Properties and Morphology of Impact-Modified RIM Nylon - American

12 Properties and Morphology of Impact-Modified RIM Nylon J. L. M. VAN DER LOOS and A. A. VAN GEENEN

Downloaded by RUTGERS UNIV on May 29, 2018 | https://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch012

Polymer Chemistry Department, DSM, Research andPatents,PO Box 18, 6160 MD Geleen, The Netherlands

RIM nylon is a new development in the long -established technique of anionic polymerization of ε -caprolactam. For most applications the toughness of dry non-modified nylon is insufficient. By dissolving an impact modifier (a rubber-like material, such as a polyol, with low Tg) in the caprolactam melt before polymerization the impact strength can be improved, though with a decrease in flexural modulus. The various kinds of morphology which can occur with rubbertoughening and the relation between morphology and mechanical properties will be discussed. For the ABA type block copolymers the postulated morphology is that of a continuous rubber network extending through a nylon phase, which would explain the high toughness and the low flexural modulus of these block copoly mers. The

anionic polymerization

polymerization in

a m o u l d b y means o f

temperature formed.

lower

With

mization

of

completed

in

For

most

the

toughness

than

choice

3 minutes

applications, for

of

nylon

of

point

of

decrease

that

in

properties of

a fairly is

polymerization

conditions

so t h a t

RIM

the polymer

old

polymerized

the

reaction

particular

i n s u f f i c i e n t . The most

brittle amount

flexural of

in

and by

opti c a n be

c a n be c a r r i e d

the automotive

polymers of

is

is

industry,

successful

method

rubber-toughening.

a dispersed

rubber

phase

and t e n s i l e

modified

Several

There is

kinds

nylon of

and the

an una

strength, Is

By

(impact

improved s i g n i f i c a n t l y

modulus

the rubber nylon.

a

machine.

resistance

unmodified

system

at

to be

the polymerization

in

a minor

the fracture

of

is

is

modifying of

(CL)

caprolactam

s t r e n g t h c a n be i n c r e a s e d s e v e r a l f o l d .

voidable balance

the melting

a s p e c i a l l y adapted

incorporation impact

about

molten

an a c c e l e r a t o r and a b a s i c c a t a l y s t

than

a correct

in

modifier)

caprolactam

the polymerization

out

developed

of

technique by which

much

morphology

but

the

better which

0097-6156/ 85/0270-0181$06.00/ 0 © 1985 American Chemical Society

Kresta; Reaction Injection Molding ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

182

REACTION INJECTION M O L D I N G

can

occur with

logy

rubber-toughening

and m e c h a n i c a l p r o p e r t i e s

and the

will

be

relation

between

morpho-

discussed.

Experimental The At

polymerization a temperature

one

half

of

modifier mixed

perature was In a

the

were

and

taken this

polymerization


a flat

caprolactam while

the

catalyst

in

the

was

°C.

After

mould

other

poured

about or

the

was

catalysed with sodium

10

two

minutes

modifier

was

of

common b a s i c

lactamate

and/or

solutions

was

template

used. reaction

as

were

had a

finished

the

used

in

impact

which

the

agent

mould.

dissolved

and the

mould,

product

aluminium

was

The

the

release

the

and

lactamate,

impact

half.

into

no m o u l d

a diisocyanate

diisocyanate

in

initiator

the

100

out

the

130-160

from

carried °C,

mixture

study

potassium

were

about

dissolved

the of

runs

of

between

accelerator.

catalysts

such

bromomagnesium

The

as

lac

tamate. The

Izod

notched

modulus number

of

perties The

impact

(ASTM D-790) specially

were

rubber

strength

of

the

selected was

(EM).

Fracture

micrography

(SEM)

were

alloy. tion

in

liquid

The

For

Philips

EM

A

number

are

nylon,

the

were

flexural

measured.

