Aligned Carbon Nanotubes Implementation in Aerospace Fiber Polymer Composites for Multi-

functional Property Enhancement

Namiko Yamamoto, Roberto Guzman deVilloria, and Brian L. Wardle

Technology Laboratory for Advanced Materials and Structures Dept. of Aero/Astro, MIT

7th ESA Round-Table on MNT for Space ApplicationsSeptember 14, 2010

Summary: Nano-engineered Hybrid Advanced Composites

• Advanced fiber-matrix composites hybridized with aligned carbon nanotubes (CNTs) as the 3rd phase– Multi-functional

Aerospace Structures [Meters]

Sept 14, 2010 22

– Multi-functional(mechanical, electrical, thermal, etc.) property enhancement

– Possible weight reduction

• Scaling challenges ~10-9 mCNTs [Nanometers]

Effective use of nano-scale CNTs, but in macro-scale structures

Applications of Nano-engineered CompositesLightning strike protection

EMI shieldingMechanical interface enhancement

Sept 14, 2010 33[Farmer, Nano Materials, 2007]

[NASA]

Damage detection

[Wicks et al., AIAA, 2010]

[Wicks et al., Comp. Sci. Tech., 2010]

1.E-01

1.E+00

1.E+01

Specific Thermal Conductivity [(W/mK)/(kg/m3)]

Metals

A luminum

Steel

Copper

Ceramic

Compos

CFRP In-

CFRP Th

GFRP

Polymers

Polymer

Ceramics

MWNT individual

Carbon fiber (axial)

SWNT individual

Al

Specific thermal conductivity [(W/mK)/(kg/m

3 )]

CNT Scaling and Compositing Effects

MWNT bundles

MWNT in

SWNT bundles

SWNT in

?

Sept 14, 2010 4

1.E-05

1.E-04

1.E-03

1.E-02

1.E-24 1.E-21 1.E-18 1.E-15 1.E-12 1.E-09 1.E-06 1.E-03 1.E+00 1.E+03 1.E+06

Specific Electrical Conductivity [(S/m)/(kg/m3)]

Specific Thermal Conductivity [(W/mK)/(kg/m3)]

SWNT in

MWNT in

SWNT b

MWNT b

SWNT in

MWNT in

Baseline

FFRP TT

Alumina

Carbon

CF

Series23

Series24

Metals

Foams

Polymers Composites

GFRP

Alumina CFRP in-plane

CFRP through-thickness

Fe

Cu

Specific electrical conductivity [(S/m)/(kg/m3)]

Specific thermal conductivity [(W/mK)/(kg/m

MWNT in polymer

SWNT in polymer

Limiting Factors of Electrical/Thermal Transport in CNT-Composites

CNT itself• CNT properties• CNT composite fabrication• CNT composite testing• Transport model of CNT composites

Sept 14, 2010 5

[Iijima, Nature, 1991]

[Yamamoto, 6th US-Japan Joint Seminar on Nanoscale Transport Phenomena, 2008]

MWNTs SWNTs

CNT Morphologies

[Hart et al., J. Phys. Chem. B,2006]Diffusive vs. Ballistic

Aligned CNTs

Aligned CNT polymer nano-composite (A-CNT-PNCs, 2-phase)

Representative volume element (RVE)

Multi-Scale ApproachAn individual CNT

small, simple

Comparison with models to extract individual CNT properties

Sept 14, 2010 6

CNTs

Polymer matrix

Representative volume element (RVE)

Radially grown CNTs

Advanced fiber

CNT nano-engineered composites (3-phase)

large, complex

Evaluation of limiting factors in scaling of transport properties

CNT Nano-engineered Composites:Fuzzy Fiber Reinforced Plastic (FFRP) • Radially aligned CNTs grown on fiber surfaces (as the 3rd phase)

• Mechanical bridging and thermal/electrical conductive pathways made of CNTs throughout the structure

• Good CNT dispersion in matrix

Sept 14, 2010 7

Fiber tows

Aligned CNT forest

Fiber woven cloths

Epoxy matrix

FiberX-section

• Good CNT dispersion in matrix

1 cm

FFRP FabricationCapillary-driven epoxy infiltration:

retained CNT alignment and dispersionBaseline

Sept 14, 2010 8

FFRP

20 µm

20 µmRadially aligned CNTs

[Yamamoto et al., ICCM, 2007]

1.E-02

1.E+00

1.E+02

0 2 4 6 8 10Electrical Conductivity

FFRP Electrical TestingX106-108 conduction enhancement with ~1-3% Vf of CNTs

EMI shielding

2 probe, bulk (DC/AC) [Yamamoto et al., AIAA, 2010]

Sept 14, 2010 9

1.E-10

1.E-08

1.E-06

1.E-04

1.E-02

CNT Volume Fraction [%]

Electrical Conductivity

[S/mm][ASTM D150]

[Valdes, Proceedings of the IRE,1952]

DC

AC

Surface

Through-thickness In-plane

4 probe, surface

0.6

0.8

Thermal Conductivity [W/mK]

FFRP Thermal Testingx1.9 conduction enhancement with ~3% Vf of CNTs

suggests larger inter-CNT resistance effects in thermal conduction

Laser-flash

Flash

L

[Yamamoto et al., AIAA, 2010]

Sept 14, 2010 10

0.0

0.2

0.4

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

CNT Vf [%]

Thermal Conductivity [W/mK]

1ply 2ply

Through-thicknessError ranges are shown, but not visible since they are underneath

the data point marks.

