Volumetric Behavior of Propene Y. S. FARRINGTON
AND B.
H. SAGE
California Institute of Technology, Pasadena, Calif.
T h e volumetric behavior of propene has been investigated at temperatures from 40" to 460' F. and pressures from 10,000 pounds per square inch absolute to values well below vapor pressure at 40" F. The results are tabulated and are compared graphically with the data of other investigators.
I
h-FORMATIOX concerning the vapor pressure and volumetric behavior of propene is of value in industrial practice
since this hydrocarbon can serve as the starting point in the preparation of a relatively large nuniber of compounds. Experimental data pertaining to this substance are scattered and incomplete except for the recent studies of Vaughan and Graves ( 7 ) . Their work covered t'he influence of pressure and temperature on the specific volume of propene a t pressures up to approximately 1200 pounds per square inch absolute for temperatures between 32" and 573" F. The measurements ryere carried out in glass over mercury and contributed the most complete data avaihble for this olefin. Limited information concerning the vapor pressure of this hydrocarbon was presented by Gilliland and Scheeline ( 2 ) . The specific weight of the bubble-point liquid and dew-point gas near the critical temperature was studied by Winkler a r 4 Maass (8). Seibert and Burrell ( 6 ) determined the critical constants and vapor pressure of propene, whereas Po.lvell and Giauque (5) est.ablished the heat capacity, the specific volume a t atmospheric pressure, and certain other physical propert,ies of this compound. The specific volume at atmospheric pressure was determined also by Batuecas ( 1 ) and Roper
(4). METHODS AYD Al't'A RATU S
The equipment employed in the volumetric studies reported n-as described earlier ( 6 ) . In principle it consisted of a stainless steel chamber whose effective volume could be varied by introducing or withdrawing mercury. This chamber was submerged in an agitated oil bath, the temperature of which was controlled within 0.03" F. of the desired value. Mechanical agitation of the contents of the chamber xas provided by a cylindrical cage of vertical rods activated by meam of an electromagnet rotating about the outside of the chamber. The samples of propene n-ere introduced into the apparatus in accordance with a n-veighing-bomb technique that, has been described ( 6 ) . The uncertainty in the weight of the material added was probably less than 0.1%. After introducing the propene, the pressure witshin the equipment was raised t o the desired upper value by inject>ingmerciiry. Thn oil bath was maint,aincd a t a predetermined temperature and after equilibrium had been attained as iiidicat,ed by the const,aiicy of pressure viith respect to time, the total volume occupied by the hydrocarbon was determined. The pressure then was decreased somewhat and t,he process rcpeatcd. From t,hese ineasuremerits a series of corresponding equilibriuni values of pressure and total volunie were obtained for each of several temperatures. The same proceduws were employed in the gas, liquid, and hetcrogcnrQUS regions. MATERIALS
The propme ciupioyed in t.his investigai ion \\-as o b i ainid froi:i the Phillips Petroleuni Company, and a special amlysis of t,hr $ample submitted indicated that it contained less thaii 0.005 .mole fract,im of materisl other than p r o p r n ~ . T h c hydi~iw~!ihon