For

dynamic m e c h a n i c a l

a

pro-

b y means for

by b r e a k i n g

They were

alloy

electron

the

electron samples

sputter-coated

a Philips

electron

Pt/Pd

of

scanning

SEM

505,

micrography

after

with

maximum (TEM)

an

Au/Pd

resolu-

a carbon-

was

used,

the

microscope being

a low

glass

transition

a

300. of

polymers

soluble

were

obtained

obtained

transmission

shadowed w i t h

large

studied surfaces

nitrogen.

replica

which

samples,

m i c r o s c o p e u s e d was

7 nm.

and the

products

determined.

distribution

micrography cooling

(ASTM D-256)

obtained

in

tried

with

with

molten

out.

The

c a p r o l a c t a m , but best

not

polymerization

temperature,

compatible

results

with

were

polyols.

Morphology Depending lerator,

on the three

Intermediate System

1

between achieved glycol

forms

This the

are

by u s i n g II"

of

of

course is

modifier as

contains

modifier

the

CH3-0-(C-C-0) -CH3

Solution

II

0CN-R-NC0 +

mixing there

n

no

the

acce-

"Figure

1").

possible. no

reaction

accelerator.

This

a methoxylated

can occur c a n be

polypropylene

+

CL +

basic

catalyst

CL

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

with

(see

accelerator.

I

Because

also

the

modifier

can occur

I").

Solution

After

impact

p r o d u c e d when and

impact

("solution

the

morphologies

morphology

impact

(PPG)

"Solution

interaction

different

interfacial

only

a horaopolymer

adhesion

the

rubber

is

formed.

segregates


as

12. VAN DER LOOS AND VAN GEENEN

Impact-Modified RIM Nylon


183

F i g u r e 1. described.

Morphology of

the

various

polymerization

systems


184

R E A C T I O N INJECTION M O L D I N G

shapeless This

patches

procedure

and i s

was

System 2

By

which

reactive

mers In

are

(block

this

poorly

already

application to

copolymer)

case

of

the

distributed

described

in

an impact

polypropylene

the

nylon

phase.

(1).

modifier

accelerator

c a n be

in

1965

containing

("solution

I"),

groups

graft

poly

formed.

glycol with

t e r m i n a l - O H g r o u p s was

used.

CHo


I Solution

I

HO-(C-C-0)£-H

Solution

II

OCN-R-NCO +

The

isocyanate

the

following

+

CL +

basic

catalyst

CL

accelerator

("solution

II")

can react 0

0

Hi! -• 0CN-R-NC0

of

(1)

n

W

0 Il H HO

HOvwOH

0

»

formation

0

U

H

(2)

0-C-N-R-NCO

urethane

HH

CL'

0

OCN-R-N-C-(NC) -N-C

0 +

either

Κ

II

κ

polymerization ~

+

Ν (2)

in

ways:

0

II

H

H

HOa*w*o-C-N-R-N-C-(N

C) -N-C

(n

m

polymerization

^

and m

about

100

or

higher) Because only

"reaction

a minor

modifier the

segregates

nylon

acting this

(1)"

quantity

phase.

as

is of

as

The

fine

block

an e m u l s i f i e r

polymeric

'oil

considerably block

in

spheres

for

the

is

than

two

incompatible the

The

(2)",

impact

distributed

concentrates

emulsion

"reaction

formed.

homogeneously

copolymer

oil'

faster

copolymer

at

the

polymers

lnterfaclal

ln

interface, (2_).

adhesion

In is

good. A disadvantage

of

the

rubber

phase

thé

rubber

is

patent

lymer

low,

This

between is

prepared and,

by if

systems the

System 2

rubber

occurs

and

consisting

the

in

the

nylon

of

case

phase.

a rubber

is

described

of

complete

Separately,

segment

with

0 +

2 is

that

weight in

of

several

interaca

prepo-

terminal

groups.

Η

Η0*~Μ·0Η

1 and

molecular

(3-5).

morphology

the

prepared

accelerator

polymers

can even exude.

applications

System 3 tion

the

c a n be e x t r a c t e d

2 0CN-R-NC0

»

«

OCN-R-N-C-0 ~ ~ ~ w ~

0

II

Ν

0C-N-R-NC0


12.

