Polymerization of Pivalolactone - Advances in Chemistry (ACS

11

Polymerization of Pivalolactone

N. R. M A Y N E

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Koninklijke/Shell-Laboratorium, Amsterdam, The Netherlands

Pivalolactone

(α,α-dimethyl-β-propiolactone)

can be polym

erized via a "living" anionic mechanism to yield a linear polyester exhibiting properties suitable for use as a textile fiber or as an engineering plastic. polymerization

Two process for the

have been successfully developed

to the pilot-plant stage.

by Shell

The first is a continuous melt-bulk

process in which the monomer is rapidly polymerized in a gear-pump reactor under almost adiabatic conditions.

The

molten polymer is directly degassed, cooled, and cut into nibs.

The second

process involves

polymerization

slurry system with a heterogeneous initiator. is, in fact, "living" low-molecular-weight

in a

The initiator polymer,

and

yields a free-flowing powder with a high bulk density. Development

and chemical background of these two proc

esses are described here and some typical mechanical prop erties of the product are briefly discussed.

TJivalolactone

(α,α-dimethyl-^-propiolactone)

is a colorless l i q u i d that

c a n b e p r e p a r e d f r o m p i v a l i c a c i d via c h l o r i n a t i o n a n d s u b s e q u e n t r i n g closure of the s o d i u m salt of t h e c h l o r o a c i d . CH CH

3

0

CH Cl,

3

CH,

3

CH

3

C I CH C1

ο

I •C

3

(

I

OH

CH

I

CH

3

X

CH C1 2

CH C H Ν

3

— C

I

3

C

I

ONa

I

CH —Ο

2

2

175

Platzer; Polymerization Reactions and New Polymers Advances in Chemistry; American Chemical Society: Washington, DC, 1973.

OH

176

POLYMERIZATION REACTIONS A N D N E W POLYMERS

B e c a u s e o f t h e h i g h l y s t r a i n e d r i n g system, p o l y m e r i z a t i o n r e a d i l y occurs via r i n g o p e n i n g , y i e l d i n g a l i n e a r p o l y e s t e r t h a t e x h i b i t s p r o p e r ties s u i t a b l e f o r use as a textile fiber o r as a n e n g i n e e r i n g p l a s t i c .

CH

I

η C H

3

3

Ο

— C

/

C

I

CH3

- ^ C H

I

2

— C

reaction

II

\

C — O-j-

I

CH:

CH2-0 The

Ο

I

is e x o t h e r m i c ,

k j / m o l e (18.4 k c a l / m o l e ) .

w i t h a heat of p o l y m e r i z a t i o n of 77

T h i s v a l u e i n c l u d e s the heat of c r y s t a l l i z a t i o n

of 12.1 k j / m o l e (2.9 k c a l / m o l e ) . Before has

d i s c u s s i n g i n d e t a i l the t w o p o l y m e r i z a t i o n processes S h e l l

d e v e l o p e d u p to t h e p i l o t - p l a n t stage, w e w i l l c o n s i d e r h e r e t h e

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

Polymerization The ety

Reaction

p o l y m e r i z a t i o n of p i v a l o l a c t o n e c a n b e i n i t i a t e d b y a v a r i

of n u c l e o p h i l e s .

F o r example,

tributylphosphine

(TBP)

attacks

the m o l e c u l e e x c l u s i v e l y at t h e b e t a p o s i t i o n , c a u s i n g r i n g o p e n i n g a n d p r o p a g a t i o n via

a carboxylate ion.

T h e h i g h s t a b i l i t y of this g r o w i n g

m a c r o z w i t t e r i o n results i n a " l i v i n g " p o l y m e r i z a t i o n system. C

r · · ·

τ,

1

Initiation: Bu P\ 3

η 2 5 0 ° C L o w viscosity

Process Constraints Polymer m.p. 240°C AH = 77 k J / m o l e H i g h viscosity


11.