a5 received was subjected t o two fractionations at a reflux ratio of approvimately 40 to 1in a column packed 17-ith small glass helices. The first and last tenths of the material were discarded in the course of each fractionation. At 100" F. the purified material showed less than 0.5 pound per square inch change in vapor pressure from bubble point to a quality of 0.5. Two separate purifications were carried out to obtain an adequate supply for investigating the volumetric behavior of this compound. The material after purification was stored in a steel bomb until transfrr to thc volumetric equipment. EXPERIMENTAL RESULT§
Of the three samples of propene employed, the largest Jveighed approximately 0.22 pound and was used in the study of the condcnsed-liquid and single-phase regions at' the higher pressures. An intermediate saniple weighing approsiinately 0.06 pound \\-as employed for investigations in the critical region and for studies a t intermediate pressures at the higher temperatures. A small sample of about 0.015 pound was used for t'he study of the low pressure, gaseous region and provided information concerning the specific voluine a t dew point for 40", 70", and 100" F. Dewpoint data a t temperatures from 130" to 190" F. were obtained from the measurements with the sample of intermediate size. The range of specific volumes investigated with a given filling of the apparatus was such that it overlapped those measurcd with another sample. On completing a series of measurements covering tn-elve temperahres between 40' and 460" F. a redeteriiiina.tion of totil volumes a t 100" F. a3 a function of pressure x a s made to detzct occurrence of any change in smiple. In the case of the intermediate and sinal1 samples no significant change in the characteristics of the material was noted. However, in the case of tlie larger sample a slight diminution in the total volume of the system IYRS detected and it was not possible t o rccover by conventional high-vacuum weighing-bomb tcchiiiqucs ( 5 ) all of the sariiple originally introduced. On opeiiiiig t'he equilibriuni vessel a small quantity of an oily liquid n-as found. This polymerized material apparently resulted froin the niaintcnaiice of the large sample a t temperatures above 400 F. for approsiniately 25 liours. Iluriiig t,his interval the system was a t prcssurcs in ~ s c e s sof 5000 pounds per square inch for &out 6 hours. At xhich the data for the large sample overlapped those for ncdiate sample the only significant discrepancy in speme was noted a t 460" E'. For tliesc reasons the data at 460" F. :ind pressures above 1500 pounds per square iiicli may iuvolvr uncertainties of as much as 0.2570 beyond those associ:ired \?-ith the measurements a t the lovier p'essures and tempcrxtiires. The experimental data for the thwe sets of measurenieiittx \wrc compared in terms oi" the residual specific volume, atid the compressibility factor, 2. The maximum difference 1 hiis found between the specific volumes as established from two ~ m p l ~was s 0.43%. The avernge deviation of the specific
1,
1734
August 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
40° F.
Vapor press., Ib./sq. in. abs. Bubble point Dew point Pressure, lb./ sq. in. abs. 0 14.696 20 30 40
70° F.
z
V
V
(97.5) 0.02969 0.02271 1.1227 0.8589
