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Comparison of thermal and radiation curing of silicone rubber
Radiat. Phys. Chem. Voi.28, No.5/6, pp.497-499, 1986 I n t . J. Radiat. Appl. Instrum. Part C Printed in Great B r i t a i n .
0146-5724/86 $3.00 + 0.00 Copyright(~)1986. Pergamon Journals Ltd
All r i g h t s reserved
COMPARISON OF TH~RUAL AND RADIATION CURING OF SILICONE R U B B ~ A. Vok~l ÷, P. Kou~im ÷, J. S~ssmilchov~*, M. Heidingsfeldov/++, B. Kopeck~ +++ +Nuclear Research Institute, ~e~, Czechoslovakia ++Prague Institute of Chemical Technology, Prague, Czechoslovakia ++÷Kablo Vrchlab~ Work, Vrchlab~, Czechoslovakia
ABS~ACT Some physico-mechanical properties of ~adiation- and peroxlde-cured silicone r u b b e r b o t h b e f o z e and a f t e r t h e r m a l a g i n g h a v e b e e n c o m p a r e d .
INTR ODUC T I ON Owing t o t h e known f a c t t h a t c u r i n g o f c u r r e n t t y p e s o f s i l i c o n e r u b b e r p u t s modest demands f o r r a d i a t i o n d o s e s i t a p p e a r e d t h a t t h i s p r o c e s s when i n t r o d u c e d t o p l a n t s c a l e c o u l d be a p r o f i t a b l e o n e . E x p e r i m e n t a l work done i n t h e institutions mentioned in the title contributed to the introduction of industr i a l scale electron beam curing of silicone rubber insulated wires in 1981 in the cable work Kablo Vrchlab~. Part of this work focused to the comparison of peroxidic with radiation curing has been the subject of this paper.
E X P ~ IMENTAL The f o l l o w i n g s i l i c o n e r u b b e r compounds w e r e u s e d : Dow C o m i n g XL 1655u and Wacker SLM 31089 ( b o t h o f m e t h y l v i n T l p o l y s i l o x a n e t y p e ) . I r r a d i a t i o n was a c c o m p l i s h e d by means o f a l i n e a r e l e c t r o n a c c e l e r a t o r ; mean e l e c t r o n e n e r g y was 4 MeV, power o u t p u t 1 . 2 kW. The v u l c a n i z a t i o n d o s e u s e d i n these experiments was 50 MGT. Peroxidic vulcanization was carried out in a press at 150°C for I0 minutes with added 2,4-dichlo~obenzoyl peroxide. T e n s i l e s t r e n g t h , u l t i m a t e e l o n g a t i o n , 100 and 300 % m o d u l i , and h a r d n e s s were estimated before and after aging at 200, 225 and 250°C in an oven with circulating h o t al.w. The s o l c o n t e n t and t h e d e g r e e o f s w e l l i n g w e r e d e t e r m i n e d by t h e e x t r a c t i o n w i t h t o l u e n e a t room t e m p e r a t u r e f o r 72 h o u r s .
RESULTS From t h e p r a c t i c a l p o i n t o f view t h e s t u d y o f r a d i a t i o n v u l c a n i z a t i o n was f o c u s e d on c o m m e r c i a l i n s u l a t i o n compounds i n g e n e r a l u s e . I n a d d i t i o n t o t h e two materials studied in this work several other marks were used for comparison. It was found that practically all investigated insulation compounds
497
498
Physi~o-Mochanioa~ Pronertias 9f.Sl~eoae Rubber C o ~ o u n d 8 b e f o r e Thermal AJ~o~ Compound Property
Weaker 'SLM 31089 Cured by Peroxide Radiation
Dow Coraing XL 1655~u Cured b7 Peroxide Radiation
Tensile Strength (MPa)
11.55
9.40
8.15
8.88
Ult i m t s Elongation (%)
395
315
450
440
100 % Modulus (MPa)
3.00
3.05
2.49
2.15
300 % ModulUs
8.90
9.00
5.30
5.90
68
65
59
55
2.13
2.05
2.04
2.21
4.67
4.73
3.74
3.81
Cm~a)
H0rdaess (~Shor • A) D e n s e of Swelling C oat eat of Sol (%)
designated for peroxidic vuleaalzation could be used for radiation vulcanization as well. T a b l e 1 t h e p r o p e r t i e s o f r a d i a t i o n and p e r o x i d i c w a l e a n i s a t e s b e f o r e t h e r mal aging ere given. The data give evldenee that the differences between the properties of radiatlea euad peroxldie waleaninateg are mederate.
