Carbon nanotubes and graphenenanoplatelets for multi-functionalnanoplatelets for multi functional

composites

Dr. Aiping YuDepartment of Chemical EngineeringDepartment of Chemical Engineering

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Outline

1. Brief introduction to carbon nanotubes (CNTs) and graphene nanoplatelet

2 Single walled carbon nanotubes (SWNTs) Nylon 62. Single walled carbon nanotubes (SWNTs)- Nylon 6 composite fiber

3 Graphene epoxy composite3. Graphene-epoxy composite

4. CNTs/carbon fiber 3D matrix composite4. CNTs/carbon fiber 3D matrix composite

5. Work @ Sabic Innovative Plastics

6. Work @ UWIP

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Carbon nanotube & graphene nanoplatelet

1991-1993 2002-2005

:High mechanical strength and tensile modulus (Young’s modulus ~1TPa carbon fiber: 400-600 MPa conventional(Young s modulus 1TPa, carbon fiber: 400-600 MPa conventional

carbon fibers (200-800 GPa).Unique electrical properties (~1*105 S/cm )

Exceptional thermal conductivity (~3000 W/mK )

low density(~1.3-2g/ml) high aspect ratio (L/D~1000)y( g ) g ( )IP

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Synthesis of carbon nanotubesSynthesis of carbon nanotubes

Graphitecathode

C Ni-Y

Chemical vapor depositionArc-dischargeArc-dischargeIP

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Applying SWNTs & GNPs to polymersHigh mechanical properties

EMI shieldingAntistaticHigh mechanical properties

Against lighting strikeAgainst lighting strike

Nano-materials will bring revolution to industry

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Brief example-strongest polymer composite ever made

1.6

1.8

2.0 SWNT/PVA FiberSpider Silk

600

700

E

a

1.6

1.8

2.0 SWNT/PVA FiberSpider Silk

600

700

E

a

1.6

1.8

2.0 SWNT/PVA FiberSpider Silk

600

700

E

a

1.6

1.8

2.0 SWNT/PVA FiberSpider Silk

600

700

E

a

0 8

1.0

1.2

1.4

tress

(GP

a)

300

400

500

Energy Abso0 8

1.0

1.2

1.4

tress

(GP

a)

300

400

500

Energy Abso0 8

1.0

1.2

1.4

tress

(GP

a)

300

400

500

Energy Abso0 8

1.0

1.2

1.4

tress

(GP

a)

300

400

500

Energy Abso

0.2

0.4

0.6

0.8

True

St

100

200

orption (J/g)0.2

0.4

0.6

0.8

True

St

100

200

orption (J/g)0.2

0.4

0.6

0.8

True

St

100

200

orption (J/g)0.2

0.4

0.6

0.8

True

St

100

200

orption (J/g)0 10 20 30 40 50 60 70 80 90 100 110 120

0.0

Strain (%)

0

0 10 20 30 40 50 60 70 80 90 100 110 120

0.0

Strain (%)

0

0 10 20 30 40 50 60 70 80 90 100 110 120

0.0

Strain (%)

0

0 10 20 30 40 50 60 70 80 90 100 110 120

0.0

Strain (%)

0

Tensile strength matches spider silk and modulus (80 GPa) is much higher than spider silk

R. Baughman, 290,1310, Science, 2000

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N l 6/SWNT Ad d C itNylon 6/SWNT Advanced Composites--- mechanical/electrical enhancement

Yu,A. et at., J. of American Chemical Society 2005, 127, , y ,IPR 20

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Motivation and challengesMotivation and challenges

Nylon is a widely used thermoplastics owing to its good strength high elongation, excellent abrasion resistance, etcThere is need to improve the mechanical strength, toughness and electrical conductivityelectrical conductivity.

Highly hydrophobic surfaceg y y p

• Lack of functionality resulting chemical incompatibility with the polymer matrix and the self-aggregation of SWNTs into bundles due to van der Waals attractionvan der Waals attraction

• Homogeneous dispersion & SWNTs not pull out from polymerIP

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Strategy

Ensure efficient load transfer from the matrix to the fiber, the interfacial bonding between the polymer matrix and the carboninterfacial bonding between the polymer matrix and the carbon nanotubes is necessary to prevent fiber pull out

Controlled HNO3 treatment of SWNTs, brings –COOH to the end of SWNT

In-situ grafting PA6 chain to SWNT surface

Nylon matrixNylon matrix

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Step one: HNO3 treatment

1. SWNT surface hydrophilic2. Removed catalyst particles

Atomic Force Microscopy

40 AP-SWNT

0

20

al (m

V)

-40

-20 SWNTs-COOH

ta p

oten

tia

2 4 6 8 10-80

-60 AC

zet

2 4 6 8 10pH

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Step 2: In-situ grafting nylon 6 to SWNT

