Radiation polymerization in the emulsion systems

Radiation polymerization in the emulsion systems

PAys.CAc~n.Vol. 18,No. 5-6,pp. 1109-1123,1981 Printedin GreatBritain. 0146--572d/lll/lll109-1J~d}2.00/0 (~ 1981PerllumoaPressLtd. R=d/aC RADIATION ...

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PAys.CAc~n.Vol. 18,No. 5-6,pp. 1109-1123,1981 Printedin GreatBritain.

0146--572d/lll/lll109-1J~d}2.00/0 (~ 1981PerllumoaPressLtd.

R=d/aC

RADIATION POLYMERIZATION IN THE EMULSION SYSTEMS F. S u n d a r d i , A. Z u b l r and Centre for the Application and R a d i a t i o n P . O . BOX 2 KBL J a k a r t a ,

I. Marllyantl of Isotopes Indonesia

Abstract Klneflcs aspects of radiation polymerization of methylm e f h a c r y l a t e , s t y r e n e and v i n y l a c e t a t e monomers In t h e e m u l s i o n s y s t e m s h a v e been s t u d i e d . A p a n o r a m l c gamma s o u r c e w i t h an a c t i v i t y o f a b o u t 7 0 , 0 0 0 CI was e m p l o y e d as a v a r i a b l e dose rate irradlator. Influence of the emulsifier c o n t e n t and i r r a d i a t i o n d o s e r a t e on t h e r a t e o f p o l y m e r i z a t i o n and t h e m o l e c u l a r weight o f t h e p r o d u c t s h a v e been s t u d l e d . In t h i s study, Smith-Ewarf r a t e t h e o r y was used t o e x p l a i n the experimental results. Tween 20 was used as t h e e m u l s i f i e r . In t h e c a s e o f v i n y l acetate monomer, I t was f o u n d t h a t t h e I r r a d l a t l o n dose needed for obtaining a certain degree of conversion Increased with the Increase of the emulsifier content. However, in the case of s t y r e n e and m e t h y l m e t h a c r y l a f e monomers i t was f o u n d t h a t t h e irradiation dose n e e d e d f o r o b t a i n i n g a certain degree of conversion decreased with the rncrease of the emulsifier c o n C e n t . The m o l e c u l a r w e i g h t o f p o l y m e r s , w e r e f o u n d t o be much I n f l u e n c e d by the Irradiation dose rate, emulsifier c o n t e n t and t h e d e g r e e o f conversion, t f was f o u n d ~ h a f t h e t h r e e monomers showed d i f f e r e n t characteristics, Several deviation from Smlth-Ewart rate theory h a v e been d e t e c t e d .

1109

1110

F. Sut,m.,~.D[ et al.

INTRODUCTION

The mechanism of rally

emulsion p o l y m e r i z a t i o n which is now gene-

accepted Is based on the work done by Harkin and h i s c o l -

l a b o r a t o r , p u b l i s h e d in 1974 ( I ) was f i r s t

The q u a n t i t a t i v e d e s c r i p t i o n

given by Smith and Ewart (1948) and is known as the

Smlth-Ewart r a t e t h e o r y ( I ) .

According to t h i s

t h e o r y , the p o i y -

m e r i z a t i o n r e a c t i o n can be devlded i n t o t h r e e stages. The f i r s t stage

is the p a r t i c l e

f o r m a t i o n . The r a t e of

depends on the r a t e of emulsifier,

it

particle

formation

r a d i c a l s p r o d u c t i o n and the amount of

Is assumed t h a t the p a r t i c l e s f o r m a t i o n s t a r t s

w i t h i n the e m u l s i f i e r m i c e l l e s and grow w i t h the monomer supply from the d r o p l e t s . During t h i s appear to

stage,

some of the m i c e l l e s d i s -

balance the growing p a r t i c l e s .

m i c e l l e s disappear and the p a r t i c l e s

Finally,

all

the

f o r m a t i o n stops.

The second one is the stage between the disappearance of m l c e I l e s and the disappearance of polymerization rate

droplets.