MAYNE

Polymerization

of

179

Pivalolactone

I n p r i n c i p l e , t h e p o l y m e r i z a t i o n c a n b e c a r r i e d o u t either i n b u l k or w i t h a d i l u e n t present.

F o r a b u l k process, t h e most attractive r o u t e

w o u l d b e o n e i n w h i c h t h e p o l y m e r is p r o d u c e d i n t h e m o l t e n state so that i t c o u l d b e f e d d i r e c t l y to a n extruder.

Melt-Bulk Polymerization

Process

C o n s i d e r i n g t h e process constraints i n T a b l e I, t h e d e s i g n o f a m e l t b u l k p o l y m e r i z a t i o n process ( 8 ) m u s t take f o u r factors i n t o a c c o u n t : (a)

T o p r o d u c e p o l y m e r i n t h e m o l t e n state, t h e r e a c t i o n t e m p e r a ture s h o u l d b e h i g h e r t h a n 2 4 0 ° C .

Pressure m u s t t h e n b e

a p p l i e d to p r e v e n t m o n o m e r loss b y e v a p o r a t i o n . (b)

I n v i e w of a p p r e c i a b l e m o n o m e r d e c o m p o s i t i o n at these t e m peratures, i t is essential that t h e p o l y m e r i z a t i o n r e a c t i o n p r o c e e d extremely r a p i d l y .

(c)

A r a p i d p o l y m e r i z a t i o n w o u l d m a k e heat r e m o v a l f r o m t h e viscous p o l y m e r mass difficult, l e a d i n g to a n almost a d i a b a t i c reaction.

(d)

T h e a d i a b a t i c t e m p e r a t u r e rise s h o u l d n o t b e so h i g h as t o m a k e t h e w h o l e process i m p r a c t i c a l because of excessive m o n o mer decomposition.

It w a s , therefore, i m p o r t a n t t o k n o w t h e a d i a b a t i c t e m p e r a t u r e rise e x p e c t e d f o r a 100% y i e l d .

U s i n g t h e heat of p o l y m e r i z a t i o n a n d specific

heat d a t a , a v a l u e of a b o u t 3 3 0 ° C w a s c a l c u l a t e d f r o m t h e r e l a t i o n Δ Η = C · dT, a n d u s i n g m e a s u r e d a n d e x t r a p o l a t e d values of C p

p

ferent temperatures f o r b o t h m o n o m e r a n d p o l y m e r .

This 330°C

at d i f figure

w a s c o n f i r m e d b y results o b t a i n e d f r o m a d i a b a t i c b a t c h p o l y m e r i z a t i o n s

MASS TEMR °C 400 r

12

13 TIME, min

Figure 1.

Adiabatic

bulk polymerization

of

pivalolactone


180

POLYMERIZATION

REACTIONS A N D N E W POLYMERS

c a r r i e d o u t i n a n a u t o c l a v e ; a m a x i m u m t e m p e r a t u r e of 3 5 0 ° C w a s r e corded ( F i g u r e 1 ).

T h e r e is a d r a m a t i c increase i n p o l y m e r i z a t i o n rate

at a b o u t 7 0 ° C , a n d t h e m a x i m u m t e m p e r a t u r e is r e a c h e d w i t h i n o n e minute. T o o b t a i n a c o n t i n u o u s p o l y m e r i z a t i o n system, transport o f t h e v i s cous p o l y m e r is r e q u i r e d .

Furthermore, the initiated monomer should

not p o l y m e r i z e u p s t r e a m o f t h e r e a c t i o n z o n e .

These requirements were

met b y c o n t i n u o u s l y i n j e c t i n g T B P - i n i t i a t e d m o n o m e r u n d e r pressure i n t o a h e a t e d gear p u m p .