N H 2 (C H 2 ) 5 C O O HN H

O

O HO

in it ia to r S W N T sc a p ro la c ta m (m o n o m e r)

OH6,aminocaproic acid sonication, 80 oC

NH

Protonated monomer

H2N(CH2)5COO++ -

2. polymerization, 250 oC

H3N CHN C N

Hn

+ -250 oC

O

O

COO- nH2O Advantages:

OHO

+ H N CHN C N+ -

O

COO

No solvent PA6 grafted to SWNT

OH +

O H O

H3N C N C NHnO

COO

NH C N C NHn

-

OCOO

- nH2O

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Characterization of SWNTs with grafted Nylon 6

IR spectra samples prepared using different initiator concentrations

AFM of SWNT

0 0

different initiator concentrationsBefore

0.0

0.4

0.8

After

wt% initiator

1500 2500 3500

1640 cm-1 C=O group of the amide functionalityg p y1540 cm-1 combination of N-H bond C-N bond of the amide group

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In situ polymerization setup & fiber preparation

N2

Composite fibersComposite fibers

fiber spinneretLab reactor Cross-section IP

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Characterization of SWNTs-Nylon 6 composite

SEM TEMSEM

300 1.0

1.5

4 wt% SWNT in Nylon 61.51.0

Differential thermal analysis. Thermal decomposition T.

150

300

0.0

0.5

0.2

μg/M

in)

0

A

(μv)

0.50.2

0.0

0

150

wt% SWNT in Nylon 6

DTG

(μ

-4

DTA

420 440 4600

Temperature (oC)

150 200 250 300

Temperature (oC)

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Results of electrical conductivity

Samples @ 1wt % loading

Electrical conductivity@ 1wt % loading conductivity (S/cm)

PA6 graftedSWNT it

1.1E-6SWNT composite

Electrical conductivity data show:Th it i th ti t tiThe composites are in the anti-static range 1 wt % SWNT loading

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Mechanical properties of SWNTs-Nylon 6 composite

8 0

6 0

s (M

Pa) Pure N ylo n

0.1 wt% 0.2 wt%

%4 0

2 0

Stre

ss 0.5 wt% 1.0 wt% 1.5 wt%

0

4003 0020010 00 4003 0020010 00St ra in (% )

The PA6 grafted leads to 84 % increased tensile strength and 170%Young’s modulus (1.5 wt% loading)

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Modeling calculation of SWNTs-Nylon 6 compositeModeling calculation of SWNTs Nylon 6 compositeHalpin–Tsai modelIs widely used to predict the modulus of unidirectional or randomlyIs widely used to predict the modulus of unidirectional or randomly distributed filler-reinforced composites

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SummarySummary

The PA6 chains are found to be grafted to the SWNTs by aThe PA6 chains are found to be grafted to the SWNTs by a condensation reaction between the –COOH groups of the SWNTs and the terminal amino group of PA6

The grafted PA6 chains enhance the SWNT-nylon6 interfacial interaction and improve their compatibility, a homogeneous dispersion of the SWNTs in the nylon matrix

The Young’s modulus, tensile strength, and thermal stability of nylon 6 fibers are greatly improved by the incorporation of SWNTs via the process

p y

The composite is also anti-static in the pursued concentration rangeIPR 20

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Graphene/ Epoxy Resin Composites--- Thermal Interface Materials

Patent : US and WO patent: WO/2008/143692

Yu,A. ;Ramesh P. ;Itkis M.; Bekyarova E.; Haddon R., J. of Physical , ; ; ; y ; , yChemistry C 2007,111,7565-7569

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Composites: Thermal management in high density electronics

Source : Intel

With continued scaling of devices heat transport problems will most

Thermal interface material (TIM)

With continued scaling of devices, heat-transport problems will mostlikely be aggravated at all levels

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GNPs as fillers in epoxy matrix for TIMs

Thermal conductivity ofpolymer matrix: 0.2-0.4 W/mK

Requirements of TIMs:Thermal conductivity ≥ 2 W/mKLow thermal expansion

Conventional Particles: Using GNPs as filler

Low thermal expansion

SiO2, AlN, Ag

Ad f GNPAdvantages of GNPs • High thermal conductivity• High aspect ratio

L CTE

Disdvantages:Low aspect ratio • Low CTE

• Low density

Low aspect ratio high loading

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Schematic process to obtain GNPs

Natural graphite

IntercalationH2SO4/HNO3

Thermal shockExfoliated graphite

Physical processy pIP

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Microscopic observation of GNPs

(a) (b)

Optical Microscopic

800 oCC

Exfoliated graphite

400 oC

200 oCNatural graphite

0.5 mm5 mm

Scanning Electron MicroscopicIP

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AFM of GNPs

800 oC800 oC

Statistic size

L ~ 1.1 μm, t ~ 1.7 nm, AR = 200; 4 layer graphene (G4)

