Synthetic Rubbers in Cables & Wire Industry

7/30/2019 Synthetic Rubbers in Cables & Wire Industry

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S T P 6 1 - E B / J u n . 1 9 4 4

S Y N T H E T I C R U B B E R S I N T H E W I R E A N D C A B L E I N D U S T R YBY R. A. SCHATZEL1

P r i o r t o t h e w a r , c o m p o u n d s m a d ef r o m n a t u r a l r u b b e r w e r e u se d f o r c a bl ei n s u l a t i o n a n d p r o t e c t i v e j a c k e t s f a r i ne x c es s o f a n y o t h e r m a t e r i a l . T h i s w i d e -s p r e a d a p p l i c a t i o n o f r u b b e r w a s t h er e s u l t o f m a n y y e a r s o f d e v e l o p m e n t i nc o m p o u n d i n g a n d p r o c e s s i n g t e c h n i q u e ,t o g e t h e r w i t h n e w m e t h o d s f o r t h ee v a l u a t i o n o f th e i m p r o v e d p r o p e r t ie s o ft h es e n e w c o m p o u n d s . R u b b e r h a d b e -c o m e t h e a c c e p t e d s t a n d a r d i n s u l a t i o nf o r p o w e r c a b l e f r o m l o w - v o l t a g e b u i l d -i n g w i r e s t o 3 3 k v . s u b m a r i n e c a b l e ,c o m m u n i c a t i o n w i r e , a n d s h e a t h s f o rp o r t a b l e c o r d s a n d c a b le s . N e o p r e n es h e a t h s a n d v i n y l p o l y m e r s ( i n su l a ti o na n d s h e a t h s ) h a d b e g u n t o f i n d a c o n -s i d e r a b l e p l a c e i n t h e i n d u s t r y d e s p i t et h e i r r e l a t i v e l y h i g h e r co s t. T h i s w a sp a r t i c u l a r l y t r u e o f f l a m e p r o o f s h i p b o a r dc a b le f o r t h e U . S. N a v y . T h e u s e o ft h e s e m a t e r i a l s i n p l a c e o f r u b b e r f o rs pe c i f i c a pp l i c a t i ons w a s f u l l y j u s t i f i e db e c a u s e t h e y w e r e s u p e r i o r t o r u b b e r i nc e r t a i n r e s pe c t s , c h i e f l y i n o i l, f lame, a n dox i da t i on r e s i s t a nc e , a nd s t a b i l i t y i nt he p r e s e nc e o f oz one o r d i r e c t s un l i gh t .I n t h e c a s e o f v i n y l p o l y m e r in s u l a ti o n s ,s om e s a c r i f i c e s i n e l e c t r i c a l c ha r a c t e r i s -t i c s w e r e n e c e s s a r y i n o r d e r t o o b t a i nt h e a b o v e - m e n t i o n e d p h y s i c a l p r o p e r ti e s.

S h o r t l y a f t e r th e s t a r t o f E u r o p e a nh o s t il it ie s , i t b e c a m e e v i d e n t t h a t c o n t r o lo v e r t h e u s e o f n a t u r a l r u b b e r , N e o p r e n e ,a n d v i n y l p o l y m e r s w a s n e c e s s a r y b e -c a u se o f u n p r e c e d e n t e d d e m a n d s f o rt h e s e m a t e r i a l s . I n 1 94 1, a t t h e r e -

1Director of Research, General Cable Corp., Bayonne,N.J.; Chairman, Technical Advisory Committee on In-sulated Wire and Cable, War Production Board.

q u e s t o f t h e R u b b e r a n d R u b b e r P r o d -u c t s b r a n c h o f t h e O f fice o f P r o d u c t i o nM a n a g e m e n t ( l a t e r s u p e r s e d e d b y t h eW a r P r o d u c t io n B o a r d ) , a n i n d u s t r y c om -m i t t e e w a s f o r m e d t o a s s is t in f o r m u l a t -i n g t h e p r o p e r r e s t r i c t i o n s f o r e f f e c t i n gTABLE I--FIRST WAR PRODUCTION BOARDLIMITATION ORDER ON INSULATED WIREAND CABLE.Supplem entary Order No. M-15-b-1, as Amended.

List 12(Effective Ap ril 1, 1942)

Specifications for th e M anufacture of InsulatedW ire and Cable.(a) Compounds

Type

(1) Insulations.

(2) Jackets .. .. .

I tA

/ D

TradeIdentification

Performance type,otherwise knownas A.S.T.M. D 353-41A.S.T. M. D 353--Emergency; A.S.T.M. D 574Code grade 2/11/42A.S .T.M . D 532--Emergency

For each per cent of rubber by volu m e re-duced, reclaim and scrap rubber m ay be in-creased 2.5 per cen t by volume.t h e c o n s e r v a t io n o f r u b b e r . T h i s c o m -m i t t e e o p e r a t e d t h r o u g h 1 9 4 2 , a n d t h ef i r s t W P B r u b b e r o r d e r w a s i s s u e d i nM a r c h o f t h a t y e a r . T a b l e I s h ow s t h es e c t i o n o f t h i s f i r s t o r d e r p e r t a i n i n g t ow i r e s a n d c a b l e s a n d i l lu s t r a t e s t h e e a r l y

109Copyright* 1944 by AS TM International www .astm.org

Copyright by ASTM Int'l (all rights reserved); Thu Apr 4 14:38:27 EDT 2013

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110 S '~mOSlUM ON SYNTHETIC RUBBERSm e t h o d s o f s ta n d a r d i z a t i o n u s e d t o e f fe c tc o n s e r v a ti o n . C a b l e s m a d e f o r w a r u s ew e r e e x e m p t e d f r o m t h i s c l a s s i f i c a t i o n ,a l t h o u g h c a b l e s f o r c o m m e r c i a l a p p l i c a -t i o n w e r e c a r e f u l l y a n a l y z e d a s t o t h e i rs e r v i c e r e q u i r e m e n t s a n d t h e m a x i m u mg r a d e o f i n s u l a t i o n e s t a b l i s h e d a s af u r t h e r p a r t o f t h i s o r d e r. W i t h t h ea p p r o a c h o f t h e n e c e s s i t y t o c o n v e r t t os y n t h e t i c r u b b e r a n d t h e n e c e s s it y f o rc o o p e r a t i v e d e v e l o p m e n t a s a g u i d e t ot h e c o n v e r s i o n , i t b e c a m e e v i d e n ~ t h a ta le g a l ly s a n c t i o n e d i n d u s t r y c o m m i t t e ew a s n e c e ss a ry . T h i s w a s c r e a t e d b y M r .J ef fe rs , R u b b e r D i r e c t o r , o f t h e W a r

c onsum i ng p r oduc t s. T h a t ge ne r al p r o -gram has been c lea red formal ly wi th theAt torney Genera l , a s ev idenced by the en-closed cer t i f ica te , and you may accept thisl e t t e r a s a reques t on beha l f o f the cha i r -m a n o f t he W a r P r oduc t i on Boa r d . "

I n t h e o p e r a t i o n o f t h i s t e c h n i c a l a d -v i s o r y c o m m i t t e e s e v e r a l s u b c o m m i t t e e sw e r e c r e a t e d t o w o r k w i t h t h e v a r i o u sb r a n c h e s o f t h e a r m e d s e r v i c e s , g o v e r n -m e n t d e p a r t m e n t s , U n d e r w r i t e r s ' L a b -o r a t o r ie s , a n d t h e A m e r i c a n S o c i e t y f o rT e s t i n g M a t e r i a l s i n t h e p r o b l e m s r e -l a t e d t o t h e c o n v e r s i o n f r o m n a t u r a lr u b b e r t o t h e s y n t h e t i c r u b b e r s . O n e o f

TABLE II . - -WAR PRODUCTION BOARD LIMITATION ORDER, JUNE, 1943 .

Use

Insulat ion . . . . . . . .

Jacket s . . . . . . . . . . .