In t h i s

stage, the

is c o n s t a n t . According t o the Smith-Ewart

rate t h e o r y , the p o l y m e r i z a t i o n r a t e can be w r i t t e n

:

m

Rp = kp N (M)/2N A where

N Is the

number

is the m o n o m e r Avogadro sion

content

number.

systems,

be a s s u m e d

of

As

polymer

in the

long

polymer

as the

the m o n o m e r

to be c o n s t a n t

particles

and

particles

droplets

content

still

in the

hence

per volume and

the

NA

exist

polymer

unit,

(M)

is the

in the

particles

polymerization

emulcan

rate

will

be constant. The

third

In this

stage,

decrease

with

nelghbourlng rate will This induced under

Is the

the m o n o m e r time

decrease paper

that

dose

speaking,

Hence

disappearance

In the

absent

in this

polymer

supply stage,

of

droplets.

particles

of m o n o m e r the

w~ll

from

the

polymerization

time. the rate of

@xperimental which

between

dose

rates

Is not much

results has

been

on

radiation

carried

20 to 80 krad/hour,

investigators

irradiation there

the

content

polymerization,

a number

but at d i f f e r e n t nerally

wlth

presents

emulsion

after

due to the

droplets.

irradiation

be noted

stage

also and

out It must

work on this procedure

difference

in the

field,

2-6).

Ge-

reaction

Radiation polymerization in the emulsion systems

kinetics and

between

radicals

llqued

enter

into the

the

polymer

by the

advantages

of

polymer

chemical

obtained

Inltlator

from

production

independent from

either

Hence,

radicals

water

in the

phase

one

Some of the

for

do not by one

potential

chemical

initiation

are

is c o n s t a n t

throughout

the

and

radiation

the

difference

polymerization,

particles.

the

over

The main

phases,

theory.

Initiation

radicals

temperature

the

polymer

rate

polymerization

emulsion

polymerization,

particles

radiation

induced

at all

in the

Smith-Ewart

rate of

reaction,

or

emulsion

emulsion

po!ymerlzation.

occurs

micelles

induced

induced

radiation

production

phase,

as stated

that

emulsion

in the case of

radiation

the

radiation

heat or chemical

is that the

the

I 111

easy

to control.

polymerization

Furthermore,

is free

from

residues.

EXPERIMENTAL Irradiation

facility

A panoramic

gamma

70,000 these thw

CI of Co-60, experiments.

well

known

20 to 80

Irradlator

was

employed

Dose

Frlcke

krad/hour

with

as an

an a c t i v i t y irradiation

rate m e a s u r e m e n t s

Dosimeter.

were

employed

were

Irradiation for these

of

about

source

carried

dose

for

out

rates

using

between

experiments.

Materials Monomers (MMA)

and

nique

under

sorbltan was of

such

styrene

as vinyl (St)

reduced

synthetical water

grade

was

Experimental The

emulsion

(Tween

water

water

: monomer

= 70

vessel.

irradiated

The

HLB

without

distillation

tech-

polyoxyethylene

value

of about

further

preparation

dose

and

sion of the

polymer

by graphical

were

prepared

and m o n o m e r s

with

: 30 and a c e r t a i n emulsion

in glass

irradiation

slmeter

by using

emulsifier, with

used

for the

samples

dlstllled

were

The

20),

methylmethacrylate

13.3

purification

(7).

of the e m u l s i o n .

procedure

re of

a glass

and

used

(VAc),

purified

pressure.

monolaurate

Distilled

were

acetate

samples,

vessels

irradiation was

then

by stirring the

quantity

with

of about dose

at

of e m u l s i f i e r ,

in

composition,

with

Percentage

with

zero

a mixturatio of

a certain 100 ml

rate.

determined

extrapolation

weight

a certain of c o n v e r -

an U b b e l o h d e

concentration

viscoof

the

1112

~

F. SUND~tl)I et aL

sp/C

values at different

of the polymer

was determined

case of MMA polymer, can be computed

concentration. using Mark-Ho

the viscosity

according

weight

wink equation.

average molecular (2) :

In the

weight,

Mv,

to formula

~ = 1.81 x 103 [~]

1.22

Where P is the degree of polymerization sic viscosity

The molecular

end ~

is the

intrin-

in CHCL 3 solution.

