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Title: Materials Chapter 3:


1
Materials Chapter 3
  • Carbon Nanotube Properties

2
Table of Contents
  • Introduction
  • Potential Applications
  • Properties
  • Functionalized CNTs
  • Property Data for Specific Themoplastics
  • Micrographs of Carbon Nanotubes

3
Introduction
4
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 MWNTs suggest that
    significant improvements should be added to the
    mechanical and other properties of the polymer
    matrix, which they reinforce.

5
Introduction
  • To alter the properties, strength, stiffness,
    permeability, optical clarity and electrical
    conductivity of the nanocomposites consistently,
    two things need to occur
  • the MWNTs need to be dispersed homogeneously
    throughout the matrix material, and there needs
    to be good interfacial bonding between the MWNTs
    and the polymer matrix material.

6
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
    de-lamination giving instant mechanical failure.

7
Introduction
  • Weak interfacial bonding is a result of a
    non-wetting phenomenon between the CNT and
    polymer matrix, which is caused by the lack of
    functional groups on the CNTs.

8
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.

9
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.

10
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.

11
History
  • 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

12
Potential CNT Applications
13
Potential CNT Applications
  • Reinforcement within a polymeric matrix.
  • Outstanding mechanical properties
  • High Youngs 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.

14
Potential Applications
  • 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

15
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

16
Potential Applications
  • Use as coatings
  • Antistatic coatings
  • Flame barrier coatings
  • Fouling release coatings
  • On boats to prevent marine life from adhering to
    the ships bottom

17
Potential Applications
Markets Markets Markets Markets Markets Markets Markets Markets Markets Markets
Energy Energy Electronics Electronics Automotive Automotive Stuctural Composites Stuctural Composites Others Others
Battery Wind Semicon and Disk Drive ITO replacement Electrostatic painting Fuel systems Aerospace Sporting goods Thermal Management Flame Retardant
CNT Performance Attribute High electrical conductivity X   X X X X X      
CNT Performance Attribute High thermal conductivity X   X           X X
CNT Performance Attribute High tensile strength X X         X X    
CNT Performance Attribute High elasticity   X         X X    
CNT Performance Attribute High absorbency   X     X   X X    
CNT Performance Attribute High aspect ratio (L/D) X X X X X X X X X X
CNT Performance Attribute Low weight   X     X X X X    
18
Potential Applications
19
Potential Applications
BMC bicycle frame made of nanotube-reinforced
resin, 2005 Tour de France. ARKEMA belongs to the
network of partners.
20
CNT Properties
21
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 Youngs modulus of the multi-walled carbon
    nanotubes is 09 Tpa.

22
CNT Properties
23
Physical Properties of Carbon Nanotubes Physical Properties of Carbon Nanotubes Physical Properties of Carbon Nanotubes
Below is a compilation of research results from scientists all over the world. Below is a compilation of research results from scientists all over the world. 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. All values are for Single Wall Carbon Nanotubes (SWNT's) unless otherwise stated. All values are for Single Wall Carbon Nanotubes (SWNT's) unless otherwise stated.
     
Equilibrium Structure    
Average Diameter of SWNT's   1.2 -1.4 nm
Distance from opposite Carbon Atoms (Line 1)   2.83 Å
Analogous Carbon Atom Separation (Line 2)   2.456 Å
Parallel Carbon Bond Separation (Line 3)   2.45 Å
Carbon Bond Length (Line 4)   1.42 Å
C - C Tight Bonding Overlap Energy   2.5 eV
Group Symmetry (10, 10)   C5V
Lattice Bundles of Ropes of Nanotubes   Triangular Lattice (2D)
Lattice Constant   17 Å
Lattice Parameter    
  (10, 10) Armchair 16.78 Å
  (17, 0) Zigzag 16.52 Å
  (12, 6) Chiral 16.52 Å
Density    
  (10, 10) Armchair 1.33 g/cm3
  (17, 0) Zigzag 1.34 g/cm3
  (12, 6) Chiral 1.40 g/cm3
Interlayer Spacing    
  (n, n) Armchair 3.38 Å
  (n, 0) Zigzag 3.41 Å
  (2n, n) Chiral 3.39 Å
.    
Optical Properties    
Fundamental Gap    
  For (n, m) n-m is divisible by 3 Metallic 0 eV
  For (n, m) n-m is not divisible by 3 Semi-Conducting 0.5 eV
     
