INDUSTRIAL AND ENGINEERING CHEMISTRY
December, 1944
I171
TABLE 11. (Continued) Cleaning Stage -
C
v
-Ca-
Rea ent Rea ent, Time, Ib.yton' Time, 1b.yton min.4' mm. of ore min. of ore 2 2 0.01 0.01 2 0.01 2 0.01 3 0.1 3 0.1 3 3 0.1 0.1, 3 3 3 0.1 0.1 3 3 0.1 0.1 3 3 3 0.1 0.1 3 3 3 0.1 0.1 3 3 3 0.1 3 0.1 3 3 0.1 3 0.1 3 0.1 3 3 0.1 3 3 0.1 3 0.1 3 3 0.1 3 0.1 3 3 3 0.1 0.1 3 3 3 0.1 0.1 3 3 3 0.1 0.1 3 3 3 0.1 0.1 3 0.I 3 3 0.1 3 3 0.1 0.1 3 3 0.1 3 3 0 1 3 3 0 :i 3 0.1 3 3 0.1 3 0.1 3 3 3 0.1 0.1 3 3 3 0.1 0.1 3 3 0.1 0.1 3 No reagent used in CI. CI
Run Tim:
No. a3 34 37 38 39 41 42 4a 44 46 47 48 67
62
64 61 66
63 69 71 72 7s 76 77 78 80 a
...
. . I
Conc. 262.S 2S7.S
3S6.S 363.6 380 347 349.5 337.8 326 332 327.S 330 347.6 344.6 346 329 339.s 321 333 306.6 311 320.1 320.S 317 333 294.6
Products, G r a m
Mi 80 82.S 36.6 31 38 4i ~. 40 41,s 49.5 (12.6 S8.S 153 S3.6
A7
ii.s
4s 46.5 48 46 S6 17 49 46.S 60 49,s 4s.s
&ft
MMI
44.s 60.6 20
34.s (11.6 11 14.S 13.6
3
28 22.11 32.s 2s 21 26.1
22.6 22.s
24.6 20.6 21 19,s 20 2s 33 28 24 17 31.6 31 29
bracho, with somewhat higher yields of calcium fluoride, would appear t o be possible from the technical use of redwood stumpwood tannin in sodium carbonate solution under the conditions described. Cone tannin would also be used, but this is a moduct of only theoretical interest. Incidentally, the conditions giving the best results with the redwood tannin are also those which result in the best leather in the tanning of calfskin. Acbowledflent is made t o The Pacific Lumber company for making poasible this project and to the MahQning Mining Com-
1s
12.s 17.0 19 14.6 13.6 13.S 11 14.5 9.s 13 14 10 12 1s 13,s 13.6 10 20.s 20 11.8
Tails
67.8 s3.3 62.S
47.s 48.6 60.6 66 67 76.1 73 68.6
7s
64.1 60.S 68.8 79.6 68 90 a2 86.11 88.S 79 90.6 73.6 62.6 106.6
Purity Of Con% % CaCOt SiO: CaFz
1 .6
2.4 2.6 3.4 6.2 1.9 2.0 2.4 2.1 2.S
2.7 1.9 4.7 2.4 2.8 1.7 1.7 1.4 1.4 1.6 1.7 1.6 1.6 1.9 18 2.1
0.1 0.1 0 0 0.2 0 0 0.4 0.4 0.4 0.6 0.6
...
... ... I.. ... ... ... ... ... ... ... ..* . I .
e . .
97.6 96.7 96.8 96.0 94.3 97.4 97.6 97.0 97.4 96.7 97.4 97.6
...
96.6
... ... 98.b ... 97.s 97.0 ... 97.4
96.7 96.6
Con&
~~~~~~
PH
After Conoen-
% tioningroughing trate 66.8 9.6 8.8 63.9 ... 8.9 9.4 i:i 88.7 8.6 9.4 9.9 88.9 9.2 92.2 8.8 9.3 8.9 86.9 8.7 9.3 8.6 8.7 9.4 87.8 8.8 9.0 9.4 84.3 9.0 81.7 8.7 9.5 8.7 82.7 8.7 9.6 9.0 82.1 8.9 9.6 9.1 9.4 8.9 8.8 82.9 9.0 8.7 8.7 9.3 8.8 8.8 86:O 8.6 9.2 8.6 ... 9.2 8.6 8.8 ... 8.8 9.3 8.S 8.7 8.S 9.2
...