TABLE I. VOLUMETRIC BEHAVIOR OF PROPENE looo F. 190' F.
z
V
Z
(227.3) 0.03318 0.05284 0.4718 0.7513
(152.1) 0.03121 0.03514 0.7207 0.8114
220" F.
z
(622.1) 0,05000 0.18772 0.1088 0.4083
280' F.
V
z
V
...
... ...
... ...
...
z
...... .. ..
1,000 0.9821 0,9754 0.9626 0.9494
9.053 6.615 4.362 3.235
0.9793 0.9686 0.9578
9.589 7.013 4.633 3.443
1.000 0.9873 0.9826 0.9738 0.9649
50 60 80 100 125
2.3848 1.9568 1.4178 0.02968 0.02966
0.9357 0.9213 0.8900 0.0233 0,0291
2,5578 2,1061 1.5399 1,1982 0.9220
0.9467 0.9354 0.9119 0.8870 0.8532
2,7287 2.2522 1.6556 1.2966 1.0080
0.9558 0.9467 0.9279 0.9084 0.8927
50 60 80 100 125
3.225 2.6722 1.9811 1.5661 1.2336
0.9781 0.9676 0,9565 0.9451 0.9306
3.387 2.8085 2.0857 1.6518 1.3044
0.9768 0.9721 0.9625 0.9529 0.9406
3.707 3.078 2.2919 1.8201 1.4424
0,9826 0,9790 0.9719 0.9648 0.9557
150 200 300 400 500
0.02965 0.02960 0.02952 0.02944 0.02936
0,0349 0,0465 0.0695 0,0924 0.1152
0,7344 0,03115 0.03102 0.03090 0.03078
0.8155 0.0461 0.0689 0.0915 0.1139
0.8160 0,5657 0.03303 0.03284 0.03265
0.8575 0.7926 0.0694 0,0921 0.1144
150 200 300 400 500
1.0117 0.7331 0.4512 0.3059 0.21280
0,9158 0.8849 0.8170 0.7383 0.6421
1.0726 0.7820 0.4894 0.3406 0.24870
0.9281 0.9022 0.8470 0.7859 0.7173
1,1905 0,8753 0.5591 0.4001 0,3040
0,9466 0,9279 0,8892 0,8484 0,8057
600 800 1000 1250 1500
0,02928 0.02914 0.02900 0.02882 0.02866
0.1379 0.1829 0.2276 0,2827 0.3373
0.03067 0.03046 0.03026 0.03001 0.02980
0.1362 0.1804 0.2240 0.2777 0.3309
0.03248 0.03216 0.03186 0.03153 0.03122
0.1365 0.1802 0.2232 0.2761 0.3281
600 800 1000 1250 1500
0.13376 0.04287 0.04050 0.03870 0.03750
0.4844 0.2070 0.2444 0.2919 0.3395
0.18375 0.08018 0.04876 0,04356 0.04127
0.6360 0.2775 0.2813 0.3141 0.3571
0.23924 0.16665 0.10527 0,06927 0.05351
0.7609 0.6643 0.5680 0.4590 0,4255
1750 2000 2250 2500 2750
0.02850 0.02836 0,02822 0.02809 0.02796
0,3914 0.4451 0.4982 0.5510 0.6033
0.02961 0.02943 0.02927 0,02912 0.02897
0.3836 0.4357 0.4875 0.5389 0.5897
0.03094 0.03069 0.03047 0.03026 0.03007
0.3793 0.4300 0.4803 0.5300 0.5793
1750 2000 2250 2500 2750
0.03661 0.03595 0.03535 0.03486 0.03441
0.3867 0.4339 0.4800 0.5260 0.5711
0.03973 0.03856 0.03765 0.03691 0.03628
0.4011 0.4449 0.4887 0.5323 0.5755
0.04962 0.04612 0.04382 0.04225 0.04098
0.4603 0.4890 0,5226 0.5599 0.5974
3000 3500 4000 4500 5000
0.02784 0.02762 0.02742 0 02724 0.02707
0.6554 0.7586 0.8606 0.9619 1.0621
0.02883 0.02856 0.02832 0.02810 0.02790
0.6402 0.7400 0.8386 0.9360 1.0326
0.02890 0.02959 0.02931 0.02906 0.02885
0.6284 0.7256 0.8214 0.9161 1.0106
3000 3500 4000 4500 5000
0.03401 0.03331 0.03271 0.03220 0.03175
0.6158 0.7036 0.7896 0.8745 0.9581
0.03573 0.03480 0.03407 0.03342 0.03288
0.6183 0.7026 0.7862 0.8676 0,9484
0.03992 0.03835 0.03714 0.03618 0.03537
0.6348 0.7115 0.7875 0.8630 0.9375
6000 7000 ,8000 9000 10,000
0.02677 0.02652 0.02630 0.02610 0.02591
1.2604 1.4567 1.6510 1.8432 2.0331
0.02755 0.02725 0.02696 0.02670 0.02645
1.2236 1.4120 1.5966 1.7788 1.9580
0.02840 0.02801 0.02766 0.02734 0.02701
1.1938 1.3736 1.5502 1.7238 1.8923
6000 7000 8000 9000 10,000
0.03100 0.03036 0.02982 0.02934 0.02895
1.1225 1.2826 1.4397 1.5936 1.7471
0.03196 0.03125 0.03166 0.03014 0.02963
1.1062 1.2619 1.4149 1.5648 1.7093
0.03409 0.03311
1.0842 1.2286
0.03231 0.03165 0.03105
1.3702 1.5099 1.6459
Ti
1,000
-
z
0.0848
160' F.
V
z
'
#./sq. in. abs. Bubble point Dew point Pressure, lb./ sq. in. abs.
