JULY, 1939
INDUSTRIAL AND ENGINEERING CHEMISTRY
817
(SA) DeLuca, Campbell, and Maass, Can. J. Research, 16B, 273 (1938). (9) Evershed, J. Inst. Elec. Engrs. (London), 52, 51 (1913). (10) Glenn, H. H., and Wood, E. B., Trans. A m . Inst. Elec. Engrs., 48, 576 (1929). (11) Halperin, H., and Betzer, C. E., Elec. Eng., 55, 1074 (1936). (12) Hart, C. D., Trans. A m . Inst. Elec. Engrs., 47, 28 (1928). (13) Hill, C. F., Elec. J.,33, 195 (1938). (14) Kanamura and Nakamura, Kolloid Z., 77, 357 (1936); 78, 83 (1937). (15) McBain, J. W., and Foster, J. R., J . Phy8. Chem., 3 9 , 3 3 1 (1935). (16) McLean and Kohman, Elec. Eng., 53, 255 (1934). (17) McLean and Kohman, J . FranklinInst., 226, 203 (1938). (18) McLean and Wooten, IND.ENG.CHEM.,to be published. (19) Monsinger, V. M., Trans. A m . Inst. Elec. Engrs., 54, 1300 (1935). (20) Moon and Norcross, J. A m . Inst. Elec. Engrs., 49, 125 (1930). (21) Morgan, S. O., Trans. Electrochem. SOC.,55, 109 (1934). (22) Murphy, E. J., J . Phys. Chem., 33, 200 (1929). (23) Ibid., 33, 509 (1929). (24) Murphy, E. J., and Kohman, G. T., Elec. Eng., 58, 40 (1939). (25) Murphy and Lowry, J . Phys. Chem., 34, 598 (1930). (26) Murphy, E. J., and Walker, A. C., Ibid., 32, 1761 (1928). (27) Peek, “Dielectric Phenomena in High Voltage Engineering”, Chap. 8, New York, McGraw-Hill Book Co., 1929. (28) Peek and McLean, IND. ENG.CHEM.,Anal. Ed., 6, 85 (1934). (29) Piper, IND.ENG.CHEM.,28, 843 (1936); 29, 1040 (1937). (30) Race. H. H.. Elec. Ena.. 55. 590 (1936). (31) Race; H. H.; Trans. IAst. Elec. Engrs., 52, 682 (1933). (32) Ibid., 57, 573 (1938). (33) Rheiner, Angew. Chem., 46, 675 (1933). (34) Riley and Scott, Electrician, 102, 441 (1929).
(57) PRESENTED before the Division of Cellulose Chemistry a t the 97th Meeting of the American Chemical Society, Baltimore, Md.
SEED-LAC
Factors Which Affect the Flow
(35) (36) (37) (38) (39) (40) (41) (42) (43) (44) (45) (46) (47) (48) (49)
(50) (51) (52) (53) (54)
(55) (56)
Robinson, D. M., J. Inst. Elec. Engrs. (London), 77, 90 (1935). Shea, J. R., BeZE System Technical J., 10, 432 (1931). Simmones, Proc. Tech. Assoc. Pulp Paper Ind., 17, 401 (1924). Stamm, Colloid Symposium Monograph, 5 , 361 (1927). Stamm, U. S. Dept. Agr., Misc. Pub. 240 (1936). Stamm and Seborg, IND. Exa. CHEM.,28, 1164 (1936). Stock, Colloid Symposium Monograph, 4, 246 (1926). Stoops, J . A m . Chem. SOC.,56, 1480 (1934). Urban, F., White, H. L., and Strassner, E. A,, J. Phys. Chem., 39, 311 (1935). Urquhart and Williams, J. Teztile Inst., 20, T125 (1929). Wagner, K. W., “Die Isalier Stoffe der Elektrotechnik Schering”, p. 1 (1924). Walker, A. C., J. Tertile Inst., 24, T145 (1933). Walker. A. C.. and Quell, M. H., Ibid., 24, T123, T131 (1933). Walker, H. G., Bell Telephone Quart., 10, 211 (1931). Whitehead, “Impregnated Paper Insulation”, New York, John Wiley & Sons, 1935. Whitehead, Trans. A m . Inst. Elec. Engrs., 52, 667 (1933). Whitehead and Greenfield, Elec. Eng., 53, 1398, 1498 (1934); Greenfield, E. W., J . Franklin Inst., 222, 345 (1936). Whitehead and Greenfield, Physics, 3, 324 (1932). Whitehead and Jones, Elec. Eng., 56, 1492 (1937). Williams, R. R., and Murphy, E. J., Trans. A m . Inst. Elec. Engrs., 48, 568 (1929). Wiseman, R. J., Ibid., 50, 1457 (1931). Wood, E. B . , and Brobst, D. R., Bell System Tech. J., 11, 213 (1932). Wyatt, K. S., A m . Inst. Elec. Engrs., 52, 1035 (1933).