Time t

Tin

crea

se

Flash

2r0

L

Temperature measurement

FFRP Mechanical TestingShort beam shear strength

Tension bearing

Mode I fracture toughness

[Garcia et al., Comp.Sci.Tech., 2008]

Sept 14, 2010 11

[Wicks et al., Comp.Sci.Tech., 2010]

[Wicks et al., Comp.Sci.Tech., 2010]

FFRP System Health MonitoringMultiplexing micro-switch

CNT-enhanced composite laminate

Positive electrode columns

Ground electrode rows

In-plane

Through-thickness

Sept 14, 2010 12

laminateGround electrode rows

• Patterned with Ag paint electrode grids

• Applied on impact damage• Significant electrical resistance changes to represent the damage locations[Wicks et al., AIAA, 2010]

Property Baseline FFRPEnhancement

by CNTCNT Vf[%]

Short beam shear strength [MPa] 20.1 33.8 x1.7 ~1-3

Mode I fracture toughness [kJ/m2]

Non-linear initiation 1.21 2.02 x1.7~1-2

Steady-state 2.12 3.74 x1.8

Measured Multi-functional Properties of FFRP

Sept 14, 2010 13

[kJ/m2] Steady-state 2.12 3.74 x1.8

Tension bearing [MPa]

Chord stiffness 226 246 x1.2~2.5Ultimate bearing

stress236 248 x1.1

DC electrical conductivity [S/mm]

In-plane ~10-7 ~ 10-1 x106~2.7

Through-thickness ~10-10 ~10-2 x108

Thermal conductivity [W/mK]

In-plane 0.42 0.75 x1.8~5

Through-thickness 0.58 0.94 x1.6

1.E-01

1.E+00

1.E+01

Specific Thermal Conductivity [(W/mK)/(kg/m3)]

Metals

A luminum

Steel

Copper

Ceramic

Compos

CFRP In-

CFRP Th

GFRP

Polymers

Polymer

Ceramics

MWNT individual

Carbon fiber (axial)

SWNT individual

Al

Specific thermal conductivity [(W/mK)/(kg/m

3 )]

CNT Scaling and Compositing Effects

MWNT bundles

MWNT in

SWNT bundles

SWNT in

Sept 14, 2010 14

1.E-05

1.E-04

1.E-03

1.E-02

1.E-24 1.E-21 1.E-18 1.E-15 1.E-12 1.E-09 1.E-06 1.E-03 1.E+00 1.E+03 1.E+06

Specific Electrical Conductivity [(S/m)/(kg/m3)]

Specific Thermal Conductivity [(W/mK)/(kg/m3)]

SWNT in

MWNT in

SWNT b

MWNT b

SWNT in

MWNT in

Baseline

FFRP TT

Alumina

Carbon

CF

Series23

Series24

Metals

Foams

Polymers Composites

GFRP

Alumina

FFRPBaseline

CFRP in-plane

CFRP through-thickness

Fe

Cu

Specific electrical conductivity [(S/m)/(kg/m3)]

Specific thermal conductivity [(W/mK)/(kg/m

MWNT in polymer

SWNT in polymer

Scaling Down to A-CNT-PNCs• Unknowns of transport in FFRPs

– Limiting factors in scaling: even with good CNT dispersion

– Difference between electrical and thermal transport behavior

– Keys to further improvement:

Aligned CNTs

Polymer

Sept 14, 2010 15

Axial

Transverse

alignment, morphology?

• A-CNT-PNCs as RVE– Simple: easy to model, fewer parameters/unknowns

– Controlled morphology: variable aligned CNT Vf and length

– Anisotropic: amplify inter-CNT effectsLikely with larger influence by inter-CNT transfers

Consistent data on samples with morphology control

Polymer matrix

Fabrication of A-CNT-PNCsAs grown on Si, ~1%Vf

As densified, up to ~20%Vf 20% CNT Vf

1 µµµµm5 mm

Sept 14, 2010 16

1 µµµµmSi substrate

Densified A-CNTs

5 mm

5 mm

As epoxy-infiltrated/cured, up to ~20%Vf

1 µµµµm

20% CNT Vf

Contributions and Future Work

• Conclusions– Aligned CNTs as 3rd phase (2nd fiber) provides concomitant mechanical, thermal, and electrical enhancement

– Limiting factors in thermal and electrical transport were identified and quantified through characterization of A-CNT-PNCs.

Sept 14, 2010 17

CNT-PNCs.

• Future Work– Composite processing: CNT growth on carbon fibers, infusion with aero-grade epoxy

– Further FFRP characterization: mechanical and thermoelectrical properties, focusing on anisotropy due to aligned-CNTs

Collaboration with- Prof. Gang Chen, Kimberlee Collins (MechE, MIT)- Prof. Carl Thompson, Robert Mitchell (DMSE, MIT)- Prof. Kenneth Goodson, Amy Marconnet, Matt Panzer (MechE, Stanford)Helpful discussions from- TELAMS laboratory and NECST team (Aero/Astro, MIT)Technical assistance from- John Kane (Aero/Astro, MIT) - Prof. Harry Tuller, WooChul Jung, George D. Whitfield (DMSE, MIT)

Thank you!

- Prof. Harry Tuller, WooChul Jung, George D. Whitfield (DMSE, MIT)- Dave Terry, Kurt Broderick (MTL, MIT)- Patrick Boisvert, Yin-lin Xie (CMSE, MIT) - Amy L. Tatem-Bannister (ISN, MIT)

Questions to namiko@mit.edu

This work was supported by Airbus S.A.S., Boeing, Embraer, Hexcel, Lockheed Martin, Saab AB, Spirit AeroSystems, Textron Inc., Composite Systems Technology, and TohoTenax through MIT’s Nano-Engineered Composite aerospace STructures (NECST) Consortium, and by the Linda and Richard (1958) Hardy Fellowship.