Document JNj3QJdL76d6KN2OEmXKBjveO
Contemporary Topics in
Volume 4
Edited by
WilUlniiverasitmy ofJ.MarBylaanid ley
College Park, Maryland
and
Teiji Tsuruta
Science TUonkiyveor,siJtaypaonf Tokyo
PLENUM PRESS - NEW YORK AND LONDON
VINYLIDENE FLUORIDE - HEXAFLUOROPROPYLENE COPOLYMER HAVING TERMINAL IODINES
3 Masahiko Oka and Masayoshi Tatemoto
4
RDeasiekainrchKoDgeypotC.o,.,ChLetmdi.cal Division
]
700, Hitotsuya, Settsu-shi, Osaka, Japan
.
INTRODUCTION
The vinylidene fluoride(VDF)-hexafluoropropylene(HFP)
i copolymers are well-known fluorocarbon elastomers which have t= excellent thermal, oil and chemical stability. Due to their
5. inert structure, curing is more difficult compared with the hydrocarbon elastomers such as styrene-butadiene copolymer, acrylonitrile-butadiene copolymer etc. It is known that two
E curing recipes described below are practically usable for
= these fluorocarbon elastomers.
:
a) a combination of a blocked diamine and an acid
:
acceptor sych as magnesium oxide or basic lead
=
phosphite.
.
b) a combination of an aromatic polyhydroxycompoung,
E
an appropriate accelerator and an acid acceptor. 53
:
Recently, we found that when the copolymerization is
i. carried out in the presence of organic iodide compounds as
8 chain transfer agents, the copolymers obtained can be easily
i ecxucreedllebnytuspihnygsicaanl orpgraonpiecrtipeesr.o4xideInantdhisa cpaopaegre,ntwetodigsicveuss
3 the characteristics of the copolymers prepared in the presence
of the organic mono-iodide compound, (EF3hacrt, or the di-
8. iodide compounds, I(CF2)4I, 1(CF2)gI, as chain transfer agents.
5
EXPERIMENTAL
a
Polymerization
a Ee
VDF and HFP monomers were 99.9% pure. Emulsifier used
.
763
E
764
M. OKA AND M. TATEMOTO
was ammonium perfluorooctanoate obtained from Rimar Co.
5
Organic iodide compounds were prepared and purified in our
i
laboratory and their purities were confirmed to be greater
2
than 99.8% by gas chromatography. Other chemicals used were
reagent grade.
58
The copolymerization reaction was carried out in a 30- i.
Titer volume stainless steel reactor with a magnetically
i
coupled agitater. The reactor was charged with 15-liter of 7
demineralized and deoxygenated water. Then 30g. of ammonium
perfluorooctanoate was added as an emulsifier. After replacing:
air with pure nitrogen gas, a VDF/HFP monomer mixture con-
sisting of 50/50 (mol/mol) was added to the reactor until
3
the pressure went up to 13kg/cm?. Reaction temperature was -
80C. In order to initiate the polymerization, 0.2g. of
fu
ammonium persulfate dissolved in water was injected into the i
reactor using micro-pump. Since the pressure dropped with
3
the progress of the polymerization, a VDF/HFP monomer mixture i
consisting of 78/22 (mol/mol)vas added to the reactor to 9
maintain the pressure at 13kg/cm during the polymerization. 4
After about one hundred grams of the copolymer was produced PE
(about two hours after reaction
ar chain transfer agent 3
was added to control the molecular weight of the final co- Tak
polymer.
ammonium
peInrsuolrfdaetretwoasconatdidneudeetvheeryretahcrteieonh,our0s.1 duorrin0g.2gp.olyo-f
==
merization. After a definite time of the polymerization,
pe
heating and agitation were stopped and the monomers remaining be
in the reactor were removed. Polymers produced were isolated "i
from the emulsion by coagulation and dried in an oven at 100C.
5
Characterization
=
Intrinsic viscosities of the copolymers were determined V3
in THF at 35C with an Ubbelode capillary viscometer. Number average molecular weights were obtained from osmotic pressure =
measurements in THF at 35C using a Hewlett Packard osmometer
Model 502. Molecular weight distributions of the copolymers ~~
vere determined in THF at room temperature using Waters
5
Associates gel permeation chromatography having six Styragel - .
columns of the following pore size: 107, 106, 105, 104, 103 23
and 102 A. The concentrations of the samples were 1.0g./d1. Cs
and the flow rate was 1 ml./min. Mooney viscosities were
be
measured at 100C and 140C in the usual way with Shimadzu
of
Seisakusho Mooney viscometer.
