CNT Composites for High Performance 

Structural Applications: Development, 

Measurement, and Scale-up

Larry Carlson

Director of Advanced Materials

Easton Institute for Technology Advancement

UCLA

LCarlson@ITA.UCLA.edu 818 970-5532

NIST – The New Steel

Feb 28 - Mar 1, 2011
Talk Outline

1. Development: Mechanical needs, 

dispersion, functionalization

2. Measurement: Direct and indirect 

methods, testing, characterization

3. Scale-up: Value chain, materials to 

finished product 
Mechanical Needs- Sporting 

Goods, Aerospace

 Strength

◦ Dent, bending, shear, compression, impact

 Toughness 

◦ Durability, safe failure mode, external flaw trauma

 Consistency 

◦ Enhances player performance

◦ Maximum performance that always meets industry 

limits

 Environmental

◦ Corrosion, sun, chemicals, “the hot trunk”
Nanotech Technology Landscape

 The Good: Very Strong and light

◦ CNTs have awesome strength – 20x to 100x that of 

steel ... and that’s conservative

◦ 1/6 the weight of steel

 The Bad: Severe technical challenges

◦ Consistency – variable quality, hard to detect

◦ Volume of supply – able to meet demand 

◦ Tendency to agglomerate – dispersion issues

◦ Bond strength – how to bond without destroying

 The Ugly: Problems can kill you

◦ Poor quality CNTs or dispersion can lower strength

◦ Health and safety – reality, unknowns
Development Approach

 Identify an Industry partner for strategic needs

◦ CNT sourcing – volume, quality, measurement

◦ CNT dispersion – at various stages

◦ Supply arrangement

 Focus the R&D effort

◦ Maximize material properties; loading curve

◦ Define the envelope, for allowable variation 

◦ Focus on elevating minimum properties

◦ Develop effective analysis tools

 Leverage the results over wide product base

◦ Establish designs that exploit the advantage

◦ Maintain/ observe quality limits – materials, 

processes
Shear processes for CNT dispersion

(a) Parallel –

Statistical treatment 

 High-shear rotor/ stator

 Ultrasonic bath

 Sonication probe

 Shakers

(b) Serial – All elements 

see shear field

 3-Roll Milling

 Microfluidic high pressure labyrinth

0.2 m 10 nm 10 nm

0.2 m

(a)

(b)

(c) (d)

0.2 m 10 nm 10 nm

0.2 m

(a)

(b)

(c) (d) You can have too 

much...
CNT in Epoxy Resin: Bad Vs. Good Dispersion

Bad dispersion 

Good dispersion 

Island of MWNT

In Epoxy Resin (very 

stiff)

Well 

dispersed/Distributed 

MWNT

In Epoxy Resin

Nothing but Resin 

(not stiff)

Good dispersion – Fracture 

surface showing CNT pullout
Fracture – CNTs span and stop 

cracks
Premix Method – Substantial toughness gains

0

100

200

300

400

50

100

150

200 Yield stress 

UTS 

Toughness 

Strength (MPa)

Toughness (MJ/m

3

)

 CNT wt. %

0 0.5 1

0

70

140

210

280

350

0 0.2 0.4 0.6 0.8 1 1.2

E828 - 1% CNTs

E828 -.5% CNTs

E828 - 0% CNTs

 (MPa)



Loading curve: MWNT in 

E828 at 0%, .5%, 1%
Composite view – CNT and carbon fiber

CNT fortifies resin 

areas, provides 

shear bridging

Functionalization 

provides 

attachment to CF, 

alignment and 

pullout under strain
Measurement

Direct: Hegman gage – Particle size progression 

SEM Evaluation – scale feature size

Strand test – scale diameter ratio

Laser measurement

Indirect: Tensile or Short beam shear

Miniature Disk Bending Test
The Technical Reality of Nano

Strength and Toughness Range

Researchers 

report these 

values

The product is 

as good as this 

value

Put another way: 

If there is one bad flaw in every million nanotubes...

There are 30 in a kg-size object
UCLA proprietary

Miniaturized Disk-Bend Test (MDBT)

Schematic diagrams of the 

MDBT: (a) The entire fixture; 

(b) Close-up view illustrating 

the specimen and the 

important geometric 

parameters.

P is the applied load, n is Poisson’s ratio, t is the

specimen thickness and a, b, and R are the radii of the

lower die, the loading ring, and the specimen

respectively.

1) Slices are cut from resin samples

cured in glass tubes

2) 3 mm disks are punched out,

and ground to a thickness of

250-500 m using 600 carbide

paper.

3) Both sides of the disks are

polished to a mirror finish ,

then tested.
•Stress-strain curves are

plotted to the same scale on

both of the samples for each

resin. The thickness of each

sample (in m) is indicated

by the numbers in parenthesis.

•Ultimate and yield

strength are noted; Slope of

elastic region gives a

measure of modulus.

UCLA, January 28th 2009 0

50

100

150

200

250

300

350

400

0 2 4 6 8 10 12

Resin 1 (303) Resin 1 (272)

 (MPa)



0

50

100

150

200

250

300

350

400

0 2 4 6 8 10 12

Resin 2 (323) Resin 2 (386)

 (MPa)



0

50

100

150

200

250

300

350

400

0 2 4 6 8 10 12

Resin 4 (335) Resin 4 (328)

 (MPa)



•Curves are integrated to

the point of 10% drop from

the peak, to give a measure

of mechanical toughness

Miniaturized Disk-Bend Test (MDBT)
Materials Testing

Product 

Testing

Materials 

Testing

G1C Measurement

Beam and Charpy 

Impact

Short Beam Shear
Product Testing

Composite wheel static 

and fatigue testing

Composite hockey 

boot fatigue and 

wear

Handle bar fatigue
Bat Cannon –Repetitive impact at 110, 120, 

130 mph Standard Bats

0

500

1000

1500

2000

2500

3000

3500

SP-3CA5338SP-3CA5342SP-3CA5340SP-3CA5334SP-3CA5333SP-3CA5341

Cannon Hits

130 mph

120 mph

110 mph

CNT 1% all plies

0

500

1000

1500

2000

2500

3000

3500

SP-3RDA5362SP-3RDA5360SP-3RDA5357SP-3RDA5371SP-3RDA5358SP-3RDA5369

Cannon Hits

130 mph

120 mph

110 mph

Product Testing
Scale Up: Lab CNT Material 

Development Linked to 

Production

Laboratory Prepreg 

operation, Van Nuys, CA

Production Prepreg

Guangdong, China
Disperse – CNT production set to control length, 

straightness, end closure, catalyst control and removal.

Disperse – CNT supplier separates prior to 

providing functionalization; controlled bond opening by acid 

treatment, plasma, etc; or VDW polymer treatment. 

Disperse – Resin formulation. 

Chemical bonding to resin or other constituents. Pot time is 

known by aging study. Solvent additions are limited by 

formulation tolerance. 

CNT Scale up 101:
Sample CNT Composites’ Value Chain

Carbon

Nanotube

Supplier

SWNT

DWNT

MWNT

Zyvex

Additives

Processed

Nanotubes

Enhanced

Materials

Epoxy

Prepreg, 

VARTM 

infusion

Finished

Goods

Baseball Bats

Softball Bats

Bike 

Accessories

Hockey Sticks

Easton puts 

additive into 

composite 

matrix

Easton design, 

testing, 

manufacturing

Zyvex 

functionalizes

with KenteraTM

Functionalization 

technology

Binding to CNT

Covalent Epoxy 

Bond
Thanks for 

Listening.

Larry Carlson, UCLA LCarlson@ITA.UCLA.edu

818 970-5532