Compound Grade

W-AAA . . . . . . . . . . . . . . . . . . . . .W-A A . . . . . . . . . . . . . . . . .W-A ... . . : . . . . . . . . . . . ii?iiW - B . . . . . . . . . . . . . . . . . . . . . . . . .W - C . . . . . . . . . . . . .. . . . . . . . . . . .W - F . . . . . . . . . . . . .. . . . . . . . . . . . .W - D . . . . . . . . . . . . .. . . . . . . . . . .W - E . . . . . . . . . . . . . .. . . . . . . . .W-SM-6 (Neoprene) . . . . . . . . .W-SM-9 (Neoprene) . . . . . . . . .W-SS-4 (Bnna S) . . . . . . . . . . . .W-SI-4(ButyD . . . . . . . . . . . . . .

Maximum Percentage byVolume

Synthetic TotalCrude RubberRubber Ru~ er Hydro-arbon

98 9870 7055 " 65

40 0 508 0 500 0 50

50 0 7545 0 550 65 00 50 00 75 00 75 . .

Performance Reference

Performance type RP or A.S.T,M.D 353 - 41 . Heat r es i s t ant t ypeRH or A.S.T.M. EA - D 469a,A.S.T.M. EA - D 353 or A.S.T,M.EA - D 574.N.E.C. grade type R, 2/11/42.N.E.C. building wire,

A.S.T.M. EA - D 532.A.S.T,M. ES - 6.A.S.T.M. ES - 28,A.S.T,M. ES - 30.

P r o d u c t i o n B o a r d , r e c e iv e d t h e l e g ala p p r o v a l o f t h e A t t o r n e y G e n e r al , a n ds t a r t e d i ts o f fi ci al o p e r a t i o n i n J a n u a r y ,1943 . T he f o l l ow i ng c om m un i c a t i onf r o m t h e R u b b e r D i r e c t o r ' s O f fic e a u -t h o r i z e d t h e c r e a t i o n o f t h i s c o m m i t t e e :

"Thi s Technica l Commi t t ee i s be ing es -t ab l ished as pa r t o f a genera l p ro gram forthe exchange of technical inform at ion b e-t w e e n m a nu f a c t u re r s o f s yn t he t ic r ubbe rand rubber -consuming produc t s , and co l -l abora t ion be tween them in the fur the ran ceof t echnica l im provem ents , re sea rch , deve l-opm e n t a nd t e s t i ng r e l a t i ng t o t he m a nu-fac ture and u t il iza t ion of rubber and rubber -

t h e m o s t i m p o r t a n t p h a s e s o f t k i s w o r kp e r t a i n e d t o t h e s p e c i f ic a t io n s a n d t e s tm e t h o d s f o r e v a l u a ti n g t h e p r o p e r t ie s o ft h e se m a t e r i a ls . T h e e f fo r ts a n d c o -o p e r a t io n o f S u b c o m m i t te e V o n I n s u -l a t e d W i r e a n d C a b l e , o f t h e A . S . T . M .C o m m i t t e e D - 1 1 o n R u b b e r P r o d u c t s ,i n e s t a b l i s h i n g e m e r g e n c y s p e c i f i c a t i o nl i m i t s o n c o m p o u n d s m a d e f r o m s y n -t h e t i c r u b b e r s a n d l o w e r p e r c e n t a g e s o fn a t u r a l r u b b e r h a v e b e e n o f g r e a t a s -s i s t a n c e i n f a c i l i t a t i n g t h e a c c e p t a n c e o ft h e se m a t e r i al s . T h e s e A . S . T . M . e m e r -g e n c y s p e c if i ca t io n s h a v e b e e n r e c o g n i z e da s s t a n d a r d b y c i v i l i a n i n d u s t r y a n d i n





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S C H A T Z E L O N W I R E A N D C A B L E 1 1 1

t h e m a j o r i t y o f c a se s b y t h e a r m e ds e r v i c e s , a s e v i d e n c e d b y t h e i r a p p e a r -a n c e in a l l W P B o r d e r s . T h i s h a s le dt o u n i f o r m i t y , s i m p l i c it y , a n d s p e e d i nc o n v e r t i n g t h e m a n u f a c t u r e o f w i re a n dc a b l e t o t h e u s e o f t h e s e n e w t y p e s o fc o m p o u n d s . T a b l e I I sh o w s th e W P Br u b b e r o r d e r f o r w i r e s a n d c a b le s w h i c ha p p e a r e d i n J u n e , 1 9 4 3 . T h i s t i m e , t h ea r m e d s e r v i c e s w e r e n o t e x e m p t a n d

GR-S and Its Use in Wire and Cable:I t i s i n t e r e s t i n g t o n o t e t h a t a t t h e

b e g i n n i n g o f 1 9 4 3 t h e p r o d u c t i o n o fG R - S w a s a n e g li gi bl e q u a n t i t y ; b yJ a n u a r y , 1 9 44 , a t l e a st 80 p e r c e n t o f t h er u b b e r u s e d b y t h e w i r e a n d c a b l e i n -d u s t r y h a d b e e n c o n v e r t e d t o th i s s y n -t h e t i c m a t e r i a l ; a n d b y t h e e n d o f t h ef ir s t q u a r t e r o f 1 9 4 4 t h e u s e o f n a t u r a lr u b b e r w i ll h a v e p r a c t i c a l l y e n d e d , e x -

T A B L E I I I . - - C H A N G E S I N L I S T O F R U B B E R O R D E R R - 1 E F F E C T I V E A S O F S E P T E M B E R I , 1 94 3.(b) Compounds(1) Th e composit ion o f the compounds hereinafter referred to in this List 27 shal l conform to theregulat ions set fo rth in the fol lowing table:

U s e

I n s u l a t i o n . . . . . . . .

J a c k e t s . . . . . . . . . . .

C o m p o u n d G r a d e

W - A A A . . . . . . . . . . . . . . . . . . . .W - A A . . . . . . . . . . . . . . . . . . . : .W - A . . . . . . . . . . . . . . . . . . . . . . . .

W - ~ . . . . . . . . . . . . . . . . . . . . . . . .W - A S - 6 ( G R - S ) . . . . . . . . . . . . .W - C S - 1 4 ( G R - S ) . . . . . . . . . . . . .W - S S - 4 ( G R - S ) . . . . . . . . . . . . . .W - S S - 6 ( G R - S ) . . . . . . . . . . . . . .W - S M - 6 ( G R - M ) . . . . . . . . . . . .W - S M - 8 ( G R - M ) . . . . . . . . . . . .W - S I - 4 ( G R - I ) . . . . . . . . . . . . . .

M a x i m u m P e r c e n t a g e b yV o l u m eT o t a lR u b b e r

C ru q S y n t h e t i c H y d r o -c a r b o nR u b [ R u b b e r an d; y n t b e t i cR u b b e r

98 00 987 0 7 05 5 0 6 5

4 0 0 5 00 6 5 6 50 2 5 5 00 7 5 7 50 6 5 6 50 6 5 6 50 5 5 5 50 7 5 7 5

P e r f o r m a n c e R e f e r e n c e

A . S , T . M . D 3 5 3 " -'4 1H e a t r e s i s t a n t t y p e R H o rA . S . T . M . E A - D 4 6 9 aA . S . T . M . E A - D 35 3 o r A . S . T , M .E A - D 5 7 4A . S . T . M . E S - 3 3 a n d E S - 3 4N . E . C . G r a d e T y p e R

A . S . T . M . K S - 6A . S . T . M . E S - ' 2 8 "A . S . T . M . E S - 3 0

(b) (3)N ote (3) as now in the l ist should be completely el iminated, and the fol lowing inserted in i tsplace:"I n the synthet ic rubber com pounds specif ied in this L ist 27, crude rubber and reclaimed rubbe rm ay be subst ituted for synthetic rubber when required for processing reasons, provided the totalam ou nt of an y crude rubber subst ituted does not exceed 5 per cent of the m aximum volume of syn-thetic rubber designated for the synthetic rubber compound."

l im i t a t i o n s o n n a t u r a l r u b b e r f o r b o t hw a r a n d c o m m e r c i a l u s e s w e r e i n c l u d e di n t h e o r d e r. T a b l e I I I s h o w s t h er u b b e r o r d e r o f S e p t e m b e r 1 , 1 9 43 , a n di n c lu d e s p r o v i s io n f o r b o t h s y n t h e t i cr u b b e r i n su l a ti o n s a n d j a c k e ts . N a t u r a lr u b b e r h a s s i n c e b e e n p r o h i b i t e d e x c e p tb y s p e c i a l a p p r o v a l a n d l i m i t a t i o n s o nt h e a m o u n t o f g e n e r a l p u r p o s e s y n t h e t i ch a v e b e e n r e m o v e d .

c e p t i n v e r y m i n o r q u a n t i t i e s , f o r t h ed u r a t i o n . T h e r e h a v e b e e n m a n y p r o b -l e m s c o n n e c t e d w i t h t h i s c o n v e r s i o n . I ti s n o t a p p r o p r i a t e t o d i s c u s s a l l o f t h e s ep r o b l e m s i n d e t a i l in t h i s p a p e r ; b u t , t oi l l u s t r a t e a f e w o f t h e m a j o r d i f fi c u lt ie s ,t h e p r o p e r t i e s o f c r u d e G R - S , t h e i rv a r i a t io n , a n d t h e e ff o rt s m a d e b y t h ei n d u s t r y t o o b t a i n a m o r e u n i fo r m m a -t e r i a l w i l l b e d i s c u s s e d .





