Extension of GR-S Polvmers with a J
California Asphalt R . E. I S L E I , F. C. BRUCE,
AND
E. E. ST.4HLY
B u r k e Research Co., V a n D y k e , Mich.
P
REVIODS research (6) had show1 that of the five hasic types of petroleum fractions present in commercial rubber compounding oils the asphaltenes provide the greatest amoiint of reinforcement for both natural rubber and GR-S-tj-pe polymers. The purpose of the prpsent work w a s t o malie preliminary tests t o determine suitability of a Califomia petroleum oil containing large amounts of asphaltenes, as extender for GR-Stype elastomers. I n view of recent interest in cocoagulated oil-GR-S polymers (1, 2, 9-11) it appeared desiralilr. to investigate the cocoagulation of emulsions of asphaltic oils arid elnstomer latices. Commercial asphaltic oils (Exoils, produced by the 1,:seter Oil Co., Long Beach, Calif.) derived From a California crude oil s-ere used for two reasons: Large reserves of this crude oil are available, and the commercial products (Exoils) have a reiisonably uniform chemical composition. -4 few gilsonite GR-S compounds were prepared as controls, and Circosol 2 S H , a conventional asphaltene-free petroleum oil extender, !vas used for purposes of comparison (Table I). Because the asphaltene-type materials are reinforcing agents with a n ability t o absorb a high ratio of oil t o their o ~ v nhulk ( 5 ) , it is suggested that they might reduce the amount of oil migration which occurs in tires containing oil-cxtendcd polJmier. Lower oil migration should alleviate the splicing prohlem ericountered when tire treads are molded from oil-extended polymer-base compounds. GEXERAL DISCUSSION OF RESULTS
The California asphalt oils can be used t o improve the processibility of petroleum oil-extended GR-S high Mooney polymers. T h e asphaltenes act as a n ahsortwnt for petroleum oil. -e.g., Circosol 2 S H of the Sun Oil Co.-permit the use of larger amounts of total extender, and a t the same time act a s a reinforcing agent. Discrete particles are observable in elertron microscope pictures of the asphalt oil-polymer mixes: the order of particle size of the asphaltene aggregate (Figure 1) is al)out triple that, of Philblack 0 (90 m p vs. 30 mg average diameter). The advantages of t h e use of oils containing aPphaltenee admixed Kith the usually employed asphaltene-free petroleum oils are (1) the use of larger total amounts of loiv cost extender oils t o achieve the desired reduction of llooney viscosity, ( 2 ) improved processibility (compounds made from asphaltic oilextended polymer massed well in the Banbury and did not hreak u p on addition of carbon black a s the usual oil-estended polymer compounds do), ( 3 ) improved tensile strength, and (4)improved elongation and flex life when compounded t o heat huild-up values equivalent t o those obtained iyith asphaltcne-free petroleum oil-extended GR-S (Figure 2). A higher level of curingagents is used t o obtain best results with these asphalt oil-estended polymers. T h e belief t h a t asphaltenes cause high heat build-up is shown not t o apply t o appropriately compounded asphalt oilGR-S compounds. The following types of normal and high Nooney polymers have been compounded in studies of the asphaltic oil estenders: GR-S 1500 (23.5% styrene, 607, conversion); GR-S XP-138 ( 8 % styrene, 607, conversion)
458
125 \looney viscosity GII-S polymers, 23.57, styrene; 60yo conversion (S-628 type now coded GR-S 1T03) 160 ?Iooney viscosity GR-S polymers, 20% styrene, 60% conversion Unmodified, essentially quantitative conversion GR-S polymew, 25% styrcne (extrapolated 270 1Iooney viscosity) High styrene (40 t o 50 parts of styrene) GI
In present formulations both Liqro and F-insol n-ere used; however, either will form a satisfactory emulsion. The water phase was heated t o approximately 80” C. The oils were mixed and heated t o 100’ t o 130” C. The oil mixture was then poured into the water pha-e with stirring. T h e presence of the asphaltic, oil, Exoil B-100, appeared to add t o t h e st:ilility of the oil-emulsion system. (Exoil B-100 is :I very viscous material a t low temperatures :inti it must be heated above 100’ C. t o reduce its viscosity for emulsification.) The oil phase was added t o the water t o avoid the formation of a “water in oil” system. Mixtures of 50 parts of oil and 50 parts of
3 ZnO, 1 stearic acid, 1 Santocure, 1.76 s u l f u r )
C(~l1,lK’llnd
Pliilhlsck 0 Para 1 . 1 Z~O I~C oil Ciri,oiol 2 X H Exoil B-100 (aspliiilt 011, Exoil B-300 insplinlt oil) Exoii S-72 Asphaltenes (calculated) Compniinrl 3Iooney vis., AIL-4 O i ) 1 i i i t i i i i l ci;r l o o n e y \-ivositi. polyiuer n.itii 2 5 pnrts of Circosol 2XH. 99 5 1
36 1
0.5 0 1 21.8 2.1
March 1956
INDUSTRIAL AND ENGINEERING CHEMISTRY