84.0
... so.1 ... 79.7
78.0 82.8 73.2
... ... ... 9.7
9.8
... ...
9.3
... ... 9.2
...
8.8
8.6
9.2
9.0 9.0
8.9
i:i
... ...
...
...
pany for cooperation and for the samples of ores used in the experiments. LITERATURE CITED
(1) Bur. of Minee, Metallurgioal Div., Prolress Rept. 31 [Rept. Zn-
uestigation 3437 (1939)l. (2) Wilson and Kern. J. IND. Em. C E ~ M .13, . 722 (1921). P R ~ S B N T Dbefore D the Divieion of Industrial and Engineering Chemistry a t the 107th Meeting of the AMERICAN CEEXICALS O C I ~ T YCleveland, , Ohio.
ACETYLATED CASEIN FIBER ALFRED E. BROWN, W. G. GORDON, EDITH C. GALL, AND R. W. JACKSON Eastern Regional Research Laboratory,
U. S. Department of Agriculture, Philadelphia, Pa.
M
ILLIONS of pounds of casein fiber have been produced, both here and abroad. The fiber is in an active stage of development, as shown by the extensive literature. Compared with wool, casein fiber as ordinarily hardened with formaldehyde h inferior because of its lower tensile strength, particularly when wet, and because of its poor resistance to boiling, especially in mildly alkaline solution. Similar properties with consequent need of improvement have been encountered in artificial fibers prepared from a number of other proteins. A British patent (14) reported that treating fibers spun from peanut protein with acyl chlorides would improve the resistance of the fiber to hot dilute acid as well as impart water-repellent properties. Reaction with ketene and acetic anhydride was subeequently claimed (26) to produce the same benefits in artificial protein fibers. Another patent (16) deals specifically with the acetylation of casein fiber by ketene or acetic anhydride, with or without catalysts. A process for treating protein fiber such as casein, involving the use of acylating agents like ketene and acetic anhydride in the presence of fatty acid catalysts, to improve or modify dyeing affinities, resistance to water, and other properties, was patented (1). The water-resistant properties and dyeing aharacteristics of Aralac, the casein fiber made commercially in
this country, were described (9). Up to the present, however, no detailed study of the acylation of hardened casein fiber has been published. Acetic anhydride has been used to acetylate wool for the purpose of masking the basic groups and thus decreasing the afiinity of the wool for acid dyes (4). Elliott and Speakman (3)recently described such a process based on treatment with acetic anhydride and glacial acetic acid in the presence of sulfuric acid. K i and Carr (7)studied the acetylation of silk fibroin with ketene. Up t o 7.3% acetyl content waa obtained, depending on the duration of exposure to ketene, but the fibers were colored tan t o brown. No correlation with other physical properties was reported. I n a later paper, describing the acetylation of silk by acetic anhydride, Carr (9)showed that sodium acetate accelerated the reaction. The literature on the acetylation of proteins other than fibers is reviewed in another article (6). The investigation reported here was undertaken for the purpose of correlating acetylation with its effect on important properties of casein fiber. Three types of casein fiber were prepared. All were spun from One type was precipitated in a bath the same batch of -in. containing aluminum sulfate and collected in skein form (referred
1172
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
Casein fiber as ordinarily hardened with formaldehyde is inferior to wool as a textile fiber because of its lower tensile strength, especially when wet, and because of its poor resistance to boiling, particularly in mildly alkaline solutions. Claims have been made that acetylation improves some of the inferior properties of protein fiber. No quantitative report on this problem has appeared, so an investigation was made with casein fiber prepared in this Laboratory. Acetylation was carried out with acetic anhydride under various conditions, including the presence of catalysts. Acetyl contents from 1.0 to 9.0% were obtained by varying the time and temperature. Correlations between acetyl content and various properties are reported. Acetyl contents of about 6% could be introduced with no loss of wet or dry tensile strength. Fibers of such acetyl content are superior to the untreated control fiber in regard to resistance to boiling solutions simulating dye-bath conditions. They also have the desirable property of a greatly decreased affinity for acid dyesi.e., dyes with colored anions-and thus more closely approximate w o o l in dye uptake.