VAN DER LOOS A N D VAN GEENEN

This

prepolymer

tion

in

dissolved

I

Prepolymer

+

Solution

II

Catalyst

CL

In

0

this of

/

copolymer is represented

\

and m this

about

copolymers

100

the

are

The

in

2A"

rubber

system where

3. as

sion

of

the

is

to

"Figure

nylon,

as

big

block

of

the

big

in

C

by DSM,

N-C

the

are

some o l d e r

not

shows

(3)

rubber

based

on

patents

the

this

block

systems

1,

2

and

3

distribution

in

a

polymer

of

small

the

in

a polymer

made

according

phase s e p a r a t i o n

(about

3 μ)

nylon

2B")

particles

shows (about

to

poly in

this

system

few

has

active

interfacial of

prepared according

("Figure

rubber

properties

the

polymer

a

The

continuous

occur

the

and q u i t e

blocks.

a

When

can also

mechanical

2

patches

micrograph). this

a polymer

system

poor.

optimum

form

and the

rubber

shapeless in

copolymers prepared according

continuous

network

be g r e a t e r

sequence. this

in

I

than

the

thin

(14). the

case

layers, The

this to

1 μ)

adhe

polymer

system

a very

1.

regular

in

end-to-end distance not

even be

smaller,

is

about

hardly

However,

distinguishable with

system

one a t

The 3

100

("Figure

viz. Â,

a

continuous

-62

°C

3")

of

the

about

the

relaxation

to

of

200

rubber or

rubber the Â.

as

100

Â.

a

phase

stretched

Because

thickness

rubber

of

of the

the

Because

phase i n

domains

spectrum

indeed displays

owing

the

a molecular weight

about

the

3,

cylinders

the

system

3

2C").

dynamic mechanical

("Figure

about

most

stretched,

dynamic mechanical

be d e t e c t e d . by

also

thickness

at

phase w i l l SEM

be f u l l y

is

chain w i l l of

system

thin

a polyol with

rubber

resolution

to

ln

end-to-end distance

of

rubber

peaks;

II

(9-13).

very

premature

may b e a r r a n g e d

never

pared

Q

phase.

segments

can

\

optimum;

p r e p a r e d by

domains

particles

those

distribution

is

reacted to

equal to

is

is

also

but

that 1

are

2D"

micrograph of

4000,

shows

of

The

rubber

adhesion

polymers

conditions

are

nearly

°

n

2".

black

small

the

RIM

system

very

nylon

/

H/H

H

struc

extracted.

s e g r e g a t e d as

(the

have not

is

be in

"Figure

a result

segregated groups

H

chemical (3)

higher).

mechanism (6-8)

clearly

phase

merization

can

or

Interfacial

already mentioned

according

nylon

solu

discussion

EM m i c r o g r a p h s

In

H

exude or

and

"Figure

°

C-N-R-N-C-0*AA~V* O-C-N-R-N-C + N

postulated

made

II

N f~

cannot

given

0

H

The

formula

HH

new d e v e l o p m e n t s

are

0

formed. by

H \

system

Results

is

0

(n

last

+

a polymer

In The

a catalyst

CL

a n ABA b l o c k

C

phase

and mixed w i t h

such

0

C-N-4

CL

case

/II

II

in

CL.

Solution

ture


is

185


the

glass

of

two

of

about

100

a polymer separate

transition

of


Â

pre-

loss polyol


REACTION INJECTION M O L D I N G

F i g u r e s 2 a and b . E l e c t r o n m i c r o g r a p h s of f r a c t u r e s u r f a c e s of p o l y m e r i z a t i o n system 1 (a) and 2 ( b ) . F i g u r e s a and b were examined i n TEM..


VAN DER LOOS AND VAN GEENEN



12.

F i g u r e s 2c and d . E l e c t r o n m i c r o g r a p h s of f r a c t u r e s u r f a c e s of p o l y m e r i z a t i o n system 3 . F i g u r e s c and d were examined i n SEM.


