The raw material composition of fabrics is one of the most important factors for LOI value. LOI value was determined in samples of varying composition composed of cellulose, protein, and synthetic fibers and their mixtures, based on ASTM D 2863-76. Cellulose fibers and their mixtures exhibited the lowest value, while synthetic fibers had the highest LOI value

Ceric, B.

Jeler, S.

English

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NASA TECHNICAL MEMORANDUM NASA TM- 88483 
EFFECT OF THE R A W  MATERIAL COMPOSITION OF 4& 
9 FABRICS ON THE LIMITING OXYGEN INDEX (LOI) 
Jeler, S., Ceric, B. 
Translation of Vpliv surovinske sestave tkanin na limitni indeks kisika (LOI) 
IN: Tekstil, Vol. 29, No. 3, 1980, Yugoslavia, pp. 151-156 (UDC 677.16 : 677.61) 
I' 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASHINGTON, D.C. 20546 
iNASA-TM-88Ud3)  EE2'EC'I C P  'THE i i A k  M A T E 6 I A L  ~ a 7 - 1 4 4 ~ 3  
Space  Adf f i in i s t ra t ion)  I t ,  F C S C L  99E 
CCMEOSITICN C)E f A E h I C S  C M  TET:  L I M I T I N G  
O X Y G E N  TNDEX (LCI) ( N a t i o a a l  Aeronau t i c s  and 
Unc las  
G3/25 43647 
https://ntrs.nasa.gov/search.jsp?R=19870005030 2020-03-20T12:18:53+00:00Z
, 
1. R r o * r ~  Ha.  2- C.w*M*nt A c c a a a a o n  He. 
Leo Kanner Associates 
Redwood City, California 94063 
Translation of "Vpliv surovinske sestave tkanin na limitni 
indeks kisika (LOI)," Tekstil, Vol. 29, No. 3, 1980, pp. 151- 
National Aeronautics and Space Adminis- 
tration, Washington, D.C. 20546 
i ~ 
Translation 
The raw material composition of fabrics is one of the most 
important factors for LO1 value. LO1 value was determined ir 
samples of varying composition composed of cellulose, proteir 
and synthetic fibers and their mixtures, based on3STM D 
2863-76. Cellulose fibers and their mixtures eaibited the 
lowest value, while synthetic fibers had the highest LO1 
value. 
EFFECT OF THE RAW MATERIAL COMPOSITION OF FABRICS ON 
THE LIMITING OXYGEN INDEX (LOI) 
S. Jeler and B. eerie 
Technical Higher School, Maribor 
1. Introduction 
The Limiting Oxygen Index (LOI) is the minimum concentration of /151* 
oxygen in combination with nitrogen which a sample of fabric consumes 
at room temperature when burning for three minutes or a distance of 
50 mm. In the literature, various synonyms are used for the LOI: 
Critical Oxygen Index (COI) or just Oxygen Index (01). We shall ex- 
press the LO1 in accordance with ASTM D 2863-76 [2], using the formula 
n ( % )  = (0, ) . 100 
(02 + N2) 
where n is the LO1 expressed in percent, 
of oxygen (ml/sec) , and (N,) is the volumetric flow of nitrogen 
was the first standard in this area. Likewise, the International 
Standards Organization (1SO)defines LO1 [31, but instead of room tem- 
perature as the operating temperature, it prescribes execution at a 
temperature of 296,1522 K. The French standard T 51-071 [ 4 ]  likewise 
specifies the combustion time, but it differs from the ASTM standard, 
with the condition that the fabric sample burn a distance of 100 mm. 
Many authors use "temperature index", defined here as flammability or 
combustion, which is the temperature at which the LO1 value reaches 
20.8 [5]. 
(02) is the volumetric flow 
(ml/sec). ASTM D 2863-76 does not differ from ASTM D 2863-70, which 
2. Fabric Samples 
In order to carry out the investigation, we used samples of natu- 
ral and chemical raw materials and combinations of these. On an in- 
hiumbers in the margin indicate pagination in the foreign t e x t .  
1 
dustrial scale, the washing phases were among the favored phases stud- 
ied, while the thermoset phase was studied for the synthetic samples. 
In order to select the samples, we limited the density of the 
fabric to 140 g/cm2 and excluded the significance of the weave (here, 
we chose samples of various raw-material composition in a linear weave) 
We divided the samples available into three groups or series: 
1) a source of cellulose and cellulose mixtures 
2) a source of natural p-otein and protein mixtures 
3 )  a synthetic source and synthetic mixtures. 