thousands of cycles-i.e., kiloflexes-to produce a crack inch long. Tear values were determined on samples prepared with a n angle-ttar die. Mooney Viscosity Reduction Characteristics of Exoils. I “Mooney reduction” factor was determined for each oil extender employed (Table 11). K i t h such factors (per part of oil) calculations of fair accuracy were made of the amounts of extenders required for preparing oil-mixtures of Mooney viscositj- vtiluea in the range of 45 t o 65 Jlooney viscosity. Outside this range of Jlooney values the same reduction factors Kere not necessarily applicable. The reduction factor varied sonien-hat with the range of llooney viscosity of the raw polymers of high 1Iooney
BOIJND STYRENE, PER CENT
Figure 2. Tensile and heat build-up behavior for styrene-butadiene copolymers in tread recipes
viscosity t o be extended. Curves were drawn relating the Mooney reduction factors (Table 11) t o the Mooney viscopity of the raw polymer within the operating limits of this project (Figure 3). % . straight line was obtained for the Mooney reduction factor for Circosol 2 S H petroleum oil, whereas the factor increased with the increase in r a F hfooney viscosity for the asphaltene-free oil 5-72 and for the asphalt oils either alone or in mixtures n i t h S-i2. The hIooney reduction factor for Resinex L-4 was found t o be constant. ( A small amount of Resinex L-4 was incorporated into tlie Esoil mixture t o improve the tack of the polymer compounds.) D a t a on insoluble polymer (Table 11) show that the nsphaltcontaining and the aephalt-free oils are equally effective in suppressing gel formation. PROPERTIES OF A S P W ~ L TOIL-EXTENDED
cowou\ns
The five types of polymers employed in the study of the use of asphalt oil extenders are discussed below in connection n-ith data for several series of compounds. High Mooney Viscosity, 60% Conversion, Extended GR-S Polymer Compounds Containing 20yo Styrene. GR-S X-628 t j pe polymer (115-125 AIL-4 raw polymer). A series of compounds was formulated in which from 0 t o 20 parts of asphaltenes m r e added (as Exoils) in the Banbury mixer t o 55 %looney viscosity
46 1
oil-extended GIt-S polymer S-628 (now designated GR-S 1703). (This polymer as received contained 25 parts of Circosol 2XH.) Table I11 contains data for a group of these compounds. Compound €3-101 is a tread compound prepared as in commercial practice for GR-6 with 50 parts of HAF carbon black. The additional extenders present in B-101 soften the compound and lower the niodultis. To conipensate for the additiond extension, HAF cardded in the reniininder of the compounds, as is otter1 done n-ith oil-extended elastomers. In compounds B-113, B-116, and B-123 optimum properties were obtained in the range of 4.5 to 9.5 parts of asphaltenes 17 parte of Exoil B-loo), with 70 parts of H A F black showing the ; m t bnlnrice of properties. Compounds 13-123, B-124, and B127 indicate (1) that the Exoil B-100 as :Ldtiitional extender proi!rices conipounds having higher tensile strength, elongation, tear strength, and hardness than compounds extended with Circosol 2 S H or Exoil 5-72 produce, and ( 2 ) that heat build-up vulues a t this loading level are equivalent for tlie three oils. Talhle I V shows a similar group of compounds prepared by latex blending of the oils arid polymer latices. The data for the cures ( t o optimum tensile strength) indicate that the tensile strengths of the Esoil-extended stocks are considerably better than those of the Circosol 2XH-extended stocks (B-109 and R110 us. B-114); however, the JIooney viscosity of the conipound containing 16 parts of asphaltenes is a little higher and the modulus is low. T h e stock with 25 parts of Circosol 2 S H (coniniercial 5-628, now GR-S 1703) can he further extended with 25 part6 of the asphalt oil (B-112) and loaded t o 63 parts of HAF black to give a better processible stork (massed better in the Banbury and handed better on the mill). Addition of a small x n o u n t of asphaltene-free oil t o the GR-S X-628 (in B-101 control), horTever, results in too low hardness for use in tread stocks. The heat build-up values are not seriously affected by the presence of from 9 t o 16 parts of asphaltenee, and the physical properties are adequate for tire construction. GILSOSITE-OIL GR-SS-628 Coupouxos. The effect of asphaltenes swelled with oil v a s also investigated in a series of GR-S compound3 prepared x-ith gilsonites of three different ranges of softrning point. The data for t x o of these are given in Table Y, In preparation of these compounds the gilsonites were melted x i d dissolved in the Exoil 5-72 (asphaltene-free oil) t o effect oil ahsorption before addition t o the 5-628 pol?-niw on the mill. IVhiIe the further extension of GR-S S-628 (already containing 25 pnrts of oil) loIvers the tenGle properties of the coni-
Table IV.
