Flame and radiation resistant modification of ethylene-propylene-diene rubber with brominated acenaphthylenes

Radmt Phys Chem Vol 18, No 3-4, pp 701-705, 1981 Pnnted m Great Britain

FLAME A N D R A D I A T I O N

0146--57241811090701-055020010 Pergamon Press Ltd

RESISTANT

ETHYLENE-PROPYLENE-DIENE BROMINATED

MODIFICATION

OF

RUBBER WITH

ACENAPHTHYLENES

M. H a ~ l w a r a

and Y. M o r l t a

Japan Atomlc Energy

Research

Institute,

Radiation

Chemlstry

Research

Establlshment,

Takasall

Takasakl,

Japan

Gunma,

Introductlon The need years b e c a u s e cables

used

radlatlon

for flame r e t a r d a n t of i n c r e a s e d

in a c o n t a l n m e n t

oxldatlon

Furthermore,

contlnuously

intenslty

and s u p e r h e a t e d occurs.

and c a b l e s

durlng

assoclated

acenaphthylenes In order

outl~nes

to e x p o s u r e

However,

the r e s u l t s

of small

and thear c o n d e n s a t e s

propertles

the u s e f u l n e s s

due to / r a y

to s u p e r h e a t e d

there are

some

The b l g g e s t

rubber becomes

of w l r e s

rubber(EPDM)

problem

lower w h e n

at

flame r e t a r d a n t s

w h l c h are b e l n g d e v e l o p e d

to e v a l u a t e

Of C o o l a n t

Ethylene-propylene-dlene

of the b a s e

(OI) and f l a m a n g tlme by a v e r t l c a l in t e n s i l e

llfe of the plants.

when LOCA(Loss

reslstance.

and

where radlat~on wath hlgh

are w l d e l y u s e d as i n s u l a t o r s

such condltlons.

is m l x e d w a t h c o n v e n t l o n a l Thls paper

the w h o l e

polymers

reslstance

in r e c e n t W~res

aglng and slow

w a t h the use of flame r e t a r d a n t s .

is that the r a d a a t a o n

flame r e t a r d a n t s

from t h e r m a l

steam are a v a i l a b l e

as k n o w n to have a good r a d l a t l o n problems

suffer

into a c l r c u m s t a n c e

Hydrocarbon

used u n d e r

has i n c r e a s e d m a r k e d l y

on safty of n u c l e a r plants.

vessel

they are b r o u g h t

Accadent)

polymers

emphasls

were

scale p e r f o r m a n c e

for m o d l f y l n g syntheslzed

of the f l n a s h e d flame

tests of new

EPDM

Bromanated

as the flame retardants.

compounds,

oxygen

index

test m e t h o d w e r e m e a s u r e d

irradaataon

and In ~ n s u l a t a o n

Changes

reslstance

due

w a t e r w e r e also m e a s u r e d .

Experlmental The flame r e t a r d a n t s

used

in thls w o r k w e r e

syntheslzed

by f o l l o w l n g

steps

__Synthesis of Brommated Acenaphthylene Sduble with hot acetone F, BrCH-CHBr Acenaphthene (ZnCI2cF, COOH) L~ (Br) Br

Monomer BrC:CH

1

(Br) Br

/ KOH

:1~ J C2HsOH

or FeCI~ ~n CC[4

Jn C~H6

Acenaphthylenes-

Condensation Product Insoluble • [ BrC:C(H)

5-10"C,dark

hot acetone

B

Br 701

=2-

702

M HAGIWARAand Y MORITA

For the syntheszs of monomerlc acenaphthene

was

CF3COOH

as c a t a l y s t s .

chalns,

the catalysts were

a n d the b r o m z n a t z o n

In o r d e r

was

temperature. accomplzshed

obtazned

by recrystalzzatzon

natlon was

unnecessary

EPDM was usual

peroxlde

wzde

wt =435,

wlth

f r o m Its a c e t o n e

solutlon.