187

REACTION INJECTION MOLDING

188 and

one a t

about

Apparently, as

a separate An

Table

70


System

1

System

2

System

the

to

the

glass

of

the

mechanical

properties

3

Polyol

Izod

%

kJ/m

(wt)

(notched)

4

3250

20

5

2420

10

9

2700

20

12

2310 1850

10

26

20

54

1370

30

60

420

the t a b l e

it

appears

the

that

Izod

adhesion increases. nylon

6.6

(15).

Addition

(30

%)

affords

the

flexural in

of

above

the

transition

the

modified

nylon).

The

the

strength

a soft

region

nylon

systems

the

points

in

»

of

networks

of

we p o s t u l a t e is

in

-

the

they

crazes is

from

case

the

that

of

phase

less

of

at

flexural of

the

4

shows due a

the

to

tem-

phase and below

mainly

bands

lower

prediction

(E/Eo)

modulus

of

unmodified fit

fairly

are

difference

is

3

but

already

Fig.

1 and 2

that

system

well

wellin

Impact

due t o are

the

better

stabilized

initiated. theoretical

a higher

for

curve.

example

rubber

content,

reversion.

that

network

and t h e r e f o r e

the

phase

a nylon

the

(E

soft

an anomalous s t r u c t u r e ,

or,

state

the

by w h i c h

shear

in

the

in

a hard matrix

The 2

3 deviate widely of

as

a

toughness,

for

modulus

systems

of

through

small

2,

in

halved.

the

proves

inclusions.

system

than

modulus

1 and system

in

line

phase

of

system

rubber

copolymers is theory

of

flexural This

improves

concluded

The

phase i n

points

curve.

of

region hard

modulus

2

strength

also more

more

(16-18).

formation

fraction

included

is

reduction

the Q

without

% impact modifier

rubber

of

a d h e s i o n of

intermediate

extending

ABA b l o c k

rubber

and E

an i n d i c a t i o n

Therefore,

in

transition

between system

interlocking

20

the

experimental

interfacial

is

for

the

of

have g i v e n a b a s i c

theoretical

dispersed

an

nylon. present

compounded w i t h p o l y e t h y l e n e - g -

system,

a composite

curve

incorporation perature

of

which

rubber

authors

is

any a d d i t o n a l improvement

modulus,

modulus

theoretical

and/or

hardly

a dispersed

Several the

polymer

impact

This

p u b l i c a t i o n about

This

the is

given

-

anhydride

The

is

N/mm

recent

onto

of

polyol

Flexural

2

maleic

of

bonded

M e c h a n i c a l P r o p e r t i e s (Measured Dry as Made)

interfacial

than

transition

copolymer the

I.

nylon

From

a block

phase.

overview

Table I .

AP

°C o w i n g

even i n

morphology of an almost ("Figure

will nylon

be more

system

continuous 5").

By

perfect.

can contribute

3,

with

rubber

increasing More to

the

nylon

about

network the is

modulus.



12.

VAN DER LOOS A N D VAN G E E N E N

189


F i g u r e 4 . Modulus r e d u c t i o n as a f u n c t i o n of the s o f t rubber phase volume (temperature 23 ° C ) . Key: • , system 1 ; O , system 2 , and #, system 3 .

Figure

5.

P o s t u l a t e d morphology

of

ABA b l o c k

copolymers

(system


3) .

REACTION INJECTION MOLDING

190 The

net

effect

Furthermore, by

the

nism

rubber

will

plastic

no

ot

during

concluded the

Is

phase,

place

testing

in

true,

observed, which

of

is

that

flow.

