s.
Introduction
• There are two styles of polymer treatments to
promote adhesion at the polymer/CNT
interface:
– wrapping and non-wrapping.
• Polymer wrapping means the treating polymer
completely envelops the CNT surface.
Introduction
• Non-wrapping polymer treatments are where
the polymer backbone extends along the
length of the CNT without any portion of the
polymer treatment covering more than half of
the diameter of the CNT.
• Non-wrapping polymer treatments contain a
rigid backbone, which results in parallel
stacking phenomena between the polymer
and the CNT.
Introduction
• The addition of treatments to the surface of
the nanotubes is being researched and is
intended to improve dispersion during
processing, such as injection molding.
• These treatments consist of functionalizing
the CNT by attaching polymeric chains to its
surface.
History
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1991 Discovery of multi-wall carbon nanotubes
1992 Conductivity of carbon nanotubes
1993 Structural rigidity of carbon nanotubes
1993 Synthesis of single-wall nanotubes
1995 Nanotubes as field emitters
1996 Ropes of single-wall nanotubes
1997 Quantum conductance of carbon nanotubes
1997 Hydrogen storage in nanotubes
1998 Chemical Vapor Deposition synthesis of aligned
nanotube films
1998 Synthesis of nanotube peapods
2000 Thermal conductivity of nanotubes
2000 Macroscopically aligned nanotubes
2001 Integration of carbon nanotubes for logic circuits
2001 Intrinsic superconductivity of carbon nanotubes
Potential CNT Applications
Potential CNT Applications
• Reinforcement within a polymeric matrix.
• Outstanding mechanical properties:
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High Young’s modulus
Stiffness and flexibility
Unique electronic properties
High thermal stability
• The nearly perfect structure of CNTs, their small
diameter, and their high surface area and high
aspect ratio, provide an amazing inorganic
structure with unique properties extremely
attractive to reinforcing organic polymers.
Potential Applications
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Tips for Atomic Force Microscopy
Cells for hydrogen storage
Nanotransistors
Electrodes for electromechemical applications
Sensors of biological molecules
Catalysts
Reinforcement of composite materials
Semiconductor or metallic conductive
nanomaterials
• Various aerospace applications
Potential Applications
• Flat Panel Displays
– Prototypes have been made by Samsung
• Gas-Discharge Tubes in Telecom Networks
• Energy Storage
• Electrochemical Intercalation of Carbon
Nanotubes with Lithium
– CNTs can be used as the cathode to make a
battery hold 3x as much charge and output 10x as
much power
• Nanoprobes and Sensors
Potential Applications
• Use as coatings
– Antistatic coatings
– Flame barrier coatings
– Fouling release coatings
• On boats to prevent marine life from adhering to the
ship’s bottom
Potential Applications
Markets
Energy
CNT Performance
Attribute
Battery
Wind
Electronics
Automotive
Semicon and
ITO
Electrostatic
Disk Drive replacement
painting
High electrical conductivity
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High thermal conductivity
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High tensile strength
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Stuctural
Composites
Fuel
systems
Aerospace
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Sporting
goods
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High elasticity
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High absorbency
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High aspect ratio (L/D)
Low weight
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Others
Thermal
Flame
Management Retardant
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Potential Applications
Potential Applications
BMC bicycle frame made of nanotube-reinforced resin,
2005 Tour de France. ARKEMA belongs to the network of partners.
CNT Properties
CNT Properties
• When small quantities of nanotubes are
incorporated into the polymer, the electrical,
optical and mechanical properties improve
significantly.
• CNTs in large amounts form clusters,
diminishing their interaction.
• The Young’s modulus of the multi-walled
carbon nanotubes is 0⋅9 Tpa.
CNT Properties
Physical Properties of Carbon Nanotubes
Below is a compilation of research results from scientists all over the world.
All values are for Single Wall Carbon Nanotubes (SWNT's) unless otherwise stated.