RESULTS AND DISCUSSION I r r a d i a t i o n dose r a t e I r r a d i a t i o n of the emulsion samples were c a r r i e d o u t glass vessels of

100 ml.

in

The i r r a d i a t i o n dose r a t e s used f o r these

experiments were 20,40,60,70 and 80 k r a d / h o u r . The i n f l u e n c e of

I r r a d i a t i o n d o s e r a t e on the average r a t e of

been s t u d i e d .

In t h i s

case, the average r a t e of

p o l y m e r i z a t i o n has polymerization

means the average r a t e of p o l y m e r i z a t i o n between 15 t o 85% conversion. I t Rp, is

is found t h a t the average r a t e of

of

polymerization,

p r o p o r t i o n a l to the 0.46 power o f the i r r a d i a t i o n dose

rate, I,

e i t h e r f o r the MMA or VAc emulsion ( F i g . l ) .

average r a t e of

Hence t h i s

p o l y m e r i z a t i o n can be w r i t t e n f o l l o w s : Rp = k ( I )

0.46

where k Is a c o n s t a n t . Smith-Ewart r a t e t h e o r y p r e d i c t s t h a t the p o l y m e r i z a t i o n r a t e Is p r o p o r t i o n a l to the 0.4 power of the r a d i c a l p r o d u c t i o n r a t e . A p p a r e n t l y , t h e r e is not much d e v i a t i o n of the r e s u l t s from the Smlth-Ewart r a t e t h e o r y . However,

it

must be noted t h a t

the p r o p a g a t i o n r a t e c o n s t a n t , k,

f o r the VAc monomer is much (8) h i g h e r than f o r MMA monomer. According t o the l i t e r a t u r e , the

propagation r a t e konstant k f o r VAc monomer is about 2640 l i P t e r / ( m o l e ) ( s e c ) and f o r MMA monomer is about 410 I i t e r / ( m o l e ) (sec).

E x p e r i m e n t a l l y , the average p o l y m e r i z a t i o n r a t e of MMA

emulsion was found to be h i g h e r than f o r the VAc emulsion. Hence computed from the Smlth-Ewart r a t e t h e o r y , the monomer content in the poly-MMA p a r t i c l e s must be h i g h e r than the monomer content In the poly-VAc p a r t i c l e s , p r o v i d e d a l l same.

It

is d i f f i c u l t

the parameters are the

to measure the monomer c o n t e n t in the po-

Radiation polymerization in the emulsion systems

Iymer tage

particles,

but

conversion

It can

vs

roughly

irradiation

be computed

that

Is roughly

partlcles

or VAc monomer

nomer

reason,

the

is higher

the

factor

If thls

such

In the

case

deviation to thls to the

of

of

that the

content

is true,

the

Friis

model,

the

average

0.5

power

of c o n v e r s i o n

there

VAc e m u l s i o n

from

of the

was

MMA

must

initiator

dose

needed

found

to

rate

(Fig.2),

this

experimental

according

rate of MMA

with

either

differences and

rate (10)

is a slight according

is proportional

a

the

certain increase

support

degree of the

for MMA or VAc

results

in

VAc emulsion.

in which

obtain

be due to

per unit of volume.

there

content.

mo-

diffe-

but may

MMA

model,

increase

in p o l y - M M A

Hence,

be some

between

to

dose

monomer

partlcles

polymerization

that

emulsion.

the

previuos

(Fig.l}.

