I1YD C'STRIAL A S D ENGIXEERIA-G CHEXISTR Y
November. 1925
- 016
CM
F R O M SLRFACE
AT
1185
3 .20 I ~~.
TURFACE
300 LBO
263
240 I ; 220
2
200
r I80
5
; 160 w 140
120
Iw
5
IO
15
20
25
30
35
40
UINUTLS
Figure 14 MINJTES
Figure 13
and on the same plot dotted curves indicate the average results of several tests for the same tire in the same mold with air in the bag. The temperatures of the rubber next to the mold face are practically the same for both methods of curing, all temperatures in the tire being cured with air in the bag lie between curve 3 and dotted curve 4, whereas the extreme variations when hot water is used are from curve 3 to curve 5 or 2. The effect in increasing the uniformity of cure is obvious, and the time of cure may be expected to be greatly decreased. The percentage reduction in time of cure possible
with this method will depend on the tire size and the time of cure necessary on the air bag; for the small tire tested the time of cure mas reduced by almost 50 per cent. Furthermore, the uneven blooming effect of the tire cross sections is eliminated by the water-cure process, at least in the smaller tire sizes Acknowledgment Acknowledgment is due H. A. Hands, who obtained the experimental data discussed, and to the Hood Rubber Company for permission to publish the results of these investigations.
Miscibility of Castor Oil with Gasoline Hydrocarbons' George H. Taber* and Donald R. Stevens3 ?VIELLON INSTITUTE
OF
INDUSTRIAL RESEARCH, UNIVERSITY O F PITTSBURGH, PITTSBURGB, PA.
OME forty years ago the senior author read some- gasoline, which happened to be the only kind immediately where that a mixture of approximately 50 per cent available, showed much greater miscibility than expected by each of castor oil and petroleum naphtha would form either and more than made good the author's statement. a homogeneous solution. As this was contrary to the then This led to further tests with a saturated gasoline, which generally accepted opinion-apparently largely held to this duplicated the earlier results. It became obvious that the d a y e h e was prompted to make a trial, which proved the miscibility in question depended very much on the charstatement to be true. Further experiment showed that if acter of the petroleum product used. With this in mind the an excess of naphtha were shaken in, it would quickly separate solubility relationships between refined castor oil and various out; that if then a volume of castor oil having the same gasolines and hydrocarbons were determined by the junior ratio to the supernatant naphtha as existed in the original author. The miscibility of castor oil with several hydronaphtha-saturated mixture were added and shaken, the carbons and commercial gasolines was tried at 24' C. The whole would become homogeneous and the mixture would results are given in Table I, and the analyses of the gasolines still remain homogeneous no matter how much additional used in Table 11. castor oil might be shaken in. So he made the off-hand deIt may be seen that the paraffin hydrocarbons used have a duction that, although castor oil is not soluble in petroleum limited, though high, solubility in castor oil, while the olefins, naphtha, petroleum naphtha is soluble in castor oil to the naphthenes, and aromatic hydrocarbons seem to be miscible extent of about 100 per cent. Although in the years since in all proportions with the oil. The gasolines which contain he has mentioned the phenomenon to many chemists, he a high proportion of paraffin hydrocarbons-Nos. 6, 7 , and never has happened upon one familiar with the facts. 8-also show limited solubility; those high in naphthenes, Recently, on hearing an aviation expert say that castor oil aromatics, and unsaturateds-Nos. 9 and 10-however show was especially indicated as a suitable lubricant for airplane the comp!ete miscibility in all proportions which would have engines on account of its non-miscibility with gasoline, he been expected frorn their composition. stated the facts given above, which were promptly doubted In this connection it is interesting to note that Atkins5found by the aviation man. A trial made, using a highly cracked Egyptian, Roumanian, and Sumatra naphthas, all believed to be high in aromatics and naphthenes, to be completely 1 Received June 6,1928. * Vice president, Gulf Refining Company, Pittsburgh. miscible with castor oil. On fractionation, however, only the 8 Industrial Fellow, Mellon Inqtitute of Industrial Research. higher boiling fractions retained this property.
S
See, for example, Mairich, Molorwagen, September 20, 1927, p 578;
Aulomotwe Abstracts, 6, 354 (1927).
6
J . Inst. Pelroleurn Tech., 6, 223 (1920).
INDUSTRIAL AND ENGINEERING CHEMISTRY
1186
of Castor Oil w i t h Gasoline CASTORHYDRONo. HYDROCARBON OIL CARBON Parts by volume 1 "heptane 5 3 5 4 2 Isodctane (2,2,4-trimethylpentane) 5 3 5 4 3 2-Hexylene 5 5 5 45 4 hlethylcyclohexane 5 5 5 45 5 Benzene 5 5 5 45 6 Straight-run midcontinent 5 5 gasoline 5 7 7 Commercial motor gasoline 5 7 5 9 8 Cracked Pennsylvania 5 10 gasoline 5 11 9 California gasoline 5 45 10 High-temperature cracked 5 5 midcontinent gasoline 5 45
Table I-Miscibility
a n d Hydrocarbons UPPER LOWER LAYER LAYER Parts by volume Miscible 1 8 Miscible 1 Miscible Miscible Miscible Miscible Miscible Miscible Miscible 1.5 Miscible 2 Miscible Cloudy Miscible Miscible Miscible Miscible
8
10.5 12
This limited solubility of paraffins, both straight and branched-chain, in castor oil, together with the unlimited solubility of other hydrocarbons, suggested that possibly a method for the determination of paraffins in gasoline mixtures could be based upon these facts. It was found, however, that the solubilities in question are much changed when the different types of hydrocarbons are present together. I n other words, it was not found possible to separate, say, h e p tane and methylcyclohexane or heptane and benzene in any Of the proportions Or at any Of the tried' Similar erratic results were encountered when the gasolines themselves were used. Table 11-Approximate SO.