or
E3
a
ik
VINYLIDENE FLUORIDE-HEXAFLUOROPROPYLENE
765
Vuicanization
hexaneP.eroCxoiadgeenutssedcwoanstai2n,i5n-gdimienthhiyb1i-t2o,r5-wdeire(tu-sbeudtylaftpeerrowxays)hing
with 5wt2
anhydrous
sodium
sodium
hydroxide
carbonate.
aqueous solution and
Copolymer, peroxide
drying with
and coagent
were milled by 200 mm mixing roll at room temperature. After
mcuirleldingat th1o6r0oCughfloyr, 3t0hmeinc.omptoounfdosrmwesrheeetpsu.t
into
Gel
the mold and
fractions of
the vulcanizates were measured to estimate the degree of vul-
canization. About ly and immersed in
0.29. of vulcanizates a large excess of THF
was weighed at 35C to
accurate-
the soluble
After three
fraction.
days, the
THF
was
renewed
twice
during
extract extraction.
swollen vulcanizates were removed and
dried under vacuum at room temperature The gel fraction was calculated by the
until constantweight. following equation:
6 =H / Wy
wahndereaftG,erWeyxtarnadctWioona,re rtehsepecgteilveflrya.ction, the weight before
RESULTS AND DISCUSSIONS
out
The results of
in the presence
the copolymerization reactions carried
of organic jodide compounds are summarized
in Table I.
time because
The
the
creoapcotliyomnerwiazsaticoanrrireedacotuiton atreegxitrredemealylonTgow
~ oafmmpoonliyummerperensduglrfoautpes cdoenrcievnetdratfiroonms amtmoonaivuomidpetrhseulpfraotdeu.ction
: molecuFliagrurewei1 ghsthowasnd tpheolyrmeelratyiioenlsdhipin btehteweepnresneunmcbeerofavvearraigoeus
amounts of perfluoroisopropyl iodide. The number
molecular weight increases linearly with the
average
polymer
yield
and
these
slopes
depend
on
the
increase in the
amount of per-
~ fluoroisopropyl iodide.
z
and
thTeheyireelldatoifonsphoilpymebretfwoeremnednuminbertheavperreagseenmceoleocfultahrreeweikgihndts
~ of fluorocarbon jodides, perfluoroisopropyl iodide, 1,4-di-
"iinodoF-ipgeurrfelu2.orobTuhteanfeirsatnd fl1u,o6r-odcia-riboodno-pieordifdleuorisoheaxmaonneo-iisodsihdoewn
"cthyapien chtariannsfterranasgfeenrtsa.gentT;he threelaltaitotnesrhitpwo baerteweedni-njuomdbiedreatvyepreage
A
766
M. OKA AND M. TATEMOTO
=al
z g(B18 711 A R8IB8 E]
>
8
s=g i||2g%8
pi
g5l Eel8g.m 118a11 28 1R1B8=RB11BI|gsg
2
25
7
s |5
335
.
E= S[EE3Lo|n2mRenedingndIiBeaunedSdniniaagndayl| EnEy
2BET
52
S
282
5 lez.
59
os [22322882833398R8858 782
Lg8gle~~cSc~-cccccss8s-So ha,
2 IE 38 (EF
- a,
5a 5,8 15s
2wos|E5z5s||aRgEREeRaRsTnEgAsRaIeEsErNRReEeRgE|.a S%
:;
Eos
F5%
IZ5 ||(g8fpEE||deoavnendcdntuunnAnncAeRoegnAancAa|nlEEsidJE2y
&
3
5 o [E8g3
"5l1s82 f<fr &8&8 =2 Zgsn ogsu | g[:Ed5f26F8
slglegg %|. &-% & B= &F 2|5Ea5g:z:l :
Niilk g 8PR >8a 8DE|E fsL ze
;
Ss Fis =
=~
=
=
Sw
2 g|l-amsnenmoomnmznex|2E EE
b
3S
=
5s =3
;
VINYLIDENE FLUORIDE-HEXAFLUOROPROPYLENE
767
4
50
]
a
A
a
Tw
or
B :
c
-
:
Fig. 1. og
:
e
fn
Le
10
&
0"
ie
0
9
2
4
6
wx 1073 (g,)
yNiuemlbderWpavaetragvearmiooulsecualmaourntwseigofhtchNaninvs.trapnoslfyemreragents:
(CF3)2CFL: (9) 3.70g.3 (a) 5.28.3 (o) 10.56g.