150
150
"
"l ~---1
o~ & 100
so
I 0
200 time
Fig. I.
400
600
0
(hr)
Changes o f p r o p e r t i e s o f t h e Wacker SLM 3108~ compound o n a g i n g a t 250~C c u r e d by pero:r£de radiation • hardness [] • tensile s i r e a c h 0 • ultimst e elongation /%
200 time
Fig. 2.
°
1
"
/
400
600
(hr)
Changes o f p ~ o p e ~ t i e s o f t h e Do~ C o=aing XT. g655u compound on a g i n g a t ~ 0 ~ C c u r e d peroxide radia~ion II herdness [] • tensile stz ength 0 A ult4~te elongation /%
499
250
temperature (oc} 225 200
106
I n F i g s . 1 and 2 zhe r e l a t i v e changes of tensile strength, ultimate elongat i o n and h a r d n e s s o f r a d i a t i o n and p e r oxtdl¢
~" 105
P 104 o
103 o
._E
101
/ , , 2.0 2.1 2.2 reciprocal temperature (1/K).103
1.9
Flg. 3.
Aging charaoterlstles o f t h e r u b b e r compounds c u r e d by peroxide radlatlon • Dow C o m i n g XL 1655u 0 A Waoker SL~ 31089 /%
Wzlcanisates
in the corpse of
t h e r m a l a g i n g a t 250°C a r e g i v e n . From these figures it follows that the prop e r t t e n o f aged samples o f r a d i a t i o n c r o s s l i n k e d s i l i c o n e r u b b e r compounds 8~e comparable or s l i g h t l y b e t t e r t h a n those of the chemicall7 cured samples. The A z r h e n i u s p l o t o f time o~ a g i n g a f t e r which t h e u l t i m a t e e l o n g a t i o n falls t o I00 % vs. temperature of aging for the investigated compounds is presented in Fig. 3. It ~ay be shown that thermal stability of vulcaninates depends on the type end composition of the individual compounds rathe~ than on t h e way o f c u r i n g .
0146-5724/86 $3.00 + 0.00 Copyright(~)1986. Pergamon Journals Ltd
All r i g h t s reserved
COMPARISON OF TH~RUAL AND RADIATION CURING OF SILICONE R U B B ~ A. Vok~l ÷, P. Kou~im ÷, J. S~ssmilchov~*, M. Heidingsfeldov/++, B. Kopeck~ +++ +Nuclear Research Institute, ~e~, Czechoslovakia ++Prague Institute of Chemical Technology, Prague, Czechoslovakia ++÷Kablo Vrchlab~ Work, Vrchlab~, Czechoslovakia
ABS~ACT Some physico-mechanical properties of ~adiation- and peroxlde-cured silicone r u b b e r b o t h b e f o z e and a f t e r t h e r m a l a g i n g h a v e b e e n c o m p a r e d .
INTR ODUC T I ON Owing t o t h e known f a c t t h a t c u r i n g o f c u r r e n t t y p e s o f s i l i c o n e r u b b e r p u t s modest demands f o r r a d i a t i o n d o s e s i t a p p e a r e d t h a t t h i s p r o c e s s when i n t r o d u c e d t o p l a n t s c a l e c o u l d be a p r o f i t a b l e o n e . E x p e r i m e n t a l work done i n t h e institutions mentioned in the title contributed to the introduction of industr i a l scale electron beam curing of silicone rubber insulated wires in 1981 in the cable work Kablo Vrchlab~. Part of this work focused to the comparison of peroxidic with radiation curing has been the subject of this paper.