The

For the preparatzon

a pressure

OI

was

measured

and

3 mm

thlck speczmen

3 mm

t h z c k a n d 127 m m

Fzg.

1 shows

content

long

tester,

Results a relatzonshlp

mol wt.=856,

to J I S - K 7 2 0 1 ,

flame test method

recorded by Instron tensile

zn one molecule

also a mlxture

together

and then wlth

zn w h z c h

the u s e o f a 6.5 m m

Flame retardant base on UL-94 speczmen.

Model

propertzes were

standard uszng

Tensile propertzes

1130.

and D1scusszon

between

acrylate)

DBDPE(decabromodzphenylether) as r e f e r e n c e m a t e r i a l s

OI

40 n-BACN

and

were

f o r the

dlcumyl

into requzred

in t h e c o m p o u n d s .

PBPA(pentabromophenyl

con-

Br cont.=65.2%)

flame retardants

fznally molded

zs s p e c l f z e d .

were

izght

o f 100 k g / c m 2 for 30 m z n .

accordzng

also tested by a vertlcal

for the bromz-

s t a t e d in t h l s p a p e r w a s

o n a h o t r o l l at 1 2 0 ° C , compound was

acenaphtyl-

mon-BACN was

3 or 4 brom&nes

one of the above

at an

of zncandescent

con-BACN was

and trzmers(average

ingredlents

n e a r 40 - 5 0 ° C

a 12.7 mm wlde,

contaznlng

Br cont.=65.5%) .

fzrst mlxed wzth

at 1 6 0 ° C u n d e r

mon-BACN

izght

to b r o m z n a t e d

alc. K O H .

lllumlnatlon

the reactzon,

derlvatzveS

of dlmers

rubber

and bromlne

and washlng wlth water, incandescent

of intermedlates

In t h l s c a s e ,

throughout

of monomerzc

szstzng mostly

shapes

Converszon

under

ZnCl 2 and

at s l d e m e t h y l e n e

B A C N ( c o n - B A C N ) , F e C I 3 w a s u s e d as t h e c a t a l y s t

(average mol.

with

10°C uslng

the reactlon

by dehydrobromlnatzon

of acenaphthene.

a mzxture

to c o m p l e t e

removed by flltratlon

elevated

condensed

acenaphthylenes(mon-BACN) ,

in d a r k b e l o w

further contznued

enes was

of

bromlnated

flrst bromznated

used

apprecla3 =.

tlon of

effectzveness

retardants.

OI

the b r o m l n e

content

s h o w n In F1q.

of the n e w

Increased

flame

iznearly wlth

zn all c a s e s .

As

i, t w o B A C N s w e r e m o r e c 3C

effectzve

than the reference

retardants, ~uperlor

and condensed

to m o n o m e r l c

showed phenomenon

of

one.

flame

type was The latter

so c a l l e d

"bloomlng". 25

C o m p o s l t l o n o f the c o m p o u n d s (wt. ratzo) EPDM(100) , Talc(100) , Flame r e t a r d a n t ( 3 0 - 6 0 ) , S b 2 O a (6-15) , H e a t - s t a b . (1.5), S t e a r l c a c l d (i) , S u l f u r ( 0 4) , ZnO(5) D1cumyl peroxlde(3)

3L 2C i

i

o,

0.2 Br

Fig.

1

OI v s

Content

o'3 (glg-EPDM)

Br content

i

05

Flame a n d r a d m t m n resistant modtficatmn of b r o m m a t e d a c e n a p h t y l e n e s

703

In the flame test for m e a s u r l n g OI accordzng to JIS-K7201, the flame propagates downwards slnce the speclmen supported w l t h zts longztudlnal axls vertlcal in a glass c y l l n d e r is zgnzted at its top end.

On the other

hand, zn the test descrlbed in UL-94 standard, the speclmen is zgnlted at zts b o t t o m edge so that the flame propagates upwards.

