Copolymers of Butadiene with A l l ~ ~Aryl, l, Alkoxyl, and Phenoxy1 tyrenes C. S. MARVEL, G. ESLER INSKEEP, RUDOLPH DEANIN, D. W. HEIN, PAUL V. SMITH, AND JOHN D. YOUNG University of Illinois, Urbana, I l l .
A. E. JUVE, C. H. SCHROEDER, AND M. M. GOFF, The B. F. Goodrich Company, Akron, Ohio Butadiene has been copolymerized with different alkyl, aryl, allroxyl, phenoxyl, and other derivatives of styrene using a typical emulsion polymerization recipe. As indicated by tests of vulcanizates, most of the resulting copolymers were approximately equal in quality to GR-S.
culated for the copolymers, only the lower carbon content of methanol would make itself known. A lowering of lTc in the carbon content would represent approximately 2% of methanol (and presumably a corresponding amount of benzene).
'
H I S paper reports the effects of a variety of alkyl, aryl, TABLEI. PHYSICAL CONSTANTS OF SUBSTITUTED STYRENES T a l k o x y l , p henoxyl, and other substituents in styrene on its Method of Boiling Point a t copolymerization with butadiene and also the evaluation of a Preparation, Temp., Pressure, number of the new copolymers as synthetic rubbers. Most of Substituent Lit. Cited C. . mni. n 'z the copolymers were prepared in emulsion from the standard 1.5410 m-Methyl 50-51 3 ratio of 75 parts by weight of butadiene and 25 parts by weight 1.5425 60 p-Methyl 15 1.5365 45 p-Ethyl 1 of the styrene and the polymerizations carried t o approximately 1 ,5290 80 p-Isopropyl 20 1.5246 m-sec-Butyl 15 98 77% conversion. A few copolymers with other monomer ratios 1,5237 m-tert-Butyl 5 75 are reported. 1.5260 13 97 p-tevt-Butyl 1.4655 55 m-Trifluoromethyl 17 hnethole, described as 100% pure, was obtained from Newport 2,4-Dimethyl 1.5423 25 90 1.5395 2.5-Dimethyl 22 82-83 Industries, Inc. T h e other styrenes used were prepared by 1..5465 3 4-Dimethyl 23 88 methods which have been or will be described in the literature; 1.5382 3:j-Dimethyl 57-58 4 1.5949 77 p-Benzyl 0.06 references to the methods are given in Table I which shows also 1,6280 112 1 m-Phenyl M.P. 115-1 16 p-Phen yl .0. . 2 the physical constants of the substituted styrenes used in this 36-37 1 .'5600 o-Methoxy study. 1,5540 14 89 m-Methoxy 1.5608 92-93 p-Methoxy 13 Butadiene was the Special Purity grade supplied by the Phillips 1.5504 96-100 4-Methoxy-3-methyl 10 1.5521 96-100 6-Methoxy-3-methyl 10 Petroleum Company; i t was passed over sodium hydroxide . . 1,5703 113-115 3,4-Dimethoxy 6-7 pellets and condensed in a dry-ice trap. 1.6031 111-113 1-2 p-Phenoxy 1,5362 p-Acetoxy 88-90 3 POLYMERIZATION. The polymerizations were carried out 1.5818 96-100 3 m-Nitro 1,5201 46 32 as described in a n earlier paper (9). o-F1uor o The new copolymers are characterized briefly in Table 11. TABLE11. EMULSIONCOPOLYMERIZATION O F BUTADIENE WITH DERIVATIVES O F STYRENE(50" C.) ANALYSIS. Samples were prepared for Wt. Ratio, Butadiene CopBenzene analysis by twice dissolving the polymer to Time, version, Solubility, Substitutod in benzene and precipitating i t with methComonomer Styrene Hr. % %" Ivlb Styrene, '70 anol, then drying it, in the vacuum oven. 75:25 11 98 2.12 77 Styrene (control) The extent to which the substituted 7 5 : 2 5 13 96 1 . 9 1 27.0 78 m-Methylstyrene styrene had entered the copolymer was 97 1.99 74 22.7 7 5 : 2 8 . 5 13 11.1 1 . 9 0 73 85:15 13.75 100 determined by comparing its ultraviolet 12 .... 1.57 76 100 p-Methylstyrene absorption spectrum with t h a t of the 11 1 . 8 4 74 100 .... p-Ethylstyrene pure polystyrene (6). 11 .... 1.38 65 100 p-Isopropylstyrene . . I .
