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Evaluation of amines as antiradiation compounds in styrene butadiene rubber.

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Die Angewandte Makromolekulare Chemie 18 ( 1 9 7 1 ) 49-53 ( N T .232)
From the National Chemical Laboratory, Poona 8, India
Evaluation of Amines as Antiradiation Compounds
in Styrene Butadiene Rubber*
By N. D. GHATGEand S. S. MAHAJAN
(Eingegangenam 27. Juli 1970)
SUMMARY:
This study describes the evaluation of various mono and polyamines as antiradiation compounds in styrene-butadiene rubber - Synaprene 1500.
ZUSAMMENFASSUNG:
In dieser Arbeit wird die Wirkung verschiedener Mono- und Polyamine als
Strahlenschutzmittel in Polybutadien-Kautschuk (Synaprene 1500) beschrieben.
Introduction
I n recent years, a great deal of research activity is going on in the development of elastomers, which remain nearly unaffected on exposure t o ionisation
radiation. For the achievement of these results, attempts are being made to
synthesize new elastomers having radiation resistance groups or to compound
radiation resistance substances in the already available elastomers. It has also
been reported that the incorporation of radiation resistant substances in
elastomers has extended the life of radiation exposed rubber articles many
times.
Various amines have been used as antiradiation compounds in rubberl. This
laboratory had already synthesized many new isocyanatesz. 3 from different
amines. It was decided to utilize these amines in an evaluation programme of
antiradiation substances in an Indian manufactured styrene-butadiene synthetic rubber- Synaprene 1500. The components that have been taken for
evaluation are listed in Table 1.
This communication describes the studies connected with the evaluation of
these amines as antiradiation compounds in styrene-butadiene rubber - Synaprene 1500.
*
NCL Communication No. 1481.
49
N.D. GHATGEand S. S. MAHAJAN
Table 1. Compounds used as antiradiation substances.
No.
1
2
3
4
5
6
name
source
code No.
.&naphthol
@-naphthylamine
tris(p-amino pheny1)cyanurate
o,o‘, 0”-tri(4-amino-3-pentadecyl phenyl)thiophosphate
4-amino-3-pentadecylphenol
6-amino- 3-pentadecyl phenol
B.D.H (Bombay)
- do N.C.L
A
- do - do - do -
D
E
F
B
C
Cornpunding and Testing
-
The elastomer waa compounded on a laboratory type 6” 12” mixing mill and the
ingredients shown in Table 2 were added according t o ASTM procedure along with
the antiradiation compounds. All the samples were cured at 15OOC and 12000 psi to
optimum cure (30 minutes) as determined by physical properties and to under cure
(15 minutes) a t 15OOC and 12000 psi. The physical testing of vulcanizates was
carried out according to ASTM procedure4.
Table 2.
Compounding recipe for the vulcanizates.
styrene/ phi1
N ~ . bata- black
diene. 0-HAF
(77/13) black
*
1
100
2
3
4
100
5
100
50
50
50
50
50
6
100
50
7
100
50
100
100
zinc
oxide
3.00
3.00
3.00
3.00
3.00
3.00
3.00
stearic sulphur santa- nonox
acid
cure
BL
A
B
c
D
E
F
-
-
-
-
-
1.75
1.00 1.00 -
1.00
1.75
1.00
1.75
1.00 1.00 5.00 1.00 1.00 - 5.00 - - 1.00 1.00 - 5.00 1.00 1.00 - 5.00 1.00 1.00 - - - - 5.00
1.00 1.00 -
1.00
1.00
1.75
1.00
1.75
1.00
1.75
1.00
1.75
-
5.00
Synaprene 1500.
Exposure to ionization radiation of the samples was made only in air. A Co-60
gamma source waa used which provided a uniform gamma radiation flux of 6.5 * 1 0 1 6
eV/min g. All the irradiation experiments were performed for 796 hrs. The results
of the vulcanizates before exposure and after exposure are described in Table 3. The
degree of crosslinking was determined by the method given by CLTJFF and GLADDING5.
50
Amines as Antiradiation Compounds
Physical properties of styrene-butadiene tread stocks before and after
exposure to Gamma Radiation.
Table 3.
~
No.
antirads
I (min.) 1
(h)
1 None
15
15
30
30
0
796
0
796
252.90
662.80
401.50
973.90
2453.00
1870.00
2265.00
2121.00
550
300
440
250
0.6022
0.9929
0.8026
1.6050
2 p-naphthol
15
15
30
30
0
796
0
796
253.60
557.70
412.70
803.20
2460.00
2466.00
2496.00
2408.00
900
500
700
420
0.6022
0.8026
0.6880
0.9929
3 j3-naphthyl amine
15
238.30
320.20
212.90
308.40
2526.00
2114.60
2578.00
2605.00
550
420
30
30
0
796
0
796
0.6022
0.8026
0.8026
0.9929
15
15
30
30
0
796
0
796
286.60
417.10
288.40
494.30
2583.60
2394.60
2773.30
2408.00
350
520
320
0.6022
0.9929
0.6880
1.204
15
(4-amino-315
pentadecyl phenyl) 30
thiophosphate
30
0
796
0
796
206.40
383.30
206.60
355.50
2916.30
2426.00
2975.00
2662.30
700
360
650
400
0.6022
0.8026
0.8026
1.204
15
15
30
30
0
796
0
796
308.60
449.40
270.30
431.80
2456.60
2133.30
2727.30
2138.30
550
290
500
280
0.6880
0.8026
0.8026
0.9929
15
15
30
30
0
796
0
796
237.80
355.60
235.60
370.80
2732.00
2161.00
2564.00
1867.00
600
350
650
300
0.6022
0.8026
0.8026
0.9929
15
4 tris (p -amino
pheny1)cyanurate
5 o,o', 0"-tri-
6 4-amino-
3-pentadecyl
phenol
7 6-amino-
3-pentadecyl
phenol
*
I
tensile
modulus strength
(psi.)