T h e monomer rapidly polymerizes between

the teeth of t h e gear w h e e l s , a n d t h e viscous p o l y m e r l e a v i n g t h e gear p u m p is passed i n t o a n extruder, w h e r e t h e v o l a t i l e d e c o m p o s i t i o n p r o d ucts a r e v e n t e d off. T h e p o l y m e r strands are t h e n c o o l e d a n d c u t i n t o nibs.

A s i m p l i f i e d d i a g r a m o f t h e system is s h o w n i n F i g u r e 2. MONOMER BOOSTER

b ο

TBP

5

-10°

10-20 ATA

REACTOR

VENT GAS

b ο

240-275° T = 10-20$

1

EXTRUDER 300° V WATER BATH

CUTTER

[POLYMER NIBS| Figure 2.

Melt-bulk

polymerization

process

T h e t o t a l residence t i m e i n t h e r e a c t i o n zone is b e t w e n 10 a n d 20 seconds.

I n i t i a l experiments w e r e c a r r i e d o u t w i t h reactor p u m p s h a v

i n g capacities of 1.2 m l a n d 20 m l p e r r e v o l u t i o n , r e s p e c t i v e l y .

Figure

3 shows the i n i t i a l l a b o r a t o r y setup of the reactor system. T h e i n i t i a t o r s c o n c e n t r a t i o n determines t h e r e a c t i o n rate, y i e l d , a n d m o l e c u l a r w e i g h t of t h e p r o d u c t . i n b e n z y l a l c o h o l at 1 5 0 ° C weight.)

( T h e l i m i t i n g viscosity n u m b e r , L V N ,

is u s e d as a measure

for the molecular

A n i m p r e s s i o n of these relationships c a n b e g a i n e d f r o m

F i g u r e s 4 a n d 5. I n t h e systems tested, t h e heat losses w e r e f a r t o o great f o r a d i a b a t i c c o n d i t i o n s to b e attained, a n d t h e reactors h a d to b e h e a t e d externally. H o w e v e r ; a n increase i n reactor size c o u l d result i n a closer a p p r o a c h to the a d i a b a t i c state, l e a d i n g p e r h a p s to temperatures h i g h e r t h a n 3 0 0 ° C .


11.

MAYNE

Polymerization

Figure 3.

of

Melt-bulk

Pivalolactone

process: initial laboratory setup

INITIATOR (TBP) CONCENTRATION, %m ON LACTONE • O.OOl A 0.002 ο 0.005 Δ 0.01 • 0.02 7 0.04 f 0.08 YIELD, % 100 ρ


181

182

POLYMERIZATION


LVN 2.5

2.0

1.5

1.0

0.05 Figure 5.

0.1

Melt-bulk

0.15

0.2 TBP,%m

process: MW control

A t these temperatures, t h e r e d u c t i o n i n y i e l d caused b y m o n o m e r d e composition might be considerable. u s i n g t w o reactors

i n series.

This problem can be solved b y

B y l i m i t i n g t h e c o n v e r s i o n i n t h e first

reactor, t h e t e m p e r a t u r e c a n b e k e p t l o w e n o u g h . c o m p l e t e d i n the second reactor.

Conversion can be

E v e n i f the t e m p e r a t u r e i n t h e latter

exceeds 3 0 0 ° C , d e c o m p o s i t i o n of t h e m o n o m e r w i l l b e less of a p r o b l e m t h a n i n a single reactor, as r e l a t i v e l y m u c h less m o n o m e r is exposed t o the h i g h e r t e m p e r a t u r e . T o demonstrate this p r i n c i p l e , w e u s e d a p i p e a t t a c h e d to t h e outlet of t h e gear p u m p as the second reactor.

T h e v o l u m e of this p i p e w a s

t w i c e that of the gear p u m p , so that the residence t i m e i n the latter w a s reduced b y two-thirds.

T o simulate the probable thermal situation i n

large-scale reactors, the t e m p e r a t u r e of the e l e c t r i c a l l y h e a t e d p i p e w a s r a i s e d to 3 5 0 ° C w h i l e t h e gear p u m p w a s m a i n t a i n e d at 2 4 5 ° C .