Certain of the polymers were analyzed further for carbon and hydrogen (Table 111). Although the hydrogen contents corresponded to the compositions of the copolymers found by ultraviolet spectrum examination, the carbon contents, in nearly every instance, were lower than predicted. The only explanation of this discrepancy is that, in spite of careful vacuum drying of the products after their reprecipitation from benzene with methanol, appreciable quantities of the liquids were retained by adsorption. Since the hydrogen contents of both solvents and the carbon content of benzene are not significantly different from those cal-
25 9.16 1.73 79 97 14 77 19.6 1.80 96 12 1.37 73 100 26:b 14.5 100 1.83 75 19.5 76 75:25 14 98 2.05 26.4 76 12.5 99 1 .81 28.6 79 13 97 1.91 19.9 15 97 1,75 75 22.2 100 2.13 11 81 10.5 100 0.95 73 11 .... 100 2.21 75-81 100 10 24.8 1.97 76 12 100 1.94 22.6 76 ....d 96 73 7 6 : 3 2 . 5 12 2.18 94 11.5 1.45 19.5 67 21.9 91 76 2.20 121/S , . . . 100 70 1.71 75325 13 20.7 100 2.62 13 77 19.3 1.32 10 98 78 p-Phenoxystyrene e 28.5 100 79 76347 10 .. . 75:25 30 4.1 70 100 2.30 Anethole 6 3.2 71 75: 24: 25 25 2.39 100 Anethole 4- styrened 27.2 83.5 75:25 10 100 1.90 o-Fluorostyrene a Determined b y standard procedure (4). b Determined on t h e gel-free benzene solution by standard procedure (4). 0 This copolymer appeared to be highly overinodified b y some trace of impurity in t h e monomer. d N o t analyzed for monomer. 6 These copolymers were not evaluated as rubbers. m-sec-Butvlstvrene m-tert-Butylstyrene p-tert-Butylstyrene m-Trifluoro methylstyrene 2,4-Dimethylstyrene 2,5-Dimethylstyrene 3,4-Dimethylstyrene 3,5-Dimethylstyrene p-Benzylstyrene m-Phenylstyrene w-Phenvlstvrene
I
t . . .
INDUSTRIAL AND ENGINEERING CHEMISTRY
2372
Vol. 40, No. 12
of thc substituted styrenes copolynierizcd with butadienv at about the same rate that styrene does. I t is not surprising that anet#hole does not appear to copolymerize, but it is of intclcst (Weight, ratio butadiene t o styrene, 75: 25) that it appears to act as a modifier which prevents insolubilization 70Carbon ~ yo . Hydrogen _ _ -~ _ of the polybutadiene formed iri its presence. In the ordinal,>Comonomer Calculated Found Calculated Found emulsion polymerization of butadiene! the polybutadiene Eorincci 89.5 87.3 10.4 10.4 ni-Xiethylstyrene 82.4 81.7 9.3 9.6 ~ o u l dbe almost completcly insoluble in benzcne at 89y0 conm-Trifluoromethylstyrene 2,4-Dimethylstyrene 89.4 87.6 10.7 10.7 version, yet in this attempted copolynieiization (see Tablt: 11) 3,5-Dirnethylstyrene 89.3 88.3 10.7 10.8 4-Methoxy-3-inethylstyrene 87.4 86.7 10.5 10.6 the 707, yield corresponds to 89% conversion of the but adienc: 6-3Iethoxy-3-niethyIstyrene 89.3 86.3 10.7 10.8 89.7; 89.21 10,3; 10.47 present and the polymer obtained was benzene soluble. p-Benzylstyrene o-h~lethoxystyrene 86.8 56.44 10.3 10.37 Of those monomers which copolymerize with hulaclic:iii: at
rpAHL.E
111. CARBON A N D HYDROGEX ~ A L Y OF BUTADIEXK~
S UI P~ COP(>I.YbIWHS
o-Fluorostyrene 86.la 86.19 9.7d 10.13 a hiicroanaiysej T Y R ~ F : ,made by H. S. c l a r k , 111inoir StatF: ~ ; ~ ~ Survey. h Calculated on a copolymer cont,aining22.2% p-benzylstyrene. C Calculated o n a copolymer containing 24.8% o-methoxystyrene. d Calculated on a copolymer containing 2i.2Y0 o-fluorostyrene.
