Carbon Fibers and Lignocellulosics

Clive Liu, Huibin Chang, Satish Kumar

School of Materials Science and Engineering

Georgia Institute of Technology

Atlanta, GA 30332-0295

Email: satish.kumar@gatech.edu

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IPST Executive Conference

March 13, 2014

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Carbon Fibers

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• Carbon fiber research began ~1960. Initially carbon fibers were made from

cellulose.

• Carbon fibers are also made from petroleum pitch. From pitch, carbon

fibers with tensile modulus (stiffness) >90% of the theoretical modulus, and

high electrical and thermal conductivity can be made. However, pitch based

carbon fibers have low compressive strength.

• Currently, carbon fibers are predominantly made from poly(acrylonitrile)

co-polymer. PAN was first made ~1950.

• Tensile strength of initial carbon fibers made in 1960s was

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PAN based Carbon Fiber Processing

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• Poly(acrylonitrile) (PAN) is polymerized from acrylonitrile. Acrylonitrile is

a product of the petroleum industry. Therefore its price fluctuates with

the price of oil.

• PAN polymer is extruded into fiber form from solution.

• PAN fiber is oxidized in air typically between 200 to 300 ºC, and the

oxidation time can be between 1 to 2 hours.

• Oxidized fiber is then carbonized to a temperature of 1400 – 1500 ºC.

This is the carbon fiber used in most structural applications today.

• Carbonized fiber can be graphitized to 2500 – 2800 ºC for specialized

applications.

• Applications in aerospace and defense systems began in 1980s and in

large scale civilian structures ~2010 (e.g. Boeing 787).

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Carbon Fibers

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Diameter: 5 µm

Tensile strength: 3.1 N/tex (5.6 GPa)

Tensile modulus: 155 N/tex (280 GPa)

Diameter: 1 nm

Tensile strength: 20 – 67 N/tex

(45 – 150 GPa)

Tensile modulus: 467 N/tex

(1060 GPa)

Science, 273, 483 (1996)

PAN based carbon fiber Carbon Nanotubes

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Solvent resistance

PAN fiber in the left vial dissolved

while PAN/CNT fiber containing 1

wt% CNT did not dissolve even

after 30 days

40 ºC increase in Tan δ peak

temperature at 10 wt% CNT

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Interphase – Comparison between

composite and nanocomposite

For creating interphase, a nano material can be 25000 times more effective than a

conventional reinforcement such as carbon fiber.

Carbon Nanotubes act as a template for polymer orientation and nucleating agent

for polymer crystallization.

Interphase

Bulk polymer

Carbon

fiber CNT

Diameter 5 µm 1 nm

Interphase

layer thickness 5 nm 5 nm

Interphase/filler

volume ratio 0.004/1 99/1

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PAN/Carbon Nanotube Fibers

PAN PAN/SWNT (99/1)

Stabilized

Carbonized

7 HG Chae, ML Minus, A Rasheed, S Kumar, Polymer, 48(13), 3781 (2007). 7

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Fiber spinning system

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Fiber drawing system

Unwinding stand Drawing stands

Water rinse

stand

Drying

stand

Take-up

winder

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Continuous carbonization line

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PAN and PAN/CNT precursor fibers manufactured

at Georgia Tech

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Carbon fiber processed at Georgia Tech

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Carbon Fibers: Current Challenges

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After nearly 50 years of development, carbon fiber technology now appears

mature

Both cost and performance appears to have reached a plateau.

Performance:

• Tensile strength is about 5% of the theoretical value

• Tensile modulus of the high strength fiber is about 26% of the theoretical

value

Cost: Energy (1/3) + infrastructure (1/3) + material (1/3)

Density: Density of current high strength commercial carbon fibers is about

1.76 g/cc. Recently carbon fibers with density of about 1.2 g/cc have been

demonstrated. Scale up of this fiber is expected to require significant effort.

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PAN/Lignin/MWNT

Composite Carbon Fiber

March 13th 2014

Hsiang-Hao (Clive) Liu

Adviser: Dr. Satish Kumar

hliu322@gatech.edu

School of Materials Science and Engineering

Institute of Paper Science and Technology

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Why Lignin?

• Abundant renewable resource:

– Lignin is the second most available biomacromolecule on

earth – Second only to cellulose.

• Low cost:

– Lignin is mostly regarded as the by-product of the paper

manufacturing industry.

• Department of Energy Targets:

– Goal: $5/lb

– Strength: 1.75 GPa

– Modulus: 175 GPa

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Precursor Spinning/Drawing

Solid Content Ratio

(PAN/Lignin/CNT) Spin DR x Cold DR x Hot DR

PAN/Lignin

(PL) 70/30/0 1 x 1.8 x 7.5 = 13.5

PAN/Lignin/CNT

(PLC) 70/30/3 1 x 2 x 6.75 = 13.5

PLC composite fiber

PL composite fiber

Precursor spinning/drawing conditions

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From precursor to carbon fiber

• Oxidative Stabilization Trial

– Stabilization of precursor fibers with

constant heating rate in temperature

range between 250 ºC and 320 ºC with

residence time from 150 minutes to 450

minutes.

