APRIL, 1938
INDUSTRIAL AND ENGINEERING CHEMISTRY
I n the absence of external stress the crystalline portions may be expected to assume positions somewhat out of alignment with respect t o the fiber axis shown in Figure 6 . Likewise in the amorphous parts the chains may be expected to take up configurations determined by the resultant effects of thermal vibration and van der Waals' attractions. On applying stress, these chain configurations are altered. Presumably the chains are extended but are unable to crystallize. The increased stress communicated to the crystalline portions also causes a betterment in their orientation in agreement with the result observed in Figure 3. On removing the stress, the original configuration is reestablished. The low tensile strength and the flow observed under. higher loads (Figure 2G) indicate that a considerable proportion of the chains terminates in the amorphous portions. Only the fraction passing through such areas and terminating in the crystalline portions would be effective in producing high tensile strength. This picture of the crystalline and amorphous state existing in the copolyesters is admittedly incomplete. However, it provides a satisfactory explanation of the results observed and suggests that further study of synthetic fibers may well throw light on the interesting problem of the constitution of the natural ones.
477
Acknowledgment The writer is indebted to C. L. Erickson and N. R. Pape for the preparation of materials used in this investigation.
Literature Cited Astbury, W. T., Trans. Faraday SOC.,29, 193 (1933). Carothers, W.H., Chem. Rev.,8,353 (1931). Carothers, W. H.,J . Am. Chem. SOC.,51, 2548 (1929). Carothers, W. H.,and Arvin, J. A., Ibid., 51, 2560 (1929). Carothers, W.H..and Hill. J. W.. Ibid.. 54. 1568. 1579 (1932). Curme, G . O., Jr., and Douglas, S. D.,.IND. EN;. CHICM., 28, 1123 (1936). Fisoher, Ernil, Ber., 39, 2893 (1906). Fuller, C. S., and Eriokson, C. L., S. Am. Chem. SOC..59. 344 (1937). Katz, J. R., "Die Roentgenspektrographie als Untersuchungsmethode," Berlin, Urban and Sohwarzenberg, 1934. Kraerner, 0. E., and Lansing, W. D., J . Phys. Chem., 39, 2893 (1935). -, Mark, H., "Physik und Chemie der Cellulose," Berlin, Julius Springer, 1932. Staudinger, H., "Die hochrnolekultiren organisohen Verbindungen," 1932. Wagner-Jauregg, T., Ber.. 63, 3213 (1930).
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RECEIVED October 1, 1937. Presented before the Division of Colloid Chemistry at the 94th Meeting of the American Chemical Society, Rochester, N. Y., September 6 to 10, 1937.
Vapor Pressures of Solvents' D. H. KILLEFFER 60 East 42nd Street, New York, N. Y.
C
ONTINUAL usefulness of vapor pressure data in convenient form for ready reference suggests plotting them on nomographic charts. No other method allows so much information to be condensed into so little space. The method used in plotting is a modification of that of Davis ( 2 ) . It is also similar in principle to that of Cox (1) and to that of Germann and Knight @). It differs somewhat from all of these methods. To give a true result, the graph of vapor pressure must be a straight line when the two scales of the nomograph are used as coordinates. The graph is a straight line over limited ranges if the logarithm of the pressure and the reciprocal of the absolute temperature are thus used. However, only empirical functions will give actual straight lines over longer ranges. Because no such relation exactly fits data for different compounds, it was decided to use the logarithm of pressure against a temperature scale determined graphically over a suitable range. For this purpose a straight line covering the range was drawn diagonally on a sheet of paper having a logarithmic ordinate scale, and from vapor pressure data of a suitable compound, points were plotted to give the temperature scale used. Necessarily the scale thus obtained fits only one group of data exactly, but because variations from mean values are slight, the completed nomograph gives vapor pressures of approximately the degree of accuracy of reading of the scales. I n setting up the nomographs, the compounds graphed were grouped as to boiling point. The chart on page 478 shows solvents boiling below 90" C.; the chart on page 479 shows a group boiling from 90" C. to 150" C. Two subsequent 1 Those interested may obtain reproductions of these four nomographs on heavy Bristol board b y sending 25 cents to Industrial and Engineering Chemistry, 706 Mills Building, Washington, D. C., to cover the cost of printing and postage. They will be mailed about M a y 1 , 1938.
