Oil-Polymer Masterbatching U
J
CONTROL OF POLYMER BREAKDOWN W. IC;. TAFT', JUNE DUKE', T. B. LARCHAR', S R . , W. G. KITZ&IILLER2,AXD JIILTON FELDONS Uniuersity of Akron, G o v e r n m e n t Laboratories, Akron, Ohio
N EQUATION expressing the tiend of the breakdown of polymers in oil-polymer masterbatches, or of the high molecular weight oil-free polymer, has been shoivn to be of the form (6) 1' - A = Be-"t \There Ti = corrected viscosity of oil-polymer masterbatches or base polymer in dilute solution viscosity (DSV) units a t time t ; t = time in days. A , B, and a are constants. The sum of A and R is the viscosity of the original polymer, and A is the limiting viscosity of the broken dov,n polymer; e is the base of the natuial logarithm. This equation has been s h o x n to hold for material heat-aged in a forced draft oven a t 140OF. Mitchell and covorkers (4) have shown that the amount of certain metals influences the sta5ility of oil-polymer masterbatches. Since Mitchell's observations R ere limited to periods of approximately 1 day, it might erroneously be deduced that removal of iron would result in stable polymers. The results of this work show that such reasoning would not necessarily be justified. The x-orli of D'Ianni (S), Albert ( I ) , and Chambers (Z), among many others, has indicated that iron in varying quantities increases the oxygen absorption of a polymer and the breakdown of GR-S polymers during milling.
approximately 60% conversion. About 1.25% phenyl P-naphthalamine based on the polymer was used in all coagulations. The oils used in t,he masterbatches x-ere selected to be representative of the three oil types est'ablished by the Office of Synthetic Rubber. Dutrex 20 is representative of the "highly aromatic type," Sundex 53 and SPX-97 of the "aromatic typc," and Circosol-2XH of t,he "naphthenic type." Secton 60 was included in order te broaden the basis of the tests. Emulsions of the oils were made as 50% emulsions of oil in a 2y0solut,ion of the sodium salt of oleic acid, mixed x4th the latex, and coagulated with salt-acid, or 5vith bi- or trivalent salts, and adjusted in all cases n-ith sulfuric acid t o about 2.5 pH. I n all cases, masterbat,ches were made t o contain 37.5 parts of oil per 100 pa& of rubber. The polymers or masterbatches were vacuum dried at room temperature and then oven aged in a forced draft, oven a t 140' F. for periods up to 30 days. This test' temperature was chosen so t'hat the results of this and previous studies are comparable. The acetone extracts were determined as necessary to est,ablish insignificant losses and also as the basis for correcting gel content and dilute solution viscosit'y (DSV). Gel content and dilute solution viscosities >yere determined, and from these 1 Present address, Olin Mathieson Chemical Corp., Aviation Division, S i a g a r a Falls, N. Y . 2 Present address, Columbian Carbon Co., .4kron, Ohio. 3 Present address, She11 Chemical Co.. Torrance, Calif.
CORRECTED D S V
PROCEDURES
Latices were made a t 41' F. according to the folloning formulas: Iron Pyrophos- SdfoxyPo!Yphate, late, amine, Type Formula Parts Parts Parts 70/30 72/28 72/28 Butadiene/styrene 0.088 0,118 0.1 ATodifiera 0 . 10b 0,lC ... Stabilizer Soap 4.5d 4.P 4.5f Hydroperoxide 0 .070 0.0iO 0.10h Ironi 11)sulfate heotahvdrate 0.10 0.015 ... Tetrapotassium pvrophosphate 0.11 ... Chelating agentL 0.02 0:622 0.01 Trisodium phosphate ... 0.1 ... Tetrapotassium pyrophosphate ., , .... 0.2 Sodium formaldehyde sulfoxylate dihydrat'e 0.07 , . . Water 180' ' 180 180 tert-Dodecyl mercaptan. * Sodium salt of condensed aryl sulfonic acid. c Sodium salt of alkyl naphthalenesulfonic acids. Potassium salt of disproportionated rosin acid and potassium salt of fatty acid. e Pot,assium salt of rosin acid, or of fatty acid, or a SOYc misture of the tn-o acids by weight. f Potassium salt of fat,tyacids. 0 p-Menthane hydroperoxide. * Diiiopropylbenaene hydroperoxide. bIixture of technical tetrasodium ethylenediaminc tet'raacetate and sodium salt of an amino acid.
- 20 c , -
IO
-
0
I cc 0 80
55
LC
2.5
2.0
I O
O
B 0
'1 " 2 " 5 " 4 ' 5
8
1
8
1 '0
,E
EO
21
DAYS AGED AT 140-F
A!1 of the reactions were shortstopped n i t h 0.15 part of potassium dimctliyl dithiocarbamate-potassium polysulfide a t
Figure 2.