WILLIAM HOWLETT GARDNER AND L. KOPROWSKI, Polytechnic Institute of Brooklyn, Brooklyn, N. Y. N. N. MURTY, Indian Lac Research Institute, Namkum, Ranchi, India Lac which is to be used for the manufacture of shellac should be neither left on thqhost tree after the swarming of the young insects, nor stored as cut stick-lac, or even as seed-lac, since the plastic flow of lacs decreases from the time they are ready for collection. This decrease in fluidity of the melted seed-lac was accompanied by changes in the chemical composition of the lac, as was shown by corresponding increases in the amount of resin which was insoluble in boiling acetone. Polymerization of the lac may occur even before the lac is removed from the trees if it is not cut at the proper time.
M
E L T E D seed-lacs are forced through canvas bags in the manufacture of shellac and button lacs (6). The plastic flow of these raw materials is a property which influences the yield of shellac obtained, the quality of the lac, and the amount of natural impurities which will be present in the manufactured products. This article describes some factors which affect the plastic flow of these raw lacs. In studying the factors which influence the bleaching quality of seed-lacs (4)it was found that the effect of age was manifest only when samples of the same host origin were compared for the length of time during which they were stored as stick-lac. Apparently only the dye and protein material had a noticeable effect on the bleaching characteristics of the lac, owing to changes in the lac which inhibited their removal during the washing in the preparation of the
seed-lac. The amount of material found in the seed-lac which was insoluble in boiling diethyl alcohol or in boiling acetone was not related to its bleaching quality, but i t was shown that the amount of resin which was insoluble in boiling acetone increased steadily with the total age of the sample. The amount of this insoluble resin could be used for obtaining an idea of the approximate total length of storage time of the lac as both stick-lac and seed-lac (Table I). The amount of resin insoluble in boiling acetone appears to be due to a chemical polymerization of the lac, for i t was in this fraction that the highest molecular weight constituents were found (8). The plastic flow, as might have been expected, was affected by such changes in the composition of the lac.
Experimental Procedure FLOW MEASUREMENTS. Plastic flow of the seed-lacs was measured a t 100” C. on the samples as received, which represent a normal condition. VaIues were determined by the newly adopted method (1) of the American Society for Testing Materials (designation D 411-37 T, method B) with a pendulum type of instrument. This method is essentially the same as the one used for a long time by the R. C. A.-Victor Company (7) and gives identical values. Results are given as the number of millimeters over which the molten lac flowed in 12 minutes. MATERIAL INSOLUBLE IN BOILING ACETONE. It was necessary in determining the material insoluble in boiling acetone to modify the method previously used by Gardner and Harris (3) to the extent of cooling the digested solutions to 10’ C. in an electric refrigerator and allowing them to remain a t that
INDUSTRIAL AND ENGINEERING CHEMISTRY
818
TABLEI. EFFECTOF AGE AND COMPOSITION Sample No. C308 C298 C297 C303 C301 C254 C256 C253 C252
C 59 C 49 C 48 C315 C154
Variety0
K X Kh, Ag, P h
P X P B A Ber X Be;, B, A P X P, B, A
Age as Age a8 StickSeedLac Lao ------Months0 1 0 2 0 2 1 1
1 2 2 2
Flow in 12 Min. Mm. 8.6 ‘43.5 42.5 38.6
2 16
3 16
16 11 16 0
40
0 4-2 12
40 14 28
Ber X Ber, B, A K X Kh, Ag K X Kh, Ag (poor wash) Ber X Ber, B Mixed, K t
K X K,Ag, P h
K X Br, Ag K X Kh Ag, P h Mixed I&, B K X Ber, Ag
ON PLASTIC
Total Age
FLOW
Resin Resin Material Insol. in Insol. in Insol: in Alcohol Bailing Boiling a t Room Acetone Alaohol Temv.
%
%
%-
15.6 2.3 2.5 2.7
1.4 4.3 4.5 4.7
6.3 0.9 1.3 1.1
44.2 48.1
2.6 3.8
3.8 1.5
0.9 0.3
16 19 20
42.1 18.9 18.2
3.5 4.7 4.9
5.0 4.1 3.6
0.5 1.1 1.6
40 40 40 ? +I6 40
6.0 8.3 15.6 3.3 12.3
12.1 11.8 9.6 11.3 14.2b
2.3 1.6 1.9 7.9 2.5
6.5 5.6 2.6 5.4 2.9
0 K = kusum host, Kh = khair host. Br = Burma kusum host, P h = phunki lac. A B = Baisakhi orop, K t = Katki crop, J = Jethwi crop, Ag = Aghun or kusmi crop. b This resin was out of line with the others.
temperature for 2 hours, before heating them to the simmering temperature for the second time before filtering. This allowed the insoluble resin to agglomerate so that it could be quantitatively removed. The difference in the condition of the wax from that found in shellac required this slight change in procedure. The am ount of resin insoluble in this solvent was obtained by subtracting the amount of extraneous inorganic and cellulose materials present in the samples from the material which was insoluble in acetone. The extraneous material was taken to b e equal to the residue left after depolymerization with boiling alcohol containing 3 per cent hydrogen chloride (6, IO). MATERIALINSOLUBLE IN ALCOHOL.The material insoluble in boiling alcohol was determined by the standard method for insolubles (9). The highly polymerized lac which was insoluble in this solvent a t room temperature was obtained by subtracting the amount of extraneous material left after depolymerization from the amounts of material which were insoluble in pure alcohol a t room temperature (6). Although a small amount of nonresinous material may be dissolved by the hot acidulated alcohol, this procedure gave a fairly accurate measure of the amount of lac which was insoluble in different solvents.