The

advantages of this a r r a n g e m e n t over a single reactor a r e s h o w n i n T a b l e II. T h e f e a s i b i l i t y of the m e l t - b u l k process has b e e n d e m o n s t r a t e d o n a p i l o t - p l a n t scale.

I n a 100 m l / r e v gear p u m p ( m a x i m u m c a p a c i t y of

60 k g / h ) c o n e c t e d to a 1 4 - m m p i p e reactor ( v o l u m e of 150 m l ) , fibergrade p o l y m e r

( L V N 0.9-1.0) w a s p r o d u c e d i n a c o n t i n u o u s

stable

o p e r a t i o n i n y i e l d s of over 90% o n intake. W e h a v e n o t s t u d i e d i n d e t a i l t h e p o s s i b i l i t y of p r o d u c i n g h i g h e r m o l e c u l a r - w e i g h t m a t e r i a l ( L V N 1.5-2.0) f o r other a p p l i c a t i o n s as a n e n g i n e e r i n g p l a s t i c ) .

(such

W i t h t h e h i g h e r m e l t viscosities a n d t h e


11.

MAYNE

Polymerization

Table II.

Pump

Residence time, s

°C

Pipe

Pump

245 245 305 355

Two-stage

183

Pivalolactone

Melt-Bulk Process: Single vs. Two-Stage Reactor

Temperature,

Single

of

5 12 12 10

245 245 245

275 305 355

5 5 5

LVN

Yield, %

Pipe

16 16 16

75-80 92 88.5 86

1.0 0.95 0.85

93 93 93

0.99 0.99 0.95

l o w e r i n i t i a t o r concentrations r e q u i r e d ( l e a d i n g to l o w e r r e a c t i o n r a t e s ) , w e expect some difficulties i n a p p l y i n g the b u l k process to the m a n u facture of s u c h m a t e r i a l . The process,

next section

deals

w i t h the

development

of o u r

alternative

i n w h i c h the heat of p o l y m e r i z a t i o n is d i s s i p a t e d i n a s l u r r y

system b y the r e f l u x i n g d i l u e n t .

A l t h o u g h this process m a y a p p e a r not

to b e so e c o n o m i c a l l y attractive as the b u l k route, it offers m u c h m o r e flexibility

i n the r a n g e of m o l e c u l a r w e i g h t s that c a n b e m a d e .

Slurry Polymerization

Process (9)

Polypivalolactone ( P P L ) tures b e l o w 1 0 0 ° C .

is i n s o l u b l e i n most solvents at

tempera-

W e therefore e n v i s a g e d c o n d u c t i n g the p o l y m e r i -

z a t i o n i n a n inert d i l u e n t f r o m w h i c h the p o l y m e r precipitates, a n d i n w h i c h the lactone m o n o m e r a n d i n i t i a t o r m a y or m a y n o t b e s o l u b l e . T h e d i l u e n t s h o u l d b e c a p a b l e of d i s s i p a t i n g the heat of p o l y m e r i z a t i o n , a n d the m o r p h o l o g y of the p r o d u c t ( b u l k density, p o w d e r s h o u l d b e as g o o d as possible.

flow,

etc.)

I n a d d i t i o n , the r e a c t i o n rates s h o u l d b e

p r a c t i c a l , a n d the p o l y m e r s h o u l d f u l f i l l p r o d u c t r e q u i r e m e n t s

s u c h as

thermal stability. One

approach

we

t r i e d was

a suspension

process.

The

lactone

monomer

c o n t a i n i n g an i n i t i a t o r s u c h as a p h o s p h i n e was s t i r r e d

at

60°-100°C

i n a l o n g - c h a i n h y d r o c a r b o n o i l ( " S h e l l O n d i n a " o i l 33)

in

w h i c h it was essentially i n s o l u b l e .

Although polymer with a high bulk

d e n s i t y was o b t a i n e d i n q u a n t i t a t i v e y i e l d s , the particles c o n t a i n e d h y d r o c a r b o n o i l that h a d to b e r e m o v e d b y a hot o r g a n i c w a s h ( h e p t a n e ) after r e c o v e r y b y We

filtration.

also i n v e s t i g a t e d

the p o s s i b i l i t y of u s i n g a s l u r r y system

in

w h i c h the m o n o m e r , d i s s o l v e d i n a r e f l u x i n g h y d r o c a r b o n ( h e x a n e ) , w a s p o l y m e r i z e d i n the presence of a s o l u b l e i n i t i a t o r such as T B P .

It t u r n e d


184

POLYMERIZATION


out that the r e a c t i o n rates h a d to b e k e p t l o w on a c c o u n t of heat trans fer p r o b l e m s , a n d the p r o d u c t was o b t a i n e d as a v e r y fine p o w d e r w i t h a l o w b u l k density.

T h e s e factors c o n s e q u e n t l y

l i m i t e d the m a x i m u m

s l u r r y concentration to 10-13 % w / w . H o w e v e r , w e f o u n d that p r o d u c t s w i t h h i g h b u l k densities (0.4-0.5) c a n easily b e p r e p a r e d b y i s o l a t i n g the p r e c i p i t a t e d p o l y m e r at l o w c o n v e r s i o n , a n d subsequently u s i n g it as i n i t i a t o r i n a separate p o l y m e r i zation reaction.

This concept

polypivalolactone (prepolymer) successful

development

of u s i n g " l i v i n g "

low-molecular-weight

as a heterogeneous i n i t i a t o r l e d to the

of a s l u r r y - p o l y m e r i z a t i o n process.

Although

m e t a l salts s u c h as p o t a s s i u m p i v a l a t e c a n also b e u s e d as heterogeneous initiators to g i v e h i g h - b u l k density m a t e r i a l , the t h e r m a l s t a b i l i t y of the p o l y m e r d u r i n g processing is at a n u n a c c e p t a b l y l o w l e v e l , as a l r e a d y described. in Table

A c o m p a r i s o n of the various processes w i t h d i l u e n t is g i v e n III. Table III.

Type of process

Polymerizations in Diluents Limitations

Initiator

Suspension

Phosphine

H o t E x t r a c t i o n Step Necessary

Slurry Homogeneous Initiator

Phosphine

Low Reaction Rate Low B u l k Density L o w M a x i m u m Slurry Concentration Unacceptable Thermal Stability

M e t a l Salt Slurry Heterogeneous Initiator

Phosphine Prepolymer

T h e structure of the p r e p o l y m e r a n d its r e c o m m e n d e d

characteris

tics are s h o w n i n F i g u r e 6 .

Bu P 3

/

C

Ο

I

II

Ο

\

ι

Ν

€

f - C — C — C — 0 4 - C — C — C — Ο

Γι

ι

Λ-,

Figure 6. Slurry process: prepolymer structure Molecular weight: 2-7 X 10 (n = 18-68) s

Particle size: 10-177 μ T h e p r e p o l y m e r is p r e p a r e d i n a separate process step b y a d d i n g the lactone to a s o l u t i o n of T B P i n r e f l u x i n g pentane. T h e p a r t i c l e size


11.

MAYNE

185

Polymerization of Pivalolactone

is g o v e r n e d b y the s t i r r i n g rate a n d the m o l e c u l a r w e i g h t b y t h e lactone/ p h o s p h i n e m o l a r ratio ( F i g u r e 7 ). A feature of the s l u r r y p o l y m e r i z a t i o n is that t h e r e a c t i v i t y of t h e c a r b o x y l a t e i o n t o w a r d the lactone r i n g is m u c h h i g h e r t h a n that o f t h e phosphine.

