February, 1943
INDUSTRIAL AND ENGINEERING CHEMISTRY
Tests made a t any future time may be linked with the original group of tests by the repetition of the proper formulations as controls. I n this way the large exposure study made a t the start of this program is not to be considered as separate and distinct from later tests. The use of a definite plan for exposure studies makes it possible to correlate the exposure work over a period of years. Similar schemes can be devised to study systematically the vehicle components of paints. To do so would demand that the components not being studied a t that particular time be kept constant. It is believed that general recognition of the fact that paint compositions for exposure study can be selected according to a systematic plan will benefit the paint industry.
Literature Cited (1) Am. Paint and Varnish Mfrs. Assoc., Soi. Sect., Circulars on testing details and types of failure obtained on exposure test-
ing. (2) Ashman, G. W., IND. ENQ.CHEM.,28,934 (1936). (3) Broeker, J. F., Oficial Digest Federation Paint & Varnish Production Clubs, 147, 268 (1935). (4) Browne, F. L., Am. SOC.Testing Materials, 30, 11, 852 (1930). ENG.CHEM.,23, 868 (1931). (5) Browne, F. L., IND. (6) Ibid., 27,292 (1935). (7) Ibid., 28, 798 (1936).
171
Ibid., 29, 1018 (1937). Ibid., 33,900 (1941). Browne, F. L., Oficial Digest Federation Pa&t & Varnish Production CZubs, 172, 18 (1938). Browne, F. L., Proc. Wood Painting Conf., 1929, 3. Calbeck, J. H., IND. ENQ.CHEM.,18, 1220 (1926). Clapson, W. J., and Schaeffer, J. A., Ibid, 26, 956 (1934). Depew, H. A., Ibid., 27, 905 (1935). Elm, A. C., Ibid., 26, 1245 (1934). Hofmann, H. E., and Reid, E. W., Ibid., 20, 431 (1928). Ibid., 20, 687 (1928). Iliff, J. W., and Davis, R. B., Ibid., 31, 1407 (1939). Ibid., 31, 1446 (1939). Jacobsen, A. E., Ibid., 30, 660 (1938). Marshall, J., Iliff, J. W., and Young, H. R., I b i d . , 27, 147 (1935). New York Paint and Varnish Production Club, Rept. of Exposure Test Comm., Sept. 27,1933. Proc. Am. SOC.Testing Materials, 11, 225 (1911). Robertson, D. W., and Jacobsen, A. E., IND.ENQ.CHEM.,28, 403 (1936). Salzberg, H. K., Browne, F. L., and Odell, I. H., Ibid., 23, 1214 (1931). Schmutz, F. C., and Palmer, F. C., Ibid., 22, 84 (1930). Schmutz, F. C., Palmer, F. C., and Kittleberger, W. W., Ibid., 22,855 (1930). Schuh, A. E., and Theurer, H. C., Ibid., 29, 182 (1937). Wachholtz and Walther, Paint Varnish Production Mgr., May, 1937,lO. Wolff, Hans, Ibid., July, 1938,221.
LPimaric Acid Content of Longleaf and Slash Pine Oleoresins BENJAMIN L. DAVIS AND ELMER E. FLECK Naval Stores Research Division, Bureau of Agricultural Chemistry and Engineering, U. S. Department of Agriculture, Washington, D. C.
The oleoresin obtained from slash pine contained 7 to 10 per cent less 2-pimaric acid than was found in longleaf pine oleoresin. Scrape contained at least as much 2-pimaric acid as ordinary pine oleoresin. Oleoresin obtained from streaks treated with 10 per cent sulfuric acid did not differ greatly from oleoresin obtained in the normal manner.
0
LEORESIN from either longleaf (Pinus palustris) or slash (Pinus caribaea) pine serves as the starting ma-
terial for the isolation of I-pimaric acid and may also be used directly for the production of the addition product of maleic anhydride and I-pimaric acid. Therefore, it is desirable to know the I-pimaric acid content of the oleoresinsobtained from various species of pine and to what extent, if any, the content varies with the season. I n the case of longleaf oleoresin, preliminary data indicated a gradual decrease of Z-pimaric acid with the progress of the season (1). I n the present work the Z-pimaric acid content of the oleoresin obtained from slash and longleaf pine collected during the 1941 season near Olustee, Fla., was determined by the gravimetric method described previously (I). The formation of the addition product of I-pimaric acid proceeded as well, if not better, from slash oleoresin as from longleaf oleoresin.
