INDUSTRIAL AND ENGINEERING CHEMISTRY
1260
T h e ultraviolet-catalyzed oxidation of ethylcellulose should be subject to control bv use of inhibitors or antioxidants in view of the free radical oxidation. The effect of scveral antioxidants on oxidation of ethylcellulose under ultraviolet irradiation is shown in Figure 9. These oxidations were carried out on ground films containing the desired antioxidants prepared as described previously (4).The rapid oxidation exhibited by the control sample was reduced by the addition of the antioxidants. Cetyl mercapt a n (thiol), which is a n excellent stabilizer in the absence of ultraviolet light ( 4 ) , was not very effective. Menthylphenol and hydroquinonemonobenzyl ether, however, were effective antioxidants. I n agreement with these observations, it is generally recommended t h a t stabilizers be used with ethylcellulose which may be subject to heat or sunlight in the presence of air. The danger of degradation of ethylcellulose due to extensive oxidation is thereby reduced and the useful life of the ethylcellulose is greatly increased.
Vol. 41, No. 6
LITERATURE CITED
Corning Glass Works Catalog, “Glass Color Filters,” p . 15, Form C-206-9-39, Corning, N . Y . Hodgman, C. D., “Handbook of Chemistry and Physics,” p. 2215, 29th ed., Cleveland, Chemical Rubber Publishing Co., 1945. Leighton, W. G., and Forbes, G . S., J . Am. Chem. Soc., 52, 3139 (1930). McBurney, L. F., ISD. ESG.CHEM.,41, 1251 (1949). Milas, N . A , , J.Am. Chem. Soc., 53,221 (1931). Noyes, W. A , and Leight,on, P. A., “The Photochemistry of Gases,” p. 83, New York, Reinhold Publishing Corp., 1941. Staud, C . J., Paint, Oil, Chem. Rec., 89, No. 18, 8 (1930). U. S. Treasury Dept., Bur. of Internal Revenue, Appendix t o Reg. h-o. 3, “Formulae for Completely and Specially Denatured Alcohol,” 1942. RECEIVEDOctober 2 . 1947. Presented before t h e Division of Cellulosr SOCIETY. New Chemistry at t h e 112th Meeting of t h e . ~ M ? E R I C A NCHEMICAL York, N . Y .
(Oxidative Stability of Cellulose Derivatives)
HEAT STABILITY QF CELLULOSE ACETATE EVAN F. EVANS AND LANE F. RICBURNEY, Hercules Powder
CLL‘
Company, Wilmington 99, Del.
TLOSE acetate is T h e heat stability of cellulose acetate has been shown to havior observed using this be a function of its ease of oxidation. During oxidation, static system. Aftcr the inthe most stable of the duction period, a rapid oxidacellulose derivatives under volatile products were formed, an orange-yellow color developed, and the viscosity decreased. The per cent comtion set in, which soon denormal conditions of aging. creased owing t o the displacebined acetic acid when determined by saponification inSamples have been reported ment of the oxygen from the creased as the oxidation progressed but evidence is pre(3) to have retained their reaction flask by the volatile sented that these results do not measure the actual initial properties after storamount of combined acetic acid. The value of various products evolved. Droplets age for 25 years. At elevated heat stability tests have been discussed briefly in the light of liquid with the odor of acetemperatures, however, celluof these data. tic acid ivere observed t o collose acetate may suffer degralect upon the cooler portions dation. but i t is more stable of the apparatus. In order t o measure the rate of oxidation, i t (3,7 , 9, 18, $O), under comparable conditions, than cellulose was necessary accordingly to remove the volatile products as soon nitrate or cellulose ethers. A variety of heat stability tests have as they were formed. This was accomplished by circulating the been described (2, 17, 18) which measured the acidic or volatile gas in the reaction flask through suitable absorption tubes in H products formed or the temperature a t 13 hich yellowing or closed system. charring occurred. I n present-day commercial practice, however, it is customary (12) to measure the amount of discoloration or the per cent loss of the original viscosity upon heating the cellulose acetate at a temperature in the range of 160” t o 210” C. for a definite period of time. I n nearly all these tests, the cellulose acetate is heated in a limited, but unknown and probably variable, amount of air. The effect of heating on the physical and chemical properties of cellulose acetate has been studied only in relatively few instances v 5 ,o a0 30 43 50 60 7c T I M E , HOURS (7, 18, 16, $0) and then only a s a function of the time of heating. Wehr (go), however, demonstrated qualitatively that the loss of Figure 1. Oxidation of Cellulose viscosity on heating in thc prcscncc of air was duc t o an osidative Acetate at 160” C. without Absorption of Reaction Gases degradation. Similarly, the changes resulting from heating ethyl cellulose in air (oxygen) have been shomm (6, 11) to be due to the oxidation of ethyl cellulose. The present investigation was, The apparatus was modified to include a pump and glass check therefore, undertaken to study the oxidation of cellulose