Examples in the first series are designated in the tables by C1, 
C2, C3, etc., examples in the second series by B1, B2, B 3 ,  etc., and 
examples in the third series by S1, S2, S 3 ,  etc. 
With samples in mixtures, we first used two-component ones. The 
raw-material composition of the entire sample is given in the tables. 
Combinations such as cellulose and synthetic are presented in two 
tables, in the tables for the C and S series, and for this reason the 
identification is given as a note. 
For both groups, the effect of the second component was taken in- 
to consideration, the effect of the synthetic upon the C and S series 
in order for us to readily establish the contribution of the cellulose 
raw material present. 
3 .  Procedure /152 
We ignited the sample (set in a frame) continuously from above in 
an oxygen and nitrogen atmosphere, and we dteermined the minimum 
amount of oxygen needed for the sample to burn three minutes or to 
burn through a distance of 50 mm. The analysis was done at room tem- 
perature or at an optional temperature of up to 400OC. 
2 
4 .  Equipment 
We used a Stanton Redcroft apparatus to carry out the analysis, 
models FTA and HFTA. 
The FTA model is made up of three major parts: 
- a device to which steel piping for the oxygen and nitrogen gas e 
A 
are connected through a two-level reducing valve (inlt pressure 1.5-2.1 
bars) 
- a meter system for the oxygen, which analyzes the gas mixture 
and determines the oxygen concentration in it. A Servome oxygen 
analyzer [ 6 ]  was used for the analysis, which established changes in 
the magnetic field which makes the oxygen a paramagnetic gas 
310-mm-high glass cylinder with a diameter of 95 mm; the gas mixture 
passes through a porous bottom. 
- a test column with a holder for the sample. The column is a 
The HFTA model is a variety of the FTA model and serves to obtain 
the LO1 at high temperatures (up to 4OOOC). The model is made up of 
an automatic temperature regulator and a special column with a heater 
and heating connections. 
5. Performing the Analysis 
Execution of the analysis on the FTA model: We placed a holder 
with a sample (40 X 100 nun) in the test column, equalized the oxygen 
concentration, bled the mixture through the column for 30 sec at a 
flow rate of 451 cm/sec (at 750 bars and 273.15 K), and with a special 
lighter ignited the sample. The sample had to burn at least 3 min or 
burn through a length of 50 mm. We calculated the LO1 to scale. 
Execution on the HFTA model: The method of measurement was the 
same as with the FTA, but we heated the column and the preheating 
chamber for the gas mixture to room temperature. 
We determined each LO1 for tem samples along the warp and ten 
samples along the woof, if the raw-material composition of the warp 
was different from that of the woof. 
3 
6. Measurements and Analysis of the Measurement 
We carried out the measurements in accordance with the instruc- 
tions of ASTM D 2863-76. We used a flame (25 mm) from a propane-butane 
mixture [7] for ignition. ASTM D 2863-76 does not specify the time 
the samples are to be in contact with the flame (ignition time). Be- 
cause we determined the effect of the ignition time in the preliminary 
measurements, we carried out the measurements for 5 sec of contact with 
the flame [81. 
Because the moisture of the samples is not specified in the ASTM 
standard (although the standard was foreseen for determining LOI.for 
synthetic sheets, whose moisture content is independent of the surround- 
ings), we carried out the measurements on climatized samples (6552% rel. 
humid. at 20 C). The results of the measurments for the climatized 
samples are presented in the following tables. 
For samples whose warp and woof were of the same raw material com- 
position, we determined the LO1 on the warp. Experimentally determined 
differences between warp and woof were minimal. For samples whose raw 
material composition along the warp differed from that of the woof, we 
also measured the LO1 on the woof. 
TABLE 1. EFFECT OF CELLULOSE COMPONENTS IN-SAPlPLES ON LO1 
Sample Raw Material LO1 
Composition ( % )  warp woof 
c1 cotton 100 19;2 
c2 viscose 100 17.8 
c3 triacetate 
thread 100 18.6 
Remarks 
Weak flame, burns uniformly 
along width, sample smoulders 
Burns very uniformly along 
width 
Burns perpendicular to strips 
c4 PES 53 15.6 16.6 Burns uniformly, thick smoke 
c5 PAC 51 18.7 17.7 Burns uniformly, burns out in 
cotton 47 arises 
cotton 25 a dark cloud 
polinose 
thread 24 
PA 6 thread 
40 
C6 viscose 80 18.0 18.4 Burns perpendicular to strips 
/153 
4 
TABLE 1 (c0nt.d) 
Sample Raw Material LO1 Remarks 
Composition ( % )  warp woof 
c7 PES thread 
48 17.0 17.8 Burns uniformly, produces 
viscose 43 thick smoke 
silk 9 
C8 triacetate 17.1 
thread 67 
PA 6 thread 
33 
Burns very uniformly 
Notes: In C1, C2, C3, and C8, the raw-material composition of the warp 
and woof is the same, but it is different in the other samples. 
