Federal AviationAdministration

FLAMMABILITY STANDARDIZATION

TASK GROUP UPDATE: Adhesives

Presented to: Materials Fire Test Working Group

Natallia Safronava, SRA International

Richard E. Lyon, FAA

March 3, 2010, Seattle, WA

Fire Test Working Group Meeting

Seattle, WA, March 3-4, 20102Federal Aviation

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ObjectivesObjectivesObjectives

Determine correlation between Microscale Combustion Calorimetry (MCC) properties and FAR flammability tests for stand-alone

adhesives.

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Seattle, WA, March 3-4, 20103Federal Aviation

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ApproachApproachApproachFSTG members provide cured adhesive specimens and FAR vertical Bunsen burner (VBB) test reults:

• 12 Second VBB

• 60 Second VBB

Conduct microscale combustion calorimeter (MCC) testing ASTM D 7309 at FAA on adhesives submitted by FSTG members.

Correlate MCC flammability properties with FAR flammability (12s and 60s VBB) of adhesives.

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Seattle, WA, March 3-4, 20104Federal Aviation

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3 companies participated in the study: Magnolia3MGulfstream

27 samples total were received for testing. 3 specimens with the same name were received from different suppliers.

25 samples came with results for 12s and 60s Vertical burn test from the supplying companies.

MaterialsMaterialsMaterials

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Specimens for VBB TestingSpecimens for Specimens for VBB VBB TestingTesting

5 X 0.5 x 0.5 inches

12 X 3 x 0.25 inches …Other?

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Seattle, WA, March 3-4, 20106Federal Aviation

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FAA Microscale Combustion Calorimeter ASTM D 7309FAA Microscale Combustion Calorimeter ASTM D 7309FAA Microscale Combustion Calorimeter ASTM D 7309

Combustor

Pyrolyzer

Mixing Section

Sample Cup

Scrubber

Flow Meter

O2 Sensor

Exhaust

Purge Gas Inlet

Sample Post & Thermocouple

Oxygen Inlet

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Seattle, WA, March 3-4, 20107Federal Aviation

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3-5 mg

MCC Reproduces Elements of Flaming Combustion in Controlled Test

MCC MCC Reproduces Elements ofReproduces Elements of Flaming Flaming Combustion in Controlled TestCombustion in Controlled Test

Pyrolysis

Sample

Gases analyzed for residual oxygento compute heat release rate

O2

N2

Combustion

Flaming Combustion

MicroscaleCombustion

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Seattle, WA, March 3-4, 20108Federal Aviation

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250 300 350 400 450 500 550

0

100

200

300

400

500H

eat

Rel

ease

Rat

e (J

/g-K

)HRC

Hc,heat of combustion

Tmax

Temperature (°C)

μ = Pyrolysis residue(char + inert filler) at 850°C

800 850

Tonset

5 Thermal Combustion Properties Measured in MCC Test

5 Thermal Combustion Properties 5 Thermal Combustion Properties Measured inMeasured in MCC MCC TestTest

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Seattle, WA, March 3-4, 20109Federal Aviation

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N ADHESIVE APPLICATION12sVBB

60sVBB

TonsetC

TmaxC

HRkJ/g

HckJ/ggss

HRCJ/g-K

R Char%

1 Low density filler P P 313 375 9 12.8 135 44 302 5 min epoxy P P 307 348 10.3 14.7 335 52 303 10 min epoxy P P 303 347 10.5 14.8 263 53 294 Adhesive P P 355 400 13.6 22.7 195 68 405 Epoxy Adhesive P P 300 336 12.5 18.9 235 69 346 Adhesive P P 300 337 14.2 19.8 490 72 297 Adhesive bonding P P 280 327 13.8 20 295 78 318 Adhesive P P 280 335 14.1 20.1 365 79 309 Epoxy Core Fill P P 311 375 17.6 23.5 220 80 25

10 Epoxy Core Fill P P 285 340 13.3 21.1 285 81 3711 Edge fill P P 270 300 15.8 20.8 228 84 2412 Epoxy Insert Adhesive P F 300 345 16.4 23.8 245 86 3113 Epoxy Adhesive P F 325 345 19.8 26.1 335 87 2414 Low density filler P P 285 364 16.2 23.1 205 88 3015 Edge fill P P 280 445 16.4 23.4 185 88 3016 Edge fill, adhesive P P 313 382 7 10 80 88 3017 Insert adhesive F F 320 379 21.2 26.2 320 88 1918 Panel inert adhesive F F 340 390 25.0 28.1 395 89 1119 Low density filler F F 280 313 16.2 23.1 181 91 3020 Adhesive P F 285 342 20 24.1 280 92 1721 Edge fill F F 275 311 18.0 23.1 310 92 2222 Adhesive F F 325 378 25.9 27.8 425 93 723 Adhesive F F 315 379 26.0 28.2 370 97 824 Epoxy Edge Fill P P 235 311 13.8 20.6 200 98 3325 Panel & Insert adhesive F F 300 394 22 28.9 200 101 24

Fire Test Working Group Meeting

Seattle, WA, March 3-4, 201010Federal Aviation

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20

60

100

140

100 300 500 700

Filler

0

40

80

120

160 320 480 640 800

Low density filler

0

100

300

500

200 400 600

Adhesive

HRR (W/g) vs. Temperature (°C ) Same Sample has Pass & Fail

VBB rating

Reproducibility of HRR for Samples from Different Sources Is Excellent

Reproducibility of HRR for Samples from Reproducibility of HRR for Samples from Different Sources Different Sources Is ExcellentIs Excellent

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Seattle, WA, March 3-4, 201011Federal Aviation

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Heat Release Rate (HRR) of Combustible SolidsHeat Release Rate (HRR) of Combustible SolidsHeat Release Rate (HRR) of Combustible Solids

