Copolymers of Dimethylstyrene Vinyl Fatty .Esters with Butadiene J
J
PAUL 0. POWERS' Armstrong Cork Company, Lancaster, P a .
I
Since the more nearly satu1942 a study mas A series of synthetic rubbers made by emulsion polyrated acids gave only a small initiated in these laboramerization of butadiene and a,p-dimethylstyrene in variresidue on distillation, the tories to find methods of proous ratios have been prepared. These rubbers are compolymerization must involve parable to copolymers with styrene but are apparently ducing new synthetic rubbers the unsaturation of the and to study the properties of superior in tensile strength, and more nearly resemble fatty acids. The vinyl esters such new polymers and their natural rubber in processing characteristics. Synthetic of the higher fatty acids rubbers have also been prepared from butadiene and vinyl possible fields of application. do not polymerize readily Butadiene, isobutylene, and esters of fatty acids from vegetable oils. These synthetics and usually require strong are somewhat softer than GR-S. Tricopolymers of butathe drying oils were conacid catalysts to effect diene, vinyl fatty acid esters, and a monovinyl compound sidered as the principal polymerization. Our work raw materials and a a i d e exhibit interesting properties, notably improved resisthas shown that they form variety of reactive comance to cut growth. copolymers readily with butapounds was used to prodiene. stvrene. acrylonitrile, duce copolymers. Materials which were available in large quantities, or could possibly be and methyl methacrylate, particularly where the amount of vinyl readily produced in large volume, were studied as copolymerizing fatty acid esters does not exceed ,704, by weight of the monomers agents. Of the many materials investigated, two materials, used in the polymerization. a,p-dimethylstyrene and the vinyl esters of long-chain fatty acids, EXPERI hI ENTA L PROCEDURE have given copolymers with butadiene which have desirable Butadiene, styrene, and acrylonitrile n-ere ot)tairmr Eroni comphysical properties. The formation of copolymers of these mamercial sources. They n ere redistilled before use to remove the terials with other materials, notably styrene and acrylonitrile, inhibitors and any polymer which might be present. Commerhas been briefly studied and offers the possibility of a wider varicial a,p-dimethylstyrene was not further purified. 2-.knino-2ety of properties than is possible in a two-component copolymer. methylpropanol and the oleate were used as reveived. Palmer ( 2 ) described one method of producing apdimethylstyrene. This consists of dehydrogenating terpenes to cymene The vinyl esters were prepared ( 3 ) from distilled fatty acids. I n many cases filtration to remove any residue, which separated which is oxidized by air to the tertiary carbinol; the latter may on cooling was the only purification step required. T h r vinyl readily be dehydrated to a,p-dimethylstyrene: esters of linseed, soybean, cottonseed, perilla, and of coconut OH fatty acids and also vinyl stearate, vinyl oleate, and the vinyl I H,CCCH, H&C=CH2 ester of tall oil were prepared. Analytical grade ammonium persulfate was used as catalyst. The.following formula is typical of the batch for emulsion polymerization: 200 parts butadiene and other reactive monomers, CH3 CHJ 300 parts water, 10 parts 2-amino-2-methylpropanol oleate, and A A 0.4 part ammonium persulfate. With conversions over 90%, It is also possible to dehydrogenate cymene a t high temperatures the solids content of the latex exceed 35%, and in some cases t o produce a,p-dimethylstyrene: the amount of u-ater \vas increased 350 parts t o reduce the viscosity of the latex. When vinyl esters of fatty acids were used, 1.5 parts of 2-amino-2-methylpropanol were added t o neutralize the free acidity. This addition gave a much tietter emulsion of the reactants and reduced the time for polymerization. , Most of the tests were carried out in quart or pint carbonated cr-ater bottles with aluminum spotted crowns. The bottles were S
~I
a,p-Dimethylstyrene boils a t 190-191" C., and its density at 15.5' C. is 0.9038. It does not polymerize on heating; a sample was refluxed for days with no appreciable increase in viscosity. The vinyl esters of fatty acids were prepared by the method of Reppe ( 3 ) . Fatty acids from vegetable oils were heated with acetylene a t 200" C. under pressure (200 pounds per square inch) with shaking in the presence of zinc oxide. After 10 hours the acid number had dropped to a low value, usually below 10. The esters could be readily purified by vacuum distillation to produce materials of low acidity and high ester content. It wa? found that vinyl esters of fatty acids with high iodine numbcrs gave sonw residue of polymer on distillation a t 1-2 mm. vacuum.
