DECEMBER, 1939
INDUSTRIAL AND ENGINEERING CHEMISTRY
1509
(15) International Critical Tables, Vol. 111, p. 3, New York, McGraw-Hill Book Co., 1927. (16) Keyes and Burks, J . Am. Chem. SOC.,49, 1403 (1927). (17) Kvalnes and Gaddy, Ibid., 53, 398 (1931). (18) Lewis, Proc. Am. Acad. Arts Sci., 43, 273 (1907). (19) Lewis and Randall, “Thermodynamics”, p. 38, New York, McGraw-Hill Book Co., 1923. (20) Ibid., p. 206. (21) Ibid., p. 207. (22) Ibid., p. 223. (23) Maas and Morrison, Trans. Rog. SOC.,Can., 18, 49 (1934). (24) Masson and Dolley, PTOC. Roll. SOC.(London), A103,524 (1923). (25) Noyes and Bray, J . Am. Chem. SOC.,33, 1693 (1911). (26) Pickering, Natl. Bur. Standards, Circ. 279, 60 (1926). (27) Randall and Sosnick, J . Am. Chem. SOC.,50, 967 (1928). (28) Rooreboom, “Die heterogenen Gleichgewichte”, Vol. 11-1, p. 288, Braunschweig, 1904. (29) Sage, Davies, Sherborne, and Lacey, IND.ENG.CHEM.,28, 1328 (1936). (30) Sane. Lacev. and Schaafsma. Ibid.. 26. 214 (1934). (31) Sage; Webiter, and Lacey, ibid., 29, 658 (1937). (32) Ihid., 29, 1188 (1937). (33) Ibid., 29, 1309 (1937). (34) Vold, J. Am. Chem. SOC.,57, 1192 (1935). (35) Young and Jasaitis, Ibid., 58, 377 (1936).
measurements reported in this paper. B. L. Hicks and Louise M. Reaney assisted materially in the extensive numerical calculations involved in the evaluation of the partial thermodynamic behavior of the components.
Literature Cited (1) Bartlett, Cupples, and Tremearne, J . Am. Chem. SOC.,50, 1275 (1928). (2) Bartlett, Heatherington, Kvalnes, and Tremearne, Ibid., 52, 1369 (1930). (3) Beattie, Ibid., 51, 19 (1929). (4) Beattie and Bridgeman, 2. P h y s i k , 62, 95 (1930). (5) Beattie, Hadlock, and Poffenberger, J.Chem.Phys., 3,93 (1935). (6) Beeck, Ibid., 4, 680 (1936). (7) Bridgeman, J . Am. Chem. SOC.,49, 1174 (1927). (8) Budenholzer, Sage, and Lacey, IND. ENG.CHEM.,31, 369 (1939). (9) Ibid., 31, 1288 (1939). (10) Dodge and Newton. Ibid.. 29. 719 (1937). { l l j E d m k e r , Ibid., 28, 1112 i1936). (12) Eucken and Berger, 2. ges. Klilte-Ind., 41, 145 (1934). (13) Eucken and von Lude, 2. physik. Chem., B5, 413 (1929). (14) Eucken and Parts, Ibid., B20, 184 (1933). ~I
Hevea Latex of Large J. McGAVACK
Particle Size T
United States Rubber Company, Passaic, N. J.
HE purpose of this paper is to report, primarily, the particle size distribution of modified Hevea latices. I n addition, the purpose is to show that the amount of nitrogen absorbed by the rubber particles in a latex thoroughly washed by aqueous ammonia is dependent upon the surface
quality and the dilution of the latex prior to creaming; therefore no definite figures which will always work can be given. The amounts used in these experiments are included in the tables and will serve as a guide to what might be employed. I n these experiments one creaming cycle was utilized, and hence the small particles originally in the top section of the creaming container still remained there after the operation. However, the additional volume of rubber caused by these smaller particles is so small that it does not materially affect the distribution curve of these fractionated latices.
, TABLE
Expt.
I.
‘IZE DATA OF SUMATRAN HEVEA LATEX
Creaming Agent,
-Av.
Particle-
VO!.,
?*
NO.