0
"w0
x t
Bb 30
Kd
ee
5
ve
i be
& 9
p
be
= Fig. 2.
os
= :
0
0
2
4
6
wx 1073 (g,)
Number average molecular weight Mn
yield Wp at three kinds of chain
vs.
polymer
(a): (a):
1(C(Fc3h)ofC1FI 9.59.292.8.;
(e):
1{CF)tIra8n.s1f3egr.a;gents:
3
3
768
M.OKAANDM.TATEMOTO 3
3
|8
Fig. 3.
/
+
4
, 2
82
5
A2
14
x
J
A
2
2
2 F5
2;
0"
4
0
bt
0
2
4
6
E>
Core) x 1073
5
Degree of polymerization Pn vs. the ratio of polymer
yield (Mp, mol) to the total amount of chain transfer
agents (C, mol):
(8): (CF3)oCF1 3.70g.; (a): (CF3)oCFI 5.28g.;
jo
be
(0):
(a):
(CF3)2CFI 10.56g.;
1(ctfs 9.929.
(e):
I(CF2)al
8.13g.3
2%
i
pe:
molecular weight and polymer yield is not influenced by the 3
kind of fluorocarbon iodide.
1
Figure 3 shows the relationship between degree of poly- =
merization and the ratio of polymer yield to the amount of fe
chain transfer agent, Mp/C. The broken line shows the re-
%
lationship if the degree of polymerization is directly pro- 4
portional to the ratio Mp/C. The experimental results are
=
in good agreement with the theoretical values. Thus the
+
degree of polymerization is found to be determined by the
A
ratio Mp/C in this copolymerization, regardless of the kind E:
of fluorocarbon iodide.
Es
A
VINYLIDENE FLUORIDE-HEXAFLUOROPROPYLENE
769
( Molecular welght of polystyrene standards )
108
10
1
:
2
3
g
uw 50 55 EC) 65
:
Elution volume (nl)
=
Fig. 4. Molecular weight distribution of the copolymer
:
p{reemmpna)r:ed (irny)theCFIp,reMsnenc=e 1o4f000c0h,ainMw/tMrnans=fe2r.71agents:
;
:
(--): Kc 3a, Mn = 143000, Mw/Mn - 1.73.
;
The molecular weight distribution curves of two copoly-
;
i mtehres parreesenscheownof in1,F4i-gduir-eiod4.o-peOrnfeluiosrotbhuetacnoep,olaymedri-piroedpiadreed in
A
type chain transfer agent, and the other is that prepared
:
+ using perfluoroisopropyl iodide, a mono-iodide type chain
3
= transfer agent. As reported previously4, the molecularweight
J
. distributions of these two copolymers are very narrow compared
:
"= with those prepared using other chain transfer agents such
3
as carbon tetrachloride and isopentane. On the other hand,
:
770 150
M. OKA AND M. TATEMOTO
- 100
=
>
ML jap (14070)
74d
]
2 wn
Se/
/
J
:
0
10
2 30
"0
3
to x 107%
Fig. 5. wMeoiognhety Mvni:scosity ML vs. Number average molecular
;
(0): (CF3)2CFI; (e): I(CF2)gl and I(CFp)gl.
%
it is evident that the copolymer prepared with di-iodide gives -
a narrower distribution of molecular weight compared with
i
vtahlautepriespasrmeadllweirththmanonot-hiaotdiodfe;thein coopthoelrymweorrdpsr,epairtesdMww/iMtnh
oR
.
mono-iodide. Such a distributional difference of two copoly-
mers seems to affect the bulk and solution properties of the =
copolymer.
viscosity
(FTihgeurMeoo6)neyofvtihsecosciotpyoly(mFeirguprerep5)areadndwiitnhtrdiin-siicodide
2
oe
are smaller than those of the copolymer prepared with mono- 5%
iodide at the same number average molecular weight.
2
a
VINYLIDENE FLUORIDE-HEXAFLUOROPROPYLENE
771
= 20
8
7%)= 3.99 x 1074 wa0-635 O27
~ 0u7 p? Pd A
E&os
07" 9) = 3.96 x 1074 un0-625
0.3 ~
0.2
Fig. 6.
3 05710 22 30 507010
Max 10
Intrinsic viscosity (3) vs. number agerage molecul-
a(r0):wei(gChFt3)M2nC:FL; (#): 1(CFp)ql and 1(CFp)gl.
:
In the case of mono-todide
OmE onane, r Rpm
oF pm
1
@ Reel Initiator fmm
(3) Rpm smeRp In the cose of di-todide
>RpmRp decd polymer )
Fig. 7.