acetate valves by which the gases in thk reaction flask were pumped through a n absorption tube and back into the flask. A photoby oxygen under the influence of heat. graph of the pump, valves, and absorption tube is shown in Figure 2 as well as the oxvgen buret and pressurr-regulating device deAPPARATUS AND PROCEDURE scribed previously ( 1 1 ) . The pump was constructed from a 20-ml. hvpodermic syringe similar to a pump described by Olson and A commercial sample of secondary cellulose acetate containing Spurr ( 1 4 ) . The mercury seal recommended by them mas not 52.5% combined acetic acid was selected a t random for orienting used. The plunger was lubricated with dibutyl phthalate which purposes. It could not be oxidized, a t least a t a measurable rate, formed a n effective seal. Even after several years’ usage, no leakage occurred around the plunger. The pump was driven by n. under the conditions which mere sufficient for the rapid oxidation 32-r.p.m., constant-speed electric motor supplied by the Merkleof ethylcellulose (5, 11). Oxidation was obtained a t 145” C. only Korff Gear Company of Chicago. The length of t h r stroke of the after a n induction period of 160 hours (approximately 1 week), plunger, although adjustable within limits, was arbitrarily set to and at 160” C. after a n induction period of 12 hours using the give a displacement of 10 ml. per stroke. The absorption tube was filled a t first with Drierite, Ascarite, and Drierite in that order apparatus described by McBurney ( 1 2 ) . Figure 1 shows the be-
June 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
Figure 3.
1261
Oxidation of Cellulose Acetate a t 160 O C. without Carbon Monoxide Absorption
1, plastics-ty e (52.5-53.5% HOAc) sample of poor stability; 2, water resisting-type 86.5-57.5% HOAc) sample; 3, film-type (55.4%HOAc) sample of fair stability; 4, film-type (52.5%HOAc) sample, 6 and 7, plastics-type (52.1% HOAc) sample of very good stability; 8, plastics-type sample of excellent stability
Figure 2.
Constant-Pressure Measuring Buret and Absorption Apparatus
t o remove any water, carbon dioxide, or acidic products acetic acid-that might be formed. With this modification, the data shown in Figure 3 were obtained for various commercial samples of cellulose acetate. T h e samples, granular in form, were oxidized after drying for 3 hours in a vacuum oven at 105 O C. T h e curves for the oxygen absorbed versus time are characterized by an induction or retardation period, which may, however, be zero, followed by a period of rapid a n d linear oxidation. Then, after a n apparent absorption of around 200 t o 250 ml. of oxygen per 15 grams of cellulose acetate, the rate decreased rapidly. T h e induction periods were found t o correlate roughly with the viscosity stability of the samples a s measured by the retention of their viscosity after heating for 2 hours a t 210 C. Thus, two samples with poor stability values showed no induction periods upon oxidation a t 160 O C. (curves 1 a n d 4)- A sample with a very good stability value, however, exhibited an induction of about 40 hours. Curve 8 represents the oxidation of a sample of excellent stability. T h e portion of the oxidation curve shown was a retardation period, for a more rapid, linear oxidation set in after about 140 hours. T h e excellent stability of this sample can undoubtedly be attributed t o its outstanding resistance toward oxidation. T h e fact t h a t the rate of oxidation decreased after 200 t o 250 ml. of oxygen had been absorbed seemed t o be anomalous. It appeared as if some gas was being evolved which was not absorbed by Ascarite a n d Drierite and, hence, was diluting a n d displacing the oxygen in the reaction flask. This idea was further confirmed by the experiment' shown in Figure 4, curve 1. A sample of cellulose acetate was allowed to oxidize until the rate decreased appreciably. T h e reaction flask was then flushed out with pure
oxygen. T h e oxidation continued a t a faster rate a s would be expected if the oxygen previously had been diluted by a nonabsorbed gas. The only likely possibility for the nonabsorbed gas was carbon monoxide. T h e absorption tube was accordingly changed so as t o absorb carbon monoxide also. For this purpose the tube was filled with Drierite, Hopcalite, Ascarite, a n d Drierite in t h a t order. Curve 2 of Figure 4 shows the effect of this change on the oxidation curve for the same cellulose acetate used for curve 1. Curves 3 a n d 4 represent duplicate oxidations of another cellulose acetate sample with the removal of the evolved gas. This gas, which is absorbed by Hopcalite, is presumed t o be carbon monoxide and will be so called in this paper, although no direct evidence was obtained definitely establishing its identity. Curve 1of Figure 4 and all the curves of Figure 3 give neither the true rate of oxidation, as the oxygen concentration was continuously decreased by t h e evolved carbon monoxide, nor the true amount of oxygen ab-
Figure 4.