Emulslfler

content

Smlth-Ewart tlcles

rate

per volume content

duced

the

that

of emulsion power of

to the

emulslfler

the 1.38

to the

difference

difference

radlatlon

Induced

emulsion A

great

found

on the

whlch

the

to the from

that

0.86

of

parof the

it can

second

is proportional

for

styrene

rate,

emulsion

radiation

Rp

be de-

stage

to the

0.6

monomer

e-

, is proportional

content,

power

particles

deviation VAc

point

rate of the

and for MMA

of the e m u l s i f i e r

the S m i t h - E w a r t

rate

formation

polymerization

polymerization

average

this

number

0.6 power

content.

polymerizatlon

of the

the

to the

From

reaction

of the e m u l s i f i e r

Is proportional

A slight

emulsion.

results, show

average power

that

polymerization

polymerlzation

the

predicts

is proportional

In the

average

Experimental mulslon,

theory

unit

emulslfler

tion

polymer

Is not due to the

Nyhagen

It Is clear

slon

technique

polymerization,

and

Irradlatlon data

this

particles,

formation

percen-

in the

polymerization

of

the

(M}

particles.

in the

number

particle

Irradiation

for e i t h e r

from

Using

content

in p o l y - V A c

as the

assumption

the m e c h a n i s m

curve.

for VAc monomer,

rence of the m o n o m e r other

dose

same

fact

than

be computed

the monomer

particles

to thls

it can

1113

and

theory

emulcontent.

may

be due

mechanism

between

chemical

initia-

(Fig.3).

from

Smlth-Ewert

Induced

polymerization

emulsion

rate,

~

rate

theory

was

polymerization, , is proportional

in

1114

F. Stmo,,w,m et al.

approximately average

rization

content.

that

Increase are

particle the

the

of

rate

on VAc

in quite

different due to the

mer,

as stated Fig.4 needed

with

the

case

of

degree

of

conversion

the

previous

Intrlnsic The

data

and

trinsic

and

St monomer,

dose

is found

increase

of

case

viscosity

irradiation

dose

have of

induced

been

of

studied

rate.

with

it

the

It is clear

that

increase

of

vely

transfer

constant

to polymer.

intrinsic

is d i f f i c u l t

viscosity

It is found

increase

can

be e x p l a i n e d

of the

increase

of

increase

that

of the

fact

content.

that

the

emulsifier

polymer of

that

the

increase

of

the

result theory.

viscosity

intrinsic relati-

dose

rate

is c o n t r a The has

influence also

been

increases

experimental

polymerization

content.

and

increase

irradiation

This

in-

of c o n v e r s i o n

viscosity

intrinsic

emulsifier

of

is due to the

of

rate

intrinsic

the

irradiation

polymerization

However,

increase

Smith-Ewart

on the

by the

the

conversion

the

and

is found

Thi~ experimental

classical content

the

the

with

to explain.

to the

of e m u l s i f i e r

with

a certain

support

solution

increase

the

studied.

in the

(Fig.5-7).

VAc monomer,

increases

the

emulsion

with

dictory

the

results

content

viscosity

radiation

VAc m o n o m e r s the

emulsifier

intrinsic

from the

high

decreases

to o b t a i n

with

experimental

to poly-

However,

needed

of

irradiation

of c o n v e r s i o n

viscosity

of

the

content.

This

solubility

transfer

degree

poly-

two m o n o m e r s .

high

content (10) investigator

emulsifier

to

emulsion

(fig.3).

influence

In

high

that

viscosity

rate on the

obtained

the o t h e r

re-

on the

be c o n c l u d e d

induced

relatively

previous

These

also

with

theory

it can

irradiation

content.

radiation

decreases

rate

a certain the

VAc monomer,

emulsifier

MMA

of

gamma

rate

polyme-

Smith-Ewart

with

for MMA

to o b t a i n

Increase

the

dose

that

of the

radiation

experimental

to the

by some of

shows

dose

and

increase

The

This

radiation

might

in water

the on

content.

c o n t e n t (9)

Hence,

difference VAc m o n o m e r

with

intermittent

to the

merization

be

emulsifier

polymerization

mechanism.

formation

the

investigation

the e m u l s i f i e r

contradictory

of

decreases

using

average

formation

particle

power

Previous

of VAc e m u l s i o n

concluded

sults

-0.37

polymerization

emulsifier

the

to the

rate

with

result decrease

Radiation polymerization in the emulsion systems

in

the

influence of

case

of MMA monomer,

it

is f o u n d

1115

that

the

I r r a d i a t i o n dose rate and conversion on the i n t r i n -

sic v i s c o s i t y or v i s c o s i t y average molecular weight, M--~, is not clear.