0 14.696 20 30 40 50
(327.1) 0.03572 0.07769 0,3109 0.6762
10,125 7.411 4.904 3.650
1,000 0,9894 0.9855 0.9782 0,9707
(456.6) 0.03983 0.11507 0.2002 0.5782
10.657 7.805 5.170 3.853
1.000 0.9909 0.9876 0.9813 0.9750
,
11.187 8.197 5.435 4.054
(562.0) 0.04501 0.15506 0.1404 0.4836
11,010 8.066 5.347 3.987
1,000 0.9918 0.9888 0.9831 0,9774
100 125
0.9632 0,9556 0.9400 0.9239 0.9031
3.062 2.5344 1.8748 1.4786 1.1611
0.9686 0.9621 0.9490 0.9355 0.9183
3.171 2.6265 1.9459 1.5373 1.2099
0.9717 0,9659 0.9542 0.9423 0.9270
150 200 300 400 500
0.8837 0.6276 0.3598 0.03553 0.03521
0.8814 0.8346 0.7177 0.0945 0.1171
0.9489 0.6823 0.4103 0.26393 0,03950
0.9005 0.8633 0.7789 0.6680 0.1230
0.9912 0.7166 0.4382 0.29327 0.19750
0,9113 0.8784 0.8058 0.7190 0.6033
800 1000 1250 1500
600
0.03491 0.03437 0.03391 0.03337 0.03291
0.1393 0.1828 0.2255 0.2774 0.3283
0.03863 0.03740 0.03650 0.03562 0.03492
0.1467 0.1893 0.2309 0.2817 0.3314
0.04365 0.04053 0.03896 0.03755 0.03655
0.1605 0.1987 0.2388 0,2877 0.3360
1750 2000 2250 2500 2750
0.03251 0.03216 0.03185 0.03157 0.03132
0.3783 0.4277 0.4765 0.6248 0.5727
0.03435 0.03384 0.03347 0,03310 0.03276
0.3803 0.4282 0.4765 0,5236 0.8700
0.03579 0.03520 0.03470 0,03428 0.03386
0.3839 0.4315 0.4786 0.5253 0.5707
3000 3500 4000 4500 5000
0.03108 0.03067 0.03031 0.03000 0.02071
0.6200 0.7138 0.8062 0.8977 0.9878
0.03248 0.03190 0.03143 0.03102 0.03066
0.6159 0.7064 0.7954 0.8832 0.9700
0.03350 0.03288 0,03234 0,03186 0.03145
0.6160
6000 7000 8000 9000 10,000
0.02922 0.02878 0.02836 0.02799 0.02763
1.1658 1.3396 1.5086 1.6750 1.8372
0.03008 0.02954 0.02909 0.02869 0.02830
1.1412 1.3083 1.4725 1.6337 1.7906
0.03076 1.1312 0.03012 1.2923 0.02960 1.4514 0.02914 1.6075 0.02873 1.7610
0.7054 0,7929 0,8788 0.9638
1.000 0.9922 0.9894 0.9840 0.9786
11.716 8.588 5.698 4.254
Pressure, lb./ sq. in. ahs.
0 14.696 20 30 40 50 60 80 100 125
V
13.826 10.144 6.745 5.045
1,000 0.9933 0.9908 0.9862 0.9815
12.772 9.367 6.223 4.651
z 1,000 0.9961 0.9947 0,9921 0.9895
17
14.875 10.918 7.264 5.437
z 1,000 0.9970 0.9959 0.9939 0.9918
1.000
0.9949 0.9931 0.9896 0.9861
460' F.
400° F,
340° P.
z
2.8971 2.3952 1.7671 1.3895 1.0865
::
0 14.696 20 30 40
180° F.
V
Va or press.,
s
V
8.516 6.215 4.089 3.025
-~ 130' F.
*
Vapor mess.. lb./sql in. abs. Bubble point Dew point Pressure, lb./ sq. in. abs.