Part
cu. microns
microns
42 37 35 36
0.05 0.10 0.15 0.20
1.44 0.64 0.30 0.30
1.15 0.80 0.70 0.68
Approx. ,% TotalSo]lds Recovered 10.0 60.0 85.0 90.0
THE creams thus prepared were diluted to 2.5 per cent solids
and were then added to an equal amount of 5 per cent purified exposed. Until the careful and complete work of Lucas,I gelatin solution. After thorough mixing and while the latexthere were no reliable particle size distribution I data on a normal latex by which the distribution curves of modified latices could be comOF PARTICLES OF SUMATRAN HEVEACREAMS TABLE11. DISTRIBUTION pared. Now, as a result of his excellent techD, -No. Particles-Total Vol., Cu. p---D X No. Particlesnique for measuring all of the particles,. even Microns 42 37 35 36 42 37 35 36 42 37 35 36 1 2 0 0 13.2 26.4 0 .. 3.0 5.9 ,. .. the very small ones, we are able to discuss clearly ,”: 2 0 0 0 24.4 0 , . 5.7 .. .. surface and volume changes when these smaller 2.75 1 1 0 0 1 0 . 9 10:9 0 , . 2.8 2:s .. 2.65 2 2 1 0 19.6 19.6 9.8 . . 5.3 5.3 2:6 ,. sized particles are removed. 2.55 0 2 0 0 17.4 0 .. 5.1 . . .. 2.45 2 1 0 0 15:3 7.6 0 4:9 2.5 ,. This work was so conducted as to eliminate 2,35 2 0 0 1 13.6 0 618 4.7 1:4 1 1 particle sizes which could not be photographed 2.25 1 1 5.9 5:9 5.9 5.9 2.3 213 2:3 2.3 7 5 1 3 36.426.0 5.215.7 15.1 10.7 2.2 6.5 with microscopical equipment in visible light. It 5 3 1 3 22.6 1 3 . 6 4.5 13.5 10.3 6.3 2.0 6.2 131 ,. 6 3 131 ,. 3 6 was eventually carried out in such a way as to i:: 13 5 4 3 3 43,0 19.4 1 13,2 5.4 2 94 ,. 18 7 ,. 4 8 51.,98 5 1.,98 remove all water-soluble materials not adsorbed 1.75 14 6 6 4 40.0 1 7 . 0 1 7 . 0 1 1 . 3 24.6 10.5 10.5 7.0 on or dissolved in thelatex particles which were i:!: l5 l8 35.5 42.5 9.4 2 4 , 9 28.7 15.13 8.2 9 9 9 3 17.6 17.6 17.6 5.8 13.9 13.9 13.9 4.7 2 24.5 19.6 22.5 3.2 21.0 17.4 20.3 2.9 1.45 15 12 14 to be subsequently analyzed for nitrogen. 1.35 22 4 28.8 21.0 16.9 5.2 29.8 21.6 17.6 5.4 I n the preliminary work the distribution of 1.25 14 5 1 4 . 4 1 5 . 5 5.1 5.1 1 8 . 9 18.8 6.3 6.2 latex particles creamed with varying amounts 18 17 13 14.4 1 3 . 6 4 . 0 10.4 20.7 1 9 . 6 5.S 14.9
ii
;:2
;z
of ammonium alginate was studied. Sufficient alginate was used to cause either practically Or Only a certain percentage Of the rubber in the latex to rise. The actual concentration of alginate employed will depend upon its 1
IND. ENQ.CREM..30, 146 (1938).