F r o m a practzcal

poznt of vzew, the vertlcal flame test of the latter type is m o r e suztable for 3udg~ng s e l f e x t l n g u l s h l n g propertles of plastlc or rubber materaals. Table 1 shows the results of the test carrzed out wzth reference to the UL-94. Table i. No of

none

1

Flamlng tlme zn UL-94 vertzcal flame test

BACN 30phr 60phr

burnt

flamlnE tlme (sec) con-BACN DBDPE 30phr 60phr 30phr 74phr

PBPA 30phr

0

0

0

0

0

0

0

2

0

0

45

0

0

0

5

3

0

0

5

0

0

0

0

4

2

4

7

0

0

0

5

5

0

0

0

0

37

0

15

0

40(d)

6

0

1

0

0

0

7

ll(d)

0

3

0

1

8

2(-)

8(d)

0

0

9

2(-)

47

0

0

0

0

0

i0

i(,,)

21(d)

17(")

15(d)

9(")

25(d)

lO(d)

burnt

burnt

burnt

d: burn w z t h d r l p p l n g A test flame was d l r e c t e d to a test sample for i0 sec, and removed

If the

sample was ignzted, flamlng(burnlng) t~me was measured, and the test flame was reapplzed w h e n the flame w e n t out.

Thzs procedure was repeated ten

tames(ten rounds)

The shorter the flamzng tlme, the

zn the present work.

better the self-extlngulshang propertles of the compound. that ezther of BACNs(mon- and con-BACN) flame retardants.

Table 1 shows

zs b e t t e r than any of the reference

It also shows that c o n - B A C N prevents dr~ppzng effectzvely

Fzg. 2 shows the thermal v o l a t l l z z a t z o n curves of the compounds Fig. 2

0--0

........

1(]

TG Curve of FR EPD~

L

~

Icon-BACN DBDPE',x~

72o Ul o30 .-I F R , 30PHR

60

i

I

BACN

i

300

I

400

i

I

500

Temperature (°C) o

Heatzng rate = 15 C/mzn,

i

I

600

~

I

70u

704

M HAGIWARAand Y MORITA

BL r e f e r s

to the c o m p o u n d s c o n t a l n l n g no f l a m e

retardant

accelerates

and g l v e s

stable

In c o m p a r z s o n zn the

was

as a f u n c t z o n

decomposltzon

amount

Every

stage(blow of E P D M ( 5 0 0

less e x t e n t

flame

450°C), - 600°C).

of the a c c e l e r a t l o n

of the s t a b l e

reszdue

effectlveness

at h z g h

of B A C N s m a y

behavzour.

by f o l l o w z n g

of i r r a d z a t z o n

show

retardant

~n the e x p e r z m e n t a l

evaluated

retardant.

zn l n x t z a l

BACNs

flame

such volatzlzzatlon

As d e s c r l b e d

Fig.

rapxd

and gzve much

The o b s e r v e d

from

compounds

after

P B P A or DBDPE,

stage,

temperature. results

reszdue

wzth

xnltzal

the v o l a t z l z z a t z o n

dose

sectzon,

radzatzon

the v a r z a t z o n

of

/-ray.

stabzlzty

of t e n s i l e

The r e s u l t s

of the

propertles

are

shown

zn

3. con-BACN(30)

,ooo

P

con-BACN(60)

Flg.

i

3.

Effects

zrradzatzon

of ~ - r a y

on t e n s z l e

propertxes

5OO

Irradlatzon condltlons 5 5x10 r a d / h r , r o o m temp. Tensxle

c

o_

speed:

500mm/mln

200

o~ 100 (.9o UJ

50 • 200 • 300 • 400 • 5O0 I

20 10

Tenszle

wlth

elongatlon

As

%n Fzg.

used.