HRR =Hc

Hg

( ′ ′ q ext + ′ ′ q flame − ′ ′ q rerad )

Hc = Heat of combustion of fuel gases

Hg = Heat required to generate fuel gases

External heat flux

Heat flux from attached flame

Surface heat loss by reradiation

μ = Pyrolysis residue (g/g) = HR/(1-μ)

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Seattle, WA, March 3-4, 201012Federal Aviation

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Flame Spread Criterion for Combustible SolidsFlame Spread Criterion for Combustible SolidsFlame Spread Criterion for Combustible Solids

Hc

Tonset −T0

≥2C HRR *

( ′ ′ q ext + ′ ′ q flame − ′ ′ q rerad )

Hg = C (Tonset - T0 ) + hvaporization

≈ 2C (Tonset - T0 )

• Assume critical heat release for flame spread (burning), HRR* ≈ 200 kW/m2 in radiant panel test.

• Assume heat required to generate gaseous fuel from solid is

• Condition for flame spread is:

Tonset = thermal degradation temp.

T0 = room temp.

C = heat capacity

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Seattle, WA, March 3-4, 201013Federal Aviation

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Quantifying MCC Properties as Predictors of Pass/Fail VBB Results

Quantifying MCC Properties as Predictors of Quantifying MCC Properties as Predictors of Pass/Fail VBB ResultsPass/Fail VBB Results

NFP = Number of False Positives

Npass = Number of passing results

Nfail = Number of failing results

N = Npass + Nfail = 25

False Positive Rate (%) =NFP

N - NFP

x 100

= Number failing results within range of passing results for ranked data

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Seattle, WA, March 3-4, 201014Federal Aviation

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Hc/(Tonset-T0)

PASS

FAIL

0

10

20

30

40

100 200 300 400 500 600Tonset, C

Hc,

kJ/

g-ga

s

PASS

FAIL

MCC Criteria for Radiant Panel Test of A/C Electrical WiresMCC Criteria for Radiant Panel Test of A/C Electrical WiresMCC Criteria for Radiant Panel Test of A/C Electrical Wires

Flame Spread Criterion (2-D)(J. Reinhardt, FAA,

FTWG, 2009)

Flame Spread Criterion (1-D)

10 1003 30 300

5% False Positives5% False Positives

5% False Positives5% False Positives

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Seattle, WA, March 3-4, 201015Federal Aviation

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0

5

10

15

20

25

30

200 250 300 350 400

12s VBB

cH

, KJ/

g-ga

s

Tonset, °C

PASS

FAIL

2-D Criterion Not as Good for VBB of Adhesives22--D Criterion Not as Good for VBB of AdhesivesD Criterion Not as Good for VBB of Adhesives

200 250 300 350 400

60s VBB

PASS

FAIL

Tonset, °C

0

5

10

15

20

25

30

14% False Positives14% False Positives32% False Positives32% False Positives

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0 100 200 300 400 500

HRC, J/g-K

VBB versus Heat Release CapacityVBB versus Heat Release CapacityVBB versus Heat Release Capacity

PASS

FAIL39%39%

False Positives

False Positives

PASS

FAIL 67%67%

12s VBB

60s VBB

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Seattle, WA, March 3-4, 201017Federal Aviation

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250 300 350 400 450

T max, °C

PASS

FAIL

60s VBB

PASS

FAIL12s VBB 39%39%

False Positives

False Positives

VBB versus Temperature at Max HRR (Tmax)

VBB versus Temperature at Max VBB versus Temperature at Max HRR (THRR (Tmaxmax))

67%67%

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40 50 60 70 80 90 100 110

PASS

FAIL60s VBB

Combustion Ratio, J/g-K

VBB versus Combustion Ratio, RR = Hc/(Tonset - T0)

VBB versus Combustion Ratio, RVBB versus Combustion Ratio, RR = R = HHcc/(T/(Tonsetonset -- TT00))

PASS

FAIL12s VBB 32%32%

False Positives

False Positives

56%56%

Fire Test Working Group Meeting

Seattle, WA, March 3-4, 201019Federal Aviation

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5 10 15 20 25 30 35 40 45

Pyrolysis Residue (Char Yield), %

VBB versus Pyrolysis Residue (Char Yield)

VBB VBB versusversus Pyrolysis Residue (Char Pyrolysis Residue (Char Yield)Yield)

PASS

FAIL12s VBB 39%39%

False Positives

False Positives

PASS

FAIL60s VBB 32%32%

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5 10 15 20 25 30

60s VBBPASS

FAIL

Heat of Combustion of Volatiles Hc (kJ/g-gas)

VBB versus Heat of Combustion of Volatiles, Hc

VBB VBB versus Heatversus Heat of Combustion of Combustion of Volatiles, Hof Volatiles, Hcc

12s VBB 9%9%

False Positives

False Positives

PASS

FAIL

9%9%

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5 10 15 20 25 30

Total Heat Release (kJ/g-sample)

VBB versus Total Heat ReleaseVBB VBB versus Total Heat Releaseversus Total Heat Release

12s VBB

60s VBB

9%9%

False Positives

False Positives

PASS

FAIL

PASS

FAIL9%9%

Fire Test Working Group Meeting

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ConclusionsConclusionsConclusionsMicroscale Combustion Calorimeter properties that are highly correlated (< 10% false positive) with 12s and 60s VBB results are:

• Total Heat Release of Sample (HR)

• Heat of Combustion of Fuel Gases (Hc)

More conservative choice of HR or Hc will eliminate false positives.

A limited number of samples (25 total, 22 different) were tested in this study.

Sample size was not controlled in the VBB test and is a source of variability in the P/F results.