*
TiR1.b:
Batch No. 15
21 20 29
1, ~ I . T . ~ D I E ~ . c - D T \ I I : T H - ~Co~or.-r-\rEns -I.~TYR~~s~ C0mDn.a. ' 5
75 B, 23 8 00 B, 10 D
Time, Hr. 168 168
Temp., C. 30 30 30 30 50 30 a0 50 30 30 30
UI timate Tensile, I.b./Ya. In. 2600 3080 2 770 3250
168 85 B, 15 D 108 80 B, 20 D 45 3550 z5 B, 25 D 4130 168 ( 0 B. 30 D 6073 190 65 B , 35 D 3080 65 B. 35 D 45 2 780 168 22 75 B , 10 D, 15 S 3190 168 24 75 B, 15 D, 10 S 168 3620 28 75 B, 20 D, 5 S B = butadiene, 6 = styrene, D = dimethylstyrene. 45 31 32 33A
Present address, Battelle Memorial Institute, Columbus 1 , Ohio.
837
EiongaLion.
R
260 3 30 4A(! .390 330 280
630 380 410 410 ,130
INDUSTRIAL AND ENGINEERING CHEMISTRY
838
TABLE 11. BUTADIENE-VINYL FATTY Batch No. 36
kc
c~IllpI',~,
ti7 68
--/ a 76
77 78
-
Time. Hr.
Temp.. C.
Tensile Strength
Elonpatinn
jil
30 30'' 50 ? 50' 30j 50 30 i 501 20
1440 1100
240 640
1325
310
1175
510
1165
690
1640
220
2000
370
25
1130
250
50 25 >)
W O
240
seed 80 B . 20 V linwed 7R 13, 23 T'stearate 75 B, 25 \' cottonseed 75 B, 25 V tall oil 85 13, 15 V coconut 85 B , 15 V perilla 85 B, 15 V oleate 85 B , 15 V SOYbean
fi6
B
ESTERC O P O L T J f E R 5
90 B , 10 V lin-
37
0
ACID
210 20
butadiene, V = vinyl..
agitated on mixing rolls. The temperature was varied from 3050" C., and pressures up to 60 pounds per square inch developed. All of the ingredients, except the butadiene and the catalyst, were added to the reaction vessel and cooled to - 10' C. Butadiene distilled from the cylinder was added and, finally, the catalyst. The vessel was then capped, shaken, and allowed to come to reaction temperature slowly. The finished latex was coagulated by being poured slowly into a 5% acetic acid solution. The rubber was separated, transferred to washing rolls, and washed 10 minutes with a steady stream of water. The rubber was then sheeted on a rubber mill. Two per cent by weight of phenyl+naphthylamine was milled into the rubber a t this time. The dried rubber was compounded on rubber rolls and cured in test molds. Dumbbelle were cut from these slabs, and tensile strength and elongation determined on all samples. Further tests were made in some instances. I n compounding these rubbers the following batch was used : 100 parts rubber, 40 parts channel black, 5 parts zinc oxide, 2 parts stearic acid, 2.25 parts sulfur, and 1.2 parts Santocure. For the oil resistance tests (Table IV) a somewhat modified formula was used-60 parts of Gastex and 30 parts of channel black to 100 parts of the synthetic rubber. Twenty parts of a commer-
TABLE 111.
BUTADIENE-VIXYL FATTY ACID COPOLYhfERS YITH A THIRD RE.4CTATT
Batch NO.
40 41
46 46B 47 48
59 60 61
62 64 63 79 80 81
V
--
a
75B,1 5 D., 'I"n T r
.
linseed. 75 B , 20 D ,6 V lin,seed65 B, 25 L) inv -I i n s e ed 65 B , 25 L), 10 v linseed 6.5 B, 25 Ei, 10 v linseed 65 B , 25 Ei, 10 soybear1 .._. 65 B , 20 D, 15 V cottonseed 65 B, 20 D, 15 V perilla 65 B,I 20 S, 15 VI, v
Tensile Strength Lb./Sq. 1;.
Time, Hr.