0 ,. 89 55 o
9 13 26
0.75 0.65 0.55 0.45
18 18 33 32
Total
10 13 30 41 30 24 45 63 36 57 145 50 134 187 89 168 247 211 35 115 143
5.618.6 6 1 19.2 8 ., 7
4 . 1 13.1 2.7 20.2 3 . 0 15.4 1.7 1.5
- - - - 297
628
861
614
431
6.0 21 03 ,. 24 32.2 26.8 21.6 5.5
7.8
10.1 11 11.0 12.4 19.0 7.2
9.531.5 10.0 13.6 2 .. 4 28 2 2.8 21 2 1 339.0 8,2 5 3 ., 55 S0.6 1 3 . 5 4 2 . 7 108.5 37.5 1 1 . 7 5 7 . 0 121.0 57.8 1 8 . 2 93.0 136.0 116.0 14.4 15.8 51.8 64.6
~ - - _ _ - - _ _ 406
269
189
344
504
608
417
INDUSTRIAL AND ENGINEERING CHEMISTRY
1510
VOL. 31, NO. 12
X’
35
37
42
F r c n a ~1. CONTACT PRINTS OF FOUR EXPERIMENTS (XIOOO)
gelatin mixture was still warm, a drop was put on a glass slide, arefully thinned, and fitted with a cover glass. Photomicrographs were taken with a Zmm. objective and a 3X ocular with sufficient bellows extension to give a magnification of 1000 times. The diameter of the particles was then determined by measuring the enlarged photographs with extremely sensitive calipers. Figure 1 shows contact prints of four of the experiments. The details by which these latices were prepared, together with the results obtained from their measurement, are given in Table I. As the amount of creaming agent is decreased, the average particle volume as well as average particle diameter is increased and the amount of rubber recovered is greatly decreased. Table I1 gives the actual measurement as to number of particles, their total volume, and their total diameter for various size intervals. The lirst column, D,represents a size
interval 0.05 micron on each side of the value given. Thus the first entry, 2.95 microns, indicates that particles ranging from 3.0 to 2.9 were included in this group. To give still further information as to distribution of the larger sized particles, several experiments were carried out similar to those described above except that the cream obtained was further washed by rediluting with mater and either adding sufficient creaming agent each time to cause the particles above a certain diameter to rise or suhjccting the particles to the proper centrifugal force to accomplish the same result. In the creaming process, the creaming agent, ammonium alginate, was dissolved in water containing 0.5 per cent ammonia and was then added with careful mixing to the normal ammonia latex. This mixture was then diluted to 20 per cent solids and allowed to cream until the cream had reached a value of approximately 50 per cent solids. The serum was
DECEMBER, 1939
INDUSTRIAL AND ENGINEERING CHEMISTRY
that our centrifugal speed was just right to accelerate the rising of all rubber particles now in the system,
TABLE 111. REPEATEDLY PURIFIED LATICES Expt.
No.
-Av. Vol.
Descriptiono
Particl-
D
cu. P
Ir
Creamed 5 times, 0.01 alginate 1.320 BE-5 Centrifuged 5 times a t 21 Creamed low speed 6 times, 0.04 1.310 alginate 0.590 Lucas Normal 0.035 0 In all cases the washing was done with 0.5% remove 98% of water-soluble material. b I t is believed this w a s Malayan latex.
Area 8q.r
Rubber Origin of Recovered Latex
W-5
1.27
5.44
% 5
1.31
5.64 l8 3.10 55 0.33 100 NHs solution at dilutions
0.95 0.26
removed, and additional water containing ammonia and creaming agent, in the same concentration on the water phase as used before, was added in such a manner as t o give 20 per cent total solids. This operation was repeated several times-for example, six times in experiment 21 and five times in experiment W-5. The exact amount of creaming agent to be used will depend upon the quality of the material. The amounts based on the water for the experiments carried out in this report are given in the tables. However, if the work is repeated, the amount of creaming agent to be used should be such that the recovery of rubber in the cream phase is the important and guiding principle. I n experiments W-5 and 21, 0.01 and 0.04 part of alginate were needed per 100 parts of water to recover 5 and 55 per cent, respectively, of the rubber in the cream. The repeatedly centrifuged experiment was carried out in a laboratory centrifuge of low speed. I n this case the original latex diluted to 20 per cent solids was centrifuged, and when the machine was stopped, a predetermined percentage of the lower layer was removed. The upper layer was then diluted with 0.5 per cent ammonia water to 20 per cent solids and centrifuged, and the operation was repeated for the same time and a t the same rate. Again, the lower layer was removed, an equal amount of distilled water containing 0.5 per cent ammonia was added, and the operation was repeated. This was continued for experiments BE five times. The first serum removed was very cloudy and contained much rubber; the second serum was less cloudy and contained less rubber; the last three serums were practically clear, which indicated
I2 I
I
.
I
I N THIS way three experiments involving a complete removal of water-soluble materials other than those directly absorbed on the rubber were Malaya carried out. The per cent rubber recovered was also determined. The details of the preparation sufficient t o and characteristics of these purified large-size particle latices are given in Table 111. Since the size of these particles was relatively large, they were readily photographed. The negatives were then enlarged by projection, and the particles were measured and counted. The results are given inTable IV. Malaya
TABLE IV. N
w-5
PARTICLE MEASUREMENT AND COUNT
D Microns
N &S 6
Cu. fi
v
D* N
Additive Vol.
sq. P
-
Total 267 Average
2.18 2.05 1.90 1.83 1.77 1.70 1.63 1.56 1.50 1.43 1.36 1.29 1.23 1.16 1.09 1.02 0.96 0.89 0.82 0.75 0.68 0.61 0.54 0.48
5.41 4.53 3.50 3.21 5.64 5.14 4.52 6.00 8.85 3.06 8.92 13.40 8.75 10.60 7.40 19.00 7.83 10.35 6.06 5.30 5.60 3.00 0.57 0.11
.. ..