c4: warp PES 100% 
woof cotton 100% 
c5 : warp cotton 100% 
woof PAC 68% 
polinose 
thread 32% 
Analysis of Table 1 
C6 : warp viscose 100% 
woof PA 6 100% 
c7: warp PES 48% 
viscose 52% 
woof PES 48 
viscose 43 
silk 9 
The results of determining LO1 in climatized samples of cellu- 
lose origin and mixtures are presented in this table. The difference 
between the lowest and highest values is 3.6 (19.2-15.6). 
Of the samples with pure raw materials, 100% cotton has the high- 
est LO1 value (19.2), and the viscose sample has the lowest (17.8). 
The viscose sample is thus the most flammable. 
In the mixed samples, the effect of a second component is evident. 
The PES-cotton mixture (C4) has a much lower LO1 (15.6) than cotton 
along (19.2). The PES component makes the LO1 value smaller. 
In sample C5, 51% PAC is included with cotton and polinose thread. 
The LO1 value (18.7) is lower than the LO1 for cotton alone. With the 
addition of 4 0 %  PA 6 to viscose, LO1 increases by 0.2. The difference 
is small but unexpected, although practically all the mixtures have a 
lower LOI than the single components. Sample C7 is a three-component 
5 
mixture and has a lower LO1 than viscosee by itself. 
The mixture of triacetate and PA is more flammable than triacet- 
ate alone (18.6). 
All the samples in the C series have an LO1 under 20 and therefore 
are defined as flammable. All the mixtures in the table have a lower 
LO1 than components of cellulose origin. The LO1 for the woof (PAC/ 
polinose thread) of sample C5 has a lower value. The woof is more 
flammable or combustible than the warp, which is cotton alone. The 
LO1 of sample C7 is interesting, in having a higher value for the woof 
(17.8) than for the warp (17.0). The woof is a three-component mix- 
ture containing silk (9%). 
TABLE 2. EFFECT OF PROTEIN COMPONENTS IN SAMPLES ON LO1 
Sample Raw Material LO1 
Composition warp woof 
Remarks 
B1 wool 10 0 
B2 silk 100 
B3 PES 55 
wool 45 
B4 wool 92 
PA 8 thread 
8 
B5 wool 84 
PA 6 thread 
16 
48 
viscose 43 
silk 9 
B6 PES thread 
24.0 Burns perpendicular to strips 
27.0 Burns perpendicular to strips, 
produces soot 
20.1 Burns uniformly, produces thick, 
black smoke 
21.4 21.2 Burns perpendicular to strips, 
produces very rare smoke 
22.5 20.6 Burns uniformly 
17.0 17.8 Burns uniformly, produces thick 
smoke 
Notes: In B1, B2, and B 3 ,  the raw-material composition of warp and 
woof is the same: in the remaining samples, it is different. 
/I54 
B4: warp wool 85% 
PA 6 15% 
woof wool 100% 
B6: warp PES 48% 
viscose 52% 
woof viscose 4 3 %  
silk 9% 
B5 : warp PA 6 100% 
woof wool 100% 
6 
Analysis of Table 2 
Results and indicated interrelationships of climatized samples 
of natural protein origin and mixtures of the remaining synthetics 
polymers are included in this table. All the samples in the series 
except for B6 have higher LOI's than the samples in the preceding 
series, where cellulose samples were included in the mixtures. The 
difference between the lowest and highest values in the B series is 
from 17 to 24. 
With a single-component sample, wool and silk, LO1 decreases. 
Both samples have a higher LO1 than the samples in series B. Silk 
has the highest LOI, amounting to 27. which means that it is barely 
flammable. The LO1 is 24.0 for the woolen sample. 
All the mixtures have a lower LO1 than the single components do; 
55% PES component in a mixture with wool reduces the LO1 to 20.1. The 
mixture is more flammable than wool alone. 
In sample B4, 8% PA 6 is in the wool, but in B5, it is 16% PA 8. 
In the first example (8% PA), the LO1 decreases to 21.4, but in the 
second, it is reduced to 20.6. The reduction is not linear. The 
mixture with more PA 6 is more flammable. 
The three-component sample has the lowest LO1 value in the series 
[17]. The protein component in the sample is only 9%. The PES compon- 
ent increases the rise in flammability, which is, as a result of the 
framework (viscose!), much more flammable. 