Pols mer breakdowm during heat-aging
Sulfoxylate activated formula-Dresinate
1220
3@
INDUSTRIAL AND ENGINEERING CHEMISTRY
July 1956
analyses the corrected dilute solution viscosity was determined in each case for the contained polymer.
Table I.
Variables and Parameters of Breakdown Equation I r o n Content, % Parameters
RESULTS AND CONCLUSIONS
Examination of data doncerning breakdown of polymers indicated t h a t the equation mentioned above should be modified to V - A = Be-'('-') where z expresses an induction period prior to breakdown. This seeming induction period might be a period during which oxygen is absorbed or added chemically to the polymer b u t does not react further to cause chain scission or cross linking. In this discussion, therefore, this alteration in the previously reported equation (6) will be used. With polymers made by the polyamine, the sulfoxylate, and the iron-pyrophosphate formulas, the dilute solution viscosity, corrected to a polymer hydrocarbon basis, was plotted against time of heating the polymer a t 140' F., as shown in Figures 1-5. The so!id lines represent the curves of the empirical equation. Gel, where it occurred, is shown by a separate scale in the figures. The variables and parameters of breakdown represented by the constants and z in the equation are given in Table I. Table I and the figures show that the base polymers varied in dilute solution viscosity from 3.24 to 3.61; the latter value was obtained for the polymer made according to the polyamine formula. The colorimetric determination of iron is not precise in this region, and the results are given to show the approximate levels. The data indicate, however, that the total iron content is smallest in polymers prepared according to the amine formula, about three to five times greater in polymers prepared according t o the sulfoxylate formula, and 100 times greater in polymers p r e p s e d according to the iron-pyrophosphate formula than in polymers based on the amine formula. A tabulation of the breakdown parameters indicates (comparing polyamine and sulfoxylate formulas in Table I) that masterbatched polymers from the charges made according to
1221
Latex
Oil
Anal.
Calcd.
B
a
x
2.31 2.17 1.69 1.11
0.80 0.21 0.13 0.14
0.76 1.5 3.0 6.0
2.14 2.20 2.10 2.10 1.22 0.93
0.40 0.18 0.25 0.10 0.09 0.06
0.75 0.7 0.7 ,2.0 555 6
2.25 2.26 2.42 2.20 1.39 0.96
0.9 0.23 0.25 0.10 0.09 0.06
0 0.5 0.5
A
Polyamine Formula ( F a t t y Acid Soap) Iron free, no Dutrex 20 i r o n i n f o r m - Sundex-53 ula Circosol-2XH Base
0.0017 0.0010 0.0010 0.0017
0.0026 0.0015 0.0015 0.0018
1.30 1.44 1.92 2.50
.
Sulfoxylate Formula (Rosin Soap)
Lowiron, 0.04
Dutrex 20 Sundex-53 SPX-97 Circosol-2XH Necton 60 Base
Low iron 0.004dartd
Dutrex20 Sundex-53 SPX-97 Circosol-2XH h'ecton60 Base
parta
0.014 0.005 0.007 0.001 0.005 0.006
0.021 0.007 0.010 0.006 0 007 0.007
1.20 1.20 1.24 1.30 2.20 2.40
Sulfoxylate Formula (Mixed Soaps) 0.010 0.013 0.016 0.011 0.009 0.012
0.015 0.019 0.024 0.016 0,013 0.013
1.15 1.22 1.10 1.32 2.15 2.50
1
2.5 6
Sulfoxylate Formula ( F a t t y Acid Soap) Low iron 0.004
Dutrex20 Sundex-53 SPX-97 Circosol-ZXH Necton 60 Base
darts
0.006 0.005
0.006 0.006 0.004 0.003
0.009 0.007 0.009 0.009 0,006 0.003
1.13 1.30 1.22 1.46 1.80 1.90
2.38 0 . 6 2 . 1 8 0.35 2.23 0.38 2 . 0 0 0.10 1.65 0.08 1 . 4 6 0.06
0 0
0
0.5
1 4
Iron-Pyrophosphate Formula (Mixed Soaps) Ironpyrophos- D u t r e x 2 0 phate, 0 . 0 2 Sundex-53 SPX-97 parta Circosol-2XH Necton 60 Base
0.019 0.018 0.013 0.018 0.016 0,022
0.028 0.027 0.019 0.027 0.024 0,024
1.18 1.21 1.21 1.54 1.81 2.51
2 . 1 3 1.41 0 2.10 0.24 0 2.10 0.34 0 1.56 0.17 2 . 5 1.50 0.09 3 0.73 0.06 3
a Per 100 parts of rubber.