(37) [mmRymms snmp] -- ImgmmmRemen]
( not dead polyner ) Mechanism of copolymerization in the presence of
organic iodide compounds as chain transfer agents.
|
772 M. OKA AND M. TATEMOTO i
Now, we suppose such a distributional difference comes
i
from a difference in the copolymerization mechanism, as
described in Figure 7. In this copolymerization, the fluoro-
carbon iodide is very reactive; it is easily attacked by a
|
radical and forms the copolymer (shown in Figure 7-1). As
3
mtahiensterrmeiancatlivei,oditnhies ofcotphoelymceoprolsyumcecresfsoirvmeeldy
in this
becomes
way re-
a higher
P
y
molecular weight copolymer by repeating the propagation re-
I
action and the chain transfer reaction (7-2). On the other
hand, this copolymerization reaction was carried out at ex-
:
tremely low ammonium persulfate concentration, as mentioned
3
above. Therefore, in the case of mono-iodide, the iodine-
free-copolymer(dead polymer) is generated by the recombination &
reaction (7-3). But in the case of di-iodide, iodine-
A
terminated copolymer is generated by the recombination re-
$
action (7-3'). Tt seems that such a difference in the re-
&
combination reactions affects the mode of molecular weight
By
distributions of two copolymers formed.
:
&
Now, the gel fractions of peroxide-cured-vulcanizates
3
were measured to estimate the degree of vulcanization.
&
Table II shows the effect of coagent on peroxide vulcanization. =
Polymer A is the copolymer prepared in the absence of organic i
iodide compound. Therefore, it has no terminal iodine.
xX
Polymer B is that prepared with perfluoroisopropyl iodide;
3
it can be considered to have terminal iodine on one side
=
(mono-iodide-copolymer). Polymer C is that prepared with
5
1,4-di-iodo-perfluorobutane; it can be considered to have
2
terminal iodines on both sides (di-iodide-copolymer). In
5
the cases of polymer B and C, it is found that the gel frac-
tions of thier vulcanizates are increased using various kinds
of multifunctional vinyl compounds, and that triallyl iso-
=
cyanurate(TAIC)
hand, no gel is
fisountdhe imnosttheefcfaescetiovfevuclocagaennitz.atesOn prtheeparoetdher
Ho
"
from polymer A even it was cured using TAIC. These experi-
mental results suggest the terminal iodines react with TAIC o
and form gel.
aah
oe
Figure 8 shows the effect of TAIC on gel fractions of Sak
Npoergoexlideis-cfuoruendd-vuilncatnheizaatbessencperepoafreTdAICfroomn
polymer B and C.
both vulcanizates.
AH
i
But the gel fractions increase with the increase in TAIC and iE
become constant at high level. The gel fractions of vul- be
tchaannizattheosseprferpoamreddi-ifordoimdem-ocnoop-oiloydmiedre.-copolymer are smaller
A
oF
Ee5
aSafy
VINYLIDENE FLUORIDE-HEXAFLUOROPROPYLENE
:
7 TE
3 773
a
=
: 217% i i :
_
g =RnFzRsRan Gs |le2
=
7
7 | a2
:
22.01%
8 5
3 23
S=l|glsilennnnas|dE
:
188
i
ee.
5
2 lee
E
7
:
3 Eli 11 100|2
2
:
53
;
Hl 8
i 4
:4
u-w 2 3 5
3wg2
a5
:
g2 :5| [3] Azeanzeanacd|egsl Lf3
52
E:2
2-H
5g
g2gs 82F BZ e2s
3a2 2
3::
=g ld | 52a 285=
gTc2,828852838,
3
42
:;
sS1818
|
s8E, |5z32
=5gg|lBEEE
=
=
:>
}
23
c,8f5g 25|Scg8e2sEsE
g
E5522 28gs3
=
a
EEZgEs 2822
53
i
?i
g5E3E2Z8C23E2E08=<8=0
Ei" 3
! ges Esg|fg1s i 3
2S a=~-F-r-|38288
be:
#
530
EH
4 : =i
S2E
:
5
:
3
} 3
3 ve
2
i
C i HE
----------
Ex
774
M. OKA AND M. TATEMOTO
100 --
=
ad
/ __--O0------------O0--\--0~|
i
80
Or
3
8
]
3
gEwp : Sw
g
3
8 reeled
;
0 1 2348
4
TALC (ohr)
2
Fig. 8. Effect of TAIC on gel fraction of peroxide cured
i
vulcanizates.
=
Recipe (phr): copolymer 100, peroxide 0.5
5
Conditions: press cure at 160C for 30 min.
i
(0); copolymer with terminal iodine on one side
33
(); copolymer with terminal iodines on both sides.