1735
V
15.923 11.690 7.781 5.826
z
1I000 0,9976 0,9968 0,9952 0,9936
4.025 3.345 2.4955 1.9854 1.5774
0.9868 0.9841 0.9788 0.9734 0.9667
4.340 3.609 2.6959 2.1476 1.7090
0.9898 0.9877 0.9836 0.9795 0.9743
4.654 3.872 2.8944 2.3080 1.8389
0,9920 0,9904 0.9872 0.9840 0,9800
1,3052
0.6240 0.4628 0,3495
0.9599 0.9462 0.9178 0.8880 0.8568
1.4166 1.0611 0.6851 0.5019 0.3917
0.9691 0.9588 0.9373 0.9155 0.8983
1.5261 1,1351 0,7440 0,5480 0,4304
0,9760 0,9679 0.9515 0.9345 0,9175
600 800 1000 1250 1500
0.28048 0.19504 0.14387 0.10368 0.08000
0.8231 0.7650 0.7064 0.6352 0.5890
0.3183 0.22702 0.17278 0.13021 0.10276
0.8710 0.8283 0.7330 0.7423 0.7030
0,3523 0.25529 0,19734 0.15162 0 12189
0,9012 0.8707 0.8413 0,8080 0.7795
1750 2000 2250 2500 2750
0.06631 0.05828 0.05333 0.04993 0.04743
0.5690 0.5716 0.5883 0.6120 0.6395
0.08497 0.07319 0.065;9 0.05927 0.05556
0.6782 0.6676 0.6690 0.6792 0.6968
0.10163 0.08788 0 07753 0 07012 0.06454
0,7582 0.7468 0,7437 0.7474 0.7567
3000 3500 4000 4500 5000
0.04551 0.01275 0.04090 0.03917 0.03827
0.6694
0.7336 0.8021 0.8708 0,9382
o . o m 8 0.7181 0 . 0 4 8 1 ~ 0.7688 0.04532 0.8268 0.04317 0.8860 0.04133 0.9471
0 . 0 6 0 ~ 8 0.7710 o 05430 0.8102 0,05023 0,8566 0.04732 0.9078 0,04511 0.9616
6000 7000 8000 9000 10,000
0,03648 0.03614 0.03410 0.03327 0.03257
1.0732 1.2060 1.3375 1.4681 1.5969
0.03008 0.03734 0.03603 0,03497 0.03412
0.04206 1.0759 0.03980 1.1878 0.03809 1.2911 0.03680 1.4120 0 . 0 3 ~ 7 1.5250
150 200 300 400 500
0,9649
i.otm 1.1921 1.3146 1.4354 1.5861
INDUSTRIAL AND ENGINEERING CHEMISTRY
1736
volume at ~ o m e50 states talcen i n the regions where comparisons were possible was 0.21%. A careful review of the uncertainties in the absolute values of the pressure, temperature, t,otal volume, and weight of sample indicates that the recordcd specific volume a t a particular pressure and temperature probably does not, involve an uncertainty greater than 0.3%,
2 5
1
0
si BERT
p
c
0
Ad1.YO*S
z20
I
Ah3
IAUCHAN
0
A h D
ILIL'ND
I
AND
9
CRAVES
4
BURLELL
IC*IIL 1
V L
l
I
I
Vol. 41, No. 8
a review of available data, 197.0" E'. was chosen as the critical temperature of propene, whereas 196.5" F. was established by T'aughan and Graves ( 7 ) . ISstrapolation of the relation of vapor pressure to temperat,ure from 190" F. to the critical tmnperat,urc gave a value of 668 pounds per square inch. This conipares wit'h a value of 667 pounds per square inch reported by Vaughan and Graves ( 7 ) . It is believed that this value is within
the specific volume a t the critical state of 0 0693.1 cubic foot pel pound. Tmo other published values ( 7 . 8 ) for the critical specific volume ale 0 0687 arid 0 06916 cubic foot per pound, rpspectivel\,
Bubble Point i'
100
I
I
i I
I
I ~
~
I
The vapor pessure of propene at 100" F. n-as determined also in mother apparatus ivhich utilized an independent set of temperature and pressure measuring instruments. The value so obtained was 227.1 pourids per square inch, n-hich agrees n-ell with the vapor pressure of 227.3 pounds per square inch as found in this investigation. The specific volume and compressibility factor are recorded in Ta,ble I for even values of the prcssurc a t each of the temperntures experimentally studied. I n the vicinity of the critical state, an added uncertainty of as much as 0.1% is to be expected. The values of the specific volume a t bubble point and den- point and of the tv-o-phase pressure also are recorded iri Table I for temperatures beloir- 190" F. The vapor pressure of propeue has been measured by other invest,igators (gj 6!7 ) . Figure 1 presents comparative values of the residual vapor pressure as a function of temperature. For this comparison the residual vapor pressure is used t o magnify divergences and is defined by the follon-ing two equations:
The divergence of the ea,rlier measurements of Seibert and Burrell (6) from the lat.er result,s of T-aughan and Graves ( 7 ) and from the present ones is clearly evident. The measurements of Gilliland and Scheelinc ( 2 )also differ markedly from the present data. The values of vapor pressure recorded in Table I were obtained from the smooth curve of Figure 1 and Equations 1 and 2. The critical temperature has been observed by several investigators (6, 8) and t,he data are in reasonable agreement. From
42 2 56.3 125 150 69.0 90.1 200 250 107.6 122 6 300 350 135.9 400 147,8 158.6 +50 300 168.6 350 177.9' 600 186.5 650 194.3 197,O a 668% Critical s h t e
1 0 0 0 0 0 0
0970 8787 7310 5417 4247 3446 24092 28608
0 0 0 0 0 0
20444 17380 14666 12066 09020 06944
0.8570 0.8346 0.8132 0.7727 0,7389 0.6962 0.65'92 0.6220 0,5831 0 . 5423 0.4960 0.4393 0.3516 0.2770
z 0 0233 0 0290 0 0347 0 0464 0 0583 0 0707 0 0838 0 0978 0 1129 0 1209 0 1394 0 1741 0 2168 0 2770
In the interest of convenience in the utilization of data the compressibility factor and specific volume for the dew-point gas and bubble-point liquid and the two-phase tcmperature have been recordcd for a series of even values of pressure in Table 11. It is believed that the uncertainty in the two-phase tenipcralures cited is not greater than 0 . 0 i F.
