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Dr. Amod Ogale

Dow Professor of Chemical Engineering

Director, Center for Adv. Eng. Fibers and Films

2013 Graffin Lecturer of American Carbon Society

Clemson University

ogale@clemson.edu

CARBON FIBERS FROM

MESOPHASE PITCH:

Processing and Properties

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Potential Applications

Ultra High Thermal Conductivity Composites

Ten years from now, chips will run at 30 GHz

and churn a trillion operations per sec.

Unfortunately, with today’s technology, that

would lead to chips putting out the same

amount of heat, proportionally, as a nuclear

power plant … Intel CTO Pat Gelsinger

Gen IV Nuclear Reactor: Structural materials needed to build

the advanced reactor; structural carbon-carbon composites

needed for High Temperature Internals (>1200°C) … Dr. Bill

Corwin, Natl Tech Director for Matls, ORNL

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BARRIERS TO HIGH VOLUME APPLICATIONS

• Current price of carbon fibers ranges from

~$1000/pound for high thermal conductivity carbon fibers to $15/lb for low modulus fibers.

• For electronic applications the cost of high thermal conductivity fibers must be reduced to $100/pound.

• Mesophase pitch precursors for carbon fibers with controllable molecular properties

• Process models for control and the optimization of molecular structure within fiber during processing for balance of properties

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Barriers

Carbon fibers made from mesophase pitch

• Excellent tensile modulus 800 GPa • Outstanding thermal conductivity 1100 W/m-K

• Moderate tensile strength (2000 MPa) • Poor compressive strength (700 MPa) and • Poor transverse properties (10 W/m.K)

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Topical Outline

• Molecular Structure • Flow Behavior and Processing

• Microstructure and Texture • Mechanical and Transport Properties

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Precursors: Mesophase Pitch

MW 500

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Mitsubishi AR-HP: Synthesized from Naphthalene using

BF3/HF catalysts

MALDI Analysis

Kundu,…

Ogale, Carbon,

2008

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MALDI Analysis

Petroleum Pitch-derived Experimental

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Molecular Structure: AR-HP Mesophase Pitch

5 10 15 20 25 30 35

0.00

0.02

0.04

0.06

0.08

0.10

0.12

steady-sheared at 1s-1

steady-sheared at 10s-1

as-spun fibers

graphitized fibers

au

2

normalized

intensity/4

Detector X-ray

gun

Rigaku 2-D diffractometer (Rigaku/ MSC) Cu-Kα 45

KV and 0.67 mA.

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Azimuthal Scans

0 20 40 60 80 100 120 140 160 180

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0.018

0.0020

0.0025

0.0030

0.0035

0.0040

0.0045

0.0050

0.0055

no

rmal

ized

azi

mu

thal

in

tesi

ty

, deg

Peak at 25°

Peak at 7°

Kundu, Naskar, Ogale, Anderson, Arnold, CARBON 2008

Azimuthal profiles of 25and 7 peaks display off-set by 90

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Liquid

crystalline

pitch

precursor

Pitch

precursor

fiber

Melt-

spinning

Stabilized

fiber

Oxidative

stabilization

200-300°C

1-24 h

Graphitization

2000-3000°C

inert atmosphere

Carbon fiber

Processing of Mesophase Pitch-Based Carbon Fibers

“Carbon-Carbon Materials and Composites”

NASA Reference Publication 1254, Buckely and Edie,

Eds. , 1992

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0.01 0.1 1 10 100

20

40

60

80

100

305°C

297°C

vis

co

sity

, P

a.s

strain

290°C

Transient Rheo-structural Evolution

• The local maximum in shear stress is a consequence of yielding of initial texture

300 mm

flow

direction

radial

direction

300 mm

flow direction

300 mm

flow direction

300 mm

Kundu, Grecov, Rey,

and Ogale, J.

Rheology, 2009

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Flow-Microstructure Relationship: Converging Section

• Vortex formation was observed in the contraction region.

• Vortex formation typically associated with viscoelasticity of the material.

• Dynamic rheology for this material indicated low elasticity2.