GR-S X-628 Type Polymer Latex Blended with Oils
‘ C u r i n g recipe. Compound
L5 ZnO; 1.5 stearic acid: 1.5 Altau; 1 . 5 sulfur) i0B;n
?i
1Bi
B-
112 100
B-
110 100
B100
Polymer iiiarts before extension) 100 100 100 100 Para Flux 201R 6 ., .. .. .. .. Circoso! 2XI-I 30 25 25 25 .. ., Esoil B-300 .. . 7 25 Exoil B-100 ,. ,. 10 22 18 .. Exoil 5-72 .. .. 7 . .\aphaltenes (calculated) 0 0 3 8 9 . 5 i i : 1 16.1 Pliilblack 0 .50 50 71 63 50 50 Compound AIooney vis.. A I L 4 51 iiT, 00 48 73 93 Optimum cure. min. a t 2 8 5 O F. 90 90 A0 120 90 90 Tensile. Ib./sq. inch 3240 3155 30.18 2900 3690 36.10 575 6h.5 G5.5 Elonration, % 890 505 610 800 64.5 85.5 300% modulus, Ib./sq. inch 375 1460 1223 63 67 S!IOTPA durometer 41 54 07 52 Cure, min. a t 28s3 F. 90 90 90 90 90 90 DehIattia t o s’,1 inch crack, kiloflexes ., 7.5 .. , . 20.4 Goodrich flexometer 76 77 89 94 H e a t rise. F. 9! 81 3 2 2 6 1 2(i 3 Dyn. comp. d r i f t , YC 15 25 19 30 29 22 Static comp., 4.3 2.8 4.6 5.8 6.2 11 Set. % a Banbury niixed control employing GR-SX-628 (25 parts Circosol 2 X H ) a n d additional oil ( 5 parts each Circosol 2XH a n d Para Flux 2010).
..
INDUSTRIAL AND ENGINEERING CHEMISTRY
462
I
8 I
...
1
a
w
Vol. 48, No. 3
use of a higher amount of sulfur (2.2 rather than 1.75 parts based on actual polymer) gave heat build-up values and moduli in the range required for commercial tire tread stocks. In comparison with Krynol (B-147) t h e heat build-up of R-144 was poorer, but the latter compound developed approximately thc same tensile value and a definitely higher elongation and flex life. (The often used index, flex life-heat rise, was 0.36 for Krynol us. 0.75 for B-144 which contained asphaltenes.) B140 and B-134 showed that, a t the same heat build-up level, better flex life and elongation can be obtained with the Exoil estendeti Ptock. The comparison of compounds at low states of cure \vas found permissible by use of t h e above-mcntioned flex life-hysteresis relationship (4),log flex life = 0.015~lf 3.63. I t appears that asphalt oil-GR-S compounds can be balanced or modified t o develop desired properties, and, as with asphaltene-free oil-extended stocks, improvement in one property may be accompanied by a loss in another. High Conversion Unmodified GR-S Polymers ( 2 5 q ~Styrene). I high conversion polymer of high Rlooney viscosity was used x i t h Esoil estension. Unmodified 94.5% conversion GR-S (supplied by the Government Laboratories, University of Akron) n-as extended Lj-ith several oil combinations as shown in Table VII. The SIooney viscosity was estimated t o be 270 AIL-4 (on the liasis of Circosol 2 X H extension using a RIooney viscosity reduction factor of 2.4 units per part of oil). Although t h e two asphalt-containing oil-extended polymers (B-154 and B-157) iirepared from this unmodified GR-S showed some advantage$ over the asphaltene-free extended compound ( B - 1 4 ) , all three compounds were regarded as not being sufficiently processible t o he practical. .4 compound of a 160 RIooney viscosity polymer (B-144, Table VII) was prepared for comparison with the 270 M I 4 (extrapolated viscosity) compounds. Blends of the 270 XIooney
+
I 5o
$0
u
ao
100
120
Figure 3. a
~
140
RAW POLYUSQ
_
_
160
.