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GNP/epoxy composite

Epoxy: Diglycidyl ether of bisphenol A

Challenges: High loading nano-material dispersion

Epoxy: Diglycidyl ether of bisphenol A

H2C CH

CH

OO

CH3

O CH

CH

OH

CH

O

CH3

O CH

CH

CH2

O

H H2 CH3H2 H H2 CH3

H2 H

n

H2N NH2

CH3

Even in lab scale, mechanical stirring is not enough H2N NH2

CH2CH3CH3CH2

, g g

Curing agent: Diethyl-toluenediamineDiethyl-toluenediamine

Homogenizer:Shear mixing

Three roll mill

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Schematic show of the composite processSchematic show of the composite process

Shear mixing & sonicationin acetonein acetone

Shear mixing C li ki

Exfoliated graphite

Cross-linkingepoxy

Three-roll mill curing

GNP-Epoxy5 nm5 nm

p yCross section TEM image of GNP-Epoxy

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High resolution TEM of GNP in epoxy matrixg p y

1 nm

L ~ 1.1 μm, t ~ 1.7 nm, AR = 200; 4 layer graphene (G4)

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Thermal conductivity measurements:heat flow two thickness testingheat flow two thickness testing

Samplechamber

cooler

D i d di t ASTM C518 98

cooler

Designed according to ASTM C518-98From Lasercomp. Inc.

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Thermal conductivity of the GNP/epoxy composites

%)

7.0

)

Temperature dependence of

0.25 vol loading compositeThermal Conductivity vs GNP Ratio

3000

0.25 Vol6 44 W/ Knc

emen

t (%

0.2 Vol4.76 W/mK

T=30 oC

6.8

7.0

uctiv

ity (W

/mK

)

T-dependence of GNPs of 25 voL%

2000

6.44 W/mK

vity

Enh

an

6.4

6.6

Ther

mal

Con

du

1000

Con

duct

iv

20 30 40 50 60 70 80

6.4

Temperature (oC)

0.0 0.1 0.2 0.30

Ther

mal

GNP V l F ti H tGNP-Epoxy

Heat sink

GNP Vol Farction

• Linear increase of thermal conductivity with filler loading• Thermal conductivity up to (10 12 W/mK-40 Vol%)- suitable for electronic

Heat source

• Thermal conductivity up to (10.12 W/mK-40 Vol%)- suitable for electronic packaging, superior than conventional fillers• In the T range of computer run, performance is good

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Comparison of carbon fillers

600

700nt

(%)

500

600 10 wt % Loading

nhan

cem

e

CB- carbon black

300

400

uctiv

ity E

n GMP- graphite microplateletMWNT-Multi-Walled

Carbon NanotubesSWNT- Single-Walled

100

200

mal

Con

du Carbon NanotubesGNP- graphite nanoplatelet

CB GMP MWNT SWNT GNP0

100

Ther

m

• GNPs filler perform better than other carbon fillers• GNP shows: 130% enhancement / 1 vol.% – efficient filler

Whereas it is 20 30% for conventional fillersWhereas it is 20-30% for conventional fillersReason: High aspect ratio and rigid 2D structure of – High performance

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Modeling prediction & discrepancyModeling prediction & discrepancy

1. Inverse Rule of Mixtures15

mK

)

1. Inverse Rule of Mixtures

2. Nielsen’s model accounts for

1/K=Φ1/k1+ Φ2/k2

model

10GNPs-epoxy

duct

ivity

(w/m

121

1fc ABK

K Bφφ

+=

the geometry of the fillers

5

SWNT-epoxy

erm

al C

ond1

1E

p fK B

A k

ψφ−

= − SWNT epoxyTh

0 0.1 0.2 0.3 0.4

/ 1/

E

p

p

Kf KKf K AB

−+=

21

1 ( )f

p

m

m

f

φφ

ψ φ−

= +Experimental data are significantly lower thanmodeling prediction; Th d l d difi ti f t i lmφ The model needs modification for nanomaterials

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Summary of 2D-GNP/epoxy compositeSummary of 2D-GNP/epoxy composite

Thermal conductivity of GNP epoxy resin compositeThermal conductivity of GNP-epoxy resin composite is high up to 10.12 W/mK, which is excellent for thermal

interface material application.

