INDUSTRIAL AND ENGINEERING CHEMISTRY
282
TABLE 111. CUBICALEXPANSION COEFFICIENTS AND TRANSITION TEMPEIZATURES OF VARIOUS RESINS (I1 x 106, (I2 x 106
Resin AYAT polyvinyl acetate XYSG polyvinyl partial butyral F C F Vinyon C F Y N A polyvinyl chloride MS-A-85 polystyrene
( 0
C.) - 1 232 236 206 202 211
(0
A.S.T.M. Samples Cellulose acetate, B-96 326 Cellulose acetate C-23 325 Cellulose acetate broDionate. CP-I 3 57 Cellulose apetate-butyrate, AA-5 419 Cellulose nitrate F-2 265 206 Methacrylate, K-24 207 Methaor late, Y-6 Vinyl chibride-aoetate L-9 171
C.) 694 692 562 670 589
696 677 569 708 514 593 767 590
-:
ta,
O
c.
24.9
50.1
64.6 75.0 78.0 68.6 49.2 38.8 49.9 52.6 55.0 94.9 48.2
Figure 5 shows Vre~. os. 1 curves for polyethylene resin and paraffin wax. Expansion coefficient values were not determined for the paraffin, which was run only for comparison. For the resin above 115" and at least t o 150" C., Vfilei. us. tis a straight-line function corresponding t o an expansion coefficient value of 012 = 762 X 1 0 - 6 ( " C.)-1. Below 110" C. the curve was found t o fit an equation of the form:
v,.i.l. = 0.9773 where T = temperature,
e3.664
' K.
(T -
186)2
X
Vol. 36, No. 3
Differentiating this equation with respect to T yields a, Values for polyethylene resin as calculated from the above equation, for temperatures below 115' C., follow: CI x 106, a x 106, a x 106, t , c. -35 -20 0
( 0
t,
C.) - 1 302 413 563
c.
20 40 60
80
C . )-1 719 88 1 1020 1230
t,
(0
c.
100 110 115' and above
(0
C.)-1
1420 1550 762
Polyethylene and paraffin behave very differently from all other plastics so far tested in this laboratory. The width of the transition interval appears t o be greatly increased until, for polyethylene, it extends over the greater part of the measured temperature range (from -35" to 115' C.). Over an appreciable portion of the transition interval the expansion coefficient is much higher than it is immediately above the interval. So far as has been determined, the drop in a appears t o be nearly discontinuous. Both paraffm and polyethylene soften so sharply that the softening temperature is frequently referred t o as a melting point. For samples tested in this laboratory, this temperature corresponds wit,hin 1" or 2' t o the upper end of the transition interval. LITERATURE CITED
(1) Carswell, T. S., private communication. (2)
Tamman, Gustav, "Der Glaszustand", Leipzig, Leopold VOSS, (1933).
(3) Ueberreiter, Kurt, Angew. Chem., 53,247 (1940). (4) Wiley, F. E., IND.ENG.CREM., 34,1052 (1943).
VOLUMETRIC BEHAVIOR OF 'n-BUTANE R. H. OLDS, H. H. REAMER, B. H. SAGE, AND W. N. LACEY California Institute of Technology, Pasadena, Calif.
M
ODERN developments in petroleum pro-
duction and processinghave directed interest to the behavior of hydrocarbons and their mixtures at somewhat higher pressures than were covered in earlier investigations. As a component of hydrocarbon fluids, n-butane has sufficient industrial importance to justify volumetric measurements in an increased pressure range. The vapor pressure of n-butane at several temperatures between 160" and 300" F. was accurately measured by Beattie, Simard, and Su ( I ) , who determined the critical constants and the volumetric behavior at pressures up to 5000 pounds per square inch in the temperature interval from 300" to 600" F. (8). Later Kay (3) studied in detail the volumetric and phase behavior of n-butane at pressures up to '
V
V
V
(Left) Figure 1. Isochoric Pressure-Temperature Diagram for Liquid n-Butane
INDUSTRIAL AND ENGINEERING CHEMISTRY
March, 1944 .1.0
I
I
I
I
1
.OS
Q.8
4.7
0.6
*
283
280" F. upon vaporization from a state in which 5% of the sample was in the gas phase, to a state in which 50% of the sample was in the gas phase. The laboratory methods and equipment have been described in some detail (4). Conventional vacuum technique in transferring materials to and from purification equipment, weighing bombs, and volumetric apparatus was employed. The sample weight was determined gravimetrically with a precision better than 0.01%. Temperature was measured with a platinum resistance thermometer which had previously been compared with a standard instrument of the same type. The estimated uncertainty in the temperature measurements was 0.01' F.; that in the pressure and volume measurements was less than 0.1 % throughout the observed ranges of these variables. VOLUMETRIC DATA
0.5
0.4
0.3 PRESSURE
L E PER
SQ. IN.
