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Lawrence T. Drzal
Dept of Chemical Engineering and Materials Science
Composite Materials and Structures Center Michigan State University East Lansing, MI-48824
Graphene Nanoplatelets: A Multifunctional Nanomaterial for
Polymers and Composites
‘Lightweighting’ Structures Aerospace, Military, Truck, Automotive, Wind
• Lightweighting Structures and Higher Power and Energy Densities are gaining increasing importance
• “Do More with Less” leads to…
• Multifunctional Fiber Reinforced Polymer Composites
• Solution is…’engineering’ of Nano-Particles into structures and energy devices
• Dispersion and Nano-structuring
• Use of Few layer graphene nanoplatelets (GnP)
i. Introduction to (few layer) Graphene Nanoparticles
i. Synthesis, Characterization, Properties,
ii. ‘Multifunctionality’ in Fiber Reinforced Polymer Matrix Composites – Thermoset and Thermoplastic
iii. Processing and Nano-Structuring in 1D, 2D and 3D
iv. Applications
Presentation Outline
Nano-Materials Portfolio
12
Halloysite Nanotubes
Cellulose Nanowhiskers
0.3 nm
NanoGraphite Platelets
Nanoclay
Boron Nitride NanoPlatelets
Single and Multiwall Carbon Nanotubes
Vapor Grown Carbon Fibers
Boron Nitride Nanotubes
Boehmite
Fullerene
Graphene
Multifunctional Carbon Based Nano-Materials
Carbon Nanotube
Graphene NanoPlatelets
PHYSICAL STRUCTURE
Cylinder ~1nm X 100nm
Platelet ~1nm X 100nm
CHEMICAL STRUCTURE
Graphene (chair, zigzag,
chiral)
Graphene
INTERACTIONS π - π π - π
TENSILE MODULUS
1.0-1.7 TPa ~1.0 TPa
TENSILE STRENGTH
180 Gpa ~(10-20 GPa)
ELECTRICAL RESISTIVITY
~ 50 x 10-6 Ω cm
~ 50x10-6 Ω cm║ ~ 1 Ω cm┴
THERMAL CONDUCTIVITY
3000 W/m K 3000 W/m K ║ 6 W/m K ┴
COEF THERMAL EXP.
-1 x 10-6 -1 x 10-6 ║ 29 x 10-6 ┴
DENSITY 1.2 – 1.4 g/cm3 ~2.0 g/cm3
Single and Multiwall Carbon Nanotubes
Graphene
• Mechanical Exfoliation of Graphite
• Monolayer Synthesis
• Few Layer Exfoliation via
Graphite Oxide and Reduction to Graphene
• Few Layer Intercalation and Direct Exfoliation of Graphite
Novoselov et al., Science 306, 666 (2004)
Walt A. de Heer, et al., Solid State Communications 143 (1-2), 92-100 (2007)
M. Hirata et al., Carbon 42(14), 2929-2937, 2004
Synthesis of Graphene & NanoPlatelets
Few Layer Intercalation and Direct Exfoliation of Graphite • Graphite can be a host material for chemicals
• Typical intercalates include: • alkali metals (Li, Na, K, Rb, Cs), • metal halides (FeCl3, CrO3, TiCL3, PtCl4, etc.), • acids (nitric acid, sulfuric acids, phosphoric acid, perchloric acid,
chromic acid, etc) • combinations of alkali metal/organic molecule (K/THF,
Cs/benzene, Cs/ethylene, Cs/styrene, Cs/butadiene, etc.) • Some of the GICs can be exfoliated by rapid heating.
Brodie BC. Ann Chim Phys;45:351–3, 1855 Schafhaeutl C. J PraktChem; 21:129–57, 1840
Synthesis of Graphene
‘Ex-Situ’ Exfoliation and Size Reduction of GnP
GnP Graphene
(50-100 um)
GnP Graphene (15 um)
GnP Graphene
(1 um)
Intercalated Graphite
(300-500 um)
Expanded Graphite
(300-500 um)
Stacks of 10-20 lamellae are less affected by out-of-plane bending forces and retain their platelet structure during processing.