Vol. 36, No. 12
ACETYLATED FIBER
Three flasks equipped with reflux condensers, PREPARATION. each contaidng 175 cc. of acetic anhydride, were placed in a large oil bath kept a t constant temperature. When the desired temperature had been reached, 10-gram samples of each of the three types of fiber (conditioned a t room atmosphere) were immersed in the anhydride. The large excess of anhydride was used to make sure that all the fiber was covered and thus uniformly treated. After the desired heating period the anhydride was decanted; the fibers were removed, washed in a pan of running tap water for 20 minutes, and then steeped in a pan of warm water at 55-60' C. for 20 minutes to exhaust the anhydride. The fibers were whirled in a small basket centrifuge and allowed to dry in air. I n each case the treated fiber was compared with the untreated fiber of the skein or reel from which it was taken. ANALYSIS.Moisture determinations were run simultaneously with the analyses for ash and acetyl, which are tabulated o n a moisture-free basis. Moisture content was determined on a 0.10.2 gram sample by drying to constant weight, in a vacuum oven a t 70" C. for 16 to 18 hours. Acetyl content was determined by the method of Hendrix and Paquin (6). Before analysis all samples were extracted in a Soxhlet apparatus with acetone. To retain acetic acid, a little aqueous sodium hydroxide was added to the solvent in the boiling flask. Total ash was run essentially according to the calcium acetate method as described by Sutermeister and Browne (la). The properties of the treated samplas, together with the conditions of preparation, are shown in Table I.
t o as aluminum skein fiber); another was precipitated in the same bath and collected on reels (aluminum reel fiber) ; and the third type waa precipitated in a bath free of aluminum salts and collected on reels (non-aluminum reel fiber). The fiber collected o n reels was under tension during hardening with formaldehyde; that collected in skein form was not hardened under tension. The spinTABLE 1. PREPARATION AND PROPERTIES OB ACETYLATEDFIBER ning solution contained 21.5% casein (calcuTotal lated on the dry basis) and 0.92% sodium Heating Acetyl Ash % Water Strength* Color of Sample Period, Temp., Content, Content, after Im- -Gram/Denier Acet latsd hydroxide; the pH waa 9.6 to 9.8. This No.4 % ' % mersion Dry Wet Fiier Hr. OC. solution was held for 16 hours at 55' C. The A. Nonaluminum Reel material was spun through a 500-hole tan1-lb ... 