It

Is well known t h a t MMA monomer has low value of t r a n s -

fer constant,

CTable 1 ) .

REFERENCES

I . Van der H o l t , B.M.E. " K i n e t i c s of emulsion p o l y m e r i z a t i o n " Adv. Chem. Series, 34 (1962) 2. D i e t e r Hummel, Gregor Ley and C h r i s t e l Schnelder."Radiation induced polymerization of some v i n y l monomers in emulsion systems". Adv. Chem. Series, 34 (1962) 3. Gregor J.M. Ley, D i e t e r Hummel and C h r i s t e l [email protected] "Gamma r a d i a t i o n induced polymerization of some v i n y l monomers In emulsion systems". Adv. Chem. Series, 66 (1967) 4. Stahel, E . P . and Stannett, V.T. "Chemical Engineering studies In r a d i a t i o n p o l y m e r i z a t i o n of v i n y l monomers. Emulsion p o l y m e r i z a t i o n " . Large r a d i a t i o n sources f o r Proc.

i n d u s t r i a l processes.

Symp. Munich 18-22 August (1969)

5. Osamu Matsuda, Jero Okamoto, Yoneko Tabata and Sueo Machi. "Rad i a t i o n induced emulsion p o l y m e r i z a t i o n of t e t r a f l u o r o e t h y l e n e with propylene. V[ Effects of prssure and temperature". J. Appl. Polym. S c i . ,

14, 2307 (1976)

6. Tsal, J.T. Stahel, E . P . and Stannett, V.T.

"The r a d i a t i o n

Induced emulsion copolymerization of v l n y l c h l o r i d e with v i n y l acetate In an engineering flow system" J. AppI.

Polym. S c i . ,

23, 2701 (1979) 7. Baue Becher, "Emulsion-Theory and P r a c t i c e " . Reinhold Publishing Corporation, 168-208 (1957) 8. Raymond B. Seymour. " I n t r o d u c t i o n to polymer Chemistry". Mac Graw H I l l

Kogakusha, Ltd, Tokyo (1971)

9. Sundardi, F. "Emulsion p o l y m e r i z a t i o n of v i n y l acetate i n i t i a t e d by i n t e r m i t t e n t gamma r a d i a t i o n " . J. Appl. Polym. S c i . , 24, 1031 (1979).

1116

F. Stn~ARl)i et aL

Table

I. R a d i a t i o n monomer. dose the

induced

emulsion

Influence

rate on the polymer. MMA

Irradiation

polymerization

of c o n v e r s i o n

average

Composition : Water

and

viscosity

20

irradiation

molecular

of e m u l s i o n

: Tween

on MMA

= 30

of

: : 70

: 2

Conversion•

Intrinsic viscosity

11 .I

8.1

2,322,000

33.7

6.0

1,610,000

62.1

3.7

893,000

74.8

3.2

748,000

92.3

3.7

893,000

93.8

2.9

663,000

94.9

2.9

663,000

14.1

2.7

604,000

36.7

4.0

dose rate,

FV

krad/hour 80

60

40

20

NOTE

88.0

3.7

990,000 890,000

91 .7

2.1

456,000

97.7

1.8

366,000

34.3

3.1

734,000

87.0

3.6

875,000

90.1

3.3

771,000

95.0

3.2

763,000

97.7

3.2

763,000

72.0

3.81

926,000

93.6

2.89

661,000

94.2

2.71

611,000

: The v i s c o s i t y according

to

molecular formula

:

P = 1.81 where

F = degree

weight

v



can

(2)

x I03 E~],] 1.22

of p o l y m e r i z a t i o n .

be c a l c u l a t e d

Radiation polymerization in the emulsion systems

1117

200 MMA AoA'~~ VAc

~

l:Z O °~ I,,.-

> cO U

O..O-"

/o

O

10

I

10

I

lrradialion

I

rate

RPC Vol. Ig. No. 516-~

: Monomer

I

I

I

1 dose rate on the average

induced emulsion polymerization,

Rp, at the conversion Water

I

dose rate, krad/h

of irradiation

of r a d i a t i o n

I

100

Figure Influence

I

between

15 to 85/~.