Bousmina, Macromolecules, 2006, 39 (12), pp 4259–4263
• Layers can be intercalated and exfoliated into platelets with high aspect ratios (dia ~0.3µ to 50μ and t~ 1nm to 5nm)
• Basal Plane is hydrophobic
• Functional groups at GnP edges
• Covalent bond formation at edge sites
• Surface areas from 100m2/g to 750m2/g
• Some reduction in properties from monolayer graphene
• Inexpensive to produce
XPS C/O atomic ratio 25.7
2 theta
Inte
nsit
y
X-ray diffraction analysis
26.2o graphitic peak
•< 96 % retention
wei
ght (
%)
Thermo gravimetric analysis at 5 C/min in air
Temperature (C)
1577 cm-1
1346 cm-1
Raman shift (cm-1)
G band peak
D band peak
Graphitic crystalline domain
La = (2.4 X 10-10) λlaser4 ( IG / ID)
Raman analysis
Inte
nsi
ty
‘Quality’ of Intercalated-Exfoliated GnP
Copyright 2010, Michigan State University
GnP Edge Functionalization
HNO3, O2 Plasma, or UV/O3
COOH
H2N-C2H4-NH-C2H2-NH2n
CO-HN-CH2-NH-CH2-NH2n
CH2 CHCONH2
CO
mCH2 CH
CONH2
• Water • Coatings, Paints, Inks
• Thermoset Resin • Epoxy, PU, Vinyl Ester
• Thermoplastic resin • PP, PE, Nylons
GnP Applications and Dispersion Strategies
i. Introduction to (few layer) Graphene Nanoparticles
i. Synthesis, Characterization, Properties,
ii. ‘Multifunctionality’ in Fiber Reinforced Polymer Matrix Composites – Thermoset and Thermoplastic
iii. Processing and Nano-Structuring in 1D, 2D and 3D
Presentation Outline
Thermoset Matrix NanoComposites
Epon 828 Jeffamine T403 Reinforcement
Outgas in vacuum
Cure 85°C for 2hrs 150°C for 2hrs
Pour into mold
Outgas in
vacuum • Ultrasonication • 3 roll Milling • Multi Axis Mixing
Mixing & Dispersion –(Random) Nanocomposites
GnP/Epoxy Nanocomposite Flexural Properties: Size and Surface Chemistry Effect of GnP
Effect of Surface Treatments on Modulus
2600
2800
3000
3200
3400
3600
3800
4000
0 0.5 1 1.5 2 2.5 3 3.5Reinforcement Content (Vol%)
Flex
ural
Mod
ulus
(MPa
)
No TreatmentP2 PlasmaAmine GraftingAcrylamide Grafting
Effect of Surface Treatments on Strength
50
60
70
80
90
100
110
120
0 0.5 1 1.5 2 2.5 3 3.5Reinforcement Content (Vol%)
Flex
ural
Str
engt
h (M
Pa)
No TreatmentP2 PlasmaAmine GraftingAcrylamide Grafting
Effect of Size on Flexural Strength
40
50
60
70
80
90
100
110
0 0.5 1 1.5 2 2.5 3 3.5Reinforcement Content (Vol%)
Flex
ural
Str
engt
h (M
Pa)
Heat-exfoliated Gr.(15um)Heat Milled Gr.(1.1um)MW-exfoliated Gr.(15um)MW Milled Gr.(0.86um)
Effect of Size on Flexural Modulus
2600
2800
3000
3200
3400
3600
3800
4000
0 0.5 1 1.5 2 2.5 3 3.5Reinforcement Content (Vol%)
Flex
ural
Mod
ulus
(MP
a)
Heat-exfoliated Gr.(15um)Heat Milled Gr.(1.1um)MW-exfoliated Gr.(15um)MW Milled Gr.(0.86um)
~100m2/g GnP
GnP/Epoxy Electrical Resistivity
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
-1.00 0.00 1.00 2.00 3.00 4.00 5.00Log(Freq/Hz)
Lo
g(Z
/oh
m*c
m)
Control Epoxy1.0Vol% xGnP2.0Vol% xGnP3.0Vol% xGnP
Static Dissipation
Electrostatic Painting
EMI/RFI Shielding
1.E+001.E+011.E+021.E+031.E+041.E+051.E+061.E+071.E+081.E+091.E+101.E+111.E+121.E+13
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Weight %
Res
istiv
ity [o
hm*c
m]
VGCFCarbon BlackPAN CFExfoliated GraphiteMilled Graphite
Percolation Analysis
( ) tceff pp --= 0rr
Reinforcement pc (Vol%) pc (Wt%) r0 (ohm*cm) tCF 5.90 9.76 0.4 3.26
VGCF 1.09 1.87 0.03 3.03Carbon Black 1.29 2.00 0.01 3.03Exfoliated Gr. 1.13 1.93 0.001 3.12