Figure 9 shows the effect of peroxide on gel fractions
of peroxide-cured-vulcanizates prepared from polymers B and
C. The gel fractions of vulcanizates prepared from mono- A
iodide-copolymer are smaller than those from di-iodide-copoly= 2
mer even it was cured using a great quantity of peroxide.
8
Analyses of extracts were done to investigate the cause of =
difference of gel fractions. Consequently, it was found that 3h
the extracts were low molecular weight copolymers which have 3
no iodine. Thus it seems the mono-iodide-copolymer contains
about 10-15% iodine-free-copolymer by weight.
by
Now the reaction mechanism of iodine-terminated-copolymer =
with TAIC in the presence of peroxide was proposed, as shown
in Figure 10. An initial radical formed by the decomposition of peroxide attacks the double bond of TAIC to form radical =
(11)[step(1), step(2)]. The radical (II) subtracts iodine
from iodine-terminated-copolymer to form polymer radical
5
[step(3)]. And then the polymer radical attacks the double 4
23
G
VINYLIDENE FLUORIDE-HEXAFLUOROPROPYLENE
775
kr
100 --gre-0------@
EEe8
--O0------0------0-
By
::
25 wl
a5
:
fy
H
: : 1
i
2
bt 3
:
oh
=
0
1
2
3
5
3
Peroxide (phr)
3
"Fig. 9. Effect of peroxide on gel fraction of peroxide cured
)
vulcanizates.
3
4
4
Recipe (phr): copolymer 100, TAIC 2
b
E
Conditions: press cure at 160C for 30 min.
4
A
8-
(0);
();
copolymer with
copolymer with
terminal
terminal
iodine on one side
iodines on both sides.
pe
3
Ee
=
bond of TAIC to form radical (IV) [step(4)], which subtracts
3
iodine from another iodine-terminated copolymer [step(5)].
2
;, Crosslinking network seems to be formed by repeating such
3
5&% rboenadctioofnsTAIoCf. iodine-terminated copolymer with the double
6:
33
4
oo
SUMMARY
33
y
.
.
3
Re and hTehxeaflcuooproolypmreorpiyzlaetnieonwerreeacctairornisedofoutviniynlitdheeneprfelsueonrciedeof
3a
an organic mono-iodide compound, (CF3)CFI, or di-iodide-
>
compounds, 1(CF2)gl, I(CFp)gl, as chain transfer agents and
t= the following results were obtained.
.
=
776
M. OKA AND M. TATEMOTO
I) RO-0R --> 280:
Clly=CH CHeCH, RO-CHy-EH CHeCHy
@ RO: +
jCH2=CH m
--ip:
9,
H-Chy an
0-Chy-0 HeCHy
3) (UD + mmm -->
CheClly mets
:3
an
TeeClCH =CHy
3
W lems + () ---->
;
CH=CHy
7
av
3
Tithe
:
BG) UV) + [mmmmm] =
+ mms
=
CheCHy
3
- ; w
=
9
2
hb
=
or
oy
Fig. 10. Proposed reaction mechanism of iodine-terminated- 3
copolymer with triallyl isocyanurate.
i
E
oF
i
1&
VINYLIDENE FLUORIDE-HEXAFLUOROPROPYLENE
777
3
5
(1) The number average molecular weight of the copolymer
2
is determined by the ratio of polymer yield to the
3
amount of chain transfer agent.
3
(2) The molecular weight distribution of the copolymer
E:
prepared with di-iodide is narrower than that pre-
5
pared with mono-iodide.
i
(3) Such a distributional difference seems to come from
3
a difference in the recombination reaction of the
3
copolymerization.
3
(8) The terminal iodines of the copolymer seem to react
3
winiththmeulptriefsuennccteioonfalpervoixnyilde.compounds to form gel
33
(5) The gel fractions of the vulcanizates prepared from
=a
mono-iodide-copolymer are smaller than those from
2
di-iodide-copolymer.
3
2
(6) The difference of gel fractions seem to arise from
5
that _mono-iodide-copolymer contains iodine-free-
3
:
copolymer.
%
:
References
3
1. K. L. Paciorek, Fluoropolymers, High Polymers Vol. XXV,
3
L. A. Wall, Ed., Wiley-Interscience, (1972)
2
2. R. G. Arnold, L. A. Barney and D. C. Thompson, Rubber
3
Chem. & Technol. 46, 619 (1973).
:
3. Y. Kometani, (to Daikin Kogyo Co., Ltd.), Published
:
:
Japanese patent application (examined), No. 8863 (1977)
3
4m Tatemoto, paper presented at The First Regular Meeting
3
% of Soviet-Japanese Fluorine Chemists, Tokyo Ta79)
:
5
:
:
;
5 4