CORRECTED DSV I
DSV
CouEOTrD
3
35
1
--.
so
30
50
10
PI
-
30
90
5
10
PO
0 I 5
I O
16
0
1
2
3
4
5
6
~
IO
I5
20
25
30
90
30
96
I
DAV8 AELD AT I40.t
DAYS A G E D AT 140.F
Figure 3.
Figure 5.
Polymer breakdown during heat-aging
Polymer breakdown during heat-aging Iron-pyrophosphate formula
Sulfoxylate activated formula-mixed soap CORRECTED
0s"
4001
36
3 50
LO
3 00
05
2 50
P O
200 I I O
I
I 60 15
I40 I 20
10
io0 0 so 060
'
'
'
'
.
I
.
F.
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
Vol. 48, No. 7
OORRECTED D S V
CORRECTED DSY
40
35
30
16
0 80
#
0
6
1
"
2
'
3
'
4
~ 5
' 8
s 7
'
' 8
10
I
25
20
5
30
DBY9 AGED AT 140.F
Figure 8.
Heat-aging at 140' F. base polymer plus varying quantities of Versene Fe-3 Iron-pyrophosphate formula
free latex made by the basic amine formula are shown in Figure 1; those of masterbatches from the same latex, but to which 0.167 part of iron(I1) sulfate heptahydrate was added, are shown in Figure 6; t,hose of masterbatches again prepared from the same latex, but to which 0.33 part of iron(I1) sulfate heptahydrat'e was added, are shown in Figure 7. For comparison, Figure 5 shows the results of heat-aging a similar series of mnst,erbatches from latex made according t o the iron-pyrophosphate formula, using mixed fatty acid and rosin acid soaps. The parameters for the equations for the four sets of curves are given in Table 11. Table 11. Parameters for Equation, V Latex
Oil
Fe, % Polymerp Analyzed basis A
Polyamine Formula Dutrex 20 0 0017 0 0026 Iron free 0 0010 0 0015 Sundex-53 Circosol-2XH 0 0010 0 0015 Base polymer 0 0017 0 0018 0 027 0 040 0.167 parta Dutrex 20 0 030 0 060 iron(I1) sul- Sundex-53 Circosol-2XH 0 023 0 034 fate added Base polymer 0 040 0 043 Dutrex 20 0 050 0 074 0.33 0 040 0 060 iron(I1PiteCt;f Sundex-53 0 060 Circosol-2XH 0 040 fate added 0 066 Base polymer 0 060
-
A
=
Parameters
B
x
u
1 . 3 0 2 31 1.44 2.17 1 92 1 . 6 9 2.50 1.11 0.99 2.62 1.03 2.58 1 . 0 6 2 55 2 50 1 . 1 1 0 97 2 64 1.03 2.58 1.31 2.30 2.20 1 . 4 1
0 80 0.21 0.18 0.14 0.70 0 26 0 17 0.15 0 80 0 21 0 13 0 18
Iron(I1) Sulfate-Pyrophosphate Formula 0.028 1.18 2.13 Iron equiva- Dutrex 20 0.019 0.027 1.21 2 . 1 0 0.018 lent to0.023 Sundex-53 0.057 1 . 5 4 1 56 parta Circosol-2XHb 0 . 0 1 8 Basepolymerb 0 . 0 2 2 0.024 2.51 0 73 a Per 100 parts of rubber. b D a t a from AU-1269, b u t parameters recalculated.
1.41 0 24 0 17 0 26
0 0 2.5 3
Table 111. Variables and Parameters of Breakdown Equation Added Versene, Partsa None Base 0.32 0.97 1.94 3.24 Dutrex 20 None 0.32 0.97 1.94 3.24 SPX-97 n'one 0.32 0.97 1.94 3.24 Sundex-53 None 0.97 Circosol-2XH None 0.97 None Necton GO 0.97 z, Per 100 parts of rubber. Oil
FeB Anal. 0.011 0 022 0.0088 0,013 0.013 0.011 0,011 0 0045 0.016 0,011 0,079 0.017 0,0074 0.015 0,015 0.'0039 0.070 0,0069
o.'O&o
%-
Corr. 0 012 0.024 0.0096 0.014 0.014 0.016 0.016 0 0067 0.024 0.016
Parameters ___.____A B U 2.00 3.23 3.49 ,, ,
.
.
.
1.10
1 26
133 1.52 1.76 1.13 1 22 0 . 0 1 1 1 1 29 0.023 1.33 0,023 1.69 1.15 0.'0058 2 03 0.104 1.40 0.010 2.83 2.67 o.'0059
8:;:;
1.75 0.52 0.23
0 06
0.12