~100m2/g GNP
GnP/Epoxy Thermal Conductivity and CTE
Thermal Conductivity
00.1
0.20.30.40.5
0.60.70.8
0.91
0 1 2 3 4 5 6
Exfoliated Graphite Content (Wt%)
W/m
*K
CTE below Tg
50556065707580859095
Con
trol
Epox
y CF
VGC
F
Car
bon
Bla
ck
Acr
ylam
ide
Gra
fted
Nan
ogra
phite
[um
/m*C
]
Thermal Conductivity
00.10.20.30.40.50.60.70.80.9
1
ControlEpoxy
3 vol% MWEx.Gr
3 vol% CF 3 vol%VGCF
3 vol% CB
(W/m
*K)
~100m2/g GnP
GnP-Graphite Nanoplatelets • Microwave-processed using intercalated graphite compound and then pulverized
Functionalized Elastomer • Carboxyl-Terminated poly(Butadiene-co-Acrylonitrile) (CTBN)
• (Acrylonitrile 26%, carboxyl 32%, MW=3,150
Vinyl Ester • DERAKANE 411-350
• Initiator: Methyl Ethyl Ketone Peroxide
• Accelerator: Cobalt Octoate
CTBN Functionalized GnP/Vinyl Ester Composites
CTBN concentration (wt.%)As-received VE 0 0.5 5 10
Impa
ct S
tren
gth
(J/m
)
0
50
100
150
200
250
300xGnP 0.5 wt.%xGnP 1 wt.%xGnP 3 wt.%xGnP 5 wt.%
Fle
xura
l mo
du
lus
(GP
a)
0
1
2
3
4
xGnP 0.5 wt.%/Vinyl esterxGnP 1 wt.%/Vinyl esterxGnP 3 wt.%/Vinyl esterxGnP 5 wt.%/Vinyl ester
CTBN concentration (wt.%)0Vinyl Ester 0.5 5 10
Without CTBN
Coating As-received
VE
With CTBN Coating
CTBN concentration (wt.%)F
lexu
ral s
tren
gth
(MP
a)
0
20
40
60
80
100
120
140
160
180
200xGnP 0.5 wt.% / Vinyl esterxGnP 1 wt.% / Vinyl ester xGnP 3 wt.% / Vinyl esterxGnP 5 wt.% / Vinyl ester
0Vinyl Ester 0.5 5 10
Without CTBN Coating
As-received
VE
With CTBN Coating
xGnP Contents (wt.%)0.5 1 3 5
Imp
act
Str
eng
th (
J/m
)
0
50
100
150
200
250As-received Vinyl EsterCTBN 0.5 wt.%CTBN 1 wt.%CTBN 5 wt.%CTBN 10 wt.%
CTBN Functionalized GnP/Vinyl Ester Composites
Functionalized Elastomer
• Carboxyl-Terminated poly(Butadiene-co-Acrylonitrile) (CTBN)
• (Acrylonitrile 26%, carboxyl 32%, MW=3,150
Thermoset NanoComposite
Epon 828 Jeffamine T403 Reinforcement
Outgas in vacuum
Cure 85°C for 2hrs 150°C for 2hrs
Pour into mold
Outgas in
vacuum Ultrasonicate & Mix
Thermoplastic NanoComposite
Extrude Injection
Mold
GNP
TP
GNP Coat
Powder TP
Powder
Compression Mold
PreMix Extr/InjMold
Thermoplastic GnP NanoComposite
GnP/PP Nanocomposite Flexural and Impact Properties
Impact Strength of xGnP-PP Nanocomposites
8
13
18
23
28
33
38
0% 0.01% 0.05% 0.10% 1% 2% 3%
J/m
xGnP-1xGnP-15
Modulus of Elasticity of xGnP-PP Nanocomposites
1
1.2
1.4
1.6
1.8
2
0 0.01 0.05 0.1 1 2 3vol%
GPa
xGnP-1xGnP-15
Flexural Strength of xGnP-PP Composites
35
40
45
50
55
0 0.01 0.05 0.1 1 2 3vol %
MPa
xGnP-1xGnP-15
0.01% xGnP
130oC 10min 50μm
XRD Pattern of xGnP1/PP
0
20000
40000
60000
80000
100000
10 12 14 16 18 20 22 24 26 28 302q
0 vol%0.01vol%0.1vol%1vol%
a <060> b <301>
b <300>
a <040>
xGnP promotes the formation of β phase crystals (at low %)
β-phase crystals of PP have higher impact strength and
toughness
No change in the degree of crystallinity
Tc increases by 10-20 oC (1 to 10vol% of xGnP)
1.071
3.19661 2.3965921.56378 3.062669 1.0611
3.192134 2.83434 2.382352
1.576644 3.078792 1.07553.198848 2.85568 2.348176
3.184282 3.098421.584684 3.206308 1.143 2.332512
2.882843.168694 3.101925
1.598352 3.231672 1.0737 2.3097282.9391 3.108234
3.176488 3.198848 2.2905041.605588 1.0728
2.98275 3.1222543.185148 3.201832 2.267008
1.614432 3.160108 1.09443.21153 3.007 2.247072
3.096816
Permeability of Nylon 6 Films