156.75 0.59
14.9 13.1 11.3 10.5 19.6 18.1 16.7 23.2 35.4 12.8 35.0 62.8 42.5 55.0 56.0 111.0 49.0 69.5 44.3 42.3 49.5 29.2 6.5 1.5
829.7 3.1
3.4 6.4 8.6 10.6 14.2 17.4 20.3 24.1 29.8 31.7 37.4 46.0 51.6 58.2 63.0 75.1 80.1 86.7 90.6 93.9 97.5 99.4 99.7 99.8
*.
2.18 2.05 1.90 1.83 3.54 3.40 3.26 4.68 7.50 2.86 8.21 15.50 11.02 15.11 16.40 34.80 16.30 25.00 17.22 18.00 23.20 15.25 3.78 0.96 253.95
*.
0.95
Six Times Centrifuged Latex (Recovery 180/0),Expt. BE-5 1 1 2 2 ~ 6 5 17 17 9 10 8 24 13 7 6 6 4
I
Total
138
2.03 1.95 1.87 1.79 1.72 1.64 1.56 1.48 1.40 1.32 1.25 1.17 1.09 1.01 0.94 0.86 0.78
..
..
Average
4.40 3.88 6.88 6.00 15.90 11.50 34.00 29.10 12.95 12.10 8.12 20.10 8.91 3.75 2.60 2.00 0.99
183.18 1.31
12.9 11.9 21.9 20.2 55.5 42.3 130.0 117.0 55.5 54.9 39.4 104.0 43.3 32.5 16.6 13.9 7.6
779.4
5.64
Five Times Creamed Latex (Recovery 5 % ) , 11.00 30.0 2.19 27.0 9.30 2.07 60.0 19.45 1.95 42.5 13.10 1.84 103.0 30.00 1.7'3 81.0 1.61 21.50 104.0 26.50 1.49 107.0 24.90 1.38 94.0 20.00 1.26 122.0 23.20 1.15 73.5 1.03 12.50 47.7 7.35 0.92 20.0 2.74 0.81 4.2 0.49 0.69
2 2 5 4 11 10 15 18 19 29 22 18 10 3
Total 168 Average
222.03
915.9
1.32
5.45
-
FIGURE 2. ADDITIVEVOLUME us. PARTICLE DIAMETER
N X D
%
Six Times Creamed Latex (Recovery 55%), Expt. 21 1 1 1 1 2 2 2 3 5 2 6 12 9 13 15 34 17 28 21 24 34 25 7 2
5 0
1511
..
2.4 4.5 8.3 11.6 20.3 26.6 45.0 60.9 67.9 74.5 79.0 89.9 94.7 96.7 98.2 99.3 99.8
.. ..
2.03 1.95 3.74 3.5a 10.32 8.20 26.50 25.20 12.60 13.20 12.00 28.10 14.30 7.07 5.64 5.16 3.12
182.71 1.31
Expt. W-5 4.9 4.38 4.14 9.0 9.75 17.7 7.36 23.5 19.03 36.8 16.10 47.5 22.40 59.2 24.80 70.2 24.00 79.1 33.40 89.4 22.60 95.0 16.60 98.2 8.10 99.5 2.07 99.7
*. ..
