The thermal response characteristics of fabric and fabric-foam assemblies are described. The various aspects of the ignition behavior of contemporary aircraft passenger seat upholstery fabric materials relative to fabric materials made from thermally stable polymers are evaluated. The role of the polymeric foam backing on the thermal response of the fabric-foam assembly is also ascertained. The optimum utilization of improved fire-resistant fabric and foam materials in the construction of aircraft passenger seats is suggested

Fewell, L. L.

Kourtides, D. A.

Moussa, A.

Tesoro, G. C.

English

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NASA Technical Memorandum 78617 i
i
Fire-Resistant Materials for Aircraft
Passenger Seat Construction
L. L. Fewell, G. C. Tesoro, A. Moussa,
and D. A. Kourtides
(NASA—TM-78617) FIRE —RESISTANT MATERIALS
FOR AIRCRAFT PASSENGER SEAT CONSTRUCTION
(NASA) 20 p HC A02/MF A01	 CSCL 11G
N80-13255
Unclas
G3/27 46236
November 1979
C^PS^PC,,^``^S
AVLCA
National Aeronautics and
Space Administration
'	 r
1
NASA Technical Memorandum 78617
Fire-Resistant Materials for Aircraft
Passenger Seat Construction
L. L. Fewell, Ames Research Center, Moffett Field, California
G. C. Tesoro
A. Moussa, Massachusetts Institute of Technology, Boston, Massachusetts
D. A. Kourtides, Ames Research Center, Moffett Field, California
r NAM
National Aeronautics and
Space Administration
Ames Research Center
Moffett Field, California 94035
FIRE-RESISTANT MATERIALS FOR AIRCRAFT PASSENGER SEAT CONSTRUCTION
L. L. Powell, G. C. Tesoro,* A. Moussa,* and D. A. Kourtides
Ames Research Center
SUM rI M
This study describes the thermal response characteristics of fabric and
fabric-foam assemblies. The various aspects of the ignition behavior of con-
temporary aircraft passenger seat upholstery fabric materials relative to
fabric materials made from thermally stable polymers are evaluated. The role
of the polymeric foam backing on the thermal response of the fabric-foam
assembly is also ascertained. The optimum utilization of improved fire-
resistant fabric and foam materials in the construction of aircraft passenger
seats is suggested.
INTRODUCTION
The evaluation and selection of fire-safe materials for the construction
of aircraft passenger seats is a difficult and complex problem. In a previous
study (ref. 1) basic selection criteria were established for evaluating candi-
date materials for improved seats. Those materials were evaluated on the
basis of FAA-airworthiness burn and smoke generation tests, colorfastness,
limiting oxygen index (LOI), and animal toxicity testing based on the animal's
response to the material's volatile products of decomposition. All materials
tested or evaluated in this study passed the FAR 25.853 burn and smoke tests
(ref. 1). The performance life and characteristics of the materials were also
ascertained, based on their physical, mechanical, and aesthetic properties.
Materials that had been proved to be fire resistive in our testing program
(ref. 1) generally had improved thermal responses to various thermal loads
corresponding to reasonable fire threats as they relate to in-flight fire
situations.
The variety of passenger carry-on items — such as newspapers, matches,
lighter fluid, and souvenirs (table 1) — represents a source of potentially
combustible materials whose introduction on-board a commercial passenger air-
craft would be difficult to control. The alternative is to increase the fire-
hardness or fire-resistivity of the nonmetallic materials used in the construc-
tion of aircraft passenger seats. Nonmetalliz materials, when categorized by
their fire-resistivity properties can be grouped into two classes: fire
retarded (FR) and thermally sable (TS).
*Department of Mechanical Engineering, Massachusetts Institute of Tech-
nology, Cambridge, Massachusetts.
r
}
^N
Fire-retardant treated materials have been and are currently being used
in the construction of aircraft passenger seats. Such contemporary components
as the polyurethane foam cushioning and upholstery fabrics have been treated
with fire-retardant chemicals. As a result of such treatments, fire-retardant
treated materials have varying degrees of resistance to ignition, burning
rates, and smoke production. Fire-retardant treated materials tend to propa-
gate a fire by flames once a sufficient thermal load, or flux, has been applied
and the burning process has begun. Such a burning process is accompanied
generally with an increase in the generation of smoke or toxic gas, or both,
due to the fact that the material ' s normal mode of thermal degradation has
been altered (ref. 2).
The development and utilization of thermally stable (TS) polymeric mate-
rials seems to be the desirable route to the solution of the problem of thermal
stability, smoke, and toxic gas generation. A considerable interest has
developed in recent years in fibers from thermally stable polymers for use in
upholstery fabrics. Thermally stable fabrics have been reviewed by several
investigators (refs. 3- 5); some of the fabrics have been manufactured on a
commercial scale. Fabric materials from such polymers as polyimide, aromatic