These residual solvents undoubtedly interfered with the ulti,aviolet absorption analyses, both by dilution and by absorption. DISCUSSION. p-ilcetoxystyrene was a11 active inhibit.or and almost no polymer wa.s obtained. This may be due t o some hydrolysis t o give the frcc phenol. m-Nitrostyrcnc also failed to copolymerize with butadiene under the conditions used in this n-ork. Examination of the data presented in Table IJ shows that most.
l
approximately ~ ~ i ~ ~ the l same rate as stgrene, nz-methylstvrcrlr, 171trifluoromethylstyrene, 2,5-dimethylstyreiie, 3,4-dimeth p-phenoxystyrene, and o-flucrostyrene enter the copolymer 1o a greater extent than does styrene under similar circumstances. m-sec-Butylstyrene gave unexpected results since very little appeared in the copolymer. o-Methoxgsty rene was made bv several procedure, to bc described in detail elsewhere (8). It was necessary t o mash all samples carefully with alkali to remove traces of phenolic bodies before this monomer 4 ould copolymerize satisfactorily. Aftpi this alkaline wash, o-methoxystyrene prepared by decarboxylatioii of o-methoxycinnamic acid ( 1 4 ) or by dehydration of o-methoxy(8-hydroxpethy1)-benzene (8) gave result,s essentially as indicated in Table 11. Considerable difficulty was encountered with omethoxystyrene prepared from o-methoxy-(a-hydroxyeth~~l~-
TABLE IV. EVXLL-ATION OF COPOLYMIERS Comonomer m-Xet hylstyrene
Ratio Butadiene ?rIooney. to (AIL), 4 Min. Comonomer a t 212O F 75:25
75: 2 8 . 5
.,
..
85: 15
p-Methylstyrene
5.
p-Ethylstyrene
75:25
GR-8 control
p-Isopropylstyrene
75: 26
rn-sec-Butylstyrene
75:25
75: 25
GR-R control 8.
m-tert-Butylstyrene
75325
p-tert-Butylstyrene
75:Z.j
GR-S control 10. m-Trifluoromethylstyrene
75: 2 5
GR-S control 11. 2.4-Dimethylstyrene
2.25
48
2.00
42
1.75
75: 25
75: 25
GR-S control 14. 3,5-DiniethyIstyrene GR-9 control
2.25
2.00 2.0
33-1
min.
48-1
min.
20
Dorometei Hardness
550 650
150 75
2.0 2.0
2.50 2.0
di
. I .
150
60 75
890 710 1000 Same as 620 810
...
2790 3050
....
796
755
...
3170 596 3310 600 4050 766 3760 660 3180 580 3580 620 695 3820 3550 625 2800 607 2810 560 3780 713 3640 673 2510 640 2650 600 3360 620 3360 607 3100 708 3100 608 3390 648 3380 620 3340 700 3470 620 S o . 4, p-methylstyrene 2960 780 710 3150
....
...
44
57 60 67 60
50 63 47 56 43 88 59 80 60 63 47 69 52 106 58 77 52 65
69 68
2 ,5
525:000-8 275,000-8 280.000-8
59 61 61 64 63
2.4 2.9 2.5 1.9 3 2 2.6 1.$ 3.1 1 8 2.7 2.1 2.3 3.2 2.4
..
..
$5
34
55 55
60 57
60 57 61 58 61 61 67 71 66 57 60 62 6.i
52 73 49
:2
6 1 3.4 0.6 2.1 0.9 1.6
140,'060-8 146,000-8
I .
85
..
Quality Index ( 9 ) 2.0 3 .8
2.2
1 .6 2.7 1.o 1.1 3.3 3.8 I .8 1.3 , I .
425,000-8 160,000-8
6i 66
2.4 2.0
Same as KO,3. m-methvlstvrene 75325
01%-Scontrol 13. 3,4-Diniethylstyrene
28 41 36
Flexinga
52 115 63 97 62
950 690 700
150
GR-S control 12. 2,5-Dimethylstyrene
.. 2.0
48
GK-S control 9.
yo
Hysteresis Temperatiwe Rise, ' F.
??
1.75
GR-S control 7.
Elongation,
OJ
31
GR-S control
6.
Tensile, Lb./Sq. I n .
80
2 .o
GR-S control 4.
300% Modulus, Lb./Sq. In.
2.0
39
GR-S control m-l\Iethylstyrene
Cue, Xn. at 280' F.