Effect of Carbon Monoxide on Oxidation of Cellulose Acetate at 160 O C.
1, film-type (55.5-56.5% HOAc) sample, carbon monoxide not removed; 2, same sample carbon monoxide removed; 3 and 4, plastics-type (52.5-53.5 % kOAc) sample, carbon monoxide removed
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INDUSTRIAL AND ENGINEERING CHEMISTRY
sorbed, as the observed volume was in error by the volume of carbon monoxide evolved. Curves 2, 3, and 4 of Figure 4 are believed to be devoid of any further errors due t o evolved but nonabsorbed gases and, hence, to represent the true rate of oxidation of these cellulose acetate samples. The curves are similar in shape to those obtained in the oxidation of ethylcellulose (5, 11) and demonstrate the autocatalytic nature of cellulose acetate oxidation.
short T\ ave lengths and gradually decreased to a slight absorption a t the long wave lengths. As a measure of color, one thousand times the ratio of the per cent transmittance a t 420 mp t o that a t 680 mL was used. On this basis, 1000 is colorless, and decreasing values indicate increasing color. The color produced was found to increase in direct proportion to the amount of oxygen absorbed as shown in Figure 7 . As the color of oxidized cellulose acetate was found t o obey Beer's law, the color-producing bodies were formed thus in direct proportion t o the oyygen consumed.
CHE\IICAL AND PHYSICAL CHANGES
I n order t o study the chemical and physical changes lyhich occur during the oxidation of cellulose acetate, a series of samples "as prepared by Oxidation with increasing amounts of oxygen. A highly substituted cellulose acet'ate containing 60% combined acetic acid was chosen in the expectation t h a t dcacctylation would occur and t h a t the oxidation could be carried t o a greater extent before sufficient acetyl groups were lost' to render the sample insoluble in a cominon organic solvent. The actual oxidation curves for these samples are shown in Figure 5. Oxidation was stopped a t an absorption of roughly 50, 103, 150, 200, 250, and 300 ml. of oxygen (760 mm. of mercury, 27' C.) per 15-gram sample. The reproducibility was considered sufficiently good for the purpose of this investigation.
J
. I60 m
P
I20
4
z
DETERMINATION OF CORIBlNED ACETIC ACID COVTENT
The content of combined acetic acid in the sainplea was determined fiist by using a sapoiiification method. This method indicated t h a t the combined acetic acid content of the cellulose acetates had increased upon oxidation. It was desired to check these results by another method particularly since the formation of a large number of cellulosic carboxyl groups could cause high results if measured by saponification. For this purpose the method of Cramer, Gardner, and Purves (4) was employed in which the acetyl groups are converted to methyl acetate. The latter is removed by distillation and determined by saponification. The values obtained by this procedure are shown in Figure 7. Although the precision of the results was not too good, there seems to be a slight trend toward higher acetyl content for the oxidized samples. As the two methods yielded essentially the same results. it is evident that, if cellulosic carboxyls were formed by oxidation, they must also give rise to volatile products which consume alkali during the saponification of the methyl acetate. N o satisfactory method, however, was found for measuring the carboxyl content of these oxidized cellu1o.e acetate samples. Upon oxidation of lower substitution types of cellulose acetate, this apparent increase in combined acetic acid becomes very striking as illustrated in Table I. Thus, increases of 5 t o 9 in the percentage of combined acetic acid, as determined by saponification, occurred, depending upon the degree of oxidation and upon the sample oxidized.
80 0
43
TABLE I0
20
30
d0
50 6C T I M E , HGU95
-0
80
I.