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1 1 2 S x ~ e o s i u ~ O N S Y N T H E T I C R U B B E R S .

G R - S i s t h e b u t a d i e n e - s t y r e n e c o -p o l y m e r t y p e o f s y n t h e t i c r u b b e r a sm a d e i n t h e g o v e r n m e n t - o w n e d p la n t so p e r a t e d u n d e r t h e d i r e c t i o n o f t h eR u b b e r R e s e r v e C o . T o u n d e r s t a n d i tsp r o p e r t i e s a n d v a r i a t i o n s i t i s n e c e s s a r yt o c o n s id e r h o w i t i s m a d e . C o n s i d e r -a b l e p u b l i c i t y h a s b e e n g i v e n t o t h ep r o c e s se s i n v o l v e d , b u t a t t h e r i s k o fe xc e s s ive r e pe t i t i on the y w i l l be r e -v i e w e d b r ie f ly . B u t a d i e n e a n d s t y r e n ei n t h e a p p r o x i m a t e r a t i o o f 7 5 p a r t s b yw e i g h t o f b u t a d i e n e t o 2 5 p a r t s b ywe igh t o f s ty r e ne a r e e m ul s if i ed in a soa ps o l u ti o n , to g e t h e r w i t h a c a t a l y s t t o s t a r tt h e r e a c t i o n a n d a d i r e c t iv e m a t e r i a l t oi n h i b i t t h e f o r m a t i o n o f t o u g h , r e l a t i v e l yi n e la s ti c p r o d u c t s . T h i s m i x t u r e i s h e l di n a re a c t i o n c h a m b e r a t a c o n s t a n tt e m p e r a t u r e f o r t h e a p p r o x i m a t e p e r i o do f t ime ( 15 to 20 h r . ) r e qu i r e d to ob ta int h e p r o p e r d e g r e e o f p o l y m e r i z a t i o n ,a f t e r w h i c h t h e u n r e a c t e d b u t a d i e n e a n ds t y r e n e a r e r e m o v e d b y d i s t i l l a t i o n .T h e r e a c t i o n p r o d u c t f r o m v a r i o u s r e -a c t o r s , i n t h e f o r m o f a c r e a m y l a te x , isb l e n d e d a n d m i x e d w i t h a n a n t i o x i d a n t ;t h e n s a l t a n d a c i d a r e a d d e d t o p r e c i p i -t a t e t h e p o l y m e r . T h i s p r e c i p i t a t e i sw a s h e d t o r e m o v e e x c e s s s a l t a n d a c i d ,a n d t h e w a t e r i s r e m o v e d b y fi l tr a ti o na n d d r y i n g . F i n a l l y , t h e d r y , c r u m b -l i k e p o l y m e r i s c o m p r e s s e d i n t o b a l e sa n d p a c k e d f o r s h ip m e n t .

A spe c i f ic a t ion f o r GR - S ha s b e e ne s t a b l i s h e d b u t , u n f o r t u n a t e l y f o r t h ew i r e i n d u s t r y , r e q u i r e m e n t s o f t h e t i r ei n d u s t r y w e r e g i v e n p r i m a r y c o n s i d e r a -t i on . Th i s wa s a r e a l is t i c po l i c y , s inc et h e m a j o r i t y o f t h i s r u b b e r w a s t o b eu s e d i n t h a t i n d u s t r y . H o w e v e r , i t w a sr e c o g n iz e d a t a n e a r l y d a t e b y t h e w i r ei n d u s t r y t h a t t h i s s p e c i fi c at io n fa i le d b ya l a r ge me a su r e t o de sc r ibe t he ma te r i a ln e c e s s a r y t o m a k e s a t i s f a c t o r y i n s u la t io n .T h e p r o c e s s e s i n v o l v e d i n t h e m a n u f a c -t u r e o f G R - S i n t r o d u c e c o n s t i t u e n t s s u c ha s soa p , s a l t , a c id , a nd mo i s tu r e wh ic h

m a y h a v e u n d e s i r a b l e e f fe c ts o n t h e e le c -t r i c a l p r o p e r t i e s o f t h e p o l y m e r i f n o tc o m p l e t e ly r e m o v e d .T a b l e I V s h o w s t h e s e c t i o n o f t h eR u b b e r R e s e r v e C o . s p e c i f i c a t i o n s f o rG R - S c o v e r i n g t h e t e s t s a n d l i m i t s e s t a b -l i she d f o r c he mic a l c ons t i t ue n t s . I nd i sc u s si n g t h o s e c o n s t i t u e n t s w h i c h h a v ea n in f lue nc e on the e l e c t r i c a l c ha r a c t e r -i s t i c s o f t h e f i n i s h e d c o m p o u n d , t h ei n d u s t r y i s c o n c e r n e d p r i m a r i l y w i t h t h es o a p c o n t e n t a n d a s h c o n t e n t , a n d t h eTABLE IV.--RUBBER RESERVE CO.GR-S SPECIFICATIONS.

Acetone extract, max. per cent .. .. .. .. .. .. .. 10.00Heat loss, max., per cent . . . . . . . . . . . . . . . . . . . 0.75Fat ty acid (as stearic acid), per cent .. .. .. .. 3.00 to 6.00Soap (soluble as sodium stearate), max., percen t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.75Ash, max., per cent . . . . . . . . . . . . . . . . . . . . . . . . 1.50TABLE V.--T YPICAL RE SULTS OF TESTS ONSHIPMENTS OF GR-S FROM SEVERALGOVERNMENT PLANTS.

Ash, per centWater-soluble asl~ percent of tota ashWater absorption(crude GR-S), after20 hr. at 70 C., rag.per sq. in.Tensile strength (ES-34insulation), psi.Water absorption (com-pound), after 7 daysat 70 C., rag. persq. in.Change in specific in-ductive capacity, af-ter 21 days at 25 C ,per cent .

PlantA0.490.26

25.5~30

25.6

3.42

Plant PI t PlantB ~n D1.8; 0.65 0.670.7' 0.83 0.25

50.5 54.0 15.0,35 645 110

42.5 48.5 [ 7.5

7.5 6.3 ] 3.37

PlantE1.430.41

39.7760

36.I

9.45

c o m p o s i t i o n o f t h e l a t t e r . T h i s c o n c e r ni s b a s e d o n t h e e a r l y d i s c o v e r y t h a tb a t c h e s o f G R - S f r o m v a r i o u s g o v e r n -m e n t p l a n t s v a r i e d a p p r o x i m a t e l y t e n -f o l d i n m e c h a n i c a l a b s o r p t i o n o f w a t e r .I n a d d i t i o n , t h e y d i s p l a y e d w i d e v a r i a -t i o n i n e l e c tr i c al p r o p e r t i e s o n p r o l o n g e di m m e r s io n . A s a r e su l t o f s t u d y a n di n v e s t i g a t i o n m a d e b y i n d u s t r y i t w a sf o u n d t h a t d i f fe r e n ce s i n s o a p a n d a s hc o n t e n t , a n d p a r t i c u l a r l y t h e s o l u b l ep o r t i o n o f t h e a s h , w e r e d i r e c t l y re s p o n -s ib le f o r t he d i f f e re nc e s i n wa te r - a b so r b -ing p r ope r t i e s .