-
214.73
'1.27
VOL. 31, NO. 12
INDUSTRIAL AND ENGINEERING CHEMISTRY
1512
TABLEV. N
D
1 1 1 5 15 10 2
Microns 1.85 1.38 1.20 1.15 1.11 1.06 1.02 0.92 0.88 0.83 0.78 0.74 0.69 0.64 0.60
PARTICLE MEASUREMENT AND COUNTOF N0RMAL LATEX~ w
6
z
cu. p 3.30 5.45 0.91 4.01 0.71 0.62 1.11 4.30 0.35 0.28 0.24 1.06 2.67 1 I37 0.37
wD2N
N
D
33 7 24 24 28 74 62 113 199 271 116
Microns 0.55 0.51 0.46 0.41 0.37 0.32 0.28 0.23 0.18 0.14 0.09
sq. P
10.7 23.9 4.5 20.8 3.8 3.5 6.5 29.2 2.4 2.2 1.9 8.6 22.2 12.8 2.3
Total 1012 Averaee
N & T
6
cu. p 2.86 0.48 1.21 0.85 0.74 1.26 0.71 0.72 0.60 0.38 0.04 36.60 0.0358
T 0 2
N
found nitrogen value on the rubber of the different purified latices are given in Table VI. The amount of nitrogen retained in these washed latices is proportionally very close to the amount of surface exposed.
Sq. I*
31.4 5.0 16.3 12.7 12.1 23.8 15.1 18.3 20.8 18.7 2.9 330.4 0.323
These tables give data on the additive volume of the Partides. This additive volume is plotted against particle diameter along with the data obtained by Lucasl on a normal ammonia latex (Figure 2 and Table V). The data in Tables IV and V make it possible to calculate for the same %.eight of rubber dispersed cn the various latices the exact area of surface exposed. These results and the
TABLEVI.
0
Expt. No. w-5 BE-5 21 18 Lucas Volume
CHARACTERISTICS OF 100 GRAMSOF RUBBER IN FORM OF PURIFIED HEVEALATBX" 10'2 445 465 566
No. Particles ioia 81.9 82.5 183.0
990
3017.0
Area, sq. P
-
...
108
....
% Rubber
Recovered 5 18 65 99 100
N, %
on Solids 0.038 0.042 0,051 0.097
...
00.
Hence it is possible to fractionate latex into portions containing different average particle diameters and resulting in definitely different nitrogenvalues; thus a latex is produced which is well adapted for waterproofingand insulating purposes and will give a highly purified rubber when coagulated. before the Division of Rubber Chelnistry at the 97th Meeting of the American Chemical society, Baltimore, Md. PRE~ENTED
DRYING OILS AND RESINS Insolubilization of Maleic Glycol Polyesters by Additive Polymerization' E. L. KROPA AND T. F. BRADLEY Previous work on the maleic glycol polyesters showed that gelation can be achieved by condensation reactions or polymerization reactions or both. The glycol maleate resins can also be cured through the introduction of monomeric vinyl acetate or monomeric methyl methacrylate. When the resin is appropriately modified, monomeric styrene also serves as a curing agent. Under the reaction conditions these monomeric compounds have the property of curing the maleic resin by polymerization. The speed of conversion has been found to be a function of the number of condensation units in the resin. By the use of the maleic resin it is thus possible to build up insoluble and infusible resins.
P
REVIOUS communications on this subject indicated that the transformation of a linear system to its threedimensional polymeric form occurs by means of condensation or polymerization reactions or both ( 3 ) . Condensation reactions have to be distinguished from polymerization reactions in molecules which have hydroxyl and carboxyl groups as well as carbon-to-carbon double bonds. Where all these gnroupings are present, molecular growth can occur through 1
Previous papers in this series appeared in 1937, pages 440, 579, and 1270,
and In 1938, page 689.
American Cyanamid Company, Stamford, Conn.
loss of water (condensation) as well as by a mutual decrease of unsaturation (addition polymerization). It had been shown that synthetic hybrid polymers of the type of the glycol maleic or fumaric polyesters are both heat and oxygen convertible (2). At high temperatures, both addition polymerization and condensation occur simultaneously with the formation of an insoluble product. By conducting the reaction to a point short of gelation, it was found possible to carry such materials to the insoluble stage through polymerization reactions, by oxygen alone, or activated by ultraviolet light. If the condensation had not progressed to the point where there were, on the average, two carbon-tocarbon double bonds in the system, it was found impossible to e'ffect the conversion by means of addition polymerization. The present communication further distinguishes the polymerization and the condensation reaction in these hybrid systems. Heretofore the polymerization involved addition reactions as they occurred between the maleic portions of the polymer. The present work reveals an additional method by means of which it is possible to induce polymerization without apparently initiating condensation and thus bringing about gelation.
Structure of Maleic Resin and Its Significance
A consideration of the multicondensation of the maleic or fumaric polyester indicates that repeating points of unsaturation are to be found along the chain. Schematically, the structure may be represented as follows:
