ANALYSIS OF CARBON FIBER RECOVERED FROM OPTIMIZED

PROCESSES OF COMMERCIAL SCALE RECYCLING FACILITIESJoseph Heil, Davis Litzenberger, Dr. Jerry Cuomo

TMS 2011 San Diego, CaliforniaMarch 3, 2011

Institute for Maintenance Science and Technology

February 27-March 3, 2011 – San Diego, California

2

Outline

• Recycling Overview• Test Methods• Samples Tested• Test Results

• Electron Microscopy• Filament Testing

• Questions

February 27-March 3, 2011 – San Diego, California

3

Overview of CF Recycling

Uncured Trim ScrapCured Trim ScrapEnd of Life Material

Carbon Fiber Recycling

Single Blind Testing & Analysis

Samples of CF for Testing

February 27-March 3, 2011 – San Diego, California

4

Characterization MethodsMethod Information Determined

SEMScanning Electron Microscopy

Fiber diameter,contamination

Surface texture, defects

EDS Energy Dispersive Spectroscopy

Elemental composition of bulk

XPSX-Ray Photoelectron Spectroscopy

Atomic Percent %’s of Carbon Bonding

Tensile Test3 gauge lengths

Fiber Tensile Properties Failure Probability

February 27-March 3, 2011 – San Diego, California

5

Outline• Test Methods• Samples Tested• Test Results

• Electron Microscopy• Filament Testing

• Questions

February 27-March 3, 2011 – San Diego, California

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Outline• Test Methods• Mechanical Test Results from 2006 - 2008• Samples Tested• Test Results

• Electron Microscopy• Filament Testing

• Questions

February 27-March 3, 2011 – San Diego, California

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Samples Tested

Sample Name SourceRCF 10 Uncured T300 prepreg Fabric

V-T300 Sized Cytec T300 sample from Boeing

RCF 11 Uncured T700G prepreg fabric

V-T700G Sized sample from Boeing

*RCF 12, 13 Uncured prepreg fabric

RCF 14, 15, 16 T-800s prepreg left, center, & right side of furnace

VCF 17, 18, 19 Soxhlet extraction of prepregs “14-16”

V-T800s Sized sample from Boeing

RCF-recycled carbon fiber VCF- virgin carbon fiber

*RCFs 12 & 13 are standard modulus fibers but their morphologies after recycling left them unidentifiable.

February 27-March 3, 2011 – San Diego, California

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Outline• Test Methods• Samples Tested• Test Results

• Electron Microscopy• Filament Testing

• Questions

February 27-March 3, 2011 – San Diego, California

9

T300 Prepreg Fabric

• Striations clearly present• Fiber appears coated

February 27-March 3, 2011 – San Diego, California

10

T700G Prepreg Fabric

RCF 11 V-T700G

• No pitting observed• Changes in shade of fiber suggests thin coating of resin

February 27-March 3, 2011 – San Diego, California

11

RCF 12 & 13

• RCF 12 & 13 have surfaces that have been heavily damaged• Not identifiable based on morphology or tensile properties

RCF 12 RCF 13

February 27-March 3, 2011 – San Diego, California

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T800s Prepreg Left Side of Furnace

• RCF 14 has residual matrix material; size is usually <500nm• On occasion pits were seen suggesting fiber damage• Silicon in residual material

VCF 17RCF 14

February 27-March 3, 2011 – San Diego, California

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T800s Prepreg Center of Furnace

• RCF 15 is comparatively densely covered with char • EDS indicated silicon, aluminum, sodium, and chlorine • No pitting or otherwise noticeable defects

RCF 15 VCF 18

February 27-March 3, 2011 – San Diego, California

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T800s Prepreg Right Side of Furnace

• RCF 16 has large amounts of resins stuck in-between the fibers with a lesser amount stuck on the fibers

• Some particulates >500nm • Surface appears textured• Calcium was identified in particulate based on EDS

RCF 16 VCF 19

February 27-March 3, 2011 – San Diego, California

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Outline• Test Methods• Samples Tested• Test Results

• Electron Microscopy• Filament Testing

• Questions

February 27-March 3, 2011 – San Diego, California

16

Standard Modulus Fiber Tensile Strength

RCF10 RCF11 RCF12 RCF13 VT3000

500

1000

1500

2000

2500

3000

3500 3,371

2,494

1,144 1,258

2,960

2,405 2,535

1,217 1,256

2,841

6mm25mm

Tens

ile S

treg

nth

(Mpa

)

T300 T700G

• RCFs 10 & 11 compare favorable to virgin T300 fiber• Tensile testing confirms damage to RCF 12 & RCF 13

February 27-March 3, 2011 – San Diego, California

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T800s Fiber Tensile Strength

• 30-50% fiber strength retention vs. ~70% from previous work

RCF14 RCF15 RCF16 VCF17 VCF18 VCF190

1000

2000

3000

4000

5000

6000

2,398 2,498

1,774

5,6986,020

5,124

1,635

2,621 2,490

5,0204,593 4,418

6mm

25mm

Te

ns

ile

Str

en

gth

(M

Pa

)

February 27-March 3, 2011 – San Diego, California

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Standard Modulus Fiber Elastic Modulus