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S C t I A T Z E L O N W Y R . E A N D C A B L E 1 1 3

T e s t d a t a o b t a i n e d o n G R - S f r o ms e v e r a l d i f f e r e n t g o v e r n m e n t p l a n t s , a ss h o w n i n T a b l e V , i l l u s t r a t e t h e n e c e s -s i t y f o r c l o se r c o n t r o l o f th e m a n u f a c t u r eo f t h e m a t e r i a l t o b e u s e d i n t h e w i r ei n d u s t r y . I t i s a p p a r e n t t h a t co n s i de r -a b le d i f f e re nc e in the phy s i c a l a nd e l ec -t r i c a l p r ope r t i e s e x i s t e d in the se lo t s o fG R - S f r o m v a r io u s p l an t s , a l t h o u g h t h e ya l l h a d b e e n t e s t e d t o t h e g o v e r n m e n tspe c i f i c a t ions a nd , e xc e p t f o r t he a shc o n t e n t o f t h e s a m p l e f ro m p l a n t B , m e ta l l o f t h o s e r e q u i r e m e n t s . I t s h o u l d b en o t e d t h a t t h e w a t e r a b s o r p t i o n o f t h e

m a d e t o t h e W a r P r o d u c t i o n B o a r d t os u p p l y t h e w i r e i n d u s t r y w i t h G R - Sf r o m t w o p l a n t s w h i c h w e r e c a p a b l e o fm a k i n g a p r o d u c t p a r t i c u l a r l y g o o d i nt h e s e r e s p e c t s . T h e s e r e q u e s t s w e r eg r a n t e d , a n d t h e c a b l e i n d u s t r y i s r e -c e i v i n g t h e b u l k o f i t s G R - S f r o m as ingle p lan t .T w o a d d i t i o n a l s e r i o u s c a u s e s o ft r o u b l e w e r e v a r i a t i o n s i n r a t e o f v u l -c a n iz a t ion a nd p r oc e s s ing c ha r a c t e r i s t i c so f t h e d i ff e r e n t l o t s o f p o l y m e r . T h e s ev a r i a t i o n s s t i l l o c c u r , e v e n i n t h e G R - Sf r om the sel e c t e d sou r c e s . Th e c a use s o f

T A B L E V I . - - C O M P A R I S O N O F P H Y S I C A L P R O P E R T I E S O F G R -S A N D N A T U R A L R U B B E R .N a t u r a l R u b b e r G R - S

S p ec if ic g r a v i t y . . . . . . . . . . . . . . . . . . . . . . . . . .E f f e ct o f m i l l in g . . . . . . . . . . . . . . . . . . . . . . . . . .

F a c t o r y w o r k a b i l i t y . . . . . . . . . . . . . . . . . . . . . .T e n s i l e S t r e n g t h , p s i . :N o f il le r s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N o n c a r b o n f il le r s . . . . . . . . . . . . . . . . . . . . . .C a r b o n f il le r s . . . . . . . . . . . . . . . . . . . . . . . . .A g i n g :O x y g e n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .H e a t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A t m o s p h e r i c e x p o s u r e . . . . . . . . . . . . . . . . . .A b r a s i o n r e s i s t a n c e . . . . . . . . . . . . . . . . . . . . . .T e a r r e s i s t a n c e . . . . . . . . . . . . . . . . . . . . . . . . . .P h y s i c a l p r o p e r t i e s a t e l e v a t e d te m p e r a -t u r e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .L o w t e m p e r a t u r e f l ex i b il i ty . . . . . . . . . . . . . . .

0 . 9 2P l a s t i c i z e s r a p i d l y t o g i v e a s o f t,p l a s ti c p r o d u c t ; e l e v a t e d t e m p e r a-t u r e s a c c e l e r a t e t h i s a c t i o n .G o o d

3000 to 50002000 to 30003500 to 5000G o o dF a i rP o o r , u n l e s s e s p e c i a l l y c o m p o u n d e dG o o dG o o dG o o dG o o d

0 . 9 4P l a s t i c i z e s s l o w l y o n p r o l o n g e dm i l l in g . T e n d s t o " g r a n u l a t e " a te l e v a t e d t e m p e r a t u r e s .F a i r , u n l e s s h e a v i l y c o m p o u n d e dw i t h p i g m e n t s o r o r g a n i c f i l l e r s

400 to 700600 to 10002000 to 3000E x c e l l e n tE x c e l l e n tA t l e a s t e q u a l t o r u b b e rA p p r o x i m a t e l y e q u a l t o r u b b e rF a i rP o o rC r a c k s a t a p p r o x i m a t e l y - - 55 C .

r a w a n d c o m p o u n d e d p o l y m e r is r e la t e dc l o se l y t o t h e w a t e r -s o l u b l e a s h c o n t e n ta n d t h a t t h e c h a n g e i n d ie l e c tr i c c o n s t a n to n p r o l o n g e d i m m e r s i o n i s a l s o h i g h e rf o r t h o s e p o l y m e r s w h i c h c o n t a i n t h eh i g h e r c o n t e n t o f w a t e r -s o l u b le c o n s t i t -u e n t s . V a r i a t i o n s o f t h i s n a t u r e f o r m e dthe ba s i s f o r a p r opose d r e v i s ion o f t hespe c i f i c a t ions a nd a l so f o r t he ne c e s s i tyo f o b t a i n i n g G R - S f r o m a l i m i t e d n u m -b e r o f so u r c es so t h a t v a r i a t i o n s b e t w e e nd i f f e r e n t s h i p m e n t s f r o m t h e s e s e l e c t e ds o u r c e s c o u l d b e s t u d i e d a n d r e d u c e d t oa m i n i m u m . R e c o m m e n d a t i o n s w e r e

t h e v a r i a t i o n s a p p e a r t o b e d e e p - s e a t e da n d a r e , u n d o u b t e d l y , r e l a t e d t o t h ev a r i a t i o n s i n t h e c o n t r o l e x e r c i s e d o v e rt h e p o l y m e r i z a t i o n r e a c t io n . S u c h p r o b -l e m s a r e b e i n g i n v e s t i g a t e d b y p o l y m e rr e s e a rc h g r o u p s i n c o o p e r a t i o n w i t h t h eg o v e r n m e n t p l a n t s . H o w e v e r , u n t i lt h e y a r e c o r r e c t e d t h e w i r e i n d u s t r y w i llc o n t i n u e t o h a v e s o m e m a n u f a c t u r i n gp r o b l e m s , p a r t i c u l a r l y w h e n t h e h i g h -s p e e d e x t r u s i o n , c o n t i n u o u s v u l c a n i z a -t ion p r oc e s s i s u se d . Th e se va r i a t io nsw i l l b e p a r t i c u l a r l y a p p a r e n t i n t h ep h y s i c a l p r o p e r t i e s o b t a i n e d f r o m a





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11 4 SYMPOSIUM ON SYNTHETIC RUB BER S

c o m p o u n d w h e n c h a n g ed f r o m o n e s h ip -m e n t o f G R - S t o a n o t h e r . I t i so b v i o u s t h a t p r o d u c t s m a d e t o r i g i dspe c i f i c a t ions l imi t s , suc h a s a r e e s -t a b l i she d f o r w i r e p r oduc t s , r e qu i r e r i g ids p e c i f i c a t i o n s c o n t r o l o v e r t h e r a w m a -t e ri a ls u s e d. T h e w o r k a l r e a d y d o n e i nt h a t d i r ec t io n w i th G R - S h a s p r o v e dbe ne f i c i a l i n p r oduc ing in su l a t i ng a ndj a c k e t c o m p o u n d s s u i t a b l e f o r e x a c t i n gse r v i c e c ond i t i ons . A t p r e se n t , su i t a b l es p e c if ic a ti o n s f o r G R - S t o b e u s e d b y t h ew i r e i n d u s t r y a r e b e i n g f o r m u l a t e d a n dw i ll b e o f f e re d t o t h e R u b b e r R e s e r v eC o . a t a n e a r l y d a t e .A c o m p a r i s o n b e t w e e n t h o s e p h y s i c a lp r o p e r t i e s o f G R - S a n d n a t u r a l r u b b e rwh ic h a r e s ign i f i c a n t i n w i r e a nd c a b lea p p l i c a t i o n s i s g i v e n b r i e f l y i n T a b l e V I .I t i s a p p a r e n t f r o m th i s t h a t G R - S c o m -p a r e s v e r y f a v o r a b l y w i th n a t u r a l r u b b e ri n t h o s e p h y s i c a l p r o p e r t i e s o f i m p o r -t a nc e in w i r e a nd c a b le a pp l i c a t ions .T he m os t s ign i f ic a n t d i f fe r e nc e s a r e i nthe t e ns i l e s t r e ng th a nd in su l a t i on r e s i s t -a n c e . T h e p r o p e r t i e s o f t h e p o l y m e r a r es u c h t h a t i t i s i m p o s s i b l e t o o b t a i n t h em a x i m u m t e n s i l e s t r e n g t h s w i t h o u t t h eu s e o f l a rg e p e r c e n t a g e s o f c a r b o n b l a c k .S i n c e c a r b o n b l a c k h a s t o b e l i m i t e d t ov e r y l o w p e r c e n t a g e s i n i n s u l a t i o n c o m -p o u n d s d u e t o i ts d e g r a d i n g e f f e c t o ne l e c t r i c a l p r ope r t i e s , t he t e ns i l e s t r e ng th so f t h e s e c o m p o u n d s a r e s u b s t a n t i a l l yl o w e r t h a n t h o s e o f s i m i l a r r u b b e rc o m p o u n d s .Specif ications for G R-S Insulation andJacket Compounds:

As a r e su l t o f t he j o in t e f f o r t s o f t hei n d u s t r y a n d t h e r a p i d d i s c l o s u r e o fi n f o r m a t i o n c o n c e r n i n g t h e p r o p e r t i e s o fv a r io u s i n su l a ti o n a n d j a c k e t c o m p o u n df o r m ula t ions , i t wa s pos s ib l e i n e a r ly 1943to p r e se n t spe c i f i c a tion va lue s t o t heE m e r g e n c y C o m m i tt e e o f S u b c o m m i tt e eV o n I n s u l a t e d W i re a n d C a b le , o f C o m -m i t t e e D - 1 1 o n R u b b e r P r o d u c t s , t o

a p p l y t o g e n e r a l p u r p o s e i n s u l a ti o n s a n dja c ke t s . S om e o f t he va lue s we r e ne c e s -s a r i l y l o w e r t h a n p r e v i o u s l y u s e d f o rr u b b e r c o m p o u n d s d e s i g n e d f o r s i m i l a ra p p l i ca t i o n s . T h i s w a s p a r t i c u l a r l y t r u eo f t e ns i l e s t r e ng th a nd in su l a t i on r e s i s t -t a nc e , wh ic h we r e ne ve r o f g r e a t s ignif i-c a n c e i n p e r f o r m a n c e b u t m e r e l y w e r ei n d i c a t o r s o f u n i f o r m i t y . H o w e v e r ,t e s t s f o r mos t c ha r a c t e r i s t i c s we r e i n -c l u d e d a n d p r a c t i c a l m a n u f a c t u r i n gl imi t s we r e e s t a b l i she d in ke e p ing w i tht h e b a s i c r e q u i r e m e n t s o f t h e i n t e n d e du s e. T h e li m i t s a ls o h a d t o b e s e t a tl e ve l s t o c o v e r s o m e o f t h e k n o w n v a r i a -t i o n s i n t h e m a t e r i a l w h i c h s ti ll h a v e n o tb e e n e l im i n a t e d . T h u s , a l t h o u g h t h et e n s i l e s t r e n g t h r e q u i r e m e n t o f t h eA . S . T . M . T e n t a t i v e S p e c if ic a ti o n s f o rI n s u l a t e d W i r e a n d C a b l e : P e r f o r m a n c eS y n t h e ti c R u b b e r C o m p o u n d ( D 7 5 5 -43 T ) 2 i s s e t a t 700 ps i ., t he p r e s e n tv a r i a t i o n i n t e n s i l e s t r e n g t h o b t a i n e d o nt h i s t y p e o f c o m p o u n d m a y b e f r o m 7 50to 1100 ps i . U nd e r t he p r e s e n t c ond i -t i o n s i t c a n n o t b e e x p e c t e d t o o b t a i nv a l u e s i n t h e u p p e r r a n g e c o n s i s t e n t l y ,a n d the l imi t o f 700 ps i . is c ons ide r e d a na d e q u a t e a n d p r a c t i c a b l e s p e c i f i c a t i o nl i m i t . I t i s t h e c o n s i d e r e d o p i n i o n o ft h e w i r e i n d u s t r y , b a s e d o n e x t e n s i v ei n v e s t i g a t i o n s o f t h e p a s t y e a r , t h a t t h eq u a l i t y o f t h e c o m p o u n d s c o v e r e d b ythe se e me r ge nc y spe c i f i c a t ions i s i n e x -c e s s o f t he ba s i c r e qu i r e me n t s o f u se ,a n d g o o d p e r f o r m a n c e r e c o r d s c a n b ee x p e c t e d .A t a b u l a t i o n o f t h e A . S . T . M . T e n t a -t i v e a n d E m e r g e n c y S p e c i fi c at io n s c o v e r -i n g t h e m o s t w i d e l y u s e d G R - S i n su l a -t i o n s a n d j a c k e t s i s g i v e n i n T a b l e V I I ,a n d f o r m u l a s o f t y p i c a l c o m p o u n d ssu i t a b l e f o r u se unde r t he se spe c i f i c a -t i o n s a n d t h e i r r a n g e s o f p r o p e r t i e s a r ei n c l u d e d i n T a b l e V I I I .I n t h e c a s e o f i n s u l a t i o n s u b j e c t e d t o

2 1943Supplement to Book of A.S.T.M. Standards, Pa rtIII, p. 445.





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S C H A T Z E L O N W I R E A N D C A B L E 115TABLE VII,--A.S.T.M. SPECIFICATIONS COVERING THE MOST WIDELY USED GR-S INSULATIONS ANDJACKETS.a

Heat Resistant Performance Ozone ResistantInsulation, Insulation Insulation,D 754-45T D 755- 43T EA -D 5?4a

700 700 450300 300 250

GR-S Sheath,ES - 6a

Tensile strength, rain., psi .. .. .. .. .. .. . 1800Elongation at rupture, rain., per ce nt. . 300Set in 2 in. gage length, max., in .. .. .. / 3A!Oxygen bomb test:Tensile s trength . . . . . . . . . . . . . . . . . . . . . 1400 psi. , min. b 50 per cent de-preciation,max. c

35 per cent de-preciation,max.dElongat ion a t rupture . . . . . . . . . . . . . . . . . .

Air oven test, 168 hr.:Tens i le s t rength . . . . . . . . . . . . . . . . . . . . .Elongation at rupture . . . . . . . .Air pressure heat test, 20 hr.:Tensi le s trength . . . . . . . . . . . . . . . . . . . . .

Elongat ion a t rupture . . . . . . . . . . . . . . .

Insula tion resistance const ant K per1000 f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

50 per cent, de-preciation.max .c

50 per cent de-preciation,max.50 per cent de-preciation,max.

2000

35 per cent de-preciation,max. d

2000

400 psi., i n.

200 per cent, min.

400 psi., min.200 per cent, mln.

I000~a The A.S.T.M. T entat ive and Emergt ncy Specifications referred to i n th is table are as follows:Emergency Specifications for GR-S S rnthetic R ubber Sheath Compound for Electr ical Ins ulat ed Cords and Cables(ES -6a). 1943 Supplement to Book of A.S.T.M. Standards, Pa rt II I, p. 143.Ten tat ive Specifications for Insul ated Wire and Cable: Heat- Resis ting Synthetic Rubber Compound (D 754 - 43 T).(Originally issued as ES - 33.) 1943 Supplement to Book of A.S.T.M. Standards, Par t I II, p. 441.Ten tat ive Specifications for Insulat ed Wire and Cable: Performance Synthetic Rubber Compound (D 755 - 43 T).(Originally Issued as ES - 34.) 1943 Supplemen t to Book of A.S.T.M. Standards, Pa rt It i, p. 445.Ten tat ive Specifications for Insulat ed Wire and Ca ble: Ozone-Resistant Type Insul ati on (D 574 - 40 T), as modifiedby Emergency Alternat e Provisi ons EA - D 574a. 1942Book of A.S.T.M. Standards, P art II I, p. 1379.o 4 8 h r . at 70 C .e 168 hr. at 80 C.a96 hr. at 70 C.* This value is the only change in EA - D 574, which applied to the natu ral rubber compound.