Figure 2. Comparison of Observed and Predicted Compressibility Factors for n-Butane
1200 pounds per square inch a t temperatures between 100" and 600" F. The present work extends the range of the experimental data to 10,000 pounds per aquare inch, and offers a comparison of the author's previous (6) and present results with those of the investigators mentioned, MATERIALS AND PROCEDURE
The Phillips Petroleum Company supplied the n-butane, and the analysis furnished with it indicated the presence of 0.003 mole fraction isobutane with negligible amounts of other imDurities. This material was fractionated at a reflux ratio of apiroximittely 50 to 1. The initial tenth and find fifth of the charge in the column were discarded, and the middle fraction was condensed in vacuo a t liquid-air temperatures in order to remove noncondensable gases. The sample obtained by this process showed a variation of less than 0.25% in its vapor pressure at
The volumetric behavior of n-butane was determined at seven temperatures, uniformly spaced, from 100' to 460' F., at pressures up to 10,000 pounds per square inch. The results are compared with those from recent investigations by others and with predictions based upon the BeattieBridgeman equation of state.
The experimental data were smoothed graphically with respect to pressure and temperature, and interpolated to even values of the pressure. The results are recorded in Table I. It is believed that the tabulated values are correct to 0.2'3,. I n this system the isochoric relation between pressure and temperature is nearly linear throughout wide ranges in the variables. Use was made of this property in finding inconsistencies in the experimental data by plotting isochoric curves of pressure against temperature. Figure 1 is a plot of the isochoric relation between the pressure and the temperature for n-butane at densities greater than the critical. The curves are drawn in accord with the results obtained by the authors; the data are in good agreement with the experimental results of Beattie and his coworkers, and in fair agreement with those obtained by Kay. The isochoric curves of pressure against temperature for liquid n-butane, based upon the observations of Kay, show considerably more curvature than waa found by the authors. Figure 2 compares the compressibility factor calculated from experimental data of the authors with that computed from the Beattie-Bridgeman equation of state for n-butane. The constants of the equation were determined by Beattie and his coworkers from their data at specific weights less than the critical.
PRESSURE
Figure 3.
LB. PER Sa. IN
Comparison of Observed and Predicted Specific Volumes of n-Butane at High Pressures
I N D U S T R € A E A N D E N G I N E E R I N G CHEMISTRY
284
TaBLE
Pressure, Lb./Sq. In.
SPECIFIC V O L U M E S O F
%-BUTANE
Specific Volume, Cu. Ft./Lb. 280’ F. 340’ F.
-
Abs.
100’ F.
160’ F.
220’ F.
Bubble point
0.02876 (51.5)Q 1,8040 10.136 6.833 4.968 3.245 2.383
0.03120 (120.6) 0.7836 11.287 7.630
0.03489 (241.2) 0.3716 12.426 8.415 6.150 4.058 3.011
0.04303 (436.0) 0.1651 13.557 9.193 6.728 4.451 3.313
0.02874 0.02871 0.02867 0.02863 0.02859 0.02858 0.02848 0.02841
1.7483 0.9821 0.03115 0.03108 0.03101 0.03094 0.03080 0.03068
1.9641 1.1246 0.7018 0.4865 0.03488 0.03468 0.03435 0.03406
2,1738 1.2615 0.8037 0.5729 0.4328 0.3365 0 20624 0.04150
14.684 9.966 7.301 4,840 3.609 2,3782 1,3929 0.8992 0.6518 0 . 5024 0.4020 0,2740 0.19332
0.02834 0.02821 0,02808 0.02794 0.02780 0.02768 0,02755 0.02733 0.02714 0.02698 0.02679 0.02664 0.02649 0.02621 0.02597 0.02575 0 02553 0.02534
0.03086 0.03034 0.03013 0.02990 0,02968 0.02948 0,02930 0,02895 0.02865 0.02839 0.02816 0,02794 0.02774 0.0273s 0,02702 0.02671 0,02645 0.02621
0.03379 0.03330 0,03289 0.03244 0,03205 0.03170 0.03140 0.03088 0.03044
0.04008 0.03832 0.03719 0.03616 0.03538 0.03468 0.03414 0.03324 0,03252
0.13400 0.05656 0,04641 0.04245 0.04034 0.03891 0.03786 0.03627 0.03513
0.18551 0.11449 0.07505 0,05691 0.04898 0.04543 0.04319 0.04028 0.03839
0.22161 0.14948 0.10773 0,07801 0.06304 0,08512 0.05055 0,04529 0.04229
0.03008 0,02972 0.02940 0.02912 0,02862 0.02820 0.02781 0.02747 0.02716
0.03195 0.03146 0.03104 0.03066 0.03000 0.02943 0,02896 0,02854 0.02815
0.03424 0.03350 0,03290 0.03236 0.03148 0.03076 0.03019 0,02967 0.02918
0.03703 0.03596 0,03508 0.03435 0.03318 0.03225 0.03153 0.03091 0,03033
0.04027 0.03877 0.03758 0.03662 0.03512 0.03395 0.03300 0.03222 0.03157
Dew point
10 14.696 20 30 40 60 100 150 200 250 300 400 500 GOO 800 1,000 1,250 1,500 1,750 2,000 2,500 3,000 3,500 4,000 4,500 5,000 6,000 7,000 8,000 9,000 10,000 a
I.