• Carbonization

– Stabilized fibers purged with nitrogen

for 40 minutes before heating.

– Constant heating rate to temperature

ranging from 1000 ºC to 1200 ºC. Stabilization/Carbonization Setup

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Carbon Fiber Composition Diameter

(µm)

Tensile Strength

(MPa)

Tensile

Modulus (GPa)

Elongation

at break

(%)

Reference

Stream Explosion Lignin (Hydrogenlysis)

7.6±2.7 660 40.7 1.63 (Sudo et al., 1992)

Stream Explosion Lignin (Phenilysis)

- 394 - 1.2 (Sudo et al., 1993)

Acetesolv Lignin - 355 39.1 0.98 (Uraki et al., 1995)

Alcell Lignin 31±3 388 40 1.00 (Kadla et al., 2002)

Hardwood Kraft Lignin 46±8 422 40 1.12 (Kadla et al., 2002, 2005)

Softwood Kraft Lignin (with Hardwood lignin permeate)

36±3 370 33 1.2 (Nordström et al., 2012)

“Modified Technical

(Hardwood) Lignin” 10 – 15.8 1070 82.7 2.03 (Warren, 2012 ORNL Review)

Zoltek

PAN/Lignin (65/35) - 1682 201 0.76 (Zoltek,2012)

PAN/Lignin* This work

PAN/Lignin/CNT* This work

Comparison of Lignin and PAN/Lignin Carbon

Fiber properties

*Batch carbonization

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Conclusions

• Successful production of the PAN/Lignin and

PAN/Lignin/CNT carbon fibers.

Future works

• Partially replace PAN with lignin in composite fibers.

• Continuous process of carbonization.

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Carbon Fibers from

Polyacrylonitrile(PAN) and

Cellulose Nanocrystals (CNC)

Huibin Chang

Advisor: Dr. Satish Kumar

hbchang@gatech.edu

School of Materials Science and Engineering

Institute of Paper Science and Technology

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Why Cellulose Nanocrystals (CNC)?

Moon, Robert J., et al. Chemical Society Reviews 40.7 (2011): 3941-3994.

The most abundant renewable polymer

in the biosphere

PAN CNC

Tensile strength (GPa) ~1 7.5-7.7

Elastic modulus in axial

direction (GPa) ~20 110-220

Crystallinity (%) 40-65 54–88

Objective: Polyacrylonitrile (PAN)/Cellulose nanocrystals (CNCs) composite fibers will be gel

spun using dimethyl formamide (DMF) as the

solvent. 21

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Solution preparation and spinning PAN/CNC fibers

1. CNCs were dispersed in DMF (dimethyl formamide)

2. PAN was separately dissolved in DMF

3. CNC/DMF solution was added into the PAN/DMF solution

4. Excess solvent was evaporated

5. PAN/CNC/DMF solutions were spun into precursor fiber

(Solid Content Ratio: CNC/PAN = 1/99)

6. Control PAN solution was also prepared and spun into

precursor fiber

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Conclusions

• The tensile strength, modulus and elongation at

break of PAN/CNC fibers at highest draw ratio are

increased by 20%, 9% and 16%, respectively

when 1wt% CNC is added into the PAN matrix.

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Future Work

• Characterize the thermal and dynamic mechanical

properties

• Stabilize and carbonize fibers

• Characterize the mechanical and structural

properties of carbonized fibers

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Functional Fibers, Paper, and Materials

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Current staff and students

– Dr. Han Gi Chae – Senior Research Engineer

– Dr. Kishor Gupta – Research Scientist II

– Dr. Yaodong Liu – Research Scientist II

– Dr. Prabhakar Gulgunje – Research Engineer II

– Dr. M. G. Kamath – Research Engineer II

– Dr. Sushanta Ghoshal – Postdoctoral Fellow

– Dr. Vijay Raghavan – Postdoctoral Fellow

– Dr. Chandrani Pramanik – Postdoctoral Fellow

– Dr. Ashok Singh – Postdoctoral Fellow

– An-Ting Chien – Graduate Student

– Brad Newcomb – Graduate Student

– Clive Liu – Graduate Student – IPST Fellow

– Amir Davijani – Graduate Student

– Po-Hsiang Wang – Graduate Student

– Huibin Chang – Graduate Student – IPST Fellow

• DARPA

• AFOSR

• IPST

• ONR

• NSF

• NIST

• AFRL

• Boeing

• Rice University

• UIUC

• G. P. Peterson, B. Feng

• CNI, Unidym, CCNI

• Applied Sciences Inc

• Collaborators and former group members

Current and past support and

collaborations

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