_
. i -
itr
IBC
2zc
uoorrEY
&looneyreduction factors
54.49'0 Eroil 5-72, 36.9% Exoil B-100,8.770 Resincx IA
Table V. (Curing recipe.
Gilsonite-Oil-GR-S X-628 Compounds 3 ZnO: 2 stearic acid; 1 SantocnrP: 1.75 siilfiir
Compound
+
Polymer 25 parts Circosol 2 S A Philblaok 0 Gilsonite ( m . p. 270-280' F.) Gilsonite (m. p. 320-340O F.) Exoil R-100 Exoil 5-72 dsphaltenes (calculated)
Cure, niin. a t 2 8 5 $ F. D e l I a t t i a flex. t o 11, inch Goodrich flexorneter H e a t rise, ' F. Dyn. conip. dri ft, "c Static c o m p . , 7c Set, 70
1119
B-
B1120
B116
G2882
125 G3 6.2.5
125 63
125 63
123 (i3
.
,
0:25
G'25 3.7
R:25 4 4
54 43 2610 740 700 53
54 75 2845 (iI n 1270
90 13
in
o 3 23 2.0
12 L 4 7
(I
90 13
N 12 3
9 Ll 7.a
65 0.2 24
0.5 i
71
0.2
2.4
3 0
59
3.0
o
25
Table \ I. Latex Addition of California Asphalt 3lixturea to High-hlooney Viscosity NormaLConversion GR-S ColllpGUlld
B205
B140
B-
177
B139
R144
B143
B147
27
IIxoil S-72 (petroleum) I;xoil R-100 (asphalt) Reainc.; L-4d I'arn Flnx '2016 ('irCGsol 2XII Asphaltenes (calculated)
.. .. ,
.
2.5 2,5 0
., ..
42 0
23 17
Pi 22
. ..
.. .,
0.7
s:r
.
2.5 17 4 ,
23 .. 17 .. ' 1 . .
..
fi,'j ci:s
..
0
pound, gilsonite (melting point 320" to 3-40" F.) in I-zoil S-72 i~ 30 7 0 . 3 7 0 . 5 70 i 73 73 71 Philblnrk 0 nlinoet equal t o the asphaltic B-100 oil. Thus, it a p l i e : ~tlint 3 4..3 3 3 +.4 Zinc o x i d p 3 3 1 1 I 1 1.5 1 1.g Stearic acid the solid ssphaltenes can be sa-ollen with a petroleum oil t o p1~8I 1 1 1 Snntocure I 5 1 A4 1.7; 1 7.5 2 2 I i3 1 . 2 1.75 -.I Sulfur duce a reinforcing estender oil Pimilar t o the Xxoil ny-11i:ilt nil i i i I I o o n r y visco-ity, l I L - 4 its effect on GR-S polymer. E s t m d c d polynier .i,j 02 0ri a9 56 56 ;2 GR-S OF 160 3IL-4 VISCOSITY. Table 1-1sho~vs:: gro!il>01 ~ ~ I ) I I ' ~ 7.5 70 71, $)I 72 77 t)l Coniuorind ( ~ p t i i i i i i i ic u r e . niin. a t pounds prepared from latex-extended GR-S polymc~rl(i0 Sloonc~y 285' F. 3300 go 2880 oo 302.; 60 3000 w 3130 n o ?0:33 RCI DO 3020 Tensile, Ih.,'sq. inch vivosity. Extender levels are in the range of 42 p t r t ? . ill(. 385 480 3i5 ,110 730 (i35 745 Eloneation. reported oil content of Krynol (an oil-estendrd p o I > - i n ( pi ~ ~o-~ 300% Iuod:llas, lb,/sq, inch 1900 9R5 116.5 835 1lF.i :si,11 2285 .>% Shore A diiroinerer C0 .io .J% 3.5 .13 driced by the Polymer Corp., Ltd., S:irnia. 0nt:rrio. Cmi:itlir Tear 300 2ii2 . . 286 319 2113 H o t ten,ilt 1200" F.), IbJsq. con~~ioiinds ~ I I YI c i w i (used in 13-147). T h e formulas for t h inch 1780 1410 1400 .. 1.370 . . 