Opportunities and Barrier Issues in Carbon Nanocomposites

R. Byron Pipes, NAE, IVA

Goodyear Endowed Professor

University of Akron

National Science Foundation Composites Workshop

June 9-10, 2004

The Future for Carbon Nanocomposites

• Future Trends in Technology Development• Globalization of Research• Barriers and Opportunities:

Scale

Mixing and Dispersion

Multi-Functionality

Next Generation Aerospace Material

Carbon Nanotube

Nanotube/ Polymer

Nanotube Fiber

Ultra Nanostructured Composite

Connect,ClickAnd

Control

Factory Production

Education

Chemical Plant

Heavy Machinery

DSC

TGAPolymer Industry

Process Control

Higher Level Research

Online Microscopy

Textile

The Future: Connect, Click and Control

Carbon Nanotubes

• Graphene is the stiffest material known (Young’s modulus > 1 TPa)

• Ideal reinforcement for composite materials

Single wall carbon nanotubesForms of Carbon

Diamond Buckyball

Graphite Nanotube100 nm

SCALE

Is it possible to span 12 orders of magnitude in scale and preserve

properties?

Self Similar Helical Modeling

SWCN

LatticeDymanics

Nano-wire

Micro-Mechanics

+Self Similar

Analysis

Polymer

Micro-fiber

Micro-Mechanics

+Self Similar

Analysis

Polymer

Lamina

Micro-Mechanics

+Self Similar

Analysis

Polymer

Nano-array

Self SimilarAnalysis

Self-Similar Scales

1.48 x 10-8 m

.

1.68 x 10-7 m

1.92 x 10-6 m

1.38 x 10-9 m

SWCN

SWCN Nano Array

SWCN Nano Wire

SWCN Micro Fiber

Self-Similar Scales

1.9 x 108

1.7 x 1010

1.6 x 1012

Diameter = 1.92 x 10-6 mLength = 1.0 x 10–3 m

Number of nanotubes

SWCN

Self-Similar Properties

0

200

400

600

800

1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04Diameter (m)

Sp

ec

ific

Mo

du

lus

(G

Pa

)

CarbonFiber

SWCN

Nano-wire

Nano-array

Micro-fiber

=10°

=20°

Lamina

Observations

• Nanotube – Nano Array – Nano Wire – Micro Fiber• Helical array geometry provides self-similar

platform • 71% stiffness reduction• Strength reduction may not correspond to stiffness

reduction• Multifunctional properties offer significant potential• Use the properties at the scale of applicability

Mixing and Dispersion

Van der Waals bonding – Energy for dispersion

Science 273, 483 (1996).

SWCN Array Image Analysis

DoDi

S

Do = 1.38 nm

Di = 0.73 nm

S = 1.48 nm

Nanotube Wall Thickness = 0.33 nm

Volume Fraction:Hexagonal Array = 0.79With van der Waals = 0.906

Shear and Bulk Moduli

x

2

x

3

o22321

o33

o32321

o22

xxx

xxx

o3xo3

o2o22

xxx

xxx

x

2

x

3

223

2

23 eVol4

1K

223

2

23 Vol

1G

Carbon Nanotubes Sticking Together

Continuum Approach for L-J Interactions

r

d

areaunit per atoms3

4

atoms 2for potential J-L4

),()(

2

22

612

2

0 0

b

drR

RRR

rdrddrRd

sheet

1 atom

Dilatation of SWCNT Array

4

3CellUnitofArea

2R

20

3

6

R

Cohesive Energy per unit Volume

Dilatational Cohesive Energy per Unit Volume

20

00

3

3

R

1

1.5

2

1 10 100 1000 10000

Number of Tubes

0Eactual

Unit Cell Cohesive Energy

Chirality R0, nm 0, nJ/m GJ/m3

(6,6) 1.1281 0.117 0.159

(10,10) 1.6723 0.152 0.207

(24,24) 3.5733 0.239 0.325

Conclusions for Array Flexural Properties

• The assumption that the CNT array can be represented as a uniform beam is not appropriate for arrays that are not fully bonded.

• The experimental results of Salvetat [3] for the 7- element array (4.5 nm diameter rope) with span lengths of 285 and 180 nm, revealed shearing tractions of 136 and 200 MPa, respectively.

• Fracture energies for SWCN fracture are significant!

Functionality

Can multifunctionality provide the pathway for accelerated adoption?

Are devices the fertile area?

Radial breathing mode spectra

Inte

ns

ity(

a.u

)Raman spectroscopyRaman spectroscopy

Higher Intensity in parallel polarization direction.

Similar result seen for both two grades of CNT

Orientation

0.5% nanotube(CS) composite microfiber

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

120 130 140 150 160 170 180 190 200 210 220

Perpendicular

Parallel

Raman shift(cm-1)

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

1500 1525 1550 1575 1600 1625 1650 1675 1700

Perpendicular

Parallel

Tangential mode spectra