CHANGE O F P E R CEST C O M B I N E D
00
F i g u r e 5. Replicate Oxidation at 160" C. of Cellulose A c e t a t e C o n t a i n i n g 6070 Acetic Acid Carbon monoxide removed
During the preparation of these samples the absorption tube shown in Figure 2 was replaced by two U-type absorption tubes. \17ith a suitable arrangement of the absorbents, the volatile products, exclusive of carbon monoxide, were collected in the first tube, and carbon monoxide, in the second. Figure 6 shows the amounts of these materials obtained. The substances absorbed by the Ascarite and Drierite contained in the first absorption tube were formed in nearly direct proportion t o the oxygen consumed but showed a slight decrease a t high degrees of oxidation. The identity and proportions of these absorbed substances u ere not established, although it is probable t h a t they were predominately water, carbon dioxide, and acetic acid. The carbon monoxide was formed in ever-increasing amounts as the oxidation progressed. The carbon monoxide is most probably derived from the cellulosic carbon atoms. I t is known that a-ketocarboxylic acids readily give carbon monoxide on pyrolysis ( 8 ) , and the formation of such acids by oxidation of the glucose units could explain the formation of the carbon monoxide obtained. As cellulose acetate undergoes oxidation, i t develops an orangeyellow color. The light absorption of 1% solutions of the samples !vas measured over the whole visible spectrum. There were no maxima nor minima, but the greatest absorption occurred a t the
Cellulose Acetate
OXIDATIOX Apparent Oxygen Absorption M1./15' G . 177 182 241 285 32 1 >300
390
ACETICAkCID ON
Average Per Cent Combined HOAc Original Oxidized Increase 52.2 58.0 +5.8 52.1 57.4 +5.3 52.1 57.7 +5.6 55.4 62.1 $6.7 52.5 60.2 +7.7 52.1 59.8 +7.7 52.5 61.5 +9.0
Subsequent to the conclusion of this work a n entirely independent method applicable t o the determination of acetyl groups was published by Lemieux and Purves (10). I n this method, the sample is oxidized by chromic acid converting terminal methyl groups to acetic acid which is collected and determined. As acetic acid itself (or the acetyl group) is not oxidized and as there are no terminal methyl groups in cellulose acetate except for the acetyl groups, the method measures the acetic acid content of the sample. At the time of publication of this method, however, sufficient amounts of only two of the oxidized cellulose acetate samples were available for analysis. One of these had been obtained by the oxidation of a cellulose acetate containing ?i4.570 combined acetic acid and had shown a n apparent 55.5% combined acetic acid content by the saponification method. By the chromic acid oxidation method this sample now exhibited only 50.1% combined acetic acid. The second sample had been prepared by the oxidation of a cellulose acetate containing 52.5y0
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
June i949
1263
tion up to 240 milliatsms of oxygen per glucose unit after which it increased more slowly. Under certain conditions, the intrinsic fluidity change is a measure of the number of chain breaks t h a t have occurred in the degradation of a polymer. Thus, for a given weight, W , of a polymer which suffers degradation, the number of chain breaks, Z, is equal to the increase in the number of molecules ( A N ) . Thus,
O X I G E Y ABSORBED, M I I L I A T O M S
/
where M , is the number-average molecular weight and iV,and iVs are the number of molecules present originally and after degradation, respectively. For polymers, which have been randomly degraded, the number-average molecular weight is approximately one half the weight-average molecular weight (Flory, 6). Also, when the constant a in Mark's equation
GLUCOSE UNIT
Figure 6. Formation of Volatile Products during Cellulose Acetate Oxidation at 160" C.
[?I] =
combined acetic acid and showed at t h a t time a value of 60.2% by saponification. When analyzed again after a considerable period of aging in the sample bottle, i t was found to contain 62.1% combined acetic acid by saponification but only 50.5y0 combined acetic acid by t h e chromic acid oxidation method. T h e latter method gave the theoretical result (55% acetic acid) for pure 6glucose pentacetate and a combined acetic acid content of 54.9% for a n unoxidized eellulose acetate which showed 55.9% bv saponification. 0
62
Y
60 58
; z
t
0
40
Figure 7.
80
120 IS0 200 240 OXYGEN ABSORBED, NIL-IATOMS
280 /GLUCOSE
320
360
00
KMa
is unity, weight-average molecular weights are directly proportional t o the intrinsic viscosities:
Mu
= k [VI
where M , = weight-average molecular weight.