The LOI values along the woof are higher in several samples; in 
others, it is lower than along the warp. In B4, where the LO1 along 
the woof is lower, it is wool. The difference is minor. In B8, the 
protein fiber is in the woof and therefore the LO1 is higher than in 
the warp. 
7 
TABLE 3. EFFECT OF SYNTHETIC COMPONENTS IN SAMPLES ON LO1 
Sample Raw Material LO1 
Composition ( % )  warp woof Remarks 
s1 
s2 
s3 
s4 
s5 
S6 
s7 
S8 
s9 
s10 
s11 
s12 
Notes: 
PES thread 100 31.2 
PA 6 thread 
100 27.4 
Burns non-uniformly, drops 
melt and burn 
Burns very rapidly, drops melt 
PA 6.6 
thread 58 30.3 30.3 Sample twists up, melts, burns 
PA 6 42 without smoke 
PAC cut 
thread 100 17.1 Burns uniformly, melts in the 
form of beads 
PES cut 
thread 5 3  15.6 16.6 Burns uniformly, gives off 
cotton 47 black smoke 
PES cut 
thread 55 20.1 
wool 45 
Burns uniformly, gives off 
thick black smoke 
PES 48 17.0 17.8 Burns uniformly, gives off 
viscose 43 thick smoke 
silk 9 
viscose 60 18.0 18.4 Burns perpendicular to strips 
PA 6 40 
wool 92 21.4 21.2 Burns perpendicular to strips, 
PA 6 8 gives off rare smoke 
wool 84 22.5 20.6 Burns uniformly 
PA 6 16 
triacetate 
thread 67 17.1 
PA 6 33 
Burns uniformly 
PAC 51 18.7 17.7 Burns uniformly, burns out in 
cotton 25 the form of a net 
polinose 
thread 24 
In S1, S2, S4, S6, and S11, the raw material compositions of 
the warp and woof are the same; they are different in the rest. 
s3 warp PA 6 100% 
woof PA 6.6 100% 
S8 = C6 see Table 1 
S9 = B4 see Table 2 
n 
s5 = c*4 see Table 1 S10 = B5 see Table 2 
s12 = c5 see Table 1 S7 = C7 = B6 see Tables 1 and 2 
8 
Analys is  of Table 3 
I n  t h e  t a b l e ,  t h e  L O I ' s  are determined i n  accordance w i t h  ASTM D 
2863-76. The c l i m a t i z e d  samples ( a t  65+2% rel .  humid. and 20+2OC)  are 
s y n t h e t i c  polymers and mixtures  of s y n t h e t i c  w i th  n a t u r a l  and a r t i f i c i a l  
f i b e r s .  
I n  t h e  S series, LO1 a long  the  warp i s  from a l o w  of  15.6 t o  a /155 
h igh  of 3 0 . 3 .  The d i f f e r e n c e s  i s  14.7 i n  a l l .  The raw-material composi- 
t i o n  a f f e c t e d  t h e  d i f f e r e n t  LO1 va lues .  
PES, PA, and PAC were single-component samples. 
Sample S 3  had t h e  h i g h e s t  LO1 va lue ,  which w a s  3 0 . 3 .  PA 6 and 
PA 6 . 6  (58%) w e r e  i n  t h i s  mixture.  The nex t  h i g h e s t  va lue  w a s  f o r  PES 
a t  3 0 . 3 .  This  va lue  was ve ry  high and h ighe r  t han  t h e  d a t a  f o r  PES 
i n  t h e  l i t e r a t u r e .  LO1 w a s  27.1 f o r  PA 6 a lone ,  which i s  ve ry  h igh  
h e r e ,  and t h i s  sample is  very  flammable. The lowest LO1 va lue  of t h e  
s i n g l e  components w a s  PAC t h r e a d ,  which w a s  t h e  m o s t  flammable of a l l  
t h e  s y n t h e t i c  samples p re sen ted .  A l l  t h e  mixtures  have lower L O I ' s  
t han  do t h e  s i n g l e  components (except f o r  S 1 2 ) .  With a mix tu re  of  47% 
c o t t o n  w i t h  PES, LO1 i s  reduced to  15.6. This  i s  a ve ry  g r e a t  d i f f e r -  
ence.  The mixture  i s  much more flammable, due t o  t h e  e f f e c t  of frame- 
work! A mixture  of wool (45%) with PES a c t u a l l y  a l so  e f f e c t s  a reduc- 
t i o n  i n  LOI ,  b u t  n o t  t o  t h e  same degree  as does c o t t o n .  