1i f i 0 on 100 parts of polymer. (For conip:i 011 with n r i ~ ~ n iconid 120 QO oo BO 120 C u t e ; i t 283: F., min. 90 BO mcrcial extended polymer compound, see c.onipo!iiicl 13-1:%5. U c l l n t t i a to I / $ inch crack 80 iiB 200 23 21 133 7.i kiloficxcs Table IV, a GR-S S-825 formulation containing 1 7 pal:+ of C;oodricli fiexoiiieter 03 8% 114 additional extenders added in the Banbury.) Tensile. p~'opi'rt ir90 H e a t rise, F. 82 8.5 117 0.0 1.0 5 1 I I 1.0 0 8 4 2 Uyn. c o ~ i i pd r i f t , Tc obtained OR B-140 (with no asphaltenes) me ne:irl>-e q i i i ~ ~ ~ i I !t~oi i t Rrnt1c co111p.. c"a 1D.Q 2fi 2 2 0 . 8 22 0 2 1 9 2 9 . 3 1 4 . 5 4.0 i i 7 3.0 4.0 3 G 14 2.0 Ret. 5 those for B-135 and not, as good as thope for B-147. I n compounds B-143 and B-144 a small ninount 0: I ~ P S ~ I I Y Y Oil-rxtrndcd GR-9 of 35 ML-1 viscosity (Polymer C'., Ltd.. Canada). I t n a a not gosaible to obtain ram uncitended Krynoi polymer for conirmrative L-4 was used in conjunction with the Exoils t o improve t:ick. srudies. B-13i with 110 Resines showed the effect of the Resines t o br 6 Bt.indard rold GR-S ( 3 0 l I L - 4 ) . c 101 3Iooney AIL-4 GR-S polymer kindly 8iipplied l , y Government minor. Good processing in the Banbury was attained in these 1.aboratoi.ier. University of Akron (32 H K Bld. 1.). d Coumarone-indene resin (Harwick Standard Chemic81 (20.). asphalt-oil compounds. The polymer massed n-ell in the Banbur>- and did not break up on addition of carbon blark. The O
March 1956
INDUSTRIAL AND ENGINEERING CHEMISTRY
Table VII. Latex Addition of California Asphalt )fixtures to High-Conversion High-Mooney Viscosity GR-S Compound
GR-S 1500
270 M o o n e y viscosity GR-Sa
160 >\looney viscosity GR-Sb 108 l l o o n e y \.iscosity GR-S
Exoil extenderc Asphaltenes (calculated) P a r a Flux 2010 Circosol 2XH Pliilblack 0 Zinc oxide Stearic acid Santoc-,ire Sulfur
12;
zi
l:i
io0
io0
io0
.
.. ..
.. ..
,
Q j
0
..
14.1
..
9 2 . . gfi
3 8 2.3 2 7
88 5 9 ,9 2.: 2,'
$i '
45 59 8 8 6 9 10 .. 1 0 . . 80 4 8
1.9 2.2
39
'k
73
.
.
,
4,-1
..
Q
,
73
. %-1,4I ,j 1, 1.5 1 5
2.2
.
iil ' '
2 2
+o
6.9 ,
: 73
4.4 ,j
1.5 2.2
LIooney viscosity, A I L 4 3Iasterbatcli 49 -18 101 56 59 56 135 113 117 i'2 61 38 Compound ti0 (j0 4.5 tj0 90 'JO Optimum cure, min. a t 2 8 S 3 F. 2250 2 ~ 0 Tensile, lb./sq. inch 2370 2493 2713 3130 41).3 470 483 035 3ii6 100 Elongation, % lis: 18.50 1375 1735 1430 1103 300% m o d d u s , 1b.isq. inch 3 Shore A durometer ,'j8 Tear 1190 1160 1570 H o t tensile ( 2 0 0 O F.) lb./sci. inch Cure a t 285' F.. min. 90 90 90 7.5 73 90 DeAIattia flex. to 1/2 inch c u t , 17 20 10.6 IO 3.2 ti2 kilofleses Goodrich flexometer 82 i7 (io H e a t rise, F. 0.3 2 0 0.9 1 3 D y n . conip. driit, yo 1 0 1 0 Static camp., 70 31 1 23 3 2 8 . 4 22 1 2 2 . 7 21 9 3,li 3 Q 4.5 2 3 2 2 4.1 Set, % = unmodified, si.s?, con,-cr*ion (;R-s kindly b y G~~ ernnlent Laboratories, Unirersity o f Akron. b 00% conversion GR-9. c l l i x t u r e oi Exoil S-72-Exoil B-100-Resines L-4 (34,'37/ 9).