Electrical Transport    
Conductance Quantization   (12.9 k )-1
Resistivity   10-4 -cm
Maximum Current Density   1013 A/m2
.    
Thermal Transport    
Thermal Conductivity   2000 W/m/K
Phonon Mean Free Path   100 nm
Relaxation Time   10-11 s
.    
Elastic Behavior    
Young's Modulus (SWNT)   1 TPa
Young's Modulus (MWNT)   1.28 TPa
Maximum Tensile Strength   100 GPa
24
CNT Properties
Mechanical Properties of Engineering Fibers Mechanical Properties of Engineering Fibers Mechanical Properties of Engineering Fibers Mechanical Properties of Engineering Fibers Mechanical Properties of Engineering Fibers
Fiber Material Specific Density E (TPa) Strength (GPa) Strain at Break ()
Carbon Nanotube 1.3 - 2 1 10-60 10
HS Steel 7.8 0.2 4.1 lt 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
E/S - glass 2.5 0.07 / 0.08 2.4 / 4.5 4.8
Kevlar 49 1.4 0.13 3.6 - 4.1 2.8
Kevlar is a registered trademark of DuPont. Kevlar is a registered trademark of DuPont. Kevlar is a registered trademark of DuPont. Kevlar is a registered trademark of DuPont. Kevlar is a registered trademark of DuPont.
25
CNT Properties
Table 2. Transport Properties of Conductive Materials Table 2. Transport Properties of Conductive Materials Table 2. Transport Properties of Conductive Materials
Material Thermal Conductivity (W/m.k) Electrical Conductivity
Carbon Nanotubes gt 3000 106 - 107
Copper 400 6 x 107
Carbon Fiber - Pitch 1000 2 - 8.5 x 106
Carbon Fiber - PAN 8 - 105 6.5 - 14 x 106
26
CNT Properties
27
CNT Properties
  • 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.
  • Thermal conductivity
  • Carbon nanotubes feature thermal conductivity
    close to that of diamond (3000 J/K), the best
    thermal conductor known.
  • Mechanical performance In the hexagon plane, the
    Youngs modulus for carbon nanotubes has been
    theoretically evaluated at 1TPa. Together with
    this outstanding strength, carbon nanotubes boast
    high flexibility and good plasticity.
  •  
  • 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.

28
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 O-cm
  • Current Density 107 amps/cm2
  • Thermal Conductivity 3,000 W/mK
  • Tensile Strength 30 GPa
  • Elasticity 1.28 TPa

29
CNT Properties
30
CNT Properties
31
CNT Properties
32
CNT Properties
33
CNT Properties
34
CNT Properties
35
CNT Properties
36
CNT Properties
37
CNT Properties
38
CNT Properties
39
CNT Properties
40
CNT Properties
41
CNT Properties
  • Nanotube Research Articles\Overall\nanotube
    composites.pdf
  • Very good article explaining the basics of CNTs

42
CNT Properties
43
CNT Properties
44
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47
Filling CNTs
48
CNTPolymer Interfacial Strength
49
Effects From Size
50
Functionalized CNTs
51
Additives
  • Additives can aid in the dispersion of the CNTs

52
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

53
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

54
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

55
Functionalized CNTs
56
Functionalized CNTs (Kentera)
57
Functionalized CNTs (Kentera)
58
Functionalized CNTs (Kentera)
59
Functionalized CNTs (Kentera)
60
Functionalized CNTs (Kentera)
61
Functionalized CNTs (Kentera)
62
Functionalized CNTs (Kentera)
63
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.

64
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
    Youngs modulus is around 200 for the composite
    in this study, and the difference with that from
    the continuum medium approximation based
    HalpinTsai formula suggests that interfacial
    atomic structure is crucial for a nanocomposite.

65
Adhesion and reinforcement in carbon nanotube
polymer composite
66
Property Data for Specific Materials
67
PMMA
  • Relative to pure PMMA, a 32 improvement in
    tensile modulus and a 28 increase in tensile
    strength were observed in PMMA-based
    nanocomposites using 1.0 wt nanotube filler.

68
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.

69
Epoxy
70
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71
Epoxy
72
Epoxy
73
Epoxy
74
Natural Rubber
75
Natural Rubber
76
Natural Rubber
77
PVA
  • To summarize, MWNTs have been well dispersed in
    PVA matrix through gum arabic treatment. The
    PVA/MWNT composite films exhibit good mechanical
    properties

78
PS
79
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
    Struiks relation. The use of SWCNT does not
    improve the micromechanical properties

80
PBT
81
SBR
82
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 Youngs 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.

83
SBR
84
PC
85
PC
86
PC
87
PC
88
PC
89
PC
90
PC
91
PC
92
PC
93
PC
94
PE
95
PE
96
PE
97
PE
98
PE
99
PE
100
PE
101
PE
102
PE
103
PE
104
LLDPE
105
LLDPE
106
LLDPE
107
LLDPE
108
LLDPE
109
Microscope Imaging
110
Microscope Imaging
111
Microscope Imaging
112
Microscope Imaging
113
Microscope Imaging
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