Toxicity of decomposition products: polyacrylonitrile, nylon 6 and ABS

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Toxicity of decomposition products: polyacrylonitrile, nylon 6 and ABS

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TOXICITY

OF

DECOMPOSITION PRODUCTS

-

POLYACRYLONITRILE, NYLON 6

AND

ABS

K.

Sumi and Y . Tsuchiya

A decomposition method for o b t a i n i n g quantitative data of combustion and pyrolysis products of various materials has been developed and r e p o r t e d i n an e a r l i e r paper.' T h r e e more materials, polyacrylonitrile, nylon 6 _and_ABS _{[acrylonitrile-butadiene-}

styrene), w e r e decomposed u s i n g t h a t method a v e r a w i d e range of experimental conditions and the main t o x i c p r o d u c t s [HCN, CO _and

GOZ) were quantitatively analyzed. The t o x i c i t y o f t h e three were

assessed using t h e fire t o x i c i t y concept2 (originally called t o x i c i t y i n d e x concept).

MATE RIALS

Specimens were made of (1) polyacrylanitrile y a m , (2) chopped ABS p i p e , and (3) chopped nylon 6 r e s i n .

THERMAL

DECOMPOSITION

The experimental setup for the decomposition o f t h e t h r e e materials was as described ear1ier.l Samples were decomposed in a h o r i z o n t a l q u a r t z tube through which air, n i t r o g e n , or a m i x t u r e of t h e s e gases, was m e t e r e d . The sample w e i g h t was 800 mg, gas

flow was I R min-1 and the furnace t u b e was maintained at ternpera- tures ranging from 400 to 800

"C.

Hydrogen cyanide was collected in a l i q u i d t r a p c o n t a i n i n g 0.4 p e r cent NaOH and a n a l y z e d u s i n g

a s p e c i f i c i o n e l e c t r o d e

f o r

cyanide i o n . HCN analysis was

checked w i t h a modified L i e b i g method to ensure that t h e determin- a t i o n was correct. An alternate method of a n a l y s i s i s pasticu- l a r l y u s e f u l to ascertain the absence o f i n t e r f e r e n c e from other decomposition p r o d u c t s . The gaseous sample was collected i n a p l a s t i c bag and analyzed for CO and COZ using gas chromatography.

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RESULTS

AND

DISCUSSION

Quantitative data on the decomposition products of palyacry- lonitrile, nylon 6 and ABS at v a r i o u s temperatures are presented

in T a b l e s l A , 0 and C . The ACN y i e l d increased with temperature f o r a l l three m a t e r i a l s . Experiments with d i f f e r e n t atmospheres i n d i c a t e d t h a t HCN y i e l d w a s h i g h e s t f o r a mixture containing 50

p e r cent air and 50 per c e n t nitrogen. The C 0 2 results may be Power than those actually produced

in

the experiments because of .

absorption of some of this gas in the

NaOH

t r a p .

Separate experi- ments were n o t conducted to correct t h i s discrepancy because the c o n t r i b u t i o n of C02 t o t h e t o t a l t o x i c i t y is

not

s i g n i f i c a n t .

The

quantitative r e s u l t s

for

CO,

CQ2

and HCN reported

in

Tables l A , B a n d C were used to assess t o x i c i t y from the equation

where T = t o x i c i t y f a c t o r

v

=

experimentally determined volume (at S . T . P . ) of a decompos i t i a n product

cf = concentration o f t h e same compound t h a t i s f a t a l [or dangerous) to man in 30 minutes

W = weight o f sample.

The d e r i v a t i o n o f t h e e q u a t i o n w a s reported e a r l i e r . '

C

T

o f

a material is t h e sum of t o x i c i t y factass from the decomposition

products of t h a t material.

The t o x i c i t y factors are reported in litres p e r g . , and were obtained by using cf = 4 x 10-3 (i .em, 4000 ppm) for C Q ~ ,

85 x 10-3

for

C O and ~ ~0 .I35 x 10-3 for

HCN'.

The t o x i c i t y data presented i n Tables 2A, B and C v i v i d l y

illustrate t h a t the t o x i c i t y of the decomposition products was primarily due t o HCN. The a d d i t i o n a l effect o f

CO

a n d C02 was

very small. The t o x i c i t y of t h e mixtures due to HCN, CQ and CQZ

o n l y were determined in t h i s s t u d y . O t h e r t o x i c components tnay be

present in sufficient amounts t o appreciably increase t h e f i r e t o x i c i t y

of

the materials. F o r example, the authors conducted a detailed study on t h e decomposition products o f polyacrylonitrile and determined

HCN

and s i x t e e n o t h e r nitriles6. It w a s n o t

possible to assess the c o n t r i b u t i o n of these n i t r i l e s to she fire t o x i c i t y of polyacrylonitrile because of lack of data on cf of these compounds.