32.1 0.62 0.18 White ... talum spinnerette into a 40-liter bath con1.2 2.36 31.8 0.58 0.17 White 2-1 60 0.5 1.1 2.43 31.2 0.60 0.17 White 60 3-1 1.6 taining 10% by weight of sulfuric acid, 14% 1.2 2.20 30.7 0.68 0.16 Whits 60 4-1 3.0 of sodium sulfate, 7.9% of aluminum sulfate 1.7 2.28 27.4 0.59 0.16 White 6.0 60 6-1 octadecahydrate, and 100 cc. of 37% formal0.60 0.15 White 29.1 1.7 2.12 6-1 80 0.5 31.2 0.57 0.17 White SO 3.7 2.10 7-1 1.5 dehyde. The bath was replenished with 0.55 0.18 White 28.9 5.6 2.02 80 8-3 3.0 White 0.64 0.22 28.9 9-1 6.4 2.15 6.0 80 salts, acid, and formaldehyde as needed to 35.7 0.60 Whit. 2.36 0.16 10-36 ... ... ... maintain its original composition. In the 0.18 White 25.9 5.3 0.62 1.97 11-3 100 0.5 preparation of the nonaluminum fibers, an 0.59 0.16 White 25.1 1.83 10 6.3 12-3 100 0.63 0.17 Cream 24.0 6.5 1.99 100 1.5 13-3 equivalent amount of sodium sulfate was 2.18 0.21 0.63 Cream 23.5 100 7.2 2.0 14-3 Light tan 0.21 25.7 2.02 0.60 100 7.6 15-3 4.0 substituted in the bath for the aluminum 6.4 2.07 26.8 0.60 0.18 Cream 16-3 110 0.5 salt. The skeins or reels, weighing 80 to 100 7.4 2.23 28.7 0.58 0.18 Lighttan 110 17-3 1.6 grams net, were hardened for 16 hours in a 8.1 2.37 26.7 0.54 0.23 Tan 18-3 110 3.0 . . . . . , 35.0 0.60 0.15 White . . . 19-8b solution containing 30% of sodium acetate 6.7 1.96 23.4 0.68 0.18 Cream iio 0.6 20-8 8.7 1.99 22.3 0.46 0.15 Tan 120 21-8 1.5 trihydrate and 5% of formaldehyde, adjusted 9.0 1.94 21.1 0.46 0.14 Dark tan 22-8 120 3.0 to pH 5.5 by addition of acetic acid. They B. Aluminum Reel were then washed thoroughly and dried a t 4.59 41.3 0.58 0.17 White 1-1b ... room temperature. After being removed from 1.0 4.28 40.6 0.60 0.18 White 2-1 0.5 60 1.2 4.59 38.9 0.59 0.16 White 60 1.5 3-1 the reels, the fibers were thoroughly washed 1.2 4.27 37.0 0.57 0.17 White 60 4-1 3.0 again and dried a t room temperature. 1.3 4.10 36.0 0.62 0.17 White 6.0 60 5-1 The fibers were prepared according to a 0.17 White 38.7 0.60 1.6 4.62 6-1 0.5 80 White 0.63 0.19 37.7 2.0 4.00 80 7-1 1.5 simplified formula to yield uniform batches of White 0.68 0.21 36.7 2.3 4.08 3.0 80 8-1 0.22 White 35.0 0.63 5.4 4.72 9-1 80 6.0 base fiber. Neither maximal tensile strength White 41.3 0.59 0.24 5.08 ... 10-2b . . . ... nor pronounced resistance to boiling solutions 0.22 White 0.65 34.5 3.5 4.66 11-2 100 0.6 0.22 White was sought, since it was desired to give full 4.89 0.66 34.2 5.2 100 12-2 1.0 0.66 0.23 4.86 Cream 35.3 5.7 13-2 100 1.5 range to the effects of acetylation on these 0.25 0.65 Cream 33.6 5.06 6.8 2.0 100 14-2 Light tan 0.22 4.90 33.1 0.64 6.0 15-2 4.0 100 properties. Casein fibers with considerably 0.66 0.22 Cream 5.03 32.0 4.5 16-2 110 0.5 higher tensile strengths and with greater resist0.24 Lighttan 31 3 0.62 6.3 4.92 110 17-2 1.6 Tan 0.63 0.22 ance to boiling than the control fiber used in 29.1 7.1 4.93 18-2 110 3.0 ... ... 41.5 0.59 0.19 White the present investigation have been made in 19-8b ... ... 5.7 5.01 30.9 0.60 0.22 Cream 120 20-2 0.5 this Laboratory'. 7.2 6 02 32.9 0.57 0.18 Tan 1.5 120 21-8 I The preparation of Eber of greater tenacity 88 well w further detaile of procedures employed for spinning and testing will be described in a later paper from thin L8boratory.
...
...
...
...