Accordingly,
Badgley ( 1 ) and Sookne and Harris (16) have shown t h a t the constant a in Mark's equation is essentially unity for cellulose acetate. T h e condition of random degradation during preparation is undoubtedly met by the original cellulose acetate and is probable also for the oxidized samples. Accordingly, the change of [+I with oxidation shown in Figure 8 may be considered a measure of the chain breaks t h a t have occurred. The decreased effectiveness of the oxygen in severing the chains after about 240 milliatoms of oxygen were absorbed per glucose unit may be due t o a shifting of the oxygen attack t o the ends of chains or t o a different mode of oxygen attack which consumes more oxygen before effecting a chain break. The elucidation of these questions, however, will require further experimentation.
a40
UNIT
Color and Acetic Acid Content of Cellulose Acetate Oxidized a t 160' C.
These results render uncertain any conclusions as t o the acetic acid content of t h e oxidized samples. It appears probable, however, t h a t the saponification values are too high and t h a t in reality there probably was a decrease in the combined acetic acid content upon oxidation of the celluose acetate. VISCOSITY MEASUREMENTS
The viscosities of solutions of the original and of the series of osidized cellulose acetate samples were measured in a 9 t o 1 methylene chloride2B alcohol (19) solvent mixture a t 0.25, 0.5, and 1% concentrations. From these data, the intrinsic viscosities, [7],were obtained by graphical extrapolation t o zero concentration by the method described in the previous papers (5, 11). As shown in Figure 8, oxidation of the cellulose acetate effected a rapid drop of the intrinsic viscosity which gradually decreased with increasing oxidation. The intrinsic fluidity change, A [+I, which is defined as the difference between the reciprocal of the intrinsic viscosity of the oxidized sample and of t h e original cellulose acetate, is also plotted in Figure 8 versus the oxygen absorbed. This function increased linearly with the oxygen absorp-
Figure 8.
Degradation of Cellulose Acetate on Oxidation at 160" C. HEAT STABILITY TESTS
The heat stability tests for cellulose acetate in commercial use are not wholly satisfactory, as evidenced by the lack of a n officially recognized and uniformly employed standard heat test. This situation is not surprising upon consideration of the data presented in Figures 3, 7, and 8. The changes in color or in viscosity (or A [ b ] ) ,used t o measure stability toward heating for a given length of time, are seen t o be direct functions of the degree of oxidation occurring b u t not of the time of beating. A hypo-
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INDUSTRIAL AND ENGINEERING CHEMISTRY
I
I
I
I
1
not, effect, a decrease in this initial oxidation below, that shown in curve 3. Other solvent,salso exhibited similar effects. The evaluation of the effect of other added substances iyas accordingly rendered uncertain on-ing t o the effect of rctained solvent. Thus, the addition of catalytic amounts (0.1%) of a n oxidized sample t o this cellulose acetate apparently had no effect as the oxidat,ion, shown by curve 4, mas very similar to the control oxidation (curve 3) This result is contrary to the promotion of the oxidation obtained in the similar experiment with ethylcellulose ( 1I ) . There is little doubt, however, that extremely small amounts of free sulfuric acid catalyze the osidation. Thus, curves 5 and 6 show the effect on the oxidation oi adding 0.001 and O.Ol%, respectively (based on the cellulose acetate), of sulfuric acid to the cellulose acetate films. The principal effect was to shorten the retardation period. T o a lesser degree the sulfuric acid increased the rate of t,he rapid linear oxidation. Other acids, in general, were also found to catalyze the oxidation but were not so effective as sulfuric acid. Unneutralized, combined sulfuric acid undoubtedly also catalyzes the oxidation of cellulose acetate. I
TIME
,
YOURS
Figure 9. Effect of Acids and Retained Solvents on Oxidation o f Cellulose Acetate Films a t 160’ C.