polyamide, phenolics, and Volybenzimidazoles (table 2) have had a considerable
effect on the material options available to aircraft seat manufacturers.
Polyimide fibers are promising as thermally stable polymers (ref. 6) that have
excellent mechanical properties (ref. 7). Polyamide-polyimide mixtures have
been blended with wool; they are commercially available in Europe. The future
commercial availability of polyimide fabrics is still uncertain. Aromatic
polyamides, on the other hand, are readily available commercially as Aramid.
The manufacture and properties of aromatic polyamides are described in refF:r-
ence 8. Polyamides have been modified to enhance their thermal stability and
other properties; these changes are reported in reference 9.
Phenolic fibers classed generically as "Novoloid" (personal communication
from R. Jackson, Celanese Research Company, to authors, 19 March 1975) are
commercially available, although in limited amounts. These phenolic fibers
are made by the familiar condensation polymerization of phenol and formalde-
hyde. Polybenzimidazole (PBI) fiber (produced by Celanese Research Company)
has excellent thermal stability and mechanical properties (ref. 10). A flight
suit made from this material affords the pilot maximum protection in a fire.
However, PBI is not yet available commercially.
In addition to fire resistivity and mechanical property requirements,
upholstery fabric materials for aircraft passenger seats must comply with
criteria such as appearance, weight range, wear life, and in-use performance.
Fabric performance properties and some minimal acceptable levels are summar-
ized in table 3. Properties related to the flammability level of fabric
materials (contemporary and advanced) are summarized in table 4.
The concept of the fire-blocking layer, or heat barrier, between foam
cushioning material and upholstery fabric is a design alternative for air-
craft seats; it could be used immediately to improve the fire safety of air-
craft passenger seats.
2
r
EXPERIHENTAL HETHOD
Using the apparatus shown in figure 1, samples were placed in a vertic
plane and subjected to an external point-source radiative heat flux. The
sample materials used in this study are described in table 1. The fabric
samples were pressed tightly against the foam samples (fig. 1) in order to
minimize or prevent fabric shrinkage, which would result in areas of foam
directly exposed to the radiant flux which would result in erroneous therms
responses. The actual sample area exposed to the radiant flux was 12.9 cm2.
The polyurethane foam was 10.20 cm thick; the neoprene foam was 5.08 cm thick.
All tests were conducted at ambient temperature (25° C and 67% relative
humidity). The heat flux was obtained by focusing radiation from a 500-W lamp
onto the fabric sample, using an ellipsoidal reflector (fig. 1). Such an
arrangement results in an axisymmetric radiant flux that decreases rapidly with
distance normal to the reflector axis (fig. 2). Heat flux measurements were
made by two methods: (1) a 1-cm-diameter heat sensor and (2) a 1-cm water-
cooled slug calorimeter. The results are reported as a function of the peak
heat fluxes, measured at the center of the heated region (radius - 0, fig. 2).
The samples were exposed to a heat flux range of 3 to 21 W/cm2 , as mea-
sured using a slug calorimeter at various heights and distan:es, The time at
which smoke was emitted or when there was ignition and melting was measured.
RESULTS AND DISCUSSION
When fabrics are exposed to a sufficient thermal load they exhibit several
observable changes, such as smoke evolution, melting, charring, and ignition.
The exposure times at which such changes occurred were measured under peak
heat fluxes in the range of 5 to 21 W/cm 2 , for wool-nylon, PBI, Kynol, and
cotton fabrics (figs. 3-5). The "no ignition" points (fig. 5) indicate that
ignition did not occur even after a lengthy exposure at that particular heat
flux. Quantitative comparisons of the thermal responses of the fabric sam-
ples tested are not possible because the samples varied in weight, construc-
tion, finish, weave, etc.; however, qualitative comparisons are sufficient to
identify differences that can be attributed to the fiber composition of the
materials. The exposure time required to produce observable thermophysi-
cal or thermally-induced chemical changes, such as smoke production, charring
or melting, and/or ignition decreases with increasing heat flux for all materi-
als tested (figs. 3-5). These materials were comparable in their behavior in
regard to smoking and charring-melting but their ignition behaviors varied
significantly. At high heat fluxes (>10 W/cm 2 ), cotton and wool-nylon fab-
rics ignite. Kynol and polybenzimidazole (PBI) do not exhibit ignition at
higher thermal fluxes due to an inherent thermal stability that derives from
their chemical structures (ref. 3). These results are consistent with results
obtained by other methods and by various investigators (ref. 3) in the evalua-
tion of the flammability characteristics of these materials.
Thermal responses of various fabric-foam combinations — wool-nylon, PBI,