8.2 4.94 28.8 0 51 0.17 3.0 120 22-8 Number following dash indicate6 reel from which sample wqs prepared. b Untreated control.
a
Dark tan
INDUSTRIAL AND ENGINEERING CHEMISTRY
December, 1944
A complete set of data comparable to those presented in Table '
IB for the aluminum reel fiber was obtained with the aluminum skein fiber, but since it led to the same conclusions, it is omitted. EFFECT O F TIME, TEMPERATURE, AND CATALYSTS
The data in Table I show the effects of time and temperature on acetylation. Increasing the time of reaction increased the amount of acetyl introduced a t any given temperature, although the value finally leveled off. The effect of temperature was marked, as summarized by the data in Table 11. Above 80" C. . the rate of acetylation increased rapidly with temperature. I t is important from a practical standpoint that the acetylation process shall not color the fiber; this coloration may occur when it is necessary to employ the vigorous treatment required to introduce 6% or more of the acetyl group. Any colors imparted to the fibers by the acetylation treatment are listed in Table 1. The uniformly higher total ash contents of the aluminum fibers indicate that the aluminum retained from the precipitating bath was not lost in the acetylation treatment. The nitrogen content of these fibers was not determined, but in preliminary experiments (not tabulated here) it decreased in proportion to the increase in acetylation. Some idea of the distribution of the acetyl groups in typical derivatives was obtained by treating the fibers with dilute alkali. It is well known that 0-acetyl groups are alkali labile (11). Samples (0.5 gram) of the ground fiber were treated with 25 cc. of 0.1 N sodium hydroxide a t room temperature for 6 hours, and the filtrates were analyzed for acetic acid. Acetyl in excess of 2.0 to 2.5% was removed by this treatment, an indication that much of the acetyl of highly acetylated casein fiber is of the alkali-labile type. This is also true for nonfibrous casein derivatives (6,8). I n contrast to this lability, acetylglycine and acetylsarcosine are not attacked under the same conditions after 48 hours. Since acetylation may be accelerated by either acidic or basic catalysts, the effects of various catalysts were studied. Table I11 lists the details of the experiments. Acid catalysts did not increase the degree of acetylation in any case. Addition of acetic acid alone had almost no effect. For this reason air-dried sam-
TABLE11. EFFECPOF TEMPERATURE ON ACETYLATION' Acetyl Content % Nonaiuminum reel fiber Ahminum reel fiiber ' Temp., * C. 0.5 hr. 1.5 hr. 0.5 hr. 1.5 hr. 60 1.2 1.1 1.0 1.2 80 1 .? 8.7 1.6 2.0 100 5.3 6.5 3.5 5.7 110 6.4 7.4 4.5 6.3 120 6.7 8.7 5.7 7.2 'The fibers were prepared by heating in aoetic anhydride, as described previously.
ples can be used directly for acetylation without concern for acetic acid generated from small amounts of water and acetic anhydride. Basic catalysts, on the other hand, increased the amount of acetylation slightly in every case, but this advantage was offset by the decrease in tensile strength of the fibers so treated. I n connection with the catalytic study, the effect of organic diluents on acetylation was observed. Treatment of the fibers with 5, 10, and 20% solutions of acetic anhydride in benzene for 3 hours under reflux introduced only about 10% of the acetyl groups thaf were introduced with acetic anhydride alone under the same'conditions. If acetic anhydride were used alone in a continuous process, acetic acid would accumulate in the acetylation bath. Since acetic acid has little effect on acetylation, the bath could be periodically replenished-for example, by reconverting the acetic acid to the anhydride with ketene. EFFECT O F ACETYLATION ON TENSILE STRENGTH
For tensile strength measurements the fibers were conditioned for 24 hours in a room kept a t 65% relative humidity and 70" F. (21" C.). Tensile strength was determined on a Scott tester. Each value is the mean of results on a t least ten bundles. According to this method as applied to our fiber series, a difference greater than 0.03 gram per denier is significant. The washing treatment used to free the acetylated fibers of excess anhydride and acid had no demonstrable effect on the tensile strength of unacetylated fiber. The data in Table IA indicate that acetylation of nonaluminum fiber does not increase the dry tensile strength. On the other hand treatment a t 100" C. and short treatment a t higher temperatures introduced a high acetyl content without decreasing the tensile strength. Longer treatment at temperatures of 110" C. and higher injured the fiber. Acetylation did not increase the wet tensile strength. Table I B shows that acetylation a t 100" C. may increase the dry tensile strength of aluminum reel fiber slightly. These fibers did not show the marked decrease in tensile strength exhibited by the nonaluminum fibers after acetylation for longer times at 110' C. or higher. The wet tensile strength of the fibers wm not affected by moderate acetylation treatment. From the standpoint of tensile strength, aluminum reel fibers acetylated at 100"C. were consistently best. Since these fibers could be heated for longer periods at 100' C. without decreasing the fiber strength, the safety factor for operation at this temperature is great. To correlate acetylation and heat treatment (baking) of the fiber with tensile strength, the aluminum and nonaluminum reel fibers described in Table I were studied. The results are shown in Table IV. All acetylations were performed a t 100"C. for 1hour. It is clear that baking, as carried out in these experiments, has no effect on tensile strength.