Effect of Age and Composition on Plastic Flow AGE. Table I shows that the total age of lac had a marked effect upon the plastic flow. The flow apparently decreased rapidly with age after the lac had been stored for a year and a half. This effect of age is even more convincingly illustrated in Table 11, where the plastic flow of the samples was measured two years later, after storage in closed containers in the laboratory under normal conditions. COMPOSITION.Flow depends also on the chemical composition of lac. The high molecular constituents, as pointed out above, were found in the fraction of the resin which is insoluble in acetone (8). This portion of the resin increased, in general, with the total age of the lac. An even closer correlation existed between the plastic flow of the lac and the amount of these polymerized constituents. Table I shows that lacs having flows between 38 and 48 mm. contained from 2 to 4 per cent of resin which was insoluble in boiling acetone. Samples with flows between 12 and 19 mm. contained 5 to 10 per cent, and those of zero flow to 10 mm. contained 11 to 16 per cent. ’ Only one sample did not coincide
-
ari lao,
VOL. 31, NO. 7
with this grouping. This sample is marked b in the column for resin insoluble in acetone. Table I also shows that there was no correlation between flow and the amount of material which is insoluble in boiling alcohol, or the amount of highly polymerized or aggregated lac which was insoluble in alcohol a t room temperature. It is possible that this latter portion of polymerized lac may have acted simply as a filler, and that its effect was entirely masked by the polymeride which still contained some plastic properties. We would not expect, therefore, to ascertain its actual effect unless it were present in an excess amount. This and other studies seem to show that lac may contain small and varying proportions of material in different stages of aggregation or of chemical polymerization such as were originally postulated by Nagel and Kornchen (6). The
TABLE 11. EFFECT OF STORAGE OF SEED-LAC ON PLASTIC FLOW Sample No. C308 C298 C297 C303 C301 C254 C256 C253 C252
-Flow, 1935 8.6 43.5 42.5 38.6 44.2 48.1 43.1 18.9 18.2
Mm.7 1937 0.0 22.0 24.5 22.5 25.5 21.0 17.0 9.0 7.5
.
Sample No. c 59 c 49 C315 C154 C153 C255 C226 C257 C225
-Flow, 1935 6.0 8.3 3.3 12.3 16.7 2.6 5.6 3.6 0.0
Mm.? 1937 0.0 0.0 0.0 0.0 1.0 0.0 0.5 0.0 0.0
amount of resin insoluble in cold alcohol was independent of the age of the samples. It was found in largest amounts in the three kusum lac samples where polymerization occurred before the lac was removed from the tree.
Acknowledgment This article is a’joint contribution from the Indian Lac Research Institute and the Shellac Research Bureau of the Polytechnic Institute of Brooklyn. The investigation was sponsored by the United States Shellac Importers’ Association and the Indian Lac Cess Committee. The paper for the most part was based upon the data obtained by B. Gross and L. Koprowski of the Shellac Research Bureau a t the suggestion of the senior author. This was carried out largely a t the time of the joint research project described in the article by Murty, Gardner, and Gross and was at first included as part of that project.
Literature Cited (1) Am. Soo. Testing Materials, Proceedings 37, I, 1043 (1937). (2) Gardner, W. H., IND. ENQ.CKEM.,25, 550 (1933). (3) Gardner, W. H., and Harris, H. J., IND. ENQ.CHEM.,Anal. Ed., 6 , 400 (1934). (4) Murty, N. N., Gardner, W. H., and Gross, B., IND. ENQ.CHEM., 31,678 (1939). (5) Nagel, Werner, and Kornchen, M., Wiss. VerGfent, SiemensWerken, 6,235 (1927). (6) Parry, E. J., “Shellac, I t s Production, Manufacture, Chemistry, Analysis, Commerces and Uses”, London, Sir Isaac Pitman & Sons, 1935. (7) R. C. A.-Victor Co., Purchasing Specifications, PS-54A, PS190A (1934). (8) Schaeffer, B. B., Weinberger, H., and Gardner, W. H., IND. ENQ.CHEM., 30, 451-4 (1938). (9) U. S. Shellac Importers’ Assoc. and Am. Bleached Shellac Mfrs. Assoc., Official Methods of Analysis, Specifications and General Information on Shellac and Bleached Shellac, 1934. (10) Venugopolan, M., and Aldis, R. W., Indian Lac Research Inst., Research Note 17 (1934).
