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FLAMMABILITY STANDARDIZATION TASK GROUP UPDATE: Adhesives

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. Objectives.

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FLAMMABILITY STANDARDIZATION TASK GROUP UPDATE: Adhesives

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  1. 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

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

  3. Approach FSTG 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.

  4. 3 companies participated in the study: Magnolia 3M Gulfstream 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. Materials

  5. Specimens for VBB Testing 5 X 0.5 x 0.5 inches 12 X 3 x 0.25 inches …Other?

  6. FAA Microscale Combustion Calorimeter ASTM D 7309 Oxygen Inlet Scrubber Flow Meter Combustor O2 Sensor Mixing Section Exhaust Sample Cup Pyrolyzer Purge Gas Inlet Sample Post & Thermocouple

  7. MCC Reproduces Elements of Flaming Combustion in Controlled Test Gases analyzed for residual oxygen to compute heat release rate Combustion O2 Pyrolysis N2 3-5 mg Sample Flaming Combustion Microscale Combustion

  8. 500 400 300 200 100 0 5 Thermal Combustion Properties Measured in MCC Test HRC  = Pyrolysis residue (char + inert filler) at 850C Heat Release Rate (J/g-K) Hc,heat of combustion Tonset Tmax 250 300 350 400 450 500 550 800 850 Temperature (°C)

  9. Reproducibility of HRR for Samples from Different Sources Is Excellent Adhesive Filler Low density filler 120 500 140 100 80 300 60 40 100 20 0 0 200 400 600 100 300 500 700 160 320 480 640 800 HRR (W/g) vs. Temperature (C ) Same Sample has Pass & Fail VBB rating

  10. Heat Release Rate (HRR) of Combustible Solids Surface heat loss by reradiation Heat flux from attached flame External heat flux Hc= Heat of combustion of fuel gases Hg = Heat required to generate fuel gases = HR/(1-)  = Pyrolysis residue (g/g)

  11. Flame Spread Criterion for Combustible Solids 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 Tonset = thermal degradation temp. T0 = room temp. C = heat capacity Hg= C (Tonset - T0 ) + hvaporization  2C (Tonset - T0 ) Condition for flame spread is:

  12. Quantifying MCC Properties as Predictors of Pass/Fail VBB Results Npass = Number of passing results Nfail = Number of failing results N = Npass + Nfail = 25 NFP = Number of False Positives = Number failing results within range of passing results for ranked data NFP False Positive Rate (%) = x 100 N - NFP

  13. 100 200 300 400 500 600 MCC Criteria for Radiant Panel Test of A/C Electrical Wires 40 Flame Spread Criterion (2-D) (J. Reinhardt, FAA, FTWG, 2009) 30 FAIL Hc, kJ/g-gas 20 PASS 10 0 5% False Positives Tonset, C FAIL Flame Spread Criterion (1-D) PASS 5% False Positives 10 3 30 100 300 Hc/(Tonset-T0)

  14. 30 30 25 25 20 20 15 15 10 10 5 5 0 0 200 250 300 350 400 200 250 300 350 400 2-D Criterion Not as Good for VBB of Adhesives 12s VBB 60s VBB FAIL FAIL PASS PASS Hc, KJ/g-gas 32% False Positives 14% False Positives Tonset, C Tonset, C

  15. 0 100 200 300 400 500 VBB versus Heat Release Capacity False Positives PASS 39% 12s VBB FAIL PASS 60s VBB 67% FAIL HRC, J/g-K

  16. VBB versus Temperature at Max HRR (Tmax) False Positives PASS 39% 12s VBB FAIL PASS 60s VBB 67% FAIL 250 300 350 400 450 T max, C

  17. 40 50 60 70 80 90 100 110 VBB versus Combustion Ratio, R R = Hc/(Tonset - T0) False Positives PASS 32% 12s VBB FAIL PASS 56% 60s VBB FAIL Combustion Ratio, J/g-K

  18. 5 10 15 20 25 30 35 40 45 VBB versus Pyrolysis Residue (Char Yield) False Positives PASS 39% 12s VBB FAIL PASS 60s VBB 32% FAIL Pyrolysis Residue (Char Yield), %

  19. 5 10 15 20 25 30 VBB versus Heat of Combustion of Volatiles, Hc False Positives PASS 9% 12s VBB FAIL PASS 9% 60s VBB FAIL Heat of Combustion of Volatiles Hc (kJ/g-gas)

  20. 5 10 15 20 25 30 VBB versus Total Heat Release False Positives PASS 9% 12s VBB FAIL PASS 9% 60s VBB FAIL Total Heat Release (kJ/g-sample)

  21. Conclusions Microscale 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.

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