TABLE 111. EFFECTOF ACIDICAND BASICCATALYSTS ON ACETYLATION Catalyst Used
Acetic Weight of Anhy- Heating Acetyl Catalyst, dride, Period, Tynn., Content, Grams C0.O Hr. %
..
... ...
........ None
... ...
Non;
p-Toluenesulfonic acid Cpncd. Has04 Zinc chloride Magnesiumperchlorate
0.3 0.9 0.4
0.4
...
200 200 200 200
200
...
...
...
*..
...
85 85 85 85 85
2.6 1.4 1.3 1.0 1.6
...
...
3.0 3 2 3.2 8.2 3.2
1 100 100 6.6 100 100 Coned. HrSOr 1 0.2 6.9 Stesria acid 100 6 95 1 6.4 Acetic acid 1 21 100 80 6.2 Anhydrous sodium acetate 1 100 and acetic acid 5d 85 7.0 1 Same 10' 60 100 6.9 Anhydrous sodium acetate 96 1 5 100 7.8 7.2 Pyridine 1 90 10 100 ' 5 grams of aluminum skein fiber used in each aase. b Value for untreated fiber from which next five samples were obtained. C Value for untreated fiber from wbich,remainin samples were obtained. d 10 cc. of glacial acetic acid wed to dissolve sofium acetate. 50 cc. of glacial acetic acid used.
1173
Tensile Strength, Oram/Denier Dry Wet 0.01s 0.22b 0.66 0.17 0.69 0.19 0.62 0.23 0.81 0.17 0.66 0.18 0.600 0.22c 0.64 0.22 0.60 0.24 0.47 0.22 0.46 0.19
0.41 0.86 0.44 0.46
0.18 0.16 0.19 0.18
WATER CONTENT AND DEGREE O F ACETYLATION
The water-binding capacity of. cellulose is progressively decreased by acetylation of its hydroxyl groups (19. Recently the decreased uptake of water by acylated casein plastics was demonstrated (6). To show the effect of acetylation on the water absorption of fibers, their water contents after soaking in water were determined by a modification of the method of McMeekin and Warner (8) for the water content of @-lactoglobulin crystals. A 2030 mg. a m p l e of fiber, previously extracted with acetone, and dried at room temperature, waa soaked for 1 hour in 5 cc. of twice-distilled water in a test tube maintained a t 25' C. At the end of this period the sample of fiber waa removed and immediately pressed between
INDUSTRIAL A N D ENGINEERING CHEMISTRY
1174
Vol. 36, No. 12
of distilled water. The untreated aluminum reel fiber had a WB-
TABLE IV. EFFECTOF ACETYLATIONA N D BAKING ON TENSILE ter content about 7% higher than the untreated nonaluminum STRENGTH
Treatment Untreated Bakedb Acetylated Acetylated, then bakedb a
Tensile Strength. Gram/Denier Nonaluminum reel fiber" Aluminum reel f i b s Dry Wet Dry Wet 0.84 0.21 0.80 0.19 0.82 0.24 0.80 0.20 0.82 0.20 0.60 0.18
0.63
0.21
0.82
0.20
Fibers were all taken from the Rame reel. Sample8 were baked at 120' C . for 3 hours.
