INDUSTRIAL AND ENGINEERING CHEMISTRY
1546
Vol. 45, No. 7
LITERATURE CITED
This investigation was carried out under the sponsorship of the Office of Synthetic Rubber, Reconstruction Finance Corp., in connection with the government synthetic rubber program.
Armstrong, R. T., Little, J. R., and D o a k , K. W., IND.ENG. CHEM.,36, 628 (1944). (2) Bardwell, J., and Winkler, C. A , , I n d i a Rubber World, 118, 509
(1)
f 1948). ~~
Craig, D., Juve, A. E., Davidson, W. L., Semon, W.L., and Hay, D. C., J . Polymer Sci., 8, 321 (1952). (4) Flory, P. J., Chem. Revs., 35, 51 (1944). (5) Flory, P. J., IND.ENG.CHEM.,38, 417 (1946). (6) Flory, P. J., J . Chem. Phys., 18, 108 (1950). (7) Flory, P. J., Rabjohn, N., and Shaffer, M . C., J . Polymer Sci., 4,
(3)
NOMENCLATURE
= Huggins interaction constant
p
Mc
= molecular weight between cross links
vI
= volume fraction of rubber in the swollen vulcanizate
Y
= effective number of cross-linked units/gram rubber
pr
= density of rubber
Vo
f
= molar volume of solvent = force of retraction
A,
= cross-sectional area of the test specimen
R T
= gas constant = absolute temperature
ci
= ratio of the stretched swollen length to the unstretched =
3!,
x
=
Q
= = =
ps
y
S
= =
F no
=
iM,
= nzns =
swollen length of the test specimen ratio of the swollen length to the unstretched unswollen length of the test specimen constant of the tension equation, proportional to the cross linking amount of swelling, cc. solvent imbibed/cc. rubber density of solvent ratio of the swollen weight to initial weight of the test specimen soluble fraction of the vulcanizate fraction of rubber in the compounded stock number of cross links/gram rubber primary molecular weight amount of zinc sulfide produced
225 (1949). (8) (9) (10) (11) (12) (13)
Flory, P. J., and Rehner, J., J r . , J . Chem. Phys., 11, 52 (1943). Gee, G., J . Polymer Sci., 2, 451 (1947). Gee, G., Trans. Faraday SOC.,42, 585 (1946). Guppy, Wr.D., Trans. Inst. Rubber Ind., 7, 81 (1931). Huggins, & IND. I., EBG.CHEM., 35,216 (1943). Hull, C. lf.,Olsen, S.R., and France, W.G., Ibid., 38, 1282 (1946).
Kelly, W. J., I n d i a Rubber World, 66, 491 (1922). Luke, C. L., IA-D. EA-G.CHEM.,AXAL.ED., 15, 602 (1943). Scott, J. R., Trans. Inst. Rubber I n d . , 5 , 95 (1929). Scott, R. L., and Magat, M., J . Polymer Sei., 4, 555 (1949). Stevens, H. P., Analyst, 40, 275 (1915). Treloar, L. R. G . , Trans. Faraday Soc., 39, 36 (1943). Wall, F. T., J . Chem. Phys. 10,485 (1942). Yanko, J. A , , J. Polymer Sci., 3, 676 (1948). Zapp, R. L., IND. ENG.CHEM.,40, 1508 (1948). Zapp, R. L., Decker, R. H., Dyroff, Margaret S., and Rayner, Harriet A., J . Polymer Sci., 6 , 331 (1951). (24) Zapp, R. L., and Ford, F. P., Ibid., 9, 97 (1952). (25) Zhukov, I. I., and Simkhovich,F. M., KoIEoid Z h u r , 1, 11 (1935). (14) (15) (16) (17) (18) (19) (20) (21) (22) (23)
RECEIVED for review Xovember 7, 1952. ACCEPTED March 13, 1953. Presented before the Division of Rubber Chemistry of the AUERICAN CHEMICAL SOCIETY, Buffalo, N. Y., 1952.
Plasticizers from Aconitic and
Tricarballylic.Acids J
FRANK C. MAGNE AND ROBERT R. MOD Southern Regional Research Laboratory, .Yew Orleans, La.