..
GR-S controlb
m-hf ethylstyrene
Parts Sulfur 1.75
38
2.0
..
1.75
35
2.0
46
2.0
35
1.75
43 75: 2 5
.,
2.0
..
,.
75 150 75 150 75 150 76 150 75 150 75 150 75 150 75 150
61 53 159 47 92 59 97 66 84 54 102 61 90
63
5;
3.0
2.6 , . .
2.6 3.0 2.6
3.0 3.2 2.8 3.4 1.4 2.6 1.5 2.3 2 4 3.0
December 1948
INDUSTRIAL AND ENGINEERING CHEMISTRY
benzene as the conversions were poor and the product seemed to be overmodified. This sample of o-methoxystyrene was found t o contain both o-ethylphenol and its methyl ether (8). These copolymers were evaluated by the procedure described in detail in a n earlier paper ( 9 ) . On the basis of this laboratory evaluation (see Table IV for physical data) the following conclusions have been drawn: In general, the butadiene-alkyl styrene copolymers gave vulcanizates (m-hen compounded in a tread-type recipe) equal in physical properties and quality index to vulcanizates of a similarly compounded GR-S copolymer. However, the butadiene copolymers with m-sec-butylstyrene and m-terl-butylstyrene gave vulcanizates with quality indexes inferior to those of GR-S. The butadiene copolymers with alkoxyl styrene gave vulcanizates with physical properties and quality indexes equal to those of standard GR-S. I n the case of butadiene-p-phenoxystyrene (75 to 2 5 ) copolymer, the Mooney viscosity (large rotor) at 212" F. was quite low. However, the physical properties and . quality of this vulcanizate arc equal to standard GR-S vulcanizates. SUMMARY
The copolymerization of butadiene with a number of alkyl, phenyl, alkoxyl, phenoxyl, and other styrenes in a typical emulsion polymerization recipe has been studied. Most of these substituted styrenes copolymerized with butadiene much as does styrene itself. Evaluation of these copolymers by standard
2373
methods showed t h a t they were approximately equal t o GR-8 in physical properties. LITERATIJRE CITED
Alderman, V . V., and Hanford, W.E., to E. I. du Pont de &e'm o w s & Co., U. 8.Patent 2,276,138 (1942). Frank, R. L., Adams, C . E., Allen, R. E., Gander, R., and Smith, P. V., J . Am. Chem. SOC.,68, 1365 (1946). Huber, W. F., Renoll, Mary, Rossow, A. G., and Mowry, D. T., Ibid., p. 1109. Hulse, G. E., Hohson, R. W.,Sl'all, F. T., Johnson, R. L., Yanko. J . A . , and Flory, P. J., pri.i.at,e communication from the Office of Rubber Reserve. Klagee, A., and Keil, R., N e r . , 36, 1632 (1908). Laitinen, H. A,, Miller, F. A , and Parks, T. D., , I . A m . Chem. Soc., 69, 2707 (1947). Marvel, C . S., Allen, R. E., and Overberger, C . G., Ibid., 68, 1088 (1946). Marvel, C. S.,and Hein, D. IT., Ibid., 70, 1895 (1948). Marvel, C. S., Inskeep, G.E., Dexnin, R., Jnve, A.E., Schroeder, C. H., Goff, M . M., IXD.ENG. Crrsnr., 39, 1486 (1947). Marvel, C. S.,Overberger, C. G., Allen, R. E., and Saunders, J. H., J. Am. Chem. SOC.,68, 736 (1946). Marvel, C . S., Saunders, J. €I., and Overberger, C. G., I h i d . , p . 108.5. Matsui, E., Chem. Zentr., 114 ( I ) , 1111 (1943). Mowry, D. T., Re.noll, Mary, and Huber, W. F., J . Am. Chern. SOC., 68, 1105 (1946). Walling, C . , and Wolfstirn, Katherine B., Ihid.. 69, 852 (1947). RECEIVED August 31, 1946. This investigation was carried out under the sponsorship of bhe Ofice of Rubber Reserve, Reconstruction Finance Corporation, in connection with the Government Synthetic Rubber Program.