T A B L E V III.--TYPICAL F O R M U L A S A N D P H Y S I C A L P R O P E R T I E S F O R G R- S I N S U L A T I O N A N D J A C K E TCOMPOUNDS.

Constituents, parts by weight:GR-S . . . . . . . . . . . . . . . . . . . . . . . . . . .M iuera l rubber . . . . . . . . . . . . . . . . . . .C la y . . . . . . . . . . . . . . . . . . . . . . . . . . . . .W h i ti n g .: . . . . . . . . . . . . . . . . . . . . . . . . ;Z inc oxide . . . . . . . . . . . . . . . . . . . . . . . .EPC b lack . . . . . . . . . . . . . . . . . . . . . . . . IS RF b lack . . . . . . . . . . . . . . . . . . . . . . .L i tharge . . . . . . . . . . . . . . . . . . . . . . . . . . 'A nt iox idant . . . . . . . . . . . . . . . . . . . . . . .Waxes . . . . . . . . . . . . . . . . . . . . . . . . . .S tear ic acid . . . . . . . . . . . . . . . . . . . .S ul fu r . . . . . . . . . . . . . . . . . . . . . . . . . . . .Accelera tor . . . . . . . . . . . . . . . . . . . . . . .C um ar . . . . . . . . . . . . . . . . . . . . . . . . . .Tensile s trength, psi . . . . . . . . . . . . . . .Elongat ion . per cent . . . . . . . . . . . . . . . .Modulus at 200 per cent elongation,ps i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Air pressure heat test, 20 hr .. .. .. .. .Oxygen bomb test at 70C .. . . . . . . . . .

Compound Conformingto ES - 6a

501053""27.5i ' "20.251.250.25

2300~'260(

Compound Conformingto D 755-43T

321216151530.51.50.250.750.53900 to 1100

Compound Conformingto D 754 - 43 T

351226.751053

800

0.51.750.250 l 51.25i o 1ooo450 to 550

600 . . . . . .o 800 300 to 400

10 to 20 per cent deprecia=] 0 to 10 per cent de prec ia-tion in tensile strength ] tion in tensile strengthafte r 48 hr. I aft er 96 hr.15 to 25 per cen~ deprecia- I 10 to 20 per cen t depreei -ti oni n elongation after[ ation in elongation48 hr. [ afte r 96 hr.

500 to 600 500 to 600250 to 350Gain in tensile strength,25 to 30 per cent de-preciation in elongation





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116 SYkreoslL,~[ ON SYNTH ETIC RUB BERSa s e c o n d v u l c a n i z a t i o n , s u c h a s o c c u r sw h e n i t i s u s e d u n d e r v u l c a n i z e d j a c k e t s ,l o w e r l i m i t s f o r t h e p h y s i c a l a n d a g e dp r o p e r t i e s w e r e n e c e s s a r i l y e s t a b l i s h e dt o c o m p e n s a t e f o r t h e e f f e c t o f th e s e c o n dv u l c a n i z a t i o n .Per fo rma nce Character is ti cs o f G R -S I n-sulat ion:

D a t a o n t h e i n i ti a l p r o p e r t i e s o f G R - Sc o m p o u n d s a r e r e a d il y o b t a in e d a n d h a v e

l o n g e d e x p o s u r e i n a n a i r o v e n a n do x y g e n b o m b a t 8 0 C ., a re s h o w n i nF i gs . 1 t o 4 , a s c om pa r e d t o t h e w e l l -k n o w n n a t u r a l r u b b e r c o m p o u n d s c o v -e r e d b y t h e A . S . T . M . S t a n d a r d S p e c if ic a -t i o n s f o r I n s u l a t e d W i r e a n d C a b l e :C l a s s A O , 3 0 p e r c e n t H e v e a R u b b e rC o m p o u n d (]3 2 7 - 4 1 ) s a n d f o r I n -s u l a t e d W i r e a n d C a b l e : P e r f o r m a n c eR u b b e r C o m p o u n d ( D 3 5 3 - 4 1 ) . 4 I ti s o b v i o u s f ro m t h i s d a t a t h a t t h e a g i n g

t. . . . . ~E 6 0 0 .& J i : - I ~ u~ l t o o i 9 . ii ~ - . : 3 0 0 ~ o -9 i6 0 0 , , ~ . > ~ o] ' ~ ' ~ 0i , i , , :o 2 a 6 8 Jo 0 2 4 6 8 I0T im e, d a ys T i m e , d a y s

Fro. 1.--Effect of Oxyg en Bom b Aging at 80 C. FI6. 3.--Effect of Oxyg en Bom b Aging at 80 C.on Tensile Strength. on Elongation.180C

a ~ l 2 0 C

- ~ 6 0 (

C 0 2 4 6 8 l0T i m e , w e e k s

FIG. 2.--Effec t of Air Oven Aging at 80 C. onTensile Strength.b e e n q u i t e w i d e l y d i s t r i b u t e d , s o t h a tu s e r s o f w i r e p r o d u c t s m a y b e w e l l i n -f o r m e d i n t h i s r e s p e c t . T h e se r v i c e l if ei s a l w a y s t h e c o n c e r n o f t h e u s e r o f a n yw i r e p r o d u c t s i n c o r p o r a t i n g a n e w in s u -l a t in g m a t e r i a l . T h e q u e s t i o n o f a g i n gp r o p e r t i e s a n d e l e c tr i c a l s ta b i l i t y o v e rp r o l o n g e d p e r i o d s i s o f m a j o r i n t e r e s t .T h e e x c e l l e n t a g i n g c h a r a c t e r i s t i c s o fa n E S - 3 4 t y p e o f i n s u l a t i o n , a f t e r p r o -

6 0 0

" - ES-34o

~ lo~,, 0 0 2 4 6T i m e , w e e ks

8 10

FIG. 4.--Effect of Air Oven Aging at 80 C. onElongation.p r o p e r t i e s of t h i s s t a n d a r d t y p e o f G R - Si n s u l a t i o n a r e s u b s t a n t i a l l y s u p e r i o r t ot h o s e o f c o m p a r a b l e n a t u r a l r u b b e ri n s u la t io n s . I t i s t o b e e x p e c t e d t h a tt h e s e n e w i n s u l a t i o n s w i l l p r o v e c o m -p l e t e ly e q u i v a l en t t o r u b b e r w i t h r e s p e c tt o t h e a g i ng e f f e c t i n s e r v i c e .

1 94 2 B o o k o f A . S . T . M . S t a n d a r d s , P a r t I I I , p . 49 4.4 I b i d . , p . 509 .





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S CH A TZEL O N WIRE A N D CA BLE 117TABLE IX. --ELE CTRIC AL CHARACTERISTICS OF GR-S AND NATURAL RUBBER INSULATIONS.

Insulation

ES - 33 (GR-S) . . . . . . . . . . . . . . . . . . .D 469 (natural rubber) . . . . . . . . . . .ES -34 (GR-S ) . . . . . . . . . . . . . . . . . . . . .D 353 (natural rubber) .. .. .. .. .. .EA-DS?4a (GR-S)aD 574 (natural rubb el)a ~iii : : i : ""

Dielectric Constantat 60 Cycles

Specified Actualnot now 4.5

spse,;ified 4,4not now 4.5specified6.0 4.2

5.0 4.65,0 4.2

Power Factor at60 Cycles, per cent

Specified Actu~not speci- 2.0flednot speci- 1.7flednot speci- 2.0flednot speci- 1.7fled

5.0 3 , 95.0 2.5

InsulationResistanceConstant Kper 1000 ft.

Speci- Actualfled2 000 3 500

t5 840 25 0002 000 4 500

21 120 35 0001000 1 8005 280 7 000

_p e r m i l d e g . C e n t .

300 75330 73350 60380 60450 70500 70

a Both t he EA - D 574a and D 574 compounds are eq uiv ale nt in corona (ozone) resist ance.

2 0

15%t -(3")C~ Iot )L"5(9

C21

00 50

IIII

~ " G - - . A " S -- " M

II

- ~ I

? ,II1

I00 150 200 250 300 350TemperQ deg Fahr

F i n . 5.--Change in Dielectr ic Strength (A.S.T.M. Short-Time Procedure) with Temperature.