Equilibrium Structure
Average Diameter of SWNT's
Distance from opposite Carbon Atoms (Line 1)
Analogous Carbon Atom Separation (Line 2)
Parallel Carbon Bond Separation (Line 3)
Carbon Bond Length (Line 4)
C - C Tight Bonding Overlap Energy
1.2 -1.4 nm
2.83 Å
2.456 Å
2.45 Å
1.42 Å
~ 2.5 eV
Group Symmetry (10, 10)
Lattice: Bundles of Ropes of Nanotubes
Lattice Constant
Lattice Parameter:
C5V
Triangular Lattice (2D)
17 Å
(10, 10) Armchair
(17, 0) Zigzag
(12, 6) Chiral
16.78 Å
16.52 Å
16.52 Å
(10, 10) Armchair
1.33 g/cm3
(17, 0) Zigzag
1.34 g/cm3
(12, 6) Chiral
1.40 g/cm3
Density:
Interlayer Spacing:
(n, n) Armchair
(n, 0) Zigzag
(2n, n) Chiral
3.38 Å
3.41 Å
3.39 Å
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Optical Properties
Fundamental Gap:
For (n, m); n-m is divisible by 3 [Metallic]
For (n, m); n-m is not divisible by 3 [Semi-Conducting]
0 eV
~ 0.5 eV
Electrical Transport
Conductance Quantization
Resistivity
Maximum Current Density
.
(12.9 k )-1
10-4 -cm
1013 A/m2
Thermal Transport
Thermal Conductivity
Phonon Mean Free Path
Relaxation Time
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~ 2000 W/m/K
~ 100 nm
~ 10-11 s
Elastic Behavior
Young's Modulus (SWNT)
Young's Modulus (MWNT)
Maximum Tensile Strength
~ 1 TPa
1.28 TPa
~ 100 GPa
CNT Properties
Mechanical Properties of Engineering Fibers
Fiber Material
Carbon Nanotube
Specific Density E (TPa) Strength (GPa) Strain at Break (%)
1.3 - 2
1
10-60
10
7.8
0.2
4.1
< 10
Carbon Fiber - PAN
1.7 - 2
0.2 - 0.6
1.7 - 5
0.3 - 2.4
Carbon Fiber - Pitch
2 - 2.2
0.4 - 0.96
2.2 - 3.3
0.27 - 0.6
2.5
0.07 / 0.08
2.4 / 4.5
4.8
0.13
3.6 - 4.1
2.8
HS Steel
E/S - glass
Kevlar* 49
1.4
Kevlar is a registered trademark of DuPont.
CNT Properties
Table 2. Transport Properties of Conductive Materials
Material
Thermal Conductivity (W/m.k) Electrical Conductivity
Carbon Nanotubes
Copper
Carbon Fiber - Pitch
> 3000
400
1000
106 - 107
6 x 107
2 - 8.5 x 106
Carbon Fiber - PAN
8 - 105
6.5 - 14 x 106
CNT Properties
CNT Properties
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Electrical conductivity:
Carbon nanotubes are conductors or semiconductors, based on coiling helicity.
Their conductivity ranges from 1 S/cm to 100 S/cm. This property has been
calculated and verified in experiments.
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Thermal conductivity:
Carbon nanotubes feature thermal conductivity close to that of diamond (3000
J/K), the best thermal conductor known.
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Mechanical performance:
In the hexagon plane, the Young’s modulus for carbon nanotubes has been
theoretically evaluated at 1TPa. Together with this outstanding strength, carbon
nanotubes boast high flexibility and good plasticity.
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Adsorption:
Nanotubes were first studied with the objective of becoming a means of storing
hydrogen for the new fuel cells. Although this application has been gradually
discarded, the fact remains that nanotubes have an empty space around the
cylinder axis which can constitute a nanotank. The specific surface of nanotubes is
approximately 250 m2/g, imparting good adsorption capacity.
CNT Properties
• CNTs have been shown to possess many
extraordinary properties such as strength 16X
that of stainless steel and with a thermal
conductivity five times that of copper.