(Psi.)
550
460
550
Degree of crosslinking.
Discussion
The mechanism by which changes in the properties of elastomers are brought
about by radiation are not yet clearly understood. But the two important noted
effects of the radiation are the crosslinking and the scission of the polymer
chainsl. If the crosslinking is predominately more than the scission increase in
51
N.D. GHATUEand S. S. MAHAJAN
modulus and decrease in the elongation in the elastomers is observed and if the
scission i s more than the crosslinking, a low modulus and weak elastomeric
material is obtained.
BORNet al.al 7, TURNERS,
ANDERSON~
and others have utilized a number of
compounds as radiation resistance compounds in many elastomeric materials.
ANDERSON
has observed that in butadiene-styrene rubber, the rate of cure by
sulphur crosslinking has a profound effect in the resistance of the elastomers to
radiation. I n his studies he concluded that radiation resistance obtained by
undercuring sulphur vulcanizates was caused by residual sulphur vulcanization
intermediates. fl-Naphthol, fl-naphthyl amine and other amines of Table 1were
incorporated into butadiene-styrene tread stock to determine their effectiveness
against radiation in presence and in absence of undercuring.
Table 4 shows the effects of undercuring and antirads on the radiation
resistance of synaprene 1500 tread stock in air. These results indicate that the
undercuring and the addition of antiradiation compound to the vulcanization
Table 4.
Effect of undercuring and antirads on the radiation resistance of butadienestyrene tread stock in air.
antirads
No.
change in 100%
modulus after
exposure for 796
hrs. in air (psi.)
Under cured :
1
2
3
4
5
6
7
1
2
3
4
5
6
7
none
p-naphthol
p-naphthyl amine
tris(p-amino pheny1)cyanurate
o,o’, 0” tri(4-amino-3-pentadecyl
pheny1)thiophosphate
4-amino-3-pentadecyl phenol
6-amino-3-pentadecylphenol
662.80
557.70
320.20
417.10
383.30
449.40
355.60
Fully cured :
none
p-naphthol
p-naphthyl amine
tris(p-aminopheny1)cyanurate
0,o’, 0’’tri(4-amino-3-pentadecyl
pheny1)thiophosphate
4-amino-3-pentadecylphenol
6-amino- 3-pentadecyl phenol
973.90
803.20
308.40
494.30
355.50
431.80
370.80
Amines as Antiradiation Compounds
recipe can be used to prolong the life of butadiene-styrene rubber tread stocks.
,6-Naphthyl amine and 6-amino-3-pentadecyl phenol appear to give better
protection both in the fully cured and undercured state. The next effective
compound in radiation resistance appears to be the phosphorus and sulphur
containing amine, namely 0,o’, o”-tri(4-amino-3-pentadecyl
pheny1)thiophosphate. /?-Naphthol and tris(p-amino pheny1)cyanurate may be considered as
giving nearly equal protection t o the vulcanizates in ionisation radiation.
The net effect of radiation on vulcanizates can be explained quantitatively
from the knowledge of crosslinking and scission. Since the conditions for the
determination of scission under radiation were not available, attempts t o explain the net effect of radiation quantitatively were abandoned.
Conclusion
8-Naphthyl amine and 6-amino-3-pentadecyl phenol appear to give better
protection than the other compounds evaluated.
1
2
3
4
5
6
7
8
9
R. G. BAUMAN
and J.W. BORN,J. appl. Polymer Sci. 1 (1959) 351.
N. D. GHATGEand S.D. YADAV,
J. appl. Polymer Sci. 12 (1968) 447.
N. D. GHATGEand S.D. YADAV,
Makromolekulare Chem. 124 (1969) 167.
A. S.T.M. Procedure D 412 (64T), 1965.
E. F. CLUFF,E. K. GLADDINQ
and R. PARISER,
J. Polymer Sci. 45 (1960) 341.
J.W. BORN,WADC Technical Report 55-58 Part I, 1954 and 11, 1955, ArmyNavy-Air Force Conference on Elastomer Research. ACR-Y, Vol. 4, Jan. 11 - 12,
1956, p. 65.
J.W. BORN,E.E. MOONEYand S.T. SEMEGEN,
Rubber World 139 (1958) 379.
D.T. TURNER,
J. Polymer Sci. 27 (1958) 503.
H. R. ANDERSON
JR., J. appl. Polymer Sci. 3 (1960) 316.
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compounds, evaluation, rubber, antiradiation, styrene, amines, butadiene
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