and Kynol fabrics — are shown in figures 6-8. The figures show the exposure
3
r
times required, for the fabric alone and the fabric in combination with poly-
meric foam backing (polyurethane or modified neoprene foam), to produce smok-
ing, charring, melting, or ignition. The densities of the polyurethane and
modified neoprene foams were 0.86 kg/m 3 and 3.36 kg/m 3 , respectively.
The effect of the foam backing on the fabric exposure times that produced
smoke, charring, or melting was dependent on the magnitude of the imposed heat
flux (negligible above 10 W/cm2). At the higher thermal flux, large tempera-
ture gradients develop within the fabric-foam assembly. The fabric may smoke
and char or melt before the foam senses the imposed thermal flux and therefore
the influence of the foam on the thermal response of the fabric is negligible.
At low thermal flux, large temperature gradients do not develop in the fabric-
foam assembly, and the foam backing participates in the thermal response of
the assembly. Once the foam backing is involved, its effects on the response
of the fabric become somewhat unpredictable due to the complex thermal and
fluid mechanical interactions between these materials.
The effect of the foam cushion backing on ignition is shown in figures 7
and 8. The urethane-PBI and urethane-Kynol assemblies ignite at heat fluxes
at which Kynol or PBI will not ignite when tested individually. The neoprere-
PBI and neoprene-Kynol assemblies (figs. 7, 8) did not ignite. Ignition test
results for all fabric-foam combinations tested are shown in figure 9. The
results indicate that the neoprene-fabric assembly is less likely to ignite as
the result of a thermal load than a urethane-backed fabric. These qualitative
results demonstrate the importance of the polymeric foam cushioning material
in the overall thermal response of the fabric-foam combinations to an imposed
thermal load. Therefore, the foam is an important consideration in the selec-
tion of materials and designs for fire-resistant aircraft passenger seats.
4
REFERENCES
1. Fewell, L. L.; Trabold, E.; and Speith, H.: Fire Resistivity and Toxicity
Studies of Candidate Aircraft Passenger Seats. Journal of Fire and
Flammability, vol. 9, July 1978.
2. Parker, J. A.; Kourtides, D. A.; Fish, R. H.; and Gilwee, W. J., Jr.:.
Fire Dynamics of Modern Aircraft from a Materials Point of View.
Journal of Fire and Flammability, vol. 6, 1975, pp. 534-553.
3. Van Krevelen, D. W.: Properties of Polymers — Their Estimation and Cor-
relation with Chemical Structure. Elsevier Scientific Pub. Co.,
Amsterdam, 1976, pp. 459-465.
4. Black, B.; Preston, J.; and Hofferbert, W. L., Jr.: High Modulus Wholly
Aromatic Fibers, Parts I and II. Journal of Macromolecular Science,
vol. A7, 1973, pp. 45-98.
5. Economy, J.; Wohrer, L. C.; Frechette, F. J.; and Lei, G. Y.: Oxidative
Stability of Phenolic Fibers. Applied Polymer Symposia, No. 21,
Interscience, New York, 1973, pp. 81-88.
6. Mark, H.; Atlas, S.; and Cernia, J.: Man-made Fibers. Vol. 2, Inter-
science, New York, 1968, p. 365.
7. Polyimide Fibres: A Progress Reporc. Upjohn Co., Modern Textiles,
vol. 55, no. 8, Aug. 1974, pp. 37-38.
8. Mark, H.; Atlas, S.; and Cernia, J.: Man-Made Fibers. Vol. 2, Inter-
science, New York, 1968, V. 297.
9. Hirsch, S. S.; and Holsten, J. T.: Enhancement of Aromatec Polyamide
Thermostability by Heat Treatment in Air. Applied Polymer Symposia,
no. 9, 1969, pp. 187-194.
10. Fewell, L. L.; Kourtides, D.; Rosser, R.; and Parker, J.; Eds.: Confer-
ence on the Development of Fire-Resistant Aircraft Passenger Seats.
NASA TM X-73,144, 1976.
11. Coskren, R. J.: Flame Resistant and Nonflammable Textile Fibers. SAMPE
Quarterly, vol. 4, July 1973, pp. 13-19.
5
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TABLE 3.- PERFOILMANCE REQUIREMENTS OF FABRIC MATERIALS
Property
mile strength
r strength
asion resistance (atoll flax)
ensional stability (dry cleaning)
or fastness
(to light, crocking, perspiration)
ability and seam strength
inability
me resistance (FAR 25.853(b))
Minimum acceptable val
31.8 kg
0.9 kg
1,000 cycles
22 shrinkage
Must page
Good
Good
Must pass
TABLE 4.- PROPERTIES RELATED TO FIRE HAZARD — QUALITATIVE ASSESSMENT
Cotton Polyester Nomex Kynol PBI
Ingition in air 
Calrod temp °C <550 --- 871 788 927
Time, sec Inst. 1 --- 6
Flame impingement
Heat flux-protection Nil (Melt) Good Good Good
Char yield Low (Melt) High, High, High,
characteristics --- --- friable strong strong
Smoke Moderate Low Moderate Low Low
Off-gases (toxicity) --- --- Toxic CO2/H2O CO2/H2O
predom. predom.
Thermal stability
Temp. degradation, °C --- --- 437 --- 590-680
Approx. wt. loss 900° C, X --- --- 60 40 30
Oxygen index, % 0 2 1 16-18 20-21 27-29 29-30 38-43
aFrom reference 11.
'8
IB cm
ABRI
IANSITE
(1) THREE 0.145 cm THREADED RODS AND NUTS
(2) ELLIPSOIDAL REFLECTOR No. 4085•A, RESEARCH INC.,
MINNEAPOLIS, MINNESOTA
(3) QUARTZ LIGHT BULB, 500 W, GENERAL ELECTRIC
No. O500CIJDC
(4) BULB SOCKET
(5) TRANSITE SPACER
(e) 0.317 cm ALUMINUM PLATE
Figure 1.- Schematic diagram of experimental apparatus.
9
18
1Q
PEAK FLUX,14 
'	 W/cm2
O 18.3
12
	