RCF10 RCF11 RCF12 RCF13 VT3000

50

100

150

200

250

195184

160

186181

209 213198

235

182

6mm25mm

Ela

sti

c M

od

ulu

s (

GP

a)

T300 T700G•Stiffness comparable to virgin fiber

February 27-March 3, 2011 – San Diego, California

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T800s Fiber Elastic Modulus

• Loss in stiffness not seen in previous work• Stiffer than virgin standard modulus

RCF14 RCF15 RCF16 VCF17 VCF18 VCF190

50

100

150

200

250

300

350

231

172

205

254234 224

245 238 241

299 284 2836mm

25mm

Ela

sti

c M

od

ulu

s (

GP

a)

February 27-March 3, 2011 – San Diego, California

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Summary• Recycled T300 is coated with residual resin but is strong

• Recycled T700G is clean & has high strength retention

• RCFs 12 & 13 have severe oxidative damage

• SEM observations of pitting in IM fibers does not correlate well to trends in tensile strength

• Variation in fiber properties based on location in furnace for IM fibers

•Recycled carbon fibers have high retention of their elastic modulus•Lower tensile strength retention than in previous years

February 27-March 3, 2011 – San Diego, California

21

Acknowledgments• Funded by Boeing as part of the Composites

Recycling Project; Pete George, Bill Carberry• Jerry Cuomo & Davis Litzenberger• Chuck Mooney, NCSU AIF• TMS

February 27-March 3, 2011 – San Diego, California

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T700G Prepreg Fabric

RCF 11

V-T700G

February 27-March 3, 2011 – San Diego, California

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T800s Prepreg Left Side of Furnace

RCF 14 RCF 14(pitted area)

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T800s Prepreg Center of Furnace

VCF 18RCF 15

February 27-March 3, 2011 – San Diego, California

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T800s Prepreg Right Side of Furnace

RCF 16 VCF 19

February 27-March 3, 2011 – San Diego, California

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Atomic Percentages

RCF11 V-T300 RCF14 VCF17 RCF15 VCF18 RCF16 VCF19 V-T800s0

10

20

30

40

50

60

70

80

90

100

84

7075

58

84 8186

82

71

11

27

17

38

1217

1116

29

C O

Ato

mic

Pe

rce

nta

ge

(%

)

• RCF 14 & VCF 17 low carbon content• Oxygen content reasonable

February 27-March 3, 2011 – San Diego, California

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Atomic Percentages

• Nitrogen from pyrolysis or captured onto active surface

• Na & Si in trace amounts• No N, Na, or Si seen on V-T800s

RCF11 V-T300 RCF14 VCF17 RCF15 VCF18 RCF16 VCF190.00

1.00

2.00

3.00

4.00

5.00

6.00

N Na SiA

tom

ic P

erc

en

tag

e (

%)

February 27-March 3, 2011 – San Diego, California

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Review of 2008 T800s Tensile Strength

ENEA/ Karborek Lab cured trim scrap

ENEA/ Karborek pi-lot cured trim scrap

Virgin T800s Milled Carbon Uncured trim

scrap

Milled Carbon cured trim scrap

0

1000

2000

3000

4000

5000

6000

5134

4654

4053

6mm

30mm

60mm

Te

ns

ile S

tre

ng

th (

MP

a)

February 27-March 3, 2011 – San Diego, California

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Review of 2008T800s Elastic Modulus

ENEA/ Karborek Lab cured trim

scrap

ENEA/ Karborek pilot cured trim

scrap

Virgin T800s Milled Carbon Uncured trim

scrap

Milled Carbon cured trim scrap

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

252 257263

6mm

30mm

60mm

Yo

un

gs

Mo

du

lus

(G

Pa

)

February 27-March 3, 2011 – San Diego, California

Review of T300/AS4Tensile Strength

30

T300 AS4

Virign T300 T3-MC-UTS 0

500

1000

1500

2000

2500

3000

3500

4000

2875

24662698

20752376

1896

20mm50mm100mm

Fiber

Tens

ile S

tren

gth

(Mpa

)

Virigin AS4 A-MC-EOL A-MC(O)-EOL 0

500

1000

1500

2000

2500

3000

3500

4000 4001

2953

4148

3619

2732

36913401

2464

3143

5mm10mm20mm

Tens

ile S

tren

gth

(Mpa

)

•Favorable strength retention at shorter gauge lengths

Source material: uncured trim scrap recovered by RCF, Ltd

Source material: EOL scrap recovered by RCF, Ltd

February 27-March 3, 2011 – San Diego, California

Review of T300/AS4Elastic Modulus

31

•Fibers remain stiff after recycling

Source material: EOL scrapSource material: uncured trim scrap

T300 AS4

Virign T300 T3-MC-UTS 0

50

100

150

200

250

182

203209 217

193

216

20mm

50mm

100mm

Tens

ile M

odul

us (G

Pa)

Virigin AS4 A-MC-EOL A-MC(O)-EOL

0

50

100

150

200

250

201

165

211

230211

231

257

228224

5mm10mm20mm

Ten

sile M

od

ulu

s

Source material: uncured trim scrap recovered by RCF, Ltd

Source material: EOL scrap recovered by RCF, Ltd