CORRELATION OF RESISTANCE TO BOILING WITH DEGREE OF ACETYLATION
OF BOILING FOR ONE HOUR IN SOLUTIONS OF TABLE V. EFFECT DIFFERENT pH VALUESON APPEARANCE AND FEEL^ OF NONALUMINUM REELFIBER
pHb
Untreated Fiber Disintegrated Very hard lump Very hard lump Distintegrated Distintegrated Distintegrated Distintegrated
Fiber of Low hcetyl Content
Fiber of High Acetyl Content
(1.2%)
(8.3%)
Normal Normal Normal Normal Normal Powdered when rubbed Powdered badly when rubbed Fibers were allowed to dry at room temperature. b Citrate-phosphate buffers were used for pH 2.9,4.1,6.1,and 8.1; phoaphate buffer for pH 7.1; and borax-borate buffer for pH 8.0 and 8.6.
2.9 4.1 5.1 8.1 7.1 8.0 8.6
fiber, probably owing to the water uptake by the inorganic matter. The values in Table IB, compared with those in IA, show that the decrease in water content with increase of acetylation is not so great as with the nonaluminum fibers. This difference is not surprising in view of the larger ash content of the aluminum fiber.
Very brittle: hard Rrittle -.... Very brittle Brittle. powdered Hard hkittle hkttle mas8 Hard brittle niass Hard brittle ma88
__
OF ACETYLATION ON DYE TABLEVI. EFFECTOF DEGREE
UPTAKE:' Nonaluminum Reel Fiber Aluminum Reel Fiber Acetyl, Dye e x h a a t , % Acetyl, Dye exhaust, yo yo Caloomineb PontaniineC yo Calcomineb PontamineC 81.7 0.0 88.5 0.0 97.0 Exhausted 30.0 99.4 69.6 1.2 1.1 58.3
14.4 38.1 2.3 3.7 20.3 13.8 24.3 18.5 10.8 11.1 3.5 5.3 10.0 8.1 9.4 12.6 4,s 8.5 9.s 11.4 8.3 6.8 7.8 7.6 7.8 7.1 7.1 8.8 7.1 8.7 3.0 8.2 3.0 0.2 gram of fiber was boiled in 100 cc. of dye solution at pH 4.11 for d
minutes: the concentration of dve remaininp - in solution wa8 determined bv photoelectric oolorimetr b Calcomine Fast R~C?SB:100 cc. of dve solution contained 37.5 me. dve and 10 cc. of 0.2 M acetate buffer. C Pontamine Fast Blue RRL; 100 CC. of dye solution contained 10.0 mg. dye and 10 cc. of 0.2 M acetate buffer. ~
blotters, the time being recorded by a stop watch (zero time). The fiber was pressed twice more to ensure removal of adhering water, and was weighed as soon as possible (usually within 60 seconds) on a tared watch glass with a Chainomatic analytical balance. At the instant the weight was determined to the nearest 0.1 mg., the time which had elasped since zero time was recorded. The drying fiber was allowed to remain on the balance pan, and successive 0.5-mg. losses in weight were accurately timed until three such pairs of figures were recorded. By plotting weight against time and extrapolating to zero time, the wet weight of the fiber on removal from the water was obtained. The sample was then dried to constant weight at 105' C., and the percentage of water in the wet fiber was calculated. Average values of at least two determinations, expressed as water content after immersion, are shown in Table I. The deviation of measured values from their average in no case exceeded 3y0 of this mean. Distilled water rather than buffer solutions w&s chosen because the values obtained for water content after immersion in the latter were much higher. For example, after a representative acetylated fiber was immersed in 1/15 M phosphate buffer of pH 7.0, the water content was 54.l%, in contrast to 31.8% after immersion in water. The values in Table IA indicate that nonaluminum fibers of low acetyl percentage had a water content up to 3% leas than the untreated material, whereas the water contenb of highly acetylated fibers were decreased by about 7 to 14%. The same correlation of decreased water content with increased acetyl content was also evident with buffered solutions in place
When formaldehyde-hardened casein fiber is boiled for an hour, the material becomes gelatinous and weak, the extent of change depending on the pH of the medium (IO). A boiling test simulating dye-bath conditions was used in order to correlate resistance to boiling with degree of acetylation. For the test, 0.1 gram of the fiber was boiled in 25 cc. of the buffer solution under reflux for 1 hour. The sample was then