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The maximum C T o b t a i n e d from experimental r e s u l t s f o r

various

mazerials i s useful in a s s e s s i n g the t o x i c gas-producing p o t e n t i a l of m a t e r i a l s . These data f o r t h e three materials used in the present study are presented

in

Table 3 along with e a r l i e r results on w h i t e pine

and

PVC,

CONCLUSIONS

1. The maximum E T o f the t h r e e materials used in t h i s study

w a s :

Polyacrylonitrtle 1210

Nylon 6 ₉₅₀

ABS 280

2. The t o x i c i t y

o f

decomposition products of polyacrylonitrile, nylon 6 _and_ABS_{was primarily}_due _{t o}

_HCN.

ACKNOWLEDGEMENT

The authors wish t o thank D,W. Morwick f o r his assistance in

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REFERENCES

Sumi,

K.

a n d T s u c h i y a , Y . T o x i c i t y o f D e c o m p o s i t i o n P m d u c t s - Polyvinyl C h l o r i d e and Wood. Building Research Note No. 9 9 , Division of B u i l d i n g Research, National Research Counci 1 of Canada, 3 p . [May 1975).

Sumi,

K.

and Tsuchiya, Y . Assessment o f R e l a t i v e T o x i c i t y of b t e r i a l s

-

Toxicity Index. To b e presented a t _the_{I n t e r -}

n a t i o n a l Symposium on T o x i c i t y and Physiology of Combus t i o n P r o d u c t s , U n i v e r s i t y of Utah, March 22-26, 1976.

ASm D2036-74. Standard Methods

of

T e s t f o r Cyanides in Water. Henderson, Y.

and

Haggard, H.W. Noxious Gases and the

P r i n c i p l e s of Respi~ation Influencing t h e i r Action. Chem. Catalog Co., New York, 212 p . (1927).

Documentation o f the Threshold L i m i t Values. American

Conference o f Governmental Industrial Hygienists, Cincinnati, 223 p . (1971)

.

Tsuchiya, Y. and Sumi,

K.

Thermal Decomposition products

of

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TABLE I A

DECOMPOSITION

PRODUCTS

OF POLYACRYLONITRILE

3 - 1

Gas flow rate = 1000 crn _min

Sample w e i g h t = 800 mg. Atmosphere Air t 1 I t t I I t t l 11 l I 11 1 I 50%

N2,

50% A i r t l Temperature O

C

4013 400 500 500 600 600 700 70 0 800 80 0 800 8130

Ni

t ro _gen 1 1 trace 11 0.004 0.004 0 . 0 3 8 8 00 800

-

trace ?I 0.002 0.003 0 . 2 1 7 0.162 0.162

-

0.19 0 -020 0.020 0.050 0.051 0 . 0 8 4 0.043 , 0,042 0.045 0 . 0 3 6 0.032 0.49 ; 0 -49 0 . 3 9 0 -39 0 - 2 8 0.085 0.110 0.107 0 . 1 3 1 0.132 0.194 0.197 0.221 0.246 0.251 0.230 0.241 0 . 2 3 0.15 0.14 <O .01 0 -0.6 0.12 0.13 0.036 0 . 0 3 8 0 . 0 6 2 0.071

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TABLE 1 B

DECOMPOSITION

PRODUCTS OF NYLON 6

3 Gas flow r a t e = 1000 cm m i d 1 Sample weight = 800 mg. ? Atmosphere Temperature O c 11 1 1 I I 50% Id2, 50% Air 1 r Nitrogen I 17 1 700 800 800 800 800 800 800 L Products, g / g sample Air 1 I 41 0 , 0 6 3 0.082 0,069 0.087 I 0.088 I - , - 500 5 00 6 ₀₀ 0 . 1 9 7 0.145 0.139 0.069 0.074

-

- 0.079 0 . 0 9 5 0.095 0.153 0.150 0.112 0.1l.O Residue

co

1

C02 0.069 0.059 0.085 0.072 0.078 II 1 1 11 l t I 1 I T 7r HCN 0.187 0.192 0 . 2 4 1 0.223 0 . 1 9 2 0.051 6.053 0.066 0.063 0.079 I t t l <O -01 I! 1 r 11 r r 600 70 0