This

m e c h a n i s m by means o f From

these

3 with

accordance

with

was

volume

experiments

20

a n d 30

c o m p l e t e l y due to

in

mecha-

expect

by s h e a r

system

was

determined

deformation

one would

(19,20).

products

deformation

so

be l a r g e l y the

mainly

deformation

tensile

plastic

c r a z i n g was

take

the

modulus.

this

rubber

will

that

in

behaviour w i l l

If

the

by a n a l y s i n g

% polyol

drop

properties.

be t h a t

monitoring was

a sharp

deformation

deformation

verified it

is

the

shear

the

weight flow;

morphology


postulated. Another

consequence

ties

the

of

system

of

Consequently,

a high

in

with

accordance

obtained

this

are

morphology is

largely

elongation at

the

high

that

d e t e r m i n e d by

Izod

break w i l l

values

of

the

ultimate

those

of

the

be a t t a i n e d .

the

ABA b l o c k

properrubber. This

is

copolymers

experimentally.

Conclusions -

Improvement

by

shown,

the

although -

It

with

the

is

postulated

20

% or

more

through

because

that

the

polyol

is

further

additional

is

RIM

that

of

in

of

of

highest

loss

in

ABA t y p e

the

rubber

achieved

morphology toughness,

flexural

deformation

modulus.

block

rubber

copolymers network

behaviour phase.

and

Improvement

flow.

content the

c a n be

kinds

a continuous

the

shear

polyol

perfection

the

morphology of

phase,

nylon

various

by a great

due t o

a high

improvement

decreases

of

the

b e i n g d e t e r m i n e d by

strength

A p p l i c a t i o n of

Of

copolymers possess

a nylon

strength

impact

impact strength a polyol.

accompanied

is

ultimate of

of

ABA b l o c k

this

extending

-

of

incorporation

(30

rubber

%)

is

network

impact strength,

while

not

interesting,

yields the

little

modulus

sharply.

Acknowledgments The

authors

for

his

for

their

wish

to

interest

electron-microscopy tion

of

express

experimental work,

samples

their to

and h e l p f u l studies

under

his

Dr.

a p p r e c i a t i o n to F.

Maurer

discussion,

and to

Mr.

Mr.

and Dr. to

Mr.

C. Vrinssen

J.

S.

S.

Bongers

Sjoerdsma

Nadorp for

for

the

guidance.

Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

his

examina-

Courtaulds, G.B. Patent 1126211 pr. date 1-14-1965 G.E. Molau, J . Polym. Sci A3, 1965, 4235 DSM/Stamicarbon, US Patent 3704280 pr. date 3-25-1969 DSM/Stamicarbon, US Patent 3770689 pr. date 1-24-1970 DSM/Stamicarbon, US Patent 3793399 pr. date 9-23-1970 Monsanto, European Patent 67694, pr. date 6-16-1981 Monsanto, European Patent 67695, pr. date 6-16-1981 DSM/Stamicarbon, patent applications to be published ICI, GB Patent 1.067.153, pr. date 5-17-1963 British Celanese, GB Patent 1099265, pr. date 5-11-1964 Toyo Rayon, Japanese Patent 16028/69, date 7-15-1965


12.

VAN D E R LOOS A N D VAN G E E N E N



12. Monsanto, US Patent 3862262, pr. date 12-10-1973 13. Monsanto, US Patent 4031164, pr. date 8-25-1975 14. M.J. Folkes and A. Keller, Physics of Glassy Polymers, Appl. Science Publishers, 1973, Ed. R.N. Haward Chapter 10 15. S.Y. Hobbs, R.C. Bopp and V.H. Watkins, Polym. Eng. Sci. 1983, 23, 380 16. E.H. Kerner, Proc. Phys. Soc. London 1956, B69, 808 17. C. van der Poel, Rheol. Acta 1958, 1, 198 18. L. Bohn, Copolymers, Polyblends and composites. Advances in chemistry series no. 142, 1975, Ed. N.A.J. Platzer, Chapter 6 19. C.B. Bucknal and D. Clayton, Nature (Phys. Sci.) 1971, 231, 107 20. D. Heikens, S.D. Sjoerdsma and W.J. Coumans, J. Mater. Sci. 1981, 16, 429 RECEIVED

April 16, 1984


Properties and Morphology of Impact-Modified RIM Nylon - American

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