The results in Table I show that the oleoresin from slash pine contained from 7 to 10 per cent less 2-pimaric acid than the oleoresin from longleaf pine. A comparison of the Z-pimaric acid content of the longleaf oleoresin, collected near Olustee for the 1940 ( I ) and 1941 seasons shows about the same average content. The seasonal variation of the I-pimaric acid content was much less in 1941than in 1940 and did not follow similar trends. For 1940 the highest content of I-pimaric acid occurred in April and decreased steadily through the entire season. For 1941 the high point was reached in midseason and was lower a t both the start and finish of the season. The seasonal variation of Lpimaric acid content of slash oleoresin was remarkably small; the I-pimaric acid content reaches a mipimum during midseason instead of a maximum as was found for longleaf oleoresin. These results indicate strongly that the season of the year is not a governing factor in the variation of I-pimaric acid content of pine oleoresin. Samples of both slash and longleaf “scrape” were taken in June and November, 1941, a t the same time the oleoresin was collected. (Scrape constitutes a hardened form of the oleoresin obtained by scraping the face of the tree.) Table I gives the surprisingly high results of these determinations. They undoubtedly indicate a somewhat higher Z-pimaric acid content than is actually present because the I-pimaric acid addition product with maleic anhydride isolated from these determinations had melting points of 10-15” C. lower than those obtained with pine oleoresin itself. The impurity pres-
172
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 35, No. 2
Considerable work has been done on the stimulation of pine IN RESINACID FRACTIORS oleoresin flow by treating a newly cut streak on the pine tree TABLE 1. l-PIMARIC ACID PRESENT OF PINEOLEORESIN A N D SCRAPE with acids ( 2 ) , Inasmuch as the mineral acids used are known -7% I-Pirnaiic Acidto isomerize I-pimaric acid rapidly into I-abietic acid, deterMonth of 1941 Longleaf Slash minations of I-pimaric acid content of oleoresin obtained in Pine Oleoresin this manner were made to determine to what extent, if any, April 31 2 24 5 isomerization has taken place. Analysis of pine oleoresin ob31 3 24 3 tained from streaks treated with 10 per cent sulfuric acid June 33 5 23 1 showed the presence of 22.6 per cent I-pimaric acid from slash 33.4 23 3 pine and 31.9 per cent from longleaf pine. August 33.6 23.7 33.7 23.3 These results are in contrast to those of Sandermann (3) who found no I-pimaric acid in the oleoresin from European November 32.1 24.5 32.5 24.1 Pinus sylvestris when the streaks were treated with 25 per cent hydrochloric acid. From untreated streaks of this same Pine Scrape specie of pine, 40 to 48 per cent of I-pimaric acid was found. June 39.5 32.2 39.9 32.2 The reason for this difference is not clear, but it seems safe to conclude that as far as the 10 per cent sulfuric acid treath'ovember 38.0 29.4 38.0 29.7 ment is concerned, little or no change has been effected on the composition of the oleoresin obtained. ent is undoubtedly due to oxidized resin acids not eliminated by the n-pentane when the scrape samples were putinto solntion for analysis.
Literature Cited (1) Fleck and Palkin. IND. ENG.CHEM.,ANAL.ED.,14, 146 (1942). (2) Liefield, Am. Turpentine Farm. J.,4(6), 14 (1942). (3) Sandermann, Be?., 71,2005 (1938).
Fatigue Resistance oz Flexible Plastic Sheetings F. W. DUGGAN AND K. K. FLIGOR Carbide and Carbon Chemicals Corporation, New York, N. Y.
I
N MANY of the uses to which flexible plastic sheetings are being applied, the fatigue resistance of a sheeting is an important factor in the serviceability of the material. Because of its importance, the study and control of this characteristic were desirable, and for this purpose a flex-fatigue test procedure was developed. The type of test employed in this laboratory involves simple flexing of a flat or folded sheeting. For some uses the machine is adjusted to provide alternate tension and flexing. At the flexing end of the cycle the test sheeting is bent upon itself rather sharply to a controlled radius a t the mease. This feature, the sharp creasing of the sheeting a t each cycle, provides a severe test, the severity being controlled by the tightness of creasing. Some of the flexible elastomeric sheetings included in this study possess a high degree of fatigue resistance, and a particularly severe test was required in order that fatigue failures would be obtained within a reasonable period. This test has provided useful information regarding the effects of various factors on the fatigue resistance of certain flexible vinyl resin sheetings.
Method of Test The fatigue test machine incorporates the essential features of the A. S.T. M. De Mattia flexing machine used on rubber (D430-35T). A stationary head holds one end of the,test specimen and a reciprocating head holds the other end. The heads are adjustable for the clearance between them a t the
closed end of the cycle and for the stroke or total displacement during the cycle. The clearance setting controls the radius of crease during flexing, while the stroke setting controls the degree of stretch imposed. The standard fatigue test in this laboratory is carried out on a 0.040 X 2.5 X 5 inch sample of press-polished sheeting, folded longitudinally before insertion in the grips. The motion of the reciprocating head bends the folded sample transversely during flexing. The head clearance a t the closed end of the cycle is set a t 0.090 inch plus the total thickness of sheeting. I n the bent position there are four thicknesses of sheeting between the heads so that the clearance ~ 0 . 0 9 0 (4) (0.040) = 0.250 inch. This provides a radius of 0.045 inch a t the crease. The stroke is adjusted to draw the specimen taut a t the open position but not to apply any stretch. This standard test setup is known as the fold flex a t 0.045-inch radius. Tests ordinarily are run a t 26" and 0" C.; 0" is particularly useful for accelerated testing. Figures 1, 2 , and 3 show the details of the test setup. The machine tests twenty specimens a t a time and operates at 115 cycles per minute. This speed was chosen because much of the early work on the machine was for evaluating flexible sheetings for shoes, and 115 cycles per minute simulates the flexing which occurs when walking a t a brisk rate. This relatively low rate of flexing is desirable also because it minimizes the heating of the test piece due to the intcrnal friction of flexing.
+