The c o m p o u n d

contalng

it is c l e a r con-BACN

slmzlar

even

When

has

gzves

elongatlon

protectzve

stabalzty

of B A C N h a v l n g

dlsszpate

radlatzon

energy

In o r d e r

radlatlon Flg.

4.

exposed spray

to e v a l u a t e

reactor and

shows

cables,

superheated the c h a n g e

to h z g h

absorbed

the

fused

steam

manner.

below

50%

propertles.

P B P A or D B D P E

protectxve

more

than

of 500 M r a d

rzng whzch may

of D B D P E effect.

100%

and

of /V-ray.

T h l s m a y be a t t r l b u t e d

aromatlc

falls

decreases

in the c a s e

a strong

irradzatzon

effect.

to

surve

to

zn the c o m p o u n d s .

to k n o w

of B A C N s

radzatzon

as f l a m e

the e f f e c t s

on z n s u l a t a o n

xn i n s u l a t l o n

temperature,

In a s e q u e n t l a l

tensile

the u s e f u l n e s s

we h a v e

when

Mrad

that con-BACN

after

becomes

mechnlcal

decreased 200-300

stab11-

samples

The e l o n g a t a o n

its u s e f u l was

radzatzon

of our

the e l o n g a t l o n

loses

in b e t w e e n

resonance

nuclear

elongatlon

of PBPA.

reslstance

exzsts

flexzbzllty

showed

dose. rubber

for d e t e r m l n l g

tensile

the c a s e

3, r a d l a t z o n

hand,

mon-BACN

except

The end p o l n t

enough

I

12

Oraglnal

xrradlated

On the o t h e r

retazns

I

10

is one of g o o d m e s a u r e s

Irradlatzon

the

I

08

Strength (Kg/mm2)

materlals.

increaslng

shown

I

of 6 0 0 - 7 0 0 %

(end p o l n t ) ,

was

con-BACN (60)

04 06 Tensile

ity of r u b b e r in a r a n g e

.

propertzes

reslstance and

speczmens

llquld

dzfference

for

agzng,

of the c o m p o u n d s .

when wlre

superheated

No a p p r e c l a l b l e

retardants

of t h e r m a l

were

for c h e m z c a l

in i n s u l a t z o n

Flame and radmt~on resistant modtficataon of brommated acenaphtylenes

705

reslstance b e t w e e n each was o b s e r v e d t111 the end of the ~rradlatlon stage. However,

a rather large dlfference was observed after the wlres had been dlpped in water for chemlcal spray ~

5

~

at 150°C for 24hr.

Very sharp

drop of the reslstance ~s caused by

2

io '3

\\

5

0 con-BACN

0

that the m e a s u r m e n t was carrled out at 150°C.

F~g.

4 shows that the

wlre insulated by the compound

2

contalnlng con-BACN glves the smallest

1012

drop, and that if m e a s u r e d at room

E

s

temperature,

S

2

recovered to the value recorded

,01' Z

is

before the treatment wlth superheated water.

5

U~ N

the resistance

Thls means that no permanent

change takes place durlng the treatment. 2

ld °

g

Concluslon

~

As new flame retardants

2

~ i 0 !I u~ z 5

m o n - B A C N and con-BACN were syntheslzed. Both showed excellent performance as flame retardants,

2

and act as ant~-

radlatlon agents.

Wires insulated by

E P D M whlch was modlfled wlth con-BACN

5

showed a satlsfactory d u r a b l l l t y in a

[]

2

10~

d e t e r l o r a t l o n test. I

I

I

I

I

[

,

In the test,

I

wlre speclmens was exposed sequentlally to hlgh temperature(121°C, ~

{,/')

/-ray(200 Mrad)

.

(150°C,

~

u- r

LLI

~

t.LI

-r L)

Fig.

4. Change in insulatlon reslstance

due to a sequentlal e x p o s u r e

to thermal

aglng condltlon, /-ray and superheated water

for

nuclear power plant cable insulatzon,

24hr).

168hr),

and superheated w a t e r