Kundu and Ogale, Rheologica Acta 2010

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Melt-Spinning

Single-shot batch extruder

12 capillary hole spinneret

Capillary diameter = 150 mm,

L/D = 5 Spinning temp ~ 200-220°C Winding speed ~ 100-600 m / min

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Ultra High Temperature Heat Treatment

Graphitization furnace:

2700C Ultrahigh temperature press:

10 Tons and 2100C

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Carbonization under tension

Tungsten weight

Fiber tows

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EM images of AR-MP carbon fiber

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SEM and TEM images of ARMP carbon fibers heat treated at (a) 2600, (b) 2100, (c)

1500, & (d) 1200C.

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Figure 1 Stress-strain response of AR-MP pitch based carbon fibers heat

treated at various temperatures

Carbon fibers: Stress-strain plots

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Carbon fibers

Diameter [mm]

Force [N]

Stress [GPa]

Apparent Modulus

[GPa]

Strain-to-Failure [%]

2600C 8.5 0.7 0.110.04 1.90.7 482.1 94.1 0.42 0.2

2100C 8.9 1.0 0.160.05 2.70.5 412.0 54.6 0.70 0.1

1500C 9.1 0.5 0.150.05 2.30.6 205.7 29.4 1.10 0.2

1200C 9.1 0.7 0.130.04 2.00.7 173.8 19.7 1.10 0.3

Table 1 Tensile properties of AR-MP fibers

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Electrical Conductivity

Precursor Diameter, mm Resistivity

m-m

K1100 12 1.4 0.2

P100 12 3.2 0.3

AR-HP based 13 3.5 0.6

T300 7 18.1 5.3

Terpolymer 17 31.7 11.1

Rayon-based 12 55.5 2.3

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Carbon fibers: electrical properties

Diameter [mm]

Area [m2]

R []

Electrical resistivity

[mm]

Predicted* Thermal

conductivity [W/mK]

2600C 9.0 1.1 7.1 10-11 475.5 138 3.2 0.6 466

2100C 9.3 0.8 6.9 10-11 1,200.3 266 8.0 1.2 120

1500C 9.3 0.5 7.2 10-11 1,356.2 228 9.6 1.2 66

1200C 9.6 0.7 7.3 10-11 1,524.0 313 10.9 1.8 31

Table 2 Electrical resistivities of AR-MP fibers

*Lavin-Issi Correlation

where k[W/mK] and r[mcm] 295

)258(

000,440-

rk

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HT at 2400C Diameter

[mm]

R

[]

ER

[mm]

Predicted

Thermal

conductivity

[W/mK]

thin fibers

AR 11.7 ± 0.8 541 ± 306 3.4 438

Ex2 9.8 ± 0.8 725 ± 265 4.4 338

Ex3 11.9 ± 0.7 316 ± 88 2.8 520

thick fibers

AR 16.0 ± 0.8 164 ± 27 2.8 521

Ex2 17.6 ± 1.3 180 ± 126 2.9 502

Ex3 15.9 ± 0.7 172 ± 26 2.3 603

ER properties of 2400 C HT fibers

Carbon fibers based on experimental mesophase pitch showed smaller ER (th

us higher thermal conductivity)

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DEFICIENCIES OF CURRENT CARBON FIBERS

Stresses created by high-temperature heat treatment causes splitting,

reducing the mechanical and thermal properties of the fibers.

(S. Kumar, SAMPE Qtr, 1989)

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Ongoing Clemson Studies …

Introduction of multi-walled nanotubes of high aspect ratio disrupts the otherwise highly ordered, radial structure of carbonized fiber derived from mesophase pitch

0% Nanotubes 0.1% Nanotubes 0.3% Nanotubes

Ogale, Edie, and Rao, 2006, US Patent 7,153,452

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Recoil Test: Large stress – compressive failure

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Fiber Properties: Mechanical

Fiber Type

Diameter

(μm)

Tensile Strength

(GPa)

Compressive Strength

(GPa)

Compressive/

Tensile

(%)

0% MWNTs in

MP

8.4 2.6 ± 0.4 0.77 ± 0.04 30

0.1% MWNTs in

MP

8.0 1.8 ± 0.5 0.94 ± 0.06 53

0.3% MWNTs in

MP

11.6 1.8 ± 0.3 1.13 ± 0.04 63

• Compressive strength as a ratio of tensile strength was improved for nanocomposite carbon fibers, suggesting a decrease in the anisotropic nature of the pitch-based carbon fiber

Ahn, Lee, Ogale, Park, Fibers and Polymers, 2006

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SEM images of the fractured cross section of (a) 0 wt% and (b) CB modified

carbon fibers. White boxes correspond to the positions at which the high

resolution images were obtained.