• Aspect ratio (length over diameter) ranges from
1,000 to 1,000,000
• Electrical Resistivity: 10 -4 Ω-cm
• Current Density: 107 amps/cm2
• Thermal Conductivity: 3,000 W/mK
• Tensile Strength: 30 GPa
• Elasticity: 1.28 TPa
CNT Properties
CNT Properties
CNT Properties
CNT Properties
CNT Properties
CNT Properties
CNT Properties
CNT Properties
CNT Properties
CNT Properties
CNT Properties
CNT Properties
CNT Properties
• Nanotube Research Articles\Overall\nanotube
composites.pdf
• Very good article explaining the basics of
CNT’s
CNT Properties
CNT Properties
Filling CNTs
CNT–Polymer Interfacial Strength
Effects From Size
Functionalized CNTs
Additives
• Additives can aid in the dispersion of the CNTs
Functionalized CNTs
• Oxidation on the surfaces of these materials are useful
moieties in order to bond new reactive chains that
improve solubility, processability and compatibility
with other materials and, therefore, improve the
interfacial interactions of CNTs with other substances
• The most important impact has been produced by
oxidation methods which, in addition to reducing
impurities, cause chemical modifications of CNTs
• The COOH groups generated in the oxidation process
are used to attach different molecules useful to
improve surface compatibility of CNTs with other
materials
Functionalized CNTs
• The COOH groups generated in the oxidation process
are used to attach different molecules useful to
improve surface compatibility of CNTs with other
materials
• Chemical functionalization has reached an important
position in the CNT field, as different chemical
processes have been developed to diversify CNT
properties
• The remarkable properties obtained when f-CNTs are
incorporated into polymeric composites represent a
promising route to design ideal materials for aerospace
related structural applications
• However, the field requires much deeper fundamental
research
Functionalized CNTs
• Chemical functionalized CNTs significantly
decreased the electrical conductivity of epoxy
nanocomposites due to unbalance polarization
effect and physical structure defects due to
severe condition during acidic treatment process
• Non chemical functionalized CNTs are more
suitable for the electrical applications
• Chemical functionalization of CNT is still
necessary for increase dispersion quality and
strengthens the interfacial bonding strength with
polymer matrix, which more important in
structural applications
Functionalized CNTs
Functionalized CNTs (Kentera)
Functionalized CNTs (Kentera)
Functionalized CNTs (Kentera)
Functionalized CNTs (Kentera)
Functionalized CNTs (Kentera)
Functionalized CNTs (Kentera)
Functionalized CNTs (Kentera)
Adhesion and reinforcement in
carbon nanotube polymer composite
• The interfacial shear stress is found to
increase linearly with the applied strain in
small strain regime and a lower bound value
for the shear strength is found -- 46 MPa at
low temperatures. Such value decreases with
the increase of temperature. At large strains
the interfacial bonds break successively with
the shear stress decreasing in a staircase
manner.
Adhesion and reinforcement in
carbon nanotube polymer composite
• The mechanical properties of the composite are
found to be largely enhanced over a wide
temperature range from 50 to 350 K compared
with the bulk polymer, due to the enhanced VDW
interactions. The degree of increase in the
Young’s modulus is around 200% for the
composite in this study, and the difference with
that from the continuum medium approximation
based Halpin–Tsai formula suggests that
interfacial atomic structure is crucial for a
nanocomposite.
Adhesion and reinforcement in
carbon nanotube polymer composite
Property Data for Specific
Materials
PMMA
• Relative to pure PMMA, a 32% improvement
in tensile modulus and a 28% increase in
tensile strength were observed in PMMAbased nanocomposites using 1.0 wt%
nanotube filler.
Epoxy
• No improvement in mechanical properties was
observed in epoxy-based nanocomposites.
• The poorer mechanical performance of the latter
system can be explained by a decrease of the
crosslinking density of the epoxy matrix in the
nanocomposites, relative to pure epoxy.
Epoxy
Epoxy
Epoxy
Epoxy
Natural Rubber
Natural Rubber
Natural Rubber
PVA
• To summarize, MWNTs have been well dispersed in
PVA matrix through gum arabic treatment. The
PVA/MWNT composite films exhibit good mechanical
properties
PS
PBT
• The addition of up to 0.2 wt% MWCNT to PBT
induces an increase of the microhardness of
about 12%. The H values obtained are much
smaller than those derived from the elastic
modulus using Struik’s relation. The use of
SWCNT does not improve the
micromechanical properties
PBT
SBR
SBR
• The stress value or normally known as tensile
strength has been increased to 21.0% for 1
wt% of CNTs up to 70.26% for 10 wt% of CNTs
• The Young’s modulus or modulus of elasticity
has been increased to 11.36 for 1 wt% of CNTs
up to 193.91% for 10 wt% of CNTs compared
to SBR without CNTs.
SBR
PC
PC
PC
PC
PC
PC
PC
PC
PC
PC
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
LLDPE
LLDPE
LLDPE
LLDPE
LLDPE
Microscope Imaging
Microscope Imaging
Microscope Imaging
Microscope Imaging
Microscope Imaging