: Tween 20 = 70

: 30

: 2

200

1118

F. Sumx~mmet aL

200 "C3 I-

0

/

0 "0

c 100

/° ~.-"~_a/+~

.-"

0 ° ~

..0

lb.-

0

I

i

0

i

I

I

i

i

I

I

I

50 100 Irradiation dose rate, krad/h Figure

Radiation

induced

Influence

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

dose needed

2

emulsion

to o b t a i n

polymerization.

dose

rate

a certain

conversion. 0 @'

0

VAc

, 80%

conversxon



VAc

, 70%

conversxon

A"

A

VAc

, 50% c o n v e r s x o n

@'

÷

VAc

, 30% conversxon

O .... O

?o~A , 7 0 %

A .... A

~4A

, 50% c o n v e r s x o n

• ....

~A

, 30%



conversxon

conversxon

on the

degree

of

Radiation polymerization intheemulsion systems

-0 +-+ o-o

VAc, 60 “lo VAc,70% VAc, 50% VAc > 3OOlo

-.-a0 A -.-.-A l -.-.a

,70 ‘lo MMA ,50 O/t, MMA , 300/o

0

A-A

0

0

Xgure

1

1119

0 St, A ---A St,

0

7o”to

we..

a---=

MMA

2 3 4 5 Emu&if ier content Wt part 1100 mon + Gater

St

50% 1

30%

‘P \

.\

\ Q

6

3. Radiation induced emulsion polymerization of some monomers. Influence of emulsifier content on the irradiation dose needed to obtain a certain degree of conversion. Konomer : Vater = 30 : 70

1120

F. S t n ~ t

et al.

400

f J:

••A•

100

cO I,-

> cO U

y

0

MMA

VAc ~.

/

o/o

/

o

/

o

St 10

e

05

,

I

I

I

I,

I

I

I

A,

'

e

1 2 3 4 5 Emulsifier c o n t e n t , w t part / 100 Water + monomer Figure 4

Influence of emulsifier content on the average rate of radiation induced emulsion polymerization, ~ . Irradiation dose rate : 80 krad/hour.

l

10

Radiation polymerization in the emulsion systems

10 0--0

\

A--A O--O

1121

80 krad/h 60 krad/h 40 krad/h

U

> U

5 A

0

0

50 Conversion Figure

Radiation

induced

100

5

emulsion p o l y m e r i z a t i o n

of MMA monomer.

Influence

and i r T a d i a t i o n

dose rate on the intrinsic

viscosity

of the p o l y m e r

of c o n v e r s i o n solution

in

chloroform. MMA

: Water

: Tween 20 = 30

: 70

: 2

1122

F. SU'ND~,~Iet aL

4

U1

0

0

U U')

>

2 °

^ ~~..._-&-e

U U) E

e---

/"

~

I,._ D

E

0

I

I

I

I

I

I

I

50

0

Conversion,

i

100 %

Figure 6 Radiation induced emulsion p o l y m e r i z a t i o n of vinyl acetat (VAc). Influence

of con-

v e r s i o n and emulsifier content on the intrinsic v i s c o s i t y of the p o l y m e r solution in acetone. O @[email protected]

O

emulsifier

, 2 wt p a r t / 1 0 0 m o n +

water

emulsifier

, 3 wt part/100 m o n +

water

Radiation polymerization in the emulsion systems

1123

3 o

2 O/

c

A~"

J

@I

o--o 80 k r a d l h ~--z~ 60 kradlh • - - - 40 k r a d l h

i

0

I

I

I

0

I

I

I

I

I

I

50 Conversion, °/o

100

Figure 7 Radiation of VAc.

induced emulsion p o l y m e r i z a t i o n

The influence

and i r r a d i a t i o n viscosity

of c o n v e r s i o n

dose rate on the intrinsic

of the p o l y m e r

acetone. VAc : Water

solution

: Tween 20 = 30

: 70

in : 2