It has b e e n estimated that u n d e r t h e c o n d i t i o n s of p r e p o l y -

m e r p r e p a r a t i o n , t h e p r o p a g a t i o n rate is at least 600 times h i g h e r t h a n the i n i t i a t i o n rate.

A n o t h e r aspect of t h e system is t h e s t a b i l i t y of t h e

" l i v i n g " p o l y m e r c h a i n ; a l t h o u g h t e r m i n a t i o n reactions

c a n take

place,

p r e p o l y m e r remains active almost i n d e f i n i t e l y w h e n stored at r o o m t e m perature. T h e m a i n p o l y m e r i z a t i o n r e a c t i o n is d o n e b y a d d i n g lactone to a s t i r r e d s l u r r y of p r e p o l y m e r i n r e f l u x i n g hexane.

A chain-transfer agent

MWxIO

0

4

Figure 7.

8

12 16 20 LACTONE/TBP MOLAR RATIO

Slurry process: prepolymer

Table I V .

preparation

Slurry-Process Data

Prepolymer C h a i n - t r a n s f e r agent ( E A A ) Diluent Reaction temperature Monomer addition T o t a l reaction time S l u r r y cone. P o l y m e r recovery Yield B u l k density

0 . 5 % w o n lactone 0 . 1 - 0 . 2 % m o n lactone hexane 69 ° C 4 hours 7 hours 4 3 % w/w filtration 100% 0.5


186

POLYMERIZATION


s u c h as e t h y l acetoacetate ( Ε A A ) is a d d e d either to the m o n o m e r or to the solvent.

T a b l e I V presents p r e p a r a t i v e d a t a f o r a t y p i c a l p o l y m e r i

zation. T h e a m o u n t of chain-transfer agent r e q u i r e d to o b t a i n a g i v e n m o l e c u l a r w e i g h t depends to a c e r t a i n extent o n the monomer's p u r i t y . i n d i c a t i o n of the r e l a t i o n s h i p b e t w e e n

L V N a n d the c o n c e n t r a t i o n

An of

e t h y l acetoactate that s h o u l d b e a d d e d to the solvent is g i v e n i n F i g u r e 8.

LVN 5.0 r

4.0

3.0

2.0

0'

1

1

1

0.05

0.10

0.15

Figure 8.

Slurry process: MW

1

0.20 ΕΑΔ, %m control

T h e m o r p h o l o g y of the final p o w d e r depends m a i n l y o n t h a t of the p r e p o l y m e r ; u n d e r o p t i m a l c o n d i t i o n s , the p r o d u c t is a large-scale r e p l i c a of the p r e p o l y m e r particles. h i g h b u l k d e n s i t y (0.5)

F i g u r e 9 shows a t y p i c a l p r o d u c t w i t h a

a n d a g o o d f l o w caused b y the s p h e r i c a l s h a p e

of the particles. T h e s l u r r y p o l y m e r i z a t i o n process w i t h p r e p o l y m e r has b e e n up

from

bench-scale

(100

grams)

b a t c h e s ) w i t h o u t major difficulties.

to

pilot-plant operation

scaled

(0.5-ton

A n i m p o r t a n t aspect of this process

is the absence of reactor f o u l i n g .


11.

MAYNE

Figure

9.

Polymerization

Slurry

of

Pivalolactone

187

process: morphology of product spaces=100 n)

Properties of Polypivalolactone

(2.8

calibration

(PPL)

A m a j o r e v a l u a t i o n , i n c l u d i n g c o n s u m e r testing, has b e e n c a r r i e d out o n t h e p o l y m e r to d e t e r m i n e its s u i t a b i l i t y f o r use as a textile

fiber.

P r o c e s s i n g comprises m e l t s p i n n i n g at 2 8 0 ° - 2 9 0 ° C f o l l o w e d b y s t r e t c h i n g b y usual procedures. diate

between

I n most m e c h a n i c a l properties, P P L is interme

polyethylene

terephthalate

( P E T ) a n d nylon-6.