E X P ~ IMENTAL The f o l l o w i n g s i l i c o n e r u b b e r compounds w e r e u s e d : Dow C o m i n g XL 1655u and Wacker SLM 31089 ( b o t h o f m e t h y l v i n T l p o l y s i l o x a n e t y p e ) . I r r a d i a t i o n was a c c o m p l i s h e d by means o f a l i n e a r e l e c t r o n a c c e l e r a t o r ; mean e l e c t r o n e n e r g y was 4 MeV, power o u t p u t 1 . 2 kW. The v u l c a n i z a t i o n d o s e u s e d i n these experiments was 50 MGT. Peroxidic vulcanization was carried out in a press at 150°C for I0 minutes with added 2,4-dichlo~obenzoyl peroxide. T e n s i l e s t r e n g t h , u l t i m a t e e l o n g a t i o n , 100 and 300 % m o d u l i , and h a r d n e s s were estimated before and after aging at 200, 225 and 250°C in an oven with circulating h o t al.w. The s o l c o n t e n t and t h e d e g r e e o f s w e l l i n g w e r e d e t e r m i n e d by t h e e x t r a c t i o n w i t h t o l u e n e a t room t e m p e r a t u r e f o r 72 h o u r s .
RESULTS From t h e p r a c t i c a l p o i n t o f view t h e s t u d y o f r a d i a t i o n v u l c a n i z a t i o n was f o c u s e d on c o m m e r c i a l i n s u l a t i o n compounds i n g e n e r a l u s e . I n a d d i t i o n t o t h e two materials studied in this work several other marks were used for comparison. It was found that practically all investigated insulation compounds
497
498
Physi~o-Mochanioa~ Pronertias 9f.Sl~eoae Rubber C o ~ o u n d 8 b e f o r e Thermal AJ~o~ Compound Property
Weaker 'SLM 31089 Cured by Peroxide Radiation
Dow Coraing XL 1655~u Cured b7 Peroxide Radiation
Tensile Strength (MPa)
11.55
9.40
8.15
8.88
Ult i m t s Elongation (%)
395
315
450
440
100 % Modulus (MPa)
3.00
3.05
2.49
2.15
300 % ModulUs
8.90
9.00
5.30
5.90
68
65
59
55
2.13
2.05
2.04
2.21
4.67
4.73
3.74
3.81
Cm~a)
H0rdaess (~Shor • A) D e n s e of Swelling C oat eat of Sol (%)
designated for peroxidic vuleaalzation could be used for radiation vulcanization as well. T a b l e 1 t h e p r o p e r t i e s o f r a d i a t i o n and p e r o x i d i c w a l e a n i s a t e s b e f o r e t h e r mal aging ere given. The data give evldenee that the differences between the properties of radiatlea euad peroxldie waleaninateg are mederate.
150
150
"
"l ~---1
o~ & 100
so
I 0
200 time
Fig. I.
400
600
0
(hr)
Changes o f p r o p e r t i e s o f t h e Wacker SLM 3108~ compound o n a g i n g a t 250~C c u r e d by pero:r£de radiation • hardness [] • tensile s i r e a c h 0 • ultimst e elongation /%
200 time
Fig. 2.
°
1
"
/
400
600
(hr)
Changes o f p ~ o p e ~ t i e s o f t h e Do~ C o=aing XT. g655u compound on a g i n g a t ~ 0 ~ C c u r e d peroxide radia~ion II herdness [] • tensile stz ength 0 A ult4~te elongation /%
499
250
temperature (oc} 225 200
106
I n F i g s . 1 and 2 zhe r e l a t i v e changes of tensile strength, ultimate elongat i o n and h a r d n e s s o f r a d i a t i o n and p e r oxtdl¢
~" 105
P 104 o
103 o
._E
101
/ , , 2.0 2.1 2.2 reciprocal temperature (1/K).103
1.9
Flg. 3.
Aging charaoterlstles o f t h e r u b b e r compounds c u r e d by peroxide radlatlon • Dow C o m i n g XL 1655u 0 A Waoker SL~ 31089 /%
Wzlcanisates
in the corpse of
t h e r m a l a g i n g a t 250°C a r e g i v e n . From these figures it follows that the prop e r t t e n o f aged samples o f r a d i a t i o n c r o s s l i n k e d s i l i c o n e r u b b e r compounds 8~e comparable or s l i g h t l y b e t t e r t h a n those of the chemicall7 cured samples. The A z r h e n i u s p l o t o f time o~ a g i n g a f t e r which t h e u l t i m a t e e l o n g a t i o n falls t o I00 % vs. temperature of aging for the investigated compounds is presented in Fig. 3. It ~ay be shown that thermal stability of vulcaninates depends on the type end composition of the individual compounds rathe~ than on t h e way o f c u r i n g .