TABLE 111. Temperature, 0 F.
."
70 100 130 160 180 190
IAATYST 13EllT O F ~ T A P O R I Z A T I O S All thors, R.t.ii./I,h. 15.5 6 141 6 130 6 113 1
89 1
64 5
44 8
Vaughan and Graves. B. t .II./'Lb. 158 4 116 1 132 5 11; 6 90 8 65 3 4d 6
The volumetric behavior of propeiie is similar to that of other hydrocarbons when compared on a reduced basis. The volumetric data submitted in Table I supplemented by values of t h c heat capacity as a funct,iorl of temperature (3)afford sufficient iiiformat,ion to permit the thermodynamic properties of this hydrocarbon t o be established. As an application of the data of Table I, the Clapeyron equation was used to obtain values of the latent heat of vaporization for several temperatures. The results are contained in Table 111. For comparison, values obtained by Vaughan and Graves ( 7 ) are included in this tabulation. ACKNOWLEDGMENT
This invest,igat,ion constitutes a part of the activity of the Socony Vacuum Fellowship at the California Institute of Tcchnology and was possible because of the interest of the company. The assistance of H. H. Reamer was of great value in connection ivith t,he experimental work. K. N. Lacey assisted in the preparation of the manuscript.
August 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY NOMEXCLATURE
1737
LITERATURE CITED
b = specific gas constant, 0.25504 (lb./sq. in.)(cu. fk/lb.)/
(1) Batuecas, J . chim. p h y s . , 31,165 (1934).
12. P = pressure, lb./sq. in. abs. p" = residual vapor pressure, Ib./sq. in.
specific volume, cu. ft./lb. residual volume, @ T I P ) - V , cu. ft./lb.
(2) Gilliland and Scheeline, IND. EKG.CHEM.,32,48(1940). ( 3 ) Powell and Giauque, J . Am. Chem. Soc., 61, 2366 (1939). (4) Roper, J . Phys. Chem.,44, 835 (1940). (5) Sage and Lacey, Trans. Am. Inst. Mining M e t . Enyrs., 136, 136 (1940). (6) Seibert and Burrell, J . Am. Chem. Soc., 37, 2683 (1918). (7) Vaughan and Graves, IKD. ENG.CHEIII., 32,1252 (1940). (8) Wiiikler and Maass, Can. J . Research, 9, 610 (1933).
compressibility factor, PV/b?'
RECEIVED August 2, 1948.