	
O 105
A 4.9
.1
110
X 1
8UJ
	
	 `
.
6
4
bk%%bo ^W*ft
o	 1	 2	 3	 A.,	 5	 a
RADIUS FROM SPOT CENTER, cm
Figure 2.- Imposed heat flux as function of radius from center.
•1
10
1 
W 8
H
4
2
n
12
10
O KYNOL
O COTTON
i (120 SW	 a Pal
v	 • WOOL/NYLON
k
V
1
0 2 4 8 8 -10 12 14 16 18 20 22
FLUX, W/cm2
Figure 3.- Time to smoke vs imposed heat flux.
11
1
4 4
32 (120 1	 (228
sec)
	
sec)
28
24
20
16
f-
12
8
4
A PBI, CHAR
O KYNOL, CHAR
O WOOL/NYLON, MELT
• COTTON, BURN THROUGH
2	 4 6
	 8 10 12 14 16 18 20 22
FLUX, W/cm2
Figure 4.- Time to char, burn through, or melt vs heat flux.
12
.,w
-	 -	 r
L	 -
O COTTON
• WOOL/NYLON
O KYNOL
A PBI
NO
IGNITION
i	 •1
1
11	 `^
10
8
ui 6
~ 4
2
0 4 6 8 10 12 14 16 18 20 22
FLUX, W/cm2
Figure 5.- Ignition times for fabric materials.
13
l	 ,
A NO BACKING
O WOOL/NYLON/URETHANE
O WOOL/NYLON/NEOPRENE
	