T
HE rapid expansion of the plastics industry, particularly in
the field of vinyl resins, has increased the demand for efficient plasticizing materials. Because of the presence of three ester groups, the triesters of aconitic acid and of the corresponding saturated tricarballylic acid would be expected to be compatible with many synthetic resins. With this in mind, screening tests have been made to evaluate the plasticizer characteristics of fourteen triesters, seven of aconitic acid and seven of tricarballylic acid. The preparation, purification, and characterization of these compounds are reported elsewhere ( 7 ) . The esters supplied by these authors were distilled preparations having acid numbers below 0.8 mg. of potassium hydroxide per gram, except for the propyl esters when it was 28.0, and were in most instances water white. However, some duplicate preparations were pale lemon yellow. Table I gives the densities, viscosities, and boiling points of the esters as well as the pertinent elastic properties of the plasticized polyvinyl chloride-polyvinyl acetate copolymer compared to the values obtained for a commercial di-2-ethylhexyl phthalate (DOP) as a control. I n addition, the compatibility of the esters with ethylcellulose and cellulose acetate was also determined. BOILlNG POINTS
The experimental measurements were made by means of an improved tensimeter still (6). The values a t pressures of 9 mm. or higher were determined a t least twice, before and after distilling off a 25- to 50-ml. fraction. The boiling points given in the table
were read from the graphs obtained by plotting the logarithms of the experimental vapor pressures against the reciprocals of t h e absolute temperatures. DENSITIES AND VISCOSITIES
The densities were measured pycnometrically (6) and the viscosities by means of a modified Ostaald viscometer a t lo", 25", and40' C. (6). PL4STICIZER EVALUATION PROCEDURE
The test composition was as follows: Vinyl resin VYDR (95% polyvinyl ohloride5% polyvinyl acetate) Basic lead carbonate Stearic acid Plasticizer
63 5% 1 0% 0 5%
35 0%
The firet three components of the batches were dry-mixed and the plasticizer was added just before milling. This operation was performed on a 12 X 6 inch rubber mill a t a temperature of 300" F. The sheeted resin was then molded in a standard 6 X 6 X 0.075 inch four-cavity mold. Because the sheeted resin was too thin to fill the mold completely, several layers, usually four, were placed in each mold with the milling axes parallel. The molds were gradually pressured t o a maximum of 500 pounds per square inch over a 10-minute period and then held for an additional 10 minutes a t the molding temperature, 300" F. The molds were cooled before releasing the pressure to remove the sheets. Test specimens for the determination of tensile strength, ultimate elongation, and modulus a t 1 0 0 ~ elongation o were stamped from the molded sheets along the milling axis by means of a dumbbell die ( 1 ) . The measurements were made on an IP-4 Scott
INDUSTRIAL AND ENGINEERING CHEMISTRY
July 1953
1547
TABLE I. BOILINQPOINTS, DENSITIES, AND VISCOSITIES OF SOMETRIESTERS OF ACONITIC AND TRICARBALLYLIC ACIDSA N D THEIR PLASTICIZING PROPERTIES WITH VINYLITE -Modulus, _ ,.
d
Plasticizer Aconitates Propyl Butyl n-Amyl Isoamyl Mixed amylb Hexyl 2-Ethylhexyl Tricarballylates Propyl Butyl a-Amyl Isoamyl Mixed amyl Hex 1 2-EtTfylhexyl Control (D0P)d
Boiling Points, O C., a t Specified Pressures Density, Grams/Ml. 0 . 0 4 0 . 1 0 . 5 1 . 0 5 . 0 10.0 Density, Grams/MI. 40’C. mm. mm. mm. mm. mm. mm. 10’ C. 25OC. 2 5 O C. 86 99 125 138 112 125 151 163 130 144 171 184 123 138 165 178
’ % #
P2int, ~ P2int,
c.
34.8 30.8 41.2 59.4
16.7 15.7 20.3 27.3
9.3 9.2 11.3 14.5
2890 2810 2960 3110
1260 1240 1380 1670
320 360 360 360
-27 -34 -36 -26
123 138 164 181 211 227 1.0019 0.9886 150 165 192 205 239 0.9933 0.9725 164 180 210 224 261 278 0.9654 0.9540
0.9774 0.9610 0.9428
58.4 48.4 134.7
26.5 23.9 53.6
14.2 13.3 25.9
3010 2870 2870
1500 1380 1710
310 330 340
-29 -40 -42
87 112 131 123
139 163 186 179
171 194 220 212
1.0616 1.0152 0.9933 0.9893
1.0479 1.0025 0.9812 0.9771
1.0346 0,9898 0.9691 0.9650
34.5 24.6 34.3 44.6
16.6 13.2 17.4 21.3
9.3 7.8 10.0 11.6
2900 2860 2910 2990
1220 1170 1310 1520
340 370 350 380
-30 -39 -40 -31
124 138 165 178 212 228 0.9929 149 164 192 205 238 253 0.9761 165 181 211 225 262 278 0.9589
0,9806 0.9647 0.9482
0,9685 46.5 0.9531 40.2 0.9366 102.2
21.4 19.9 42.5
11.8 11.4 20.9
2860 2890 2790
1320 1300 1630
300 360 360
-34 -44 -44
141
0.981 (6)
3040
1550
330
-33
154 181 193 224
187 209 235 225
1.0694 1.0264 1.0033 0.9990
~Inch ~~