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5 10 15 20 25 30 35 40[Hour]
[cm
3/m
2*da
y*at
m] Control N6
3v%xGnP-15um/N63v%xGnP-1um/N63v%CF/N63v%GF3v%VGCF/N63v%Nanomer®/N63v%Cloisite®/N6
GnP/Nylon 6 & GnP/Nylon 66 Nanocomposites
Flexural Modulus of N66 Composites
0
2000
4000
6000
8000
10000
12000
14000
0 5 10 15 20 25[Vol%]
[MPa
]
xGnP-1xGnP-15CFVGCFCBNanomer I34.TCNCloisite 93A
Flexural Strength of N66 Composites
0
50
100
150
200
250
0 5 10 15 20 25 [Vol%]
[MPa
]
xGnP-1xGnP-15CFVGCFCBNanomer I34.TCNCloisite 93A
Electrical Conductivity of Nylon 66 Composites
1.E-11
1.E-10
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
0 5 10 15 20 25[Vol%]
S/m
In-situ Gr.xGnP-1xGnP-15CFVGCFCB
Thermal Conductivity of Nylon 66 Composites
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
N66 20v%xGnP-1
20v%xGnP-15
20v% In-situ
20v% CF
15v%VGCF
10v% CB
[W/m
K]
i. Introduction to (few layer) Graphene Nanoparticles
i. Synthesis, Characterization, Properties,
ii. ‘Multifunctionality’ in Fiber Reinforced Polymer Matrix Composites – Thermoset and Thermoplastic
iii. Processing and Nano-Structuring in 1D, 2D and 3D
Presentation Outline
Nano-Structuring
Utilization of graphene nanoplatelets (GnP) fabricated into 1D, 2D and 3D Morphologies to
enhance multifunctional properties and applications
1-D Morphology E-Field Alignment
High voltage source Voltage detector V
Copper plates Plastic dish
Voltage divider D
E field Intensity: ~10-25KV/cm
(a) (b) (c)
GnP Modification of Fiber Reinforced Composites
n Fiber Direction: High modulus high strength electrical conductivity, thermal conductivity, etc.
n CFRP properties Fiber direction - Compressive
strength - interlaminar
fracture toughness Transverse direction - Electrical & Thermal
conductivities - Damping property
Compressive strength
CF GnP
prevent fiber buckling by enhancement of modulus and yield strength of matrix
Reduce crack propagation by bridging effect
Interlaminar fracture toughness
2w% GnP Nanoparticles Applied to Carbon Fiber Surfaces in Epoxy Composites
• Dispersion of GnP in a ‘fugitive’ sizing
• Sizing ‘swells’ during impregnation
• Nanoparticles are ‘released’ in the interphase
• Apply to ANY reinforcing fiber
• Dry, handlable sized fibers
0
10
20
30
40
50
60
70
80
90
100
Control xGnP Coated sample
[MPa
]
Interlaminar Shear Strength +42%
0
1
2
3
4
5 6
7
8
9
10
11
Control xGnP Coated sample
[GPa
Transverse Flex Modulus +11%
0
10
20
30
40
50
60
70
80
90
100
Control xGnP Coated sample
[MPa
]
Transverse Flex Strength +24%
GnP Modification of Fiber Surface
0.5%PEI and 1% GnP coated single glass fiber
PSSS (0.5%)
Coating multiple layers of GnP on glass fiber reduces adhesion and the interfacial shear stress between fiber and matrix significantly
Multilayer GnP Coated Glass Fibers in Epoxy
Bare glass fiber
1 layer GnP coated glass fiber
11 layers GnP coated glass fiber
44 MPa
24 MPa
1 MPa
Apply GnNP to fibers and filler
with a sizing Mix fibers and filler with UPE
Add Initiator and Promoter Ultrasonicate
Cast and Cure
• Strength • Modulus
•Fl
exur
al s
tren
gth
0
2
4
6
8
10
0 1 2 3 4xGnP-1 wt.%
log
(Res
istiv
ity) (
R in
Ohm
s.m
)
0
2
4
6
8
10
12
log
(Res
istiv
ity) (
R in
Ohm
s/sq
)
Volume resistivitySurface resistivity
D= 28% (glass fiber) + 47% (CaCO3 /3.2% GnP-1)
+23%(UPE)= composite (GnP™ 1.5%)