10/13

118 S Y M P O S X V M ON S Y N T H E T I C R t T B B E R S

4 0 0 0 04 - -q -oo 2 0 0 0 0o .

E I 0 0 0 0co 8 0 0 003E 6 0 0 0du 4 0 0 0co

n , 2 0 0 0co0{.8C

I" ~, ~ D 3 5 3

i I I I 'Ji' 1i

r

i t_ . . _ ~ D 5 7 4

I~ E s - , ~ 4 i

I 0 0 0 ~ _8 0 O6 0 0

EA -D 5 7 , 4o

0 4 8 12 16 20 24I m m e r s i o n T i m e , w e e k s

FTr & - - E f f e c t o f W a t e r I m m e r s i o n ( 60 F . ) o n I n s u l a t io n R e s i s ta n c e .

2 8

2 5gg 4UL .

- ~ 3

I 0

. U n d ~ -U nd erw r i fers ' Type RW (Ru bber)

I I2 4 6 8 I0 12

I m m e r s r o n T i m e , w e e k sFIG. 7 . - - E f f e c t o f W a t e r I m m e r s i o n (6 0 F . ) o n D i e l e c t ri c C o n s t an t .

t

14 16 18 2 0





11/13

SCH A T Z E L O N WIRE A N D CA BL E 1 1 9

Electrical Characteristics of GR-S In-sulations:T h e e l e c tr i c al c h a r a c t e ri s t ic s a n d p e r -f o r m a n c e o f G R - S i n s u l a t i o n s m a y b e

c o n s id e r e d , f o r t h e m o s t p a r t , e q u i v a l e n tto s imi l a r i n su la t ions u t i l i z ing na tu r a lr u b b e r a s s h o w n i n T a b l e I X . I t i st r u e t h a t p e r f o rm a n c e b a s e d o n l o n g-t i m e s e r v ic e re c o r d s f o r G R - S i s u n k n o w na n d , t h e r e f o r e , w e m u s t r e l y u p o nl a b o r a t o r y t e s t s w h i c h h a v e b e e n r e c o g -n i z e d t o b e i n d i c a t i v e o f a c t u a l s e r v i c e .C o n s i d e r a b l e d a t a f r o m s u c h l a b o r a t o r yt e s t s h a v e b e e n o b t a i n e d b y t h e c a b l em a n u f a c t u r e r s a n d t h e r e s u l t a n t i n f o r -m a t i o n d i s s e m i n a t e d i n a n e f f o r t t o e s -t a b l i s h s u i t a b l e i n d u s t r y s t a n d a r d s a sr a p i d l y a s p o s s i b l e d u r i n g t h i s p e r i o d o f" e m e r g e n c y . " I n n o e l e c tr i c al r e s p e c th a s G R - S y e t b e e n f o u n d t o b e a c t u a l l ys u p e r io r t o n a t u r a l r u b b e r . N e a r e q u i v -a l e n c y h a s b e e n f o u n d f o r s u c h i m -p o r t a n t p r o p e r t i e s as d i e l e c tr i c s t r e n g t h ,d ie lec t r ic loss , mois ture re s is tance , e tc . ,a n d t h e d i f f e re n c e s i n m a g n i t u d e b e t w e e nG R - S a n d n a t u r a l r u b b e r f o r t h e s ep r o p e r t i e s a r e b e l i e v e d d u e o n l y t o c o m -p o u n d i n g a n d v a r i a b i li t y o f t h e G R - Sa s p r e v ious ly de sc r ibe d . C e r t a in e l e c-t r i c a l c h a r a c t e r i s t i c s o f G R - S a r e de f -in i t e ly in f e r io r t o c r ude r ubbe r . I n -su la t ion r e s i s t a nc e i s on ly 10 to 30 pe rc e n t t h a t o f a s i m i l a r r u b b e r i n s u l a t in gc o m p o u n d . D i e l e c t ri c s t r e n g t h a t t e m -pe r a tu r e s i n e xc e ss o f ope r a t ing c ond i -t i ons ( F ig . 5 ) i s l owe r f o r GR - S tha nr u b b e r . F o r t u n a t e l y , t h e s e p r o p e r t i e sp l a y o n l y a v e r y m i n o r r o l e i n c a b le p e r -f o r m a n c e a n d a r e b e l i e v e d t o h a v e l i t t l eo r no e f f e c t on a c tu a l s e r v i c e l if e .A l t h o u g h t h e i n s u l a t i o n r e s i s t a n c e o fG R - S c o m p o u n d s i s l o w e r t h a n t h a t o fs im i l a r n a t u r a l r u b b e r c o m p o s i ti o n s , it i ss u b s t a n t i a l l y u n a f f e c t e d a f t e r l o n g p e r i -o d s o f w a t e r i m m e r s i o n , a s s h o w n i nF i g . 6 , a n d m a y b e c o n s i d e re d e q u a l l y a sg o o d a s r u b b e r i n t h i s r e s p e c t. E l e c -t r i c a l s t a b i l i t y i n t he p r e se nc e o f mo i s -

t u r e c a n b e o b t a i n e d e q u a l l y a s w e ll w i t hG R - S c o m p o u n d s a s w i t h r u b b e r a si n d i c at e d b y t h e c o m p a r i s o n of a p r e w a rD 5 74 a n d a s y n t h e t ic E A - D S 7 4 ai n s u l a t io n i n T a b l e X . T h i s i s f u r t h e re m p h a s i z e d b y F i g . 7 , w h i c h c o m p a r e s at y p i c a l G R - S R W ( U n d e r w r i t e r s ' ) i n -s u l a t io n w i t h a c o n v e n t i o n a l c r u d er u b b e r R W w i r e a f t e r l o n g p e r io d s i nw a t e r . P r e s e n t A . S . T . M . s p e c if ic a ti o n sf o r G R - S i n s u l a t i o n s d o n o t y e t c o n t a i nt e mpe r a tu r e c oe f f i c i e n t s f o r i n su la t ionr e s i s ta nc e . W hi l e c e r t a in va r i a t io nsh a v e b e e n f o u n d i n t h i s r e s p e c t , F i g . 8

T A BL E X . - -E L E CT RICA L ST A BIL IT Y INWATER AT 50 C.

Compound

D 574EA - D 574aD 574EA - D 374aD 574EA - D 374an 574EA - D 574aD 574EA - D 574aD 574EA - D 574a

ImmersionTime

24 hr.24 hr.1 week1 week2 weeks2 weeks4 weeks4 weeksI0 weeks10 weeks20 weeks20 weeks

Power Factor,per cent80 v. 40 v.per rail per rail2.6 2.44.0 3.92.8 2.64.1 3.92.9 2.74.2 4.02.9 2.74.3 4.23.1 2.94.6 4.53 3 ~ : ~4. 9

Sta-bilityFactor a

0. 20. 10. 20. 20. 10. 20.10.10. 20. 10. 20. 2

a Stability factor equals power factor at 80 v. per railminus power factor at 40 v. per mil. A stabilit~r factorless than 1.5 is considered electrically stable in the pres-ence of water (after 2 weeks' immersion).

i nd ic a t e s on ly a mino r de g r e e o f d i f f e r -e n c e b e t w e e n s i m i l a r c o m p o u n d s o fG R - S a n d r u b b e r . I n g e n e r al , i t h a sb e e n d e t e r m i n e d t h a t t h e s y n t h e t i c i n -s u l a t i o n s e x h i b i t a s l i g h t l y " s t e e p e r "s l o pe f o r t h i s p r o p e r t y . T h i s h a s n op r a c t i c a l s i g n i f i c a n c e o t h e r t h a n o n e o fm e a s u r e m e n t a n d t e s ti n g p r o c e d u r e a n di t is b e l i e v e d t h a t a f t e r f u r t h e r e x p e r i e n c ea n d t e s t s p r o p e r c o e ff ic i en t s m a y b einc lud e d in the spe c i fi c a tions . A l im-i te d b u t s u b s t a n t i a l a m o u n t o f fi el de x p e ri e n c e h a s b e e n o b t a i n e d w i t h G R - Si n s u l a t e d p o w e r a n d c o m m u n i c a t i o n