Elongation, % '
216
30
3200
450
336
30
3180
430
240
30 35 25)
5230 3570
580 620
144
30
4200
i80
.240
30
5;)
3280 2890
390 380
3s;)
1625
300
2350
340
30
2620 2490
380 430
25,
2310
330
35 35'
2250 2420
290 460
30
2380
390
1
v
{
nnn
^:I
65 B , 2 0 D, 15 V nleate 65-B, 20 D, 15 V coconut 65 B , 20 A, 15 V soybeap 60 B,40 Pi, ~ O V linseed 50 B, 35 A, 15 V linseed 45 B, 40 A, 15 V linseed
B butadiene, D vinyl.
-
224
j:\
4
,., neeks 144
'1
dimethylstyrene, S
-
styrene, A
-
acrylonitrile,
Vol. 38, No. 8
cia1 aromatic hydrocarbon plasticizer were incorporated. It is belicved the physical properties resulting from the use of this plasticizer are not materially diffei~ntfrom those obtained wit11 r l t ii(*rconvrntional plasticizcrg. HI T~I)lF,NE-UI.\lETHYLS'rYKE4E COPOLYMERS
111 *pit? ui I lie reluctanccx ~ v i t l i n.hich a,p-dimethylat yi.twr polymerizw, copoly-mers are formed with butadiene and rvitli inonovinyl compounds. High conversions can be obtained and the resulting rubbers have good working and tensile properties. cu-Methylstyrene forms copolymers with butadiene, but apparently ( 1 ) t'he tensile strength of the copolymers is not appreciably greater than that of the butadiene-styrene copolymers. hIany other tests are required for full evaluation of a synthetic rubber, some of which have been made in the case of the butadiene-u,pdimethylstyrene copolymers. Table I gives results with several butadiene-dimethylstyrene copolymers. Those with styrene are included to compare a GRS typca rubher made under romparable conditions.
T4~r.t:I V ,
011. R W I S T A N ( IJY ~ ~ .At'xYi.o\intII.E (~OYOLYXERS
Commercia Resistant OilBatch No. (,Table 111) Specific gravity Shore hardness Circo light oil Vol. change, "% Shore hardness Kerosene Vol. change, To Shore hardness 74 octane gas (70hr.) T'ol. change, % Ghore hardness 74 octane gas (1 week) Vol. change, % Shore hardness
63
1.17 75 24.2 62
7~
80
1.25
73 -11
86
4
1.24 ti5 -8 3 80
81 1.25 72
-6.9 80
22.8 62
29 b
-- . 4
77
68
3.5 70
25.1 64
BO
218
31.2 52
31.0 52
15.8
31 0 48
34.9 49
...
...
65
Rubber 1.24
72 3.7 80 3.5 72
23.8 67
The rnost spectacular result is the ultimate tensile strength of over 6000 pounds per square inch obtained from the batch (32, Table I) from S5'% butadiene and 35% dimethylstyrene. I t is apparent that better tensile strength is obtained as the dimethylstyrene content in the copolymers is increased (batches 20, 29, 31). Batches above 35% dimethylstyrene do not show further increase in tensile strength. The best properties were obtained when the polymerization was carried out a t 30' C.; a t higher trmpt.rat,ures the tensile strength is lower. VINYL FATTY ACID ESTER COPOLYMERS
Table I1 give the results obtained by polymerizing butadienevinyl fatty acid ester mixtures. The copolymers containing 1025% vinyl esters show relatively poor tensile strength. These polymers are soft, process easily, and apparently poseess good t a c k . No attempt was made to remove unpolymerized vinyl fatty acid esters, but the unpolymerized vinyl ester content of the finished rubbers was low, and well over 50% of the vinyl ester had formed a copolymer with butadiene. Since many of the physical properties of these copolymers seemed to be decidedly inferior, no further study was made of their possible uses. It was decided to investigate tricopolymers from butadiene and vinyl fatty acid esters, with styrene, dimethylstyrene, or acrylonitrile as the third component. These tricopolymers possess many interesting properties (Table 111). Part of the effect of the vinyl fatty acid esters is due to their behavior as softening agents. The incorporation of these esters in the polymer chain brings a stability to the plasticizing effect which plasticizing Oil6 do not. One surprising property of the compositions from some of these copolymers was their resistance to cut growth. A cut once started did not grow, but knotted and reaisted further
August, 1946
INDUSTRIAL AND ENGINEERING CHEMISTRY
growth when stretched. ('omparatirc tests showed that the rubbers from vinyl linseed esters (batch 46) possessed this property to the highest degree, although many vinyl esters of unsaturated fatty acids also gave tear resistance to cured compositions. Nore than 10% vinyl fatt,y esters results in decreased strength (Table 111). S o advantage is apparent from using larger amounts unless greater softness is desired. Table I V shows the result of swelling tests in comparison tTith one of the most oil-resistant, commercial, acrylonitrile polymers. The degree of axelling is apparently measured by the acrylnnitrilp content, and these copolymers containing 40% acrylonitrile resi.+t Pn.t.lling in oils t o the same fl+>grwas the more resistant o i 1111 I I I ~ , W I : I ~I ;iijhc.rr.