Its

u n i q u e properties are its excellent elastic b e h a v i o r , h i g h e l o n g a t i o n ( 6 g/denier at 80% e l o n g a t i o n ) , a n d whiteness r e t e n t i o n .

Table V qualita

t i v e l y compares the three fibers. Table V .

Mechanical Properties PPL

Tenacity Stiffness K n o t strength Elasticity C o l o r retention Dyeability a

+ = good; db = fair; — = poor

+ + + ++ ++

α

Nylon-6

PET

+

±

+ + ± ++


+ ++ + ±

+ +

188

POLYMERIZATION


As expected f r o m its c h e m i c a l structure P P L is h i g h l y resistant t o c h e m i c a l s , heat, a n d U V l i g h t , as s h o w n i n T a b l e V I .

Table V I .

Chemical Resistance PPL

a

Nylon-6

PET

+

±

+ + + ++ ++

Alkali Acid Solvents Heat U V light + = good; =b = fair; — = poor

a

±

+ —

+ + + ±

F o r plastic a p p l i c a t i o n s , P P L c a n b e injection m o l d e d at 2 8 0 ° C . ( N u c l e a t i n g agent s h o u l d b e a d d e d . ) good

flow,

reactions.

P r o c e s s i n g is easy b e c a u s e o f

h i g h s t a b i l i t y , a n d absence of c a r b o n i z i n g o r c r o s s l i n k i n g Its o u t s t a n d i n g p r o p e r t y as a p o t e n t i a l e n g i n e e r i n g

plastic

is its h i g h heat resistance ( s t a b l e f o r 1000 hours at 2 0 0 ° C , o r o n e y e a r at 1 5 0 ° C ) .

The

Future T h e c o m m e r c i a l f u t u r e of p o l y p i v a l o l a c t o n e is d i f f i c u l t to p r e d i c t

at the m o m e n t . competing

T h e p r o b l e m s of i n t r o d u c i n g a n e w p l a s t i c o r fiber a n d

against

well-established

materials

are n u m e r o u s .

e s p e c i a l l y t r u e i n t h e present e c o n o m i c s i t u a t i o n .

T h i s is

W e believe, however,

that there is a p l a c e f o r p o l y p i v a l o l a c t o n e i n t h e thermoplastics

field

a n d , as w e h a v e d e m o n s t r a t e d , the t e c h n o l o g y a n d expertise n o w exists to p r e p a r e i t o n a c o m m e r c i a l scale.

Acknowledgment T h e author w o u l d l i k e to a c k n o w l e d g e t h e c o n t r i b u t i o n s m a d e to this work b y numerous

colleagues

at the K o n i n k l i j k e / S h e l l - L a b o r a t o r i u m :

i n particular D . P . C u r o t t i , P . A. Desgurse, A. Klootwijk, a n d W . M . Wagner.

Literature

Cited

1. Markevich, Μ . Α., Pakhomeva, L. K., Enikolopyan, N. S., Proc. Acad. Sci. USSR, Phys. Chem. Sect. (1970) 187, 499.


11. 2. 3. 4. 5. 6. 7. 8. 9.

MAYNE

Polymerization

of

Pivalolactone

Jaacks, V., Mathes, N., Makromol, Chem. (1970) 131, 295. Jaacks, V., Mathes, N.,Makromol.Chem. (1971) 142, 209. Letts, Ε. Α., Collie, N., Phil. Mag. (1886) 22, 183. Denney, D. B., Kindsgrab, Η. Α.,J.Org. Chem. (1963) 28, 1133. Netherlands Patent Application 7,002,062. Wiley, R. H.,J.Macromol. Sci. Chem. (1970) 4, 1797. UK Patents 1,180,044 and 1,261,153. US Patents 3,578,700; 3,558,572; 3,471,456; and 3,579,489.

R E C E I V E D December 5, 1972.


Polymerization of Pivalolactone - Advances in Chemistry (ACS

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