2gA
2,g
&
viscosity polymer latex were made with loner hIooney viscosity I)olymer latices t o produce a latex of a polymer having an approximate 1Ioonej- viscosity of 160 NL-4 (similar t o the viscositj- of Kryiolj, These two elastomer blends were extended with 4(i parts (per 100 of rubberj of the mixed Esoils t o attain satisfactory processibility as well as satisfactory compound 3Iooney viscosities (Table \TI, B-163 and B-164). 1Zuch better Ranbur,v processing (qualitative observations) was obtained for the conipounds prepared from 607, conversion 160 LIL-I viscosity pol>-mer than for blends of higher and lower 1Iooney polymers which showed 160 NL-4 viscosity (B-144 rs. B-163 and B-164). -1 mnch higher elongation and much better cut growth resistance were obtained for the former polymer. 111view of the difficulty in processing polymer of high >Inone)viscwity (2iO ML-4) in oil-extended blends of GR-S, it appears that clunntitative conversion polymers should be modified t o the Krynol type (160 1IL-4) if they are t o be useful in compounds extended with asphalt oils. High-Styrene High-Mooney Viscosity GR-S Polymers. Sperial polymer was prepared with butadiene-styrene rharge ratios of 5G to 4% and 40 t o 60. D a t a obtained on these high-st>-rene polymers are shon-n in Table F'III. !Then these polymers iwre estcnded with the Exoil mixture and conipounded with 50 parts of r:irhon black (tmscd on 100 parts of '.elastomer plus extender") in a trend stock recipe, vulcanizates of higher than normal hardness and very good flex life were produced. I n B-150 and B-151 the flex life was improved a t a small sacrifice in heat build-up; by the small decrease in oil extension in B-151 n hetter degree of set, hence, better heat build-up and lower flex life, resulted. I n a n effort t o attain masimum properties, high-stp-ene Dolvnier of 100 hfoonev viscosity was estended and compounded . with 30 and 40 parts of HAF black instead of the usual 50 parts (based on 100 parts of elastomer plus extender). The conipound with 40 parts of HriF black gave a vulcanizate of 62 Shore A durometer hardness and an excellent set o f physical properties; this type of compound appears worthy of evaluation in tire construction. T h e 30-part black stock also gave good stress-strain and hvqteresis properties, but had a low Shore 1 hardness ( 5 2 ) .