839
ACKYOWLEDGMENT
The experimental viork in this paper on the preparation of the rubbers was largely done by IC. H. Weber and his assistants, and the compounding and testing were carried out under the supervision of T. W, Elkin and S. W. Eby. LITERATURE CITED
(1) Hersberger. A. B., Reid. J . C.. and H e i l i g n ~ a n n ,K . G.. I N D . KNG. CHEM.,37, 1073 (1945). 12) P a l m e r . R. C., Ibid..34, 10Bb (1942). '3) Reppe, W.. U. 9. P a t e n t 2,066,075 (1936). PRESESTBD tiefore t h e Division of Riihoer Chemistry nt t h e 109th SIPetinu nf t h o h\rmrc.4.v C H e w c A L SOCIETY, ;\tlsntic c i t y , s,1.
Some Physical Properties of
Activated Bauxite HEISZ HEISEAIAiVIU, IC. A. KRIEGER', .AND IT. S. R . 3IcC4RTER Porocel Corporation, Phikidelphin, Z'n,
Data are presented on the bulk, apparent and true densities, corresponding void and pore volumes, and surface areas and equivalent pore diameters of several bauxite ores activated at various temperatures. Bulk density and void volume depend upon granule size. The other physical properties are altered by changes in structure produced by increasing activation temperatures. It appears that bauxite granules possess a degree of rigidity sufficient to prevent collapse of the framework even under the action of forces associated with major chemical changes.
T
HERbL4LLT activated bauxite is used for the adsorbent, refining of lubricating oils and waxes (10) and of sugar liquors and sirups (I.$), as a desiccant (4, 15), as a catalyst support (6, If), and as a catalyst for desulfurization ( 1 7 ) ,defluorination (7, 11), cracking (3,11, 18), dehydrogenation (19), and dehydration ( 8 ) reactions. In all of these applications the bauxite is generally used as a granular material of appropriate mesh size (1). For each specific use there appears to be an optimum activation temperature which produces the desired adsorbent or catalytic properties in the bauxite. Since these properties develop as a result of structure chmges, it is of interest to follow the effect of heating on certain physical properties. The properties of granular porous solids are characterized in part by true density, surface area, void volume, and volume and diameter of the pores. From these a number of other quantities of practical interest can be derived. Although the true density, surface area, and void volume can be determined directly, the other two quantities are not easily measurable by direct methods. EXPERIMENTAL METHODS
The total or bulk volume, rb, occupied by a poroub solid is composed of three parts: the volume occupied by the solid and adsorbed material, VI, that occupied by pores within the granules, V p ,and that occupied by the voids between the granules, I
Harrison Laboratory TJnlveraty of Pennsylvania, Phi!adelphia, Pa.
+
1.6. In this work Vb, I-*,and (Vt V p ) ,the appaicnt volume, were determined with apparatus similar to that described by Washburn and Bunting @ I ) , using mercury under 25 cm. pressure as the displaced fluid. These quantities are related t o a set of densities so that, for one gram of solid,
1 T', = -
Dt
where D., DI, arid Db are apparent, true, and bulk densities, respectively. De was calculated from Equations 2 and 3 and Db from Equation 1. DI was measured with helium by the method of Howard and Hulett (9), using apparatus described by Iirieger (IS),and V , was calculated from Equation 3. Surface a i m was measured directly with nitrogen by the method of Brunauer, Emmett, and Teller (d), using the data of Livingston (26) and apparatus described by Krieger ( 1 2 ) . Equivalent pore diameter was calculated as follows (5): Assuming that one gram of solid contains N open-ended cylindrical pores of equivalent diameter d and length L, the total surface area S,neglecting the extt.rnal surface of the granules, is given by S = dL.Y
The pore volume is given hy l',
50
= Td2L.Y
4