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120 SY~POSKT~ ON SYNTHETIC RUBBERSc a b l e s , a n d a c c o r d i n g t o a n y e v i d e n c ep r e s e n t e d t o d a t e , t h e r e i s n o o u t s t a n d -i n g e l e c t r i c a l w e a k n e s s t h a t w i l l d e -f i n i t e l y r e s t r i c t e i t h e r a p p l i c a t i o n o rse rv ice l i fe .Neoprene and Vinyl 2Polymer Compounds:

T h e u s e o f N e o p r e n e a n d v in y s p o l y -m e r c o m p o u n d s f o r s h e a t h s h a s b e e nw i d e l y e x te n d e d b y t h e n e c e s si ty o f s u b -

8 . 07 . 06 . 05 . 084 .0f f

" ~5 . 0t~Q)~ 2 . 0t -O0~ 1 . 0_ 0 . 9o0 . -~ 0 . 6~_0.53 0 4

t h e w i d e r u s e o f t h e s e m a t e r i a l s i t b e -c a m e e s s e n t i a l t h a t s u i t a b l e A . S . T . M .s pe c i f i c a t i ons be e s t a b l i s he d a s i ndus t r ys t a n d a r d s . T h i s w a s a c c o m p l i sh e d d u r -i n g 1 9 4 3 w i t h t h e p u b l i c a t i o n o f t h efo l lowing spec i f i ca t ions :E S - 2 8 5 - - E m e r g e n c y S p e c i fi c a ti o n sf o r C h lo r o pr e ne S h e a t h C o m p o u n d f o rE l e c t r i c a l I n s u l a t e d C o r d s a n d C a b l e s ,E S - 3 0 5 - - E m e r g e n c y S p e c i fi c a ti o n s

I

I K S Y (.cry'J

4 7/

0.3

3 0 a 0 5 0 6 0 7 0 8 0 9 0T e r np e r a f u r e , de 9 . goh r

FIG. 8.--T em pe ratu re C oefficients for Insulation Resistance.s t i tu t i o n f o r n a t u r a l r u b b e r s h e a t h s.T h e q u a n t i t y o f th e s e m a t e r i a l s n o w u s e di n t h e w ir e a n d c a b l e i n d u s t r y i s m a n yt i m e s t h a t u s e d p r i o r t o t h e w a r . Ag r e a t q u a n t i t y o f t h e v i n y l p o l y m e r c o m -p o u n d s h a v e a l so b e e n u s e d a s i n s u l a ti o n .F o r t u n a t e l y , t h e s e m a t e r i a l s h a d b e e ni n s o m e w h a t l i m i t e d u s e f o r a c o n s i d e r -a b l e p e r i o d o f t i m e a n d s e v e r a l i n d u s t r ya n d g o v e r n m e n t s p e c i f i c a t i o n s h a d a l -r e a d y b e e n e s t ab l i sh e d . H o w e v e r , w i t h

f o r C h l o r o p r e n e S h e a t h C o m p o u n d f o rE l e c t r i c a l I n s u l a t e d C o r d s a n d C a b l e sw h e r e E x t r e m e A b r a s i o n R e s i s t a n c e i sN o t R e q u i r e d , a n dD 7 34 - 4 3 T G - - T e n t a t i v e S p e c if ic a -t i o n s f o r I n s u l a t e d W i r e a n d C a b l e :P o l y v i n y l I n s u l a t i n g C o m p o u n d .

5 ES- 28 and E S- 30 have since been accepted as Tenta-tive Sta ndards and bea r the designations D 752 - 43 Tand ]D 753 - 42 T, resp ecti vely , see 1943 Suppl ement toBook of A S T.M. Standards, P art III , pp 449 and 452.6 1943 Supplement to Book of A.S .T.M . Standa rds,Part III, p. 434.





13/13

SCHATZEL ON WIRE AND CABLE 121

T h e s e s p e c if ic a ti o n s h a v e p r o v e d t o b ee x t r e m e l y u s e f u l i n t h e c o n v e r s i o n p r o -g r a m a n d b y t h e i r e x i s t e n c e a l o n g w i t ht h e s p e c i fi c at io n s f o r G R - S c o m p o u n d s ,h a v e p e r m i t t e d r a p i d c h a n g e f r o m o n em a t e r i a l t o a n o t h e r d e p e n d i n g o n t h e i ra va i l a b i l i t y . T he se spe c i f ic a t ions a r eb a s e d o n t h e e x p e r i e n c e o f a n u m b e r o fy e a r s a n d c e r t a i n l y c a n b e c o n s i d e r e ds u i t a b l e w h e n j u d g e d b y t h e s e r v i c eo b t a i n e d .Bu ty l :

B u t y l h a s n o t b e e n a v a i l a b l e i n s u f -f ic i en t q u a n t i t y t o p e r m i t t h e i n d u s t r yt o i n v e s t i g a t e i t t h o r o u g h l y . S o m e p r e -l i m i n a r y w o r k w a s c o n d u c t e d b y t h eT e c h n i c a l C o m m i t t e e o f t h e W a r P r o -d u c t i o n B o a r d , b u t t h i s w a s e s s e n t i a l l yo f a n e x p l o r a t o r y n a t u r e . I t i s n o wu n d e r s t o o d t h a t B u t y l w i l l s h o r t l y b e -c o m e a v a i l a b l e t o t h e w i r e i n d u s t r y a n di t is p r o b a b l e t h a t d e v e l o p m e n t w o r k b yi n d i v i d u a l c o m p a n i e s w i l l p r o c e e d a c -c o r d i n g ly . T h e e x c e ll e n t d i e l e ct r ic p r o p -e r t i e s a nd c he mic a l i ne r tne s s a r e we l lr e c o g n i z e d b u t t h e p r a c t i c a l p r o b l e m s o ftS r oc e s s ing a nd vu lc a n iz a t ion r e ma in tob e s o l v e d .B u n a N :

T h i s m a t e r i a l h a s p r o v e d t o b e s a r i s -f a c t o r y fo r s h e a th c o m p o u n d s , b u t i ts

a v a i l a b i l i t y u n t i l r e c e n t l y h a s b e e n e x -t r e m e l y li m i t ed . T h e p h y s i c al p ro p -e r t i e s a nd o i l r e s i s t a nc e a r e e xc e p t ion a l lyg o o d a n d i t i s t o b e e x p e c t e d t h a t i t su se w i l l i nc r e a se a s i t be c ome s mor er e a d i ly a va i l a b l e .Condus ions :

T h r o u g h t h e s t i m u l u s o f n e c e s s i t yc r e a t e d b y t h e w a r , c h a n g e s h a v e b e e na c c o m p l i s h e d i n t w o y e a r s w h i c h i nn o r m a l t i m e s w o u l d h a v e t a k e n a d e c a d e.T h r o u g h t h e u t i l i z a t i o n o f s u b s t i t u t em a t e r i a l s a g r e a t e r p r o d u c t i o n h a s b e e no b t a i n e d w i t h t h e u s e o f l es s o f t h em a t e r i a l s h e l d v i t a l t o w i r e a n d c a b l ep r o d u c t s , a n d t h i s h a s b e e n a c c o m -p l i s h e d w i t h o u t j e o p a r d i z i n g t h e r e l i -a b i l i t y o f s e r v i c e he ld so v i t a l i n suc hp r o d u c t s . T h e p r i n c i p l e p r o b l e m s n o wa r e t o c o n t r o l t h e v a r i a b l e s r e s p o n s i b l ef o r n o n u n i f o r m i t y i n p r o c e s s i n g a n dc u r i n g , a n d t o o b t a i n g r e a t e r u n i f o r m i t yi n m o i s t u r e r e s is t a n ce . T h e p r o d u c e r so f G R - S h a v e d o n e a n e x c e l le n t j o b i ns u p p l y i n g u s w i t h a m a t e r i a l a s g o o d a sw e h a v e . W e h a v e e v e r y c o n fi d en c et h a t t h e y w i ll p r o d u c e a m a t e r i a l s u p e -r i o r t o n a t u r a l r u b b e r f o r e l e c tr i c al in s u l a-t i o n . W e a c k n o w l e d g e t h e i r c o o p e r a t i o na n d h a i l t h e i r a c c o m p l i s h m e n t s a s a r e a lc o n t r i b u t i o n t o V i c to r y .




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Synthetic Rubbers in Cables & Wire Industry

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