II
p,'l = reference vapor pressure, Ib./sq. in. abs. 459.69) T = absolute temperature, R = (' F.
v =
17 II
Z
=
+
ANTIFOULING PAINTS Role of Pigment Particle Size in the Performance of Toxic Paints ALLEN L. ALEXANDER, J. B. BALLENTINEl, AND M. 0. YEITER2 Naval Research Laboratory, Washington, D . C . T h e current study describes a method for classifying a standard pigment sample into fractions of measured particle size. Classified fractions were incorporated into a standard antifouling matrix and two slightly varied vehicles. The paints were studied carefully to determine characteristics resulting from variations in particle size with a view- of establishing the precise effect of particle size on performance. Viscositj characteristics imparted by the fine particles did not appear to be so severe as supposed heretofore, although paints containing high percentages of small particles may be expected to exhibit
higher viscosities in the normal pattern. Only initial leaching rate values appear to be enhanced by predominantly small particles of toxic pigment. The steady state leaching rate remains unaffected in a given matrix regardless of particle size. I n antifouling paints prepared from rosin and its derivative larger pigments seem to reinforce the physical stability of the film much more effectively than extremely small particles; however, when organic tougheners are added for the purpose of strengthening the film the influence of pigment particle size becomes less significant as a stabilizer of film integrity.
A
dieted by oil absorption values. They display also decided thixotropic properties after periods of storage. On the ot,her hand, cuprous oxide of pyrochemical origin is characterized by high apparent density, low oil absorption, and a rather dull red color. It imparts low consist'ency to the paints in which i t is incorporated. This pigment produces paints of a fairly standard consistency with much less after-bodying in storage. Each of these phenomena may be associated inimediately with pigment particle size. Because the much more finely divided electrolytic product displays more erratic physical properties in paints it is a further purpose of this research to study the influence of particle size on some of the physical properties of paints prepared from cuprous oxide of controlled particle size and apparent, surface area.
S A RESULTof researches reported in recent gears, successful
antifouling paints may be designed with the assurance that effective suppression of marine growth may be maintained for periods up to several years. A significant contribution was made by Ketchum and associates ( 6 ) with the demonstration that for paints containing metallic copper or its compounds as the toxic, ~ copper per square the rate of dissolution must exceed 1 0 of centimeter of paint surface per day to prevent the attachment and growth of fouling organisms. Subsequently a number of mechanisms for maintaining this rate were investigated. Ferry and Carritt (.2) made an exhaustive study of the solubilit,y and rate of solution of cuprous oxide (the most commonly used copper ingredient))and Ferry and Riley ( 3 )reported on the solubilities of various antifouling toxics in sea water. Such data are valuable in the design of antifouling coatings intended t o maintain adequate b u t nonexcessive leaching rates. Matrix solubility has been demonstrated by Ketchuni, Ferry, and Burns ( 5 ) to be a crit,ical factor in controlling the rate of release of toxic to sea water, while the role of film permeability as described by Young and Schneider ( Y ) and discussed further by Alexander and Benemclis ( 1 ) cannot be disregarded in the formulation of efficient' antifouling paints. Particle size or total surface area of toxic pigment obviously bears a direct relationship t o leaching rate along with each of the factors mentioned above and it is a purpose of this paper to discuss the effect of particle size on antifouling efficiency as demonstrated by leaching rate measurements and marine exposure of paints containing pigments of predetermined range of particle size. Experience in the manufacture of paint a t the Mare Island Kava1 Shipyard ( 7 ) has indicated cuprous oxide of electrolytic origin to be of relatively low apparent density and high oil absorption, arid to possess a highly brilliant yellow color attributable to its fine particle size. Paints prepared from it follow somewhat erratic patterns of consistency (on the high side) as pre1 2
Present address, University of Xorth Carolina, Chapel Hill, N. C. Present address, Rohrn & Haas Company, Philadelphia, Pa.
PARTICLE CLASSIFICATION AND MEASUREMENT
The classification or even the nieasurement of true particle size is rarely a n absolute process and owing t o the volume of material involved in a study of this nature, absolut,e methods free of numerous assumptions are not' often applicable. The results obtained are dependent' in a large degree on the physical principle3 involved and the validity of the assumptions made. I n the case of cuprous oxide the aut,hors are dealing with part,icles irregular in shape which can be classified and measured only by imaginary conversion to spheres which are assumed to be equivalent in some property to the particles. Thus, in sieving, the particles are assumed to be the largest sphere that would pass a given aperture and sedimentation assumes the particles to be spheres of identical material possessing the same falling velocity in a fluid (4).When thesedimentation process is reversed and the particle is balanced or rises in an upward flowing column of liquid or gas, it is termed elutriat'ion. Separation of particles of subsieve size into fractions may be effected by means of a series of cylindro-conical forms of succes-