6 7 8 9 10
Straight-run midcontinent Commercial motor Cracked Pennsylvania California High-temperature cracked midcontinent
NAPHTHENE
ARO-
MATIC
47.7
11.4
24.7
16.2
y of H e p t a n e a n d Castor Oil
25 20 0 45 80
...
of Temperature o n Miscibility of Heptane Castor Oil (10 cc. castor oil f 10 cc. iV-heptane) INCREASE VOLUME IN IN VOLUME OF TEMPERATURELOWER LAYER LOWERLAYER c. cc. Per cent 0 16.0 60 10 16.9 69 15 17.5 75 20 18.0 80 25 18.6 86 33.5= 20.0 (miscible) 100 Atkinss found this temperature t o be 47.9' C.
UNSATURATED
EXPT.1 EXPT.2 EXPT.3 EXPT.4 EXPT.5 Castor oil, CC. Heptane, cc. Upper layer, cc. Lower layer, cc. N-heptane dissolved in the castor oil, per cent . by volume Sample of upper layer, grams CastoroilinsamDle.rrram Castor oil per grim, upper layer Sample of lower layer, grams Castor oil in sample, grams Castor oil per gram, lower layer
Table IV-EfIect
Per cent Per cent Per cent Per cent 72.9 22.0 3.2 1.9 68.5 16.8 9.8 4.9 65.2 6.3 16.8 11.7 58.8 31.8 7.3 2.1
The carrying out, of this attempt involved the determination of various properties and constants of the materials in question. Some of these are given herewith in the hope that they may prove useful. Table 111-Miscibilit
only sufficiently accurate for the purpose, but to be practically the only one available, since aniline points, refractive indices, and specific gravities had been found not to be sufficiently sensitive. I t will be noted that the compositions of the two layers are not constant as the amount of heptane is increased. This variation is small but definite; it takes the form of a decrease in the amount of castor oil per unit in the upper layer and an increase in the amount of castor oil per unit in the lower layer. This is most readily explained as being due to the presence, in purified castor oil, of one or more constituents more soluble in heptane than the main body of the oil. This is supported by a study of Experiment 5 in comparison with those preceding it. The solubility of whole castor oil in heptane will be seen to be less than one-third that of the material dissolved by heptane from a large exces of a lower layer (heptane in castor oil). This can again best be explained by assuming the presence, in small amount, of a Constituent of fairly high solubility with a large proportion of a material of low solubility. Castor oil is ordinarily understood to consist largely of triricinolein. Among the stearic acid, tristearin, dihydroxystearic acid, and ricinoleic acid, which make up the remainder, a material of the required high solubility might easily be found. EFFECTOF TEMPER.~TURE-T~~ change in mutual sohbility of normal heptane and castor oil with temperature is as given in Table IV.
Analyses of Gasolines Used PARAFFIN
GASOLINE
25 29.7 10.2 44.5
25 35.3 16.3 44.0
25 41.3 22.5 43.8
78.2
75.5
75.2
1 81.8 82.8 1 drop
...
...
5.1917 0.2855
6.7917 0.3635
6.3699 0.3322
7.1242 0.1098
0.05215 0.01552
...
0.05499
0.5349
36.5275
8.7161
8.3835
9.1154
22.8875
5.4718
5.2695
5.7349
... ,..
0.6286
0.6278
0.6278
0.6293
.
MUTUALSOLUBILITY O F CASTOF OIL AND HEPTANE-The solubilities of heptane in castor oil and of castor oil in heptane are given in Table 111. Heptane was added to castor oil, with shaking, until saturation had been attained, and then successively increasing amounts of heptane were added in excess. The mixtures were held for 4 hours in a thermostat at 24' C. with intermittent shaking. Samples of the upper and lower layers were then withdrawn, weighed, the heptane present evaporated slowly, and the samples were finally reweighed to determine the castor oil residue. Control experiments had already shown this method of analysis to be not
VOl. 20, No. 11
and
SPECIFIC GRAVITIES-The specific gravities of mixtures of castor oil with the cracked gasoline, No. 11 referred to above, were measured and compared with those calculated from the specific gravities of the components on the assumption that no change in volume occurred on mixing. The data indicate that no change occurs, the calculated values agreeing very well with those experimentally determined. VISCOSITIES-The viscosities of the same mixtures were determined and compared with those calculated from the viscosities of the components by the use of the hrhenius formula9 log P = VI log,,
+ vz log,,
in which p , p ~and , p~ are the viscosities in poises of the blend and of the pure components, and VI and Vs are the percentages by volume of the components. The viscosity of the gasoline was of the order of 0.005 poise and of the castor oil 7.8 poisee, at 25' C. I n spite of this wide range the calculated results agreed fairly well with those experimentally determined. The figures are given in Table V. T a b l e V-Comparisonof CASTOR OIL
Per cent 100 80 60 40 20 0 6
Observed a n d Calculated Viscasities VISCOSITIES OBTAINED VISCOSITIES GASOLINE BY EXPT.AT 25O C. CALCD. Per cent 0 7.8584 1.84240 1.6967 20 0.43175 0.2955 40 0.10120 0.0817 60 0.0179 0.02372 80 0.0056 100
Herschel, Bur. Standards, Tech. Paper 164.
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