5.565 3.657 2.703
.... ....
....
400’
F.
....
....
....
15.807 10.734 7,870 5.224 3.901 2.578 1,5190 0.9891 0,7236 0.5640 0.4571 0.3227 0.2410
Figures in parentheses represent vapor pressures in pounds per square inch absolute
The agreement between the exDerimentallv observed behavior and that calculated from the equation is very good in this range. However, large discrepancies develop between the predicted and observed behaviors of this substance a t specific weights higher than those in the region from which the constants of the equation were determined. The magnitude of this divergence is further shown in Figure 3 in which the specific volume of n-butane is plotted as functions of the pressure up to io,ooo pounds per square inch.
460’ F.
....
....
16.925 11.499 8.434 5 , 604 4.189 2,774 1.6411 1.0747 0.7913 0.6211 0.5076 0.3649 0.2791
Vol. 36, No. 3
The observed vapor pressures and volumetric behaviors of the saturated liquid and gas phases were in good agreement with those determined by Beattie and eo-workers and by Kay, although the authors’ previous study ( 5 ) yielded values of the specific volume of liquid n-butane which were, on the average, about 0.6% less than the most probable values at present. No attempt has here been made to re-establish the critical constants of n-butane. ACKNOWLEDGMENT
This work was carried out as part of the activities of Research Project 37 of the Americctn Petroleum Institute. The assistance of H. A. TayIor, E. S. Turner, and W. E. Eberly in the operation of the laboratory equipment, and of Louise M. Reaney and Virginia Jones in the calculations, graphical interpolations, and preparation of the figures is gratefully acknowledged. NOMENCLATURE
b = specific gas constant P = pressure, lb./sq. in. abs. T = thermodynamic temperature, V = specific volume, cu. ft./lb. 2 = compressibility factor
R.
LITERATURE CITED
I
COMMERCIAL
(1) Beattie, Simard, and S u , J . Am. Chem. SOC.,61, 24 (1939). (2) Ibid., 61, 26 (1939). (3) K a y i IXD. ENG. C H E M . i 358 (4) Sage and Laccy, Trans. Am. Inst. Mining M e t . Engrs., 136, 136 (1940). (5) Sage, Webster, and Lacey, IND.ENG.CHEM.,29, 1188 (1937). 329
PAPFJR 42 in t h e series “Phase Equilibria in Hydrocarbon Systems”. Previous articles appeared during 1934-40 (inclusive), 1942, 1943, and in January, 1944.
T MEAL
Peptization and Extraction of Nitrogenous Constituents and the Color Comparison of Protein Solutions R. S. BURNETT AKD T. D. FONTAINE Southern Regional Research Laboratory, U. S. Department of Agriculture, New Orleans, La.
P
EANUT meal is a large and expanding potential source of vegetable protein. Sumerous uses for peanut meal and separated peanut protein are possible, but industrial utilieation depends on a knowledge of the properties of the nitrogenous and other constituents of peanut meal and the development of methods of modifying these properties to meet the requirements for particular uses. In another paper ( 2 ) the authors reported data on the peptization characteristics of the nitrogenous constituents of solventextracted peanut meal in which the proteins are present presumably in their native state. At present there is no appreciable commercial production of solvent-extracted peanut meal in this country and it is unlikely that there will be in the near future. However, a large volume of hydraulic-pressed peanut
meal is available, and it was considered of value to investigate the peptization of the nitrogenous constituents of representative meals. Except with respect to nitrogen peptization, consideration of the effect of heat and pressure treatment received during processing on the utility of hydraulic-pressed peanut meals and of proteins derived from them is not within the scope of this article. Hex-ever, most industrial protein products are cleavage or denaturation products rather than native proteins (1, 6 , 9, IO). The word “protein” is used in this paper in the broad sense and does not necessarily imply that preparations so designated are The present undenatured or free of nonprotein impurities. paper is concerned also with a comparison of the yields obtained by extracting and srparating protein fractions from hydraulic-