Cost effective production: Graphite $50/Kg

Hi h t fill ffi i i i id 2D fillHighest filler efficiency using rigid 2D fillers

32

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3 D Multi-functional Composites

Biaxial Weave

Triaxial Weave

Knit Multiaxial Multilayer Warp Knit

3-D Cylindrical C

3-D Braiding 3-D Orthogonal Angle-Interlock CConstruction Fabric Construction

T. W. Chou and F. Ko, Textile Structural Composites, Elsevier Sci., Amsterdam, 1988

B i 787 D li it t i l f h lf f th t t tiBoeing 787 Dreamliner: composite materials for half of the parts, next generationAirplane material is not metal, will be carbon fiber matrix

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Motivation and Objectivej

Matrix rich region

Crack

T W Ch F K

Carbon fiber – Kelvar –Polymer composite

T. W. Chou, F. Ko, Textile Structural Composites, 1988

Motivation:Matrix rich regions form defect in the carbon fiber - polymer compositeC ki d f il ll t t d t f th d f t itCracking and failure usually start and propagate from these defect sites

Approach:Carbon nanotube to reinforce matrix regions and void the defect in compositeIncrease the carbon fiber – polymer interfacial interaction and load transferc ease t e ca bo be po y e te ac a te act o a d oad t a s e

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Multi-Scale Composite

Bridging the scale from Bridging the scale from NanoNanoto Macroto Macro 10 μm

Epoxy Matrixto Macroto Macro

1 μm

CarbonFiber

NanocompositeNanocomposite

100 nmCarbon Nanotubes

1Zig-ZagArmchairAtomic Interactions 1 nm

g gAtomic Interactionsr0

Stretching 0θ

Bending

Torsionvan der Waals

1 Å

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Strategy

1 mm As-Received Fiber

500 nm

8 µm

500 nm

55CNT reinforcement increases the interfacial interaction and 5 nm5 nmCNT reinforcement increases the interfacial interaction and the loading transfer and can avoid fiber pull-out

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CVD Deposition of CNTs on Carbon Fiber/Fabricsp

d iti f i (F ) f l ti th f CNT

FeCl3

-deposition of iron (Fe) for selective growth of CNTs

FeCl3

Carbon fiber3

FeCl3H2

Carbon FiberFe

Fe

Iron-coatedcarbon fibers

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SEM of Carbon Fibers Coated with CVD-grown CNTs

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Epoxy  resin  system

EPON 862 – EPI‐Cure W Curing Agent (Resolution Performance Products  Inc )(Resolution Performance Products, Inc.)

Bisphenol-F Epichlorohydrin Epoxy

Aromatic Diamine (diethyltoluenediamine)

Amine hydrogen equivalent wt (AHEW) 43-46

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Vacuum assisted infusion

Peel Ply

Distribution Media

Vacuum Bag Resin Inlet

Peel Ply

Distribution Media

Vacuum Bag Resin Inlet

Tool

Layers of Gl F b i

Nanotube-Coated C b Fib B dl

Peel Ply

Vacuum Outlet

Tool

Layers of Gl F b i

Nanotube-Coated C b Fib B dl

Peel Ply

Vacuum Outlet

Glass Fabric Carbon Fiber BundlesGlass Fabric Carbon Fiber Bundles

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SEM observation of the compositep

C b fibCarbon fiber

Carbon fiber

CNTsIPR 20

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Electrical conductivity enhancement

Both in-plane and out-plane electrical conductivity increased about17 % @ 0.5 wt% CNTs loading

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Mechanical properties enhancementMechanical properties enhancement

Flexural strength and stiffness of Shear strength of CF/epoxy composites Flexural strength and stiffness of CF/epoxy composites with and without CNTs were slightly improved.

with and without CNT was enhanced at 35% (loadings of 0.2 and 0.5 wt %).IP

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Summary

• CNTs had been deposited on carbon fiber surface

• Both in-plane and out-plane electrical conductivity increased about 17 %

• Flexural strength and stiffness were slightly improved and shear strength of the carbon fiber epoxy was enhanced at 35% with 0.5 wt % of CNTs. IP

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My work in SABIC Innovative Plastics

Ai i YAiping Yu IPR 20

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M k @ t lMy work @ uwaterloo

Supercapacitors

CompositesIPR 20

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My work @ uwaterlooSupecapacitor: a new energy storage device

y @

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My work @ uwaterlooHigh loading multi-functional graphene/polycarbonate composite

SEM

Cross-section

Infiltration with polycarbonate SandwishM ltil it

Infiltration with polycarbonate

Hot press

SandwishMultilayer composite

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R t bli ti f hRecent publications of graphene

1600

mbe

r Papers published in allgraphene field

60

mbe

r Papers published in polymer composite area

1200

icat

ion

num graphene field

30

45

icat

ion

num

400

800

urna

l Pub

li

15

urna

l Pub

li

2005 2006 2007 2008 2009 20100

Jo

Year2005 2006 2007 2008 2009 2010

0Jo

YearYear Year

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Welcome collaborations and suggestions for applying carbon nanotubes and graphene to polymer composites

Thanks a lot for your attentionThanks a lot for your attentionIP

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