Multifunctional GnP Modified SMC (6x108 lbs/yr)
753 728649692
417
665
0
200
400
600
800
1000
A B C D E F
Impa
ct s
tren
gth
(J/m
)
28%(glass fiber) + 47% (CaCO3) + 23%(UPE)
A= (GnP 0%)
B= (GnP 0.3%)
C= (GnP 1.0%)
D= (GnP 1.5%)
E= (GnP 2.0%)
F= (GnP 3.8%)
109 increase conductivity
80% Impact
20% Modulus 10% Strength
GnP Modification of Composites
+
GnP GnP film
Need balance of strength and
toughness
xGnP-15um xGnP-1um
30um 5um 5um
xGnP-100um
• Electrical conductivity: 2128 S/cm
Surface resistivity: 0.1 ohm/sq
OFHC Copper: 5.8*105 S/cm
• GnP paper density ~2g/cm3
Cu density ~8.9 g/cm3
• Thermal Conductivity
~ 200 W/moK -in-plane
~ 5 W/moK –thru-plane
Cu is ~ 400 W/moK
2D Multilayer GnP ‘Paper’
Superior Electrical and Thermal Conductivity, InPlane Strength
•Highly Aligned GNP
•Controllable size 35 cm x XXX
•Controllable thickness (~3μ to ~1000µ)
•Simple process
•Scalable to large sheets 2m+ XXX
Stage I Porous structure
Stage II GnP paper
GnP Paper
Continuously Extruded GnP-5/Polymer film
Material: extrusion cast film 10wt% GnP-5/PEId composite film,
stretching ratio=2, 0.3mm thickness, 16 layers
Neat PEId film, stretching ratio=3, 0.22mm thickness, 15 layers
Film die
Extruding speed
Drawing speed
Three roll
GnP Paper + Composite Summary
Loading & xGnP type
Modulus (GPa)
Strength (MPa)
Electrical conductivity
(S/cm)*
Thermal conductivity
(W/moK)*
Relative O2 Permeability
Injection molding GnP+PEI
10wt% GnP-5 6.6 98 E-6.7
Annealed E-3.0 Compression
molding GnP+PEI
10wt% GnP-5 5.7 98 E-4.5 0.40
SSBM & Pre-coating GnP+PEI
5wt% GnP-15 3.9 65 1.25 0.85 (t- plane,
3.3 @ 10wt%)
Extrusion cast GnP-PEI film
10wt% GnP-5 6.8 106 E-6.1 0.29 (t-plane) 0.35
Annealed E-4.3 0.80
Pressed xGnP paper
GnP-15 7.0 2.8 850 246
GnP-100 2200 313 GnP paper -PEI 80wt%
GnP-15 19 23 620
GnP paper -PEI 70wt% GnP-15 22 32 550 0.01
GnP paper -epoxy
15wt% GnP-15 20.5 0.02
Blast Impact by shock –tube
Maximum air speed= Mac3 ~ 1000m/sec
=2,250 miles/hr 80 times high speed than Dynatup!
a) b) c)
a)
c) b)
a) b) c)
c) 10% holes (Dia. 6.3mm) GnP-200um (t=40um) 2.3 %/ GF 60.3%/VE , t=0.128”
a) GF 63.0 wt%/VE t=0.124” b) CTBN coated GnP-15um( t=35 um) 0.6 % / GF 61.0 wt%/ VE, t=0.128”
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
02 4 6 8 10 12 14 16 18
S21
( db
)
Frequency ( GHz )
Sheet 1U
Sheet 2U
Sheet 7P
Sheet 9P
Brass Plate+
GnP Film for EMI Shielding
Tunnel f=2 to 18 GHz
PNA –AGILENT
• Graphene Nano-Platelets offer a route to Multifunctional Materials • Direct Intercalation/Exfoliation to produce platelet morphology
• Variable Platelet Thickness; Diameter ; Surface and Edge Chemistry; • Dispersible in water, solvent and thermoset and thermoplastic polymers • Reasonable cost ~$15/lb
• GnP Polymer Nano-Composite Multifunctional Properties • High Modulus, Low Density • High Electrical Conductivity and High Thermal Conductivity
• Optically Transparency • Thermo-Oxidative Resistance • Barrier Properties • Dispersible in Polymers and Water, Variable size • Thermoset or Thermoplastic Matrices
• Nano-Engineering for 1D, 2D or 3D Morphology • Transformational Material for Multifunctional Lightweight Composites
• Placement of GnP on Reinforcing Fiber Surface of Between Lamina • Increase Adhesion, Toughness, Off-axis properties • Blast and Impact Resistance
GnP for Composites and Energy Applications