thetical case will illustrate the misleading results that may be obtained. Consider two samples of cellulose acetate exhibiting induction periods, the first ending shortly before and the second ending shortly after the end of the heat test. The first sample would have suffered oxidative degradation during the test and would have been deemed unstable, whereas the second sample would have been considered completely stable. However, had the heating been continued but a short time longer, both samples would have appeared to be unstable. It is probable that either the induction period or the length of time required t o effect a given change in color or a [+]-Le., time required for equal oxidation-would yield a more satisfactory correlation with actual use than do the usual heat stability tests. FACTORS AFFECTIRG STABILITY O F CELLULOSE ACETATE
According to Staud ( 1 8 ) , the major factors affecting the stability of cellulose acetate are: residual free acetic acid, traces of uncombined catalysts, combined sulfuric acid, and excessive degradation of the cellulose during acetylation or hydrolysis. Many patents have been granted on the stabilization of cellulose acetate, the majority of which are concerned with the neutralization or removal of the combined sulfuric acid. These factors and treatments, as well as others, also influence the oxidation of cellulose acetate. Some studies of factors influencing the oxidation are shown in Figure 9. In order to study the effects of small but known amounts of added substances homogeneously dispersed in the sample, it is necessary t o use ground films prepared from a solution of the cellulose acetate t o which the desired substance has been added. Although this technique was employed satisfactorily with ethylcellulose (5, l l ) , difficulties have arisen using cellulose acetate. Thus, curve 1 in Figure 9 described the oxidation, in the flake or granular form, of a plastic grade cellulose acetate containing 52.1% combined acetic acid. This sample exhibited an induction period of around 40 hours. Upon oxidation of the ground film of this sample obtained from an acetone solution and dried in a vacuum oven a t 105’ C. for 24 hours, the results shown by curve 3 were obtained, The sample now exhibited a n immediate and rapid, b u t limited, oxidation followed by a period of slow oxidation (retardation period). After about 35 hours, the characteristic rapid linear oxidation set in, T h e initial oxidation was apparently due t o tenaciously retained solvent. This view is supported by the osidation (curve 2) of a similar film b u t dried only in a vacuum desiccator at room temperature. This sample exhibited a n even greater initial oxidation. More intensive drying, however, did
LITERATURE CITED
Badgley, W. J., Polymer Bull., 1, 17 (1945j. Berl, E., “Chemisch-technische Untersuchungsmethoden,” Vol. V, pp. 765-6, Berlin, Julius Springer, 1934. ClBment, L., and RiviBre, C . . Congr. chim. ind., Compt. r e d . 28me congr., Rancg, 8ept.-Oct., 1938, 703-17. Cramer, F. B., Gardner. T. S., and Purves, C. B., IXD.EKG. CHEM.,ANAL.ED., 15, 319-20 (1943). Evans, E. F., and McBurney, L, F., IND. ENG.C H E M .41, , 1256 (1949).
Flory, P. J., J . Am. Chem. Soc.. 58, 1877 (1936). Hill, J. R., and Weber, C. G., J . Research iVat2. B U TStandards, . 1 7 , 8 7 1 (1936).
Hurd. C . D., “Pyrolysis of Carbon Compounds,” pp. 556-9, X e w York, Chemical Catalog Co.. 1929. Krais, P., L e i p z i g Monatschw. Tertil-Ind., 43, 257 (1928). Lemieux, R. C . , and Purves, C . B., Can. J . Research, 25, 485 (September 1947) McBurney, L . F . , IND.E r c . C H E M .41, . 1251 (1949). Malm, C. J., and Fordyce, C . R . , in Ott, E., ”Cellulose and Cellulose Derivatives,” p. 707, Xew York, Interscience Publishers, 1943.
Nowak, P., and Wolter, A . , Kzinstsioffe, 30, 129-37 (1940). Olson, W. T., and Spurr, R . .L, IND.EKG.CHEX.,ASAL.ED.,15, 467 (1943).
Schroder. W., Kitnststoffe, 32, 8 2 (1942). Sookn?, A. M., and Harris, >,I., IND.EKG.CHEM.,37, 475 ’
(1945).
Sproxt’on, F . , “Cellulose Ester Varnishes,” p. 5 5 , S e w York, D. Van Nostrand Co.. 1925. Staud, C. J., Paint. Oil,Chem. Rea., 89, h-o. 18, 8 (1930). U. S.Treasury Dept., Bur. of Internal Revenue, Appendix t o Reg. S o . 3, “Formulae for CoinDletely and Specially Denatured Alcohol,” 1942. Wehr, W., Kolloid-Z., 88, 185-208 (1939). RECEIVEDOctober 2 , 1947. Presented before t h e Division of Cellulose Chemistry at the 112th h’eeting of the A s f E R I C A N C H E I r r C . I L S O C I E T Y , Kew York, N. Y.