463
Polybutadiene and Exoils. Plttnt batches of polybutadiene have been prepared at 30 111,-4 llooney viscosity and 50% conversion rather than a t 50 1IL-4 and BO%, as employed for butadiene-stl-rene copolymer production, because a more e:tsily processible polybut.adiene pol>-mer can be obtained a t the lower viscosity and cor,i;ersion levels. A series of compounds was formulated t o investigate the possibility of directly reinforcing 50% conversion, 30 Mooney viscosity polybutadiene with asphalt oils, The better asphaltene-containing compounds-e.g., B - l i i , Table IS--Pho\ved comparatively good tensile properties. Higher elongation and slightly better D e l I a t t i a cut-growth resistance are indicated for compounds containing Exoil B-100. The compounds containing higher amounts of extenders and asphaltenes showed a loss in tensile strength properties, and are not shoir-n. h series of compounds was also prepared with 607, converPion, 30 1Iooriey lIL-4 viscaosity, polybutadiene latex (made by the Government I,a))oratories, University of Akron). This higher conversion polybutadiene was compounded both by adding Exoil extenders in the Ranbury and Iiy latex extension. The polymer containing cocoagulatd Exoil mixture-e.g., B-178 and R-194, Tahle IS- is much higher in tensile strength and elongation t h m the Banbury-extended polymer (not shown). The heat huild-up and cut-growth re~istanceof the best extended polybutadiene are q u i v a l e n t t o those obtained with the "cold" butadiene-styrene copolymer (GR-S 1500). The tensile strength of the extended 607, conversion polymer is 257, higher than for the unextended 50% conversion polybutadiene. "Cold box" tests on Exoil-extended polybutadiene, qualitative in nature, showed that elastic properties were maintained a t - i o " C. Although the compounds shoa. 1000 pounds per square inch lower tensile strength than similar cold GR-S compounds, this extended 607, conversion polynier has sufficient promise t o be evaluated in tires for arctic performance. Compounds of high lIooney polybutadiene extended with asphalt oils were also investigated. Polybutadiene of 118 hlooney viscosity ( 6 5 7 , conversion polymer) was used in these tests. The conipounds containing asphaltenes-e.g., B-165, higher terisile strength B-166, and B-167, Table IS-shoived and elongation than similarly extended asphaltene-free comp o u n d ~ . Larger aniounts of the Exoils B-100 or B-300 did not improve the tensile properties obtained with 15 or 25 parts of
Table VIII. Latex Addition of California Asphalt JZixtures to High-Styrene High->looney Viscosity GR-S C'onlpolind R- BRR- R ILX Polymer. part;
. \ l i e d oilsb. w r t s Aspha1tenc.s Pldblack o zinc oxide
Masterbatch
41 5 3 70.R
31; i3
4 2 1 4
4 1.4
:3 8
1 4
1 4 2.0
;H:iFo t tensile, lh.,'Sq. inch (200'
F.)
C u r e a t 283' F., min. D e l I a t t i a flex. to 1 1 2 inch c u t , kiloflcxes Goodrich r k x o n i c t e r
68
133
i0o
io0
4 (1 6 3 .5
2':
2i
47
io0 18
2 3.5
.I
1 3 1.1;
3.5 1.2 1 2 I 8
R i I 2 1.2 1 8
1.3
124
106
0.i
0.i
fiS 68
70 .%A
.58 161
.i8 32
,520 12.50
480 liil0
48.5 1950 81
> 140.5 G2 290
lj7
ti8
1580 90 377
lti30
II';OO
90 208
.. ..
2713
iii0
"10
.IJ
220
, ,
00
102
97 90 , . 79 4.5 3 4 .. 2 7 Static COLIIII., 70 29.0 27.8 .. 20.0 Set. % 8.7 0.1 .. 4.1 a Charge ratios indicated for butadiene-styrene po1ymerir:rtion. b Exoil 9-72-Exoil B-100-Resinex L-4 (54/37/9).
r,f:;$, :iift, so
li(i
12.5 .4j t3j
o ~ ~ ~ ~ nlin, ~ ~at 28jo , $ e , Illonantion. Tenbile. l b . l w mo. inch 300?' moduliis, 113. 'sq. inch
I52
10'3
2 1
Sillfur 3Iooneg. R a v polynLer x-i.cosity, 111-4
131
100
cm 110
1;s
1 8 28.0 3.2
INDUSTRIAL AND ENGINEERING CHEMISTRY
464 Table IX.
Polybutadiene-Exoil hlixtures
(Recipe based on 100 parts polyhutadiene) Compound
B-
B-
B-
B-
B-
B-
B-
B-
180
177
178
194
1GG
167
165
205
50
GO
50
50
50
50
50
.. ., 28 , .
3.5
gh
Polybutadiene, 70conversionraw hlL-4 HAF carbon black Extenders Resinex L-4 CircoPara plasticizer" Exoji 5-72 Exnii B-100 Exoil B-300 Asphaltencs Zinc oxide Stearic acid Santocure Sulfur
..
..
5
..
5 J
15
0 3 1 1.5 2.25 '
5 7
3 1 1.B 2.2;
..
, .
.. .
0 3 1 1.: l.i5
5
15
..
5 7 3 4 1.5 2.25
31 31 513 11 90 90 00 90 1870 1740 2215 2260 370 GO0 330 395 800 I625 1235 1483 5G 58 60 54 105 105 105 115 Cure. min. a t 285" F. D r l l a t t i a flex. t o I / ? inch c u t , kiloflexes 5 . 3 6.3 15,s 23.2 106 90 Goodrich flexonieter, F. 81 93 0.1 0 3 0.3 3 2 Dyn. comp. d r i f t , % ' 20 3 28 5 2 1 . 4 24 9 Static comp., yo 5 9 4.4 4.4 8 1 S e t , CiC Compound l l o o n e y vis., X L - 4 Optimum cure, plin. a t 285' F. Tensile, lb./sq. inch Elongation, % ' 300% modulus, lb./sq. inch bhore A duronieter
a
:A'
i:
..