charts (to be published in May) will show two groups, one boiling from 150" to 200" C., and the second, above 200" (7.1 To determine the vapor pressure at any temperature, it is necessary simply to connect the temperature on the left-hand scale and the point characteristic of the compound with the vapor pressure scale by a straight line. The inside line of each scale should be used. The precision of the nomograph is, in general, within plus or minus one division on the temperature scale. Other compounds can be included on the nomographs, if desired, by determining and plotting their characteristic points from known data. Vapor pressure data in the literature vary considerably, and it has been impossible in the present instance to do more than select what are believed to be the best available. The method used in preparing the accompanying charts and the charts themselves have been checked with the greatest care. The result is justified rather by its convenience than its extreme precision; yet it is hoped that these charts will prove useful.
Acknowledgment Cooperation of many persons in supplying data is gratefully acknowledged. The compilation of data by C. Hadlock of the Engineering Department of E. I. du Pont de Nemours and Company, loaned for the purpose, and other data and assistance from P. R. Rector of Carbide and Carbon Chemicals Corporation were particularly helpful.
Literature Cited (1) Cox, IND. ENQ.CHEM.,15,592 (1923). (2) Davis, Zbid., 30, 320 (1938). (3) Germann and Knight, Ibid., 26, 467 (1934). ReCEIVED January 19, 1938.
INDUSTRIAL AND ENGINEERING CHEMISTRY
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VOL. 30, NO. 4
loo0
-20'
G v)
v
w
3
8 Q I
VAPOR PRESSURES OF SOLVENTS
?
BOILIHO BELOW 9 0 '
9
$ t h
0.
1. Acetone
12. Dlohloromethane
24. Isopropyl e t h e
2. 1-Bromo-1-chloroethae
13. Ethanol 14. Ethyl a c e t a t e
26. Methyl a o e t a t e
15. Ethyl bromide
27. Methyl formate
16. Ethyl ohloride
28. Methyl Iodide
17. Ethyl e t h e r
29. Methyl propyl e t h e r
18. Ethyl formate
32. Propylene oxide
3. Butyraldehyde 4. darbon d i s u l f i d e 5. Usrbon t e t r a c h l o r i d e 6. Chloroform 7. Ohloroprene
25. Methanol
g. 1 ,l-Diohloroethane
19. Ethyl methyl ketone 33. l,l,l-TrIohloroethane
9 . 1,B-Dlchloroethane
21. Ethylene oxide
34. Triohloroethylene
10. Dichloroethylene ( c i s )
22. Iaopropsncl
35. Vinyl aoetate
11. Dlchloroethylene ( t r a n s )
23. Isopropyl a o e t a t e
Copyright, 1 Y 3 8 , by I n d u s t r i a l and
Engineering Chehistry.
INDUSTRIAL AND ENGINEERING CHEMISTRY
APRIL, 1938
479
IO00
900 800
700 600 500
400
Id'
300
200 /50
30'
100
40 80
70 60 50
50"
40 30
20 VAPOR PRESSURES OF SOLVENTS BOILING BETWEEN 9 0 '
and 150'
1. Acetal
12. 1,~-Dichloro-2-butene 24. Methyl aOellosolvea
2. Acetic anhydride
13. Dioxane
3. I soamyl acetate 4. n-Butyl acetate
14. 2-Ethyl butyl alcohol 26. Methyl isobutyl ketone 15. Ethyl n-butyrate 27. Monochlorobenzene
25. Methyl wOellosolven aoetate
16. Ethyl propionate 5. Isobutyl acetate 2s. n-Propyl aoe tote 17. Ethylene ohlorohydrln 29. n-Propyl ether 6. n-Butyl alcohol 7. Isobutyl leobutyrate ld. Ethylene diamine 30. Propylene ohlorohydrln g. Isobutyl propionate 19- Mesityl oxide 31. Propylene diohloride 9. 190ellosolve" 20. Yethyl amyl aoetate 32. 1,1,1,2-Tetraohloroethane 10. Crotonaldehyde
21. Methyl amyl alcohol
11. 1,2-Dlbromoe thane
22. Me thy1 n-butyrate
15
0.
33. 1,1,2,2-Tetraohloroethane 34. 1,1,2-Trlchloroethane
/o 9 8
7 6 5
4 3
2
23. Methyl isobutyrate
f.5 Copyright, 1938. by Industrial and Engineering Chemistry.
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