R. Alway-Cooper, D. P. Anderson, and A. A. Ogale, CARBON 2013

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Two theta x-ray diffraction spectra of milled 0 wt% and CB modified

experimental carbon fibers, as well as the highly graphitic, commercial

grade K1100 (a) from 25 to 29˚ and (b) from 75 to 90˚.

R. Alway-Cooper, D. P. Anderson, and A. A. Ogale, CARBON 2013

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• MWCNT and carbon black was shown to modify the structure of mesophase

pitch-based carbon fibers when added in dilute concentration of about 0.3

wt%. A decrease was observed in the number of fibers that exhibited “pac-

man” splitting.

• Despite the cross-sectional textural changes, no significant reduction was

observed in the d002 spacing or La indicating that the nano-modified carbon

fibers retained a high degree of graphitic crystallinity.

• These mesophase-pitch based carbon fibers showed a strong graphitic

development and excellent transport properties, which makes them suitable

for high electrical and thermal conductivity industrial applications

Conclusions

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PROs: MULTI-FUNCTIONALITY

Excellent Strength and Stiffness = high performance

Light-weight = fuel-efficient

Outstanding Electrical and thermal conductivity

Fire-retardant

Con: COST

• Expensive on per pound basis ($ 10 to $ 1800/lb)

Carbon Fibers: Next Steps …

Current research directions: alternative precursors and novel processing routes for

reducing costs (at current fiber properties) OR

improve properties (at current cost)

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Y-P. Jeon, R, Alway-Cooper, M. Morales, and A. A. Ogale*, “Carbon Fibers”, Chapter 2.8, pp. 143-54,

Handbook of Advanced Ceramics, 2nd Edition, Elsevier, Eds. S. Somiya and M. Kaneno, 2013.

R. Alway-Cooper, D. P. Anderson, and A. A. Ogale*, “Carbon Black Modification of Mesophase Pitch-

Based Carbon Fibers”, in press, Carbon available online 3 March 2013

R. Alway-Cooper, M. Theodore, D. P. Anderson, A. A. Ogale*, “Finite Element Modeling of Transient

Heat Flow in Unidirectional Fiber-Polymer Composites During a Laser Flash Analysis”, J. Composite

Materials, Published online before print September 4, 2012, doi: 10.1177/0021998312458130

Santanu Kundu, Dana Grecov, Amod A. Ogale*, and Alejandro D. Rey*, Shear flow induced

microstructure of a synthetic mesophase pitch, Journal of Rheology, 53(10), 85-113, 2009

Santanu Kundu, Amit K. Naskar, Amod A. Ogale*, David P. Anderson and Jonahira R. Arnold,

”Observations on a low-angle x-ray diffraction peak for AR-HP mesophase pitch”, Carbon, 46(8), 1166-

69, 2008

T. Cho, Y. S. Lee, R. Rao, A.M. Rao, D. D. Edie, and A. A. Ogale*, “Structure of carbon fiber obtained

from nanotube-reinforced mesophase pitch”, Carbon, 41(7), 1419-24, 2003

A. A. Ogale*, D. P. Anderson, C. Lin, and K. Kearns, “Orientation and dimensional changes in meophase

pitch-based carbon fibers”, Carbon, 40(8), 1309-19, 2002

References

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Acknowledgments

Collaborators: Dan Edie, Mark Thies, and Dave Anderson (UDRI/AFRL)

Graduate Students: Santanu Kundu, Becky Alway-Cooper

Post-Doctoral Research Associate: Dr. Sungho Lee, Dr. Young-pyo Jeon

Sponsors:

Department of Energy

Air Force Research Lab

Army Research Lab

National Science Foundation EEC-9731680

Various industrial members thru CAEFF

Center for Advanced Engineering

Fibers and Films (CAEFF)

CAEFF Mission: To provide an integrated research and education

environment for the study of high performance fibers, films, and

composites for applications ranging from military to medical uses

• A Graduated NSF-ERC that secured over $ 30 million from

NSF and other sponsors

• Interdisciplinary faculty team

• Served over 65 industrial members

Acknowledgments