,.
, ,
..
i:
""~~~~r",9 ..
.. 34 ..
..
22 15
..
50
..
J
..
25 0 b:7 16.1 3 3 3 1 1 1 1.5 1.5 1 5 1 d 1.5 1.5 123 111 100 GO 105 30 2220 2440 2085 265 315 325 2305 183.5 .. 63 63 59 103 0.5 83 0.6 18 1 2 2
50/50 mixture of Circosol 2XH and Para Flux 2016.
asphalt oils. K h e n the high 118 Xooney polymer ww extended t o only 50 11L-4,compound Mooney viscosities became very high during compounding, and mill processing was difficult. IT'hen extended t o 30 ML-4 viscosity n-itli F:soils, these pol?-butadienes processed satisfactorily. Further work with high RIooney polybutadienes appears worth a-hilc in c~onnectionwith possible use in arctic synthetic rubber items. Polybutadiene Extended with Exoils and Rosin. Table S shon-s several compounds of satisfactory procesaibility 17-hivh xvere prepared with combinations of wood rosin nncl the Exoils for extension of polybutadierie of 47 LIL-4 and 91 111,-1viscosity. The rosin appears t o enhance the phJ-sicnl propertics of thew compounds, a tensile strength of 2700 pounds per sclii:irc- inch being obtained in B-1102. The stress-strain propcrtiea xiid heat build-up values for the comporinds prepared from 4 i 311.4 polymer are adequate for construction of tires. Exoils and rosin, It-hen added t o polybutadieiic. of 9:3 \ l I A Mooney viscosity in amounts sufficient for proccssi1)ili:y: rc.+illtcti in compounds shon-ing tensile properties somen.l~:itIon C I ' t h i n
Vol. 48, No. 3
obtained with 30 and 47 51L-4viscosity polybutadiene (at SOY0 conversion), but still yielded usable compounds. "Cold box" tests of Exoil-extended polybutadiene, qualitative in nature, showed t h a t elastic properties were maintained a t -70" C., arid suggest testing in articles for use in arctic climates.
,.
covx~-sIon-s
0 3 1 1.5
Asphalt oils can serve alone or iii mixtures with asphdtrne-free petroleurn 1 7; 75 oil for extending GR-S high Mooney viscosity poiymers varying in styrene -180 content from 0 to -loyo. Processibility 1900 CiO and stress-strain properties of tread 10.5 90 compounds prepared from such extended 115 7.4 7 78 f3 polymers are better when the asphalt 79 0.4 0.LJ 0.8 oil extenders are present. Poor heat 1 9 . 1 18 , 10 9 4.3 4 2 4 0 build-up values usually attributed t o the w e of asphalt comporinds have riot been found inherent in the use of asphalt. By appropriate adjustment of compounding formulas both flex life and heat build-lip vslucs at satisfactory levels are obtained. K h e n a slightly higher than 1isua1 level of curing agents is cmplo>-ed, the asphalt oil esteriders alone, or in admixture v i t h mphaltenefree petroleum oils, yield extended GR-S tread compounds at least equal in heat build-up-flex relationship t o asphnltenefree pctroleurn oil-estended GR-S compounds, The optimum amount of asph:rltenes varies from 5 t o l5%, depending on the polymer employed. The improvenient in tensile strength realized by oil extenaion of pol>-butadieneand lo\v-stj-rene GR-5 is probably dilc to hetter carbon black dispersion resulting from improved procesribilitg.
33i:
~~
i:
ACKZOWLEDGIIEST
This iywk ~ v a sperformed :is n part of the research progmni 011 -ynthetic rubber sponsored hy the Reconstruction Finance Corp., O f i c e of Synthetic Ri1bbc.r. The :iuthors are indebted t o the Lseter Oil Co. for oil samples supplied to the Burke Research Co., t o thc D:lyton Ruhher Co. for the use of certain special laborator>- f:icilitics, :md t o 0. K. Ilurke, Jr., f o r ndvice :ind griitl:\Ill