NO	 NO IGNITIONIGNITION
30
25
MELT
	
20	 O(IGNITION)
ui
^ 15
H
	10	 g11GNITION)
SMOKE •
5
	
0 '	 I	 1	 1	 1	 1	 1	 V	 1 v+ 1
	
4	 6	 8	 10 12	 14 16 18	 20 22
FLUX, W/cm2
Figure 6.- Times to smoke, melt, or ignition for wool /nylon.
14
1
A NO BACKING
O PSI/URETHANE
O PBI/NEOPRENE
NO	 NO IGNITION
IGNITION
120	 O (IGNITION)
NOTE	 O(IGNITION)SCALE
CHANGE 70
40	 CHAR
20
ui
is —
SMOKE
5
4	 6	 8	 10 12 14 16	 18 20 22
FLUX, W/cm2
Figure 7.- Times to smoke, char, or ignition for PBI.
a
15
A
r
i
.j
i
A NO BACKING
O KYNOL/URETHANE
O KYNOL/NEOPRENE
i
NO
IGNITION
300
200
20
W
H 15
10
5
0
4
w	 w	 /a
IGNITION
(NOTE SCALE CHANGE)
CHAR
SMOKE
6	 8 10	 12	 14 16 18 20 22
FLUX, W/cm2
Figure 8.- Times to smoke, char, or ignition for Kynol.
16
NO
IGNITIO
30
21
2e
21
w
16
1i
8
A
r
A
i
k
f
p PBI/URETHANEr	
A PBI/NEOPRENE
O KYNOL/URETHANE
n KYNOL/NEOPRENE
r	 O WOOL/NYLON/URETHANE	 ^x
r	 ♦ WOOL/NYLON/NEOPRENE
O COTTON/URETHANE
• COTTON/NEOPRENE
^4	 6	 8 10 12 14 16 18 20 22
FLUX, W/Cm2
Figure 9.- Ignition times for fabric-foam assemblies.
17
r
1. Report No, 2. Government Accession No. 3.	 Recipient's Catalog No.
NASA TM-78617
4. Title and Subtitle S. Report Date
FIRE-RESISTANT MATERIALS FOR AIRCRAFT PASSENGER
6. Performing Organization CodeSEAT CONSTRUCTION
7. Authors) 8. Performing Organization Report No.
L. L. Fewell,* G. C. Tesoro,t A. Moussa,t and
D. A. Kourtides* A-794 610. Work Unit No.
505-08-21-02-009. Performing Organization Name and Address
*Ames Research Center, NASA, Moffett Field, CA 94035 11. Contract or Grant No.
tMassachusetts Institute of Technology
Boston, MA 02139 13. Type of Report and Period Covered
Technical Memorandum
12. Sponsoring Agency Name and Address
National Aeronautics and Space Administration 14, Sponsoring Agency Code
Washington, D.C. 20546
15. Supplementary Notes
16. Abstract
This study describes the thermal response characteristics of fabric
and fabric-foam assemblies.
	 The various aspects of the ignition behavior
of contemporary aircraft passenger seat upholstery fabric materials rela-
tive to fabric materials made from thermally stable polymers are evaluated.
The role of the polymeric foam backing on the thermal response of the
fabric-foam assembly is also ascertained. 	 The optimum utilization of
improved fire-resistant fabric and foam materials in the construction of
aircraft passenger seats is suggested.
17. Key Words (Suggested by Author(s)) 18. Distribution Statement
Thermal response, Foam Unlimited
Fire resistant, Aircraft
Polymer, Passenger seat
Fabric, Materials S'rAR Category - 27
19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22.	 Rice'
Unclassified Unclassified 19 $4.00
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Fire-resistant materials for aircraft passenger seat construction

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