Sample S7 has  t h e  lowest LO1 va lue  among t h e  mixtures .  A mixture  
wi th  r a w  material  of c e l l u l o s e  o r i g i n  has  a l o w e r  LO1 t h a n  a mix tu re  
of p r o t e i n  f i b e r s .  I n  sample S8 i n  which 6 0 %  viscose i s  mixed w i t h  
4 0 %  PA, LO1 i s  18.0,  which i s  much l o w e r  t han  f o r  PA i t s e l f .  I n  sam- 
p l e s  S9 and S10, t h e r e  
PA h a s  t h e  lower L O I .  
flammable, b u t  t h e  LO1 
The d i f f e r e n c e  between 
tr iacetate has  a g r e a t  
i s  8 t o  1 8 %  PA i n  wool. The sample w i t h  more 
Amix tu re  of t r i a c e t a t e  and PA i s  ve ry  r e a d i l y  
i s  1 7 . 1 ,  t h e  s i n g l e  lowest va lue  i n  t h e  series. 
PA a lone  and i n  a mixture  i s  c o n s i d e r a b l e ,  and 
e f f e c t  on t h i s .  
9 
Sample S12 is composed of three raw materials. The mixture has 
a higher LO1 than does PAC alone. 
LOI's here are in the same relationship as for cotton and PAC. 
The woof is as expected, but the 
7. Classification of Fabric Samples with Respect to LO1 
On the basis of the results and analyses of the contribution of 
the raw-material composition in the sample to the LOI, we classified 
the samples in all the series (C, B, and S )  in order, indicating an 
increase in the perpendicular direction in fire resistance or slight 
flammability or combustibility. 
TABLE 4 
Number Sample Raw Material Composition of Sample of Density 
Designation 60-140 g/m2 
1 
2 
3 & 4  
5 
6 
7 
8 
0 -  
10 
11 
12 
13 
14 
15 
16 
17 
c4, s5 
C7, S7, B6 
C8, S11, S4 
c2 
C6, S8 
c3 
c5, s12 
c1 
B3, S6 
B5, S10 
B4, S9 
B1 
B2 
s2 
s3 
s1 
8. Summary 
PES/cotton 
PES/viscose/silk 
triacetate/PA 6/PAC 
viscose 
viscose/PA 6 
triacetate 
PAC/cotton/polinose thread 
cotton 
PES/wool 
wool/PA 6 
wool/ PA 6 
wool 
silk 
PA 6 
PA 6.6/PA 6 
PES 
- The raw material composition of the fabric samples affects the 
LO1 . 
10 
- pure cellulose samples have a higher LO1 than do mixtures. 
- The LO1 is below 20 for cellulose samples and their mixtures, 
which means that they are readily flammable. 
- Mixtures with wool are more flammable than wool alone. 
- A large amount of PA in mixtures with wool causes a greater in- 
crease in flammability. 
- Synthetic samples have the highest LO1 values (PES, PA 6, and 
PA 6.6/PA 6) and therefore fall among the least flammable fibers. 
- Synthetic samples melt and twist up along the ignition path. 
- PAC mixed with synthetic samples: LO1 is below 20 and therefore 
PAC is determined to be readily flammable. 
- PES and PA 6 mixtures with cellulose or protein fibers have /156 
a lower LO1 value than synthetic-only samples. 
- PA mixtures with wool have a higher LO1 than do PA mixtures 
with cellulose. 
From the sample classification with respect to LOI, it follows that: 
Cellulose samples in a mixture are readily flammable; the LO1 
values are below 20. 
The LO1 for PAC is also below 20. 
Protein samples in mixtures are less flammable than cellulose 
samples. 
Mixtures of protein fibers with other fibers are more flammable 
than are protein components alone. 
Synthetic samples (PES, PA 6, PA 6.6/PA 6) are barely flammable. 
11 
The LO1 is highest among all the samples analyzed. 
12 
REFERENCES 
1. 
2. 
3. 
4. Afnor, T 51-071. 
5. Roberson, E.C . ,  Faserforsch. u. Textiltech. 27/12, 664 (1976). 
6. Taylor Servomex Limited, Sussex, England, "Instruction manual". 
7. 
8 .  eerie, B., Tekstil 27/10, 375 (1978). 
Jeler, A. and B. eerie, "LO1 and the flammability of textiles: 
ASTM D 2863-76, Measuring the minimum oxygen coneentration to 
IS0 TC 61, Plastics: determination od flammability of plastics 
experimental instruction," 1979. 
support the candle-like combustion of plastics. 
using the oxygen index method. 
- 
Jus, B., H2 134, "Condensed petroleum gases: Butane mixture program". 
- 
13 


Effect of the raw material composition of fabrics on the Limiting Oxygen Index (LOI)

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