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TABLE 1C

DECOMPOSITION PRODUCTS OF ABS

3 . -1 Gas flow r a t e = 1000

cm

mln Sample weight = 800 mg. Atmosphere

-

Temperature C C6 A i r r l I t f I ra 1 I I 1 I r 50%

N2'

50% Air f V N i t r o g e n I I 0.046 0.050 0.054 0.055 0.035 0.036 0.026 0.027 0.052 0.052 -

-

1

SO0 500 600 600 700 700 800 800 800 S O 0 800 800 P m d u c t s , g/g sample HCN 0 . 2 2 3 0.223 0 . 2 6 7 0.27'7 0.234 0.273 0 . 2 9 5 0,298 0.056 0.059 - - Residue 0.019 0.019 0.021 0.021 0 -03 0.03 0.01 <0.01 0.025 0.025 0.036 0.036 0.044 0 . 0 4 3 I T t I t I t l 0.01 0.01 0.034 0 . 0 3 4 0.02 0 _-02

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TABLE 2A

C

T

(SUM OF

TOXICITY FACTORS]

OF

WLYACRYLONITRILE

3

Gas flow rate = 1000 cm min - 1 Sample weight = 800 mg. Almospl~cre

-

A i r I 1 11 t l I F 11 1 I T I I t I t 50%

N2'

50% Air I t Nitrogen I 1 t Temperature

"C

T o x i c i t y Factor (kg-') due t

GO

123 123 308 314 525 5 3 2 686 6 6 8 514 819 1200 1219 996 996 !ICN 1 2 2 . 9 1 2 2 . 9 3 0 7 . 3 3 1 3 . 4 I 5 1 6 . 2 522.4 676 .O 6 5 7 . 6 8 0 5 . 0 811.2 1 1 9 2 . 2 1210.6 9 9 5 . 6 9 9 5 - 6 0 0

a

0 1 . 3 1.3 I 1.5 1.5 1 . 4 1.4 0 . 4 0.4 - - 400 400 500 0 0 0.8 500 600 60 ₀ 70 0 700 80 0 80 0 80 0 80 0 800 80 0 0 . 8 7 - 6 8 - 6 8.4 9 . 0 I 7 - 2 6 _{- 4} 7.2 7 - 6

-

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TABLE

213

C

T

[SUM

OF

TOXICITY FACTORS)

OF

NYLON 6

3 G a s _flow_{r a t e}₌₁₀₀₀ _n

_{m i h '}

Sample w e i g h t = 800 mg. I Atmasphere A i r 1 1 l f 11 t l I T I t 50% N2, 50% Air t t N i trsgen I f Temperature

"

C

T T o x i c i t y Factor (kg-') due to 328 3 39 4 24 403 502 499 60 3. 59 8 CO 500 500 600 C02 1 . 1 1.1 1 . 4 1.3 1.1 1 . 2 0.9 0.8 0.4 1 3 . 8 1 1 . 8 17.0 HCN 3 1 3 . 4 3 2 5 . 7 405.6 3 8 7 . 2 485.5 485 - 5 583 - 8 5 8 3 - 8 940.2 800 800 800 0.4 - - 600 70 0 700 80 0 17.6 - - 6 8 8 . 3 676 .O 1 4 . 4 15.6 12.6 1 6 . 4 800 1 3 . 8 800 1 7 . 4

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TABLE 2C

c

T

{SUM OF TOXICITY FACTORS)

OF

ABS

3

Gas

flow

r a t e

-

1000

cm

mi=-'

Sample weight = 800 mg. I Atmosphere Temperature O C 1 2 7 1 2 8 1 4 2 1 4 2 1 6 2 16 2 22 8 228 E T

Toxicity Factor (Q-') due to

A i r I r I t CO 1.3 1.3 ' 1.6 1.7 1 1 6 . 7 1 1 6 . 7 129 - 1 129.1 500 500 600 50%

N2,

50% A i r l r N i t r o g e n I! 1 5 3 . 6 1 5 3 . 6 2 2 1 . 2 221.2 c02 9 . 2 1 0 . 0 10.8 I t I f 11 II 270 ' 4 264.3 221.2 221 - 2 HCN 11

.a

I f 281 2 75 22 8 2 28 600 70 0 700 80 0 800 0.3 0 - 4 1.8 1 - 8 800 800 80 0 80 0 10.4 10.4 5 . 2 5.4 7.0 7 . 2 5.2 5 . 4 1.4 1 - 6 1.8 1 - 8

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TABLE 3

MAXIMU&¶

C

T (SUM

OF

_TOXICITY

_FACTORS)