TABLE IV (Continued) Ilysteresie Durometer 300% ElongaTemperaModulus, Tensile, tion, t y e Rise, Hard- Quality [ndex (9) Lb./Sq. In. LL./Sq. In. % F. Flexinga SUlflII ness Comonomer 61 750 645 91 140,000-8 0.5 15, m-Phenylstyrene 3.00 66 0.8 1390 565 75,000-8 56 645 450,000-8 55 3.3 960 67 2.00 GR-S control .. 1190 300,000-8 62 47 665 4.0 220,000-8 653 60 57 2.1 780 16. p-Phenylstyrene 75:25 18 2.1 200,000-8 950 593 58 56 56 480,000-8 910 673 91 1.8 41 2.00 GR-S control 58 1.8 1080 624 70 270,000-8 56 1.2 565 61 2.50 810 100,000-8 75:25 17. p-Benzylstyrene 20 57 48 80,000-8 870 605 1.0 Same as No. 5 , a-ethvlstvrene GR-5 control - 2880 340,000-8 60 1.6 75 910 740 83 18. m-Methoxystyrene 76:26 38 1.76 64 3160 150 66 1 1000 68 680,000-8 4.9 3.6 3380 75 1020 648 79 690,000-8 59 GR-S control 47 61 1040 440,000-8 4.2 160 2810 567 58 S A0 .. .. 45 500 3300 --19. p-Methoxystyrene 75: 3 2 . 5 330,000-8 .. 2.5 3200 75 I000 615 67 3300 160 1250 575 64 ., 310,000-8 3.4 GR-S control 2450 45 400 875 3300 75 756 78 330,000-8 .. 1.8 GOO .. 210,000-8 2.1 3050 160 950 630 58 .. 525 1.75 75 2750 760 102 510,000-8 20. 4-Methoxy-3-meth460,000-8 350,000-8 .. 3.2 150 GOO 2900 720 io ylstyrene 740 45 c , . 5.0 75 2700 550 GR-S control 3150 750 42 C 260,000-8 420,000-8 .. 6.6 150 600 75 565 52 .. 2.9 3000 21. 6-Methoxy-3-meth1.75 800 150 3450 4.6 1000 360,000-8 .. 595 49 yletyrene Same as S o . 20, 4-methoxy-3-methylstyrene GR-S control 45 .. 2 2 . 3,4-Dimethoxy76: 26 2.0 3 50 980 75 855 92 350',i)i)0-8 i:S 550 .. styrene (70% 150 .. 805 conversion) GOO 70 250,000-8 1.7 45 745 , . 2.0 506 .. .. ... GR-S control .. 75 750 750 80 230,000-8 1.2 850 210,000-8 150 670 57 .. 2.1 7632.5 2.0 45 600 .. .. 23. 3,4-Dimothoxy780 , . . 75 3lO:OOO-8 675 3.3 800 54 .. styrene (77% 150 260,000-8 conversion) 3.4 47 950 580 .. Same as No. 22, 3i4-dimethoxystyrene GR-S control 75 750 2310 67 24. p-Phenoxystyrene 7 5 :2 3 12 2.0 38 165,000-8 2.8 2180 36 160 145,000-8 140,000-8 67 2.7 1290 40 GR-S control 850 23 2500 68 2.3 37 960 69 1.9 1 2900 105,000-8 62 84 3400 160,000-8 26. o-Fluorostyrcne 76325 23.4 1.75 75 1150 0.7 65 3575 150 1275 67 120,000-8 0.9 925 75 3850 GI%-Scontrol 48.4 2.00 74 230,000-8 GO 1.6 4475 61 150 1100 GO 1.8 200,000-8 3180 75 4.1 2.25 1110 59 75323 17.4 68 430,000-8 550,000-8 26. o-Methoxystyrene 150 3.5 61 3190 64 1300 56 1.75 77 75 1080 4050 400,000-8 2.3 GR-S control 160 1380 4170 67 3.7 63 430,000-8 a Rating of crack length a t the number of Hexures shown: a rating of 1 means no crack and 10 is complete failure. b With each experimental polymer or group of polymers, a GR-S control was run. The values obtained for the control are shown with those for the experiinental polymer. Because of differences from time to time in the compounding materials used, the improvement of standard GR-S, and inadvertent differences in mixing, curing, and testing, conclusions as to the quality of the experimental polymer are based on its properties compared with the appropriate control. These are abnormally low hysteresis heat rise values. Ratio Butadiene blooney to (ML), 4 Min Comonomer a t 212" F. 75:25 Too soft
Parts
..
Cure, hlin. at 280' F. 75 150 75 150 00 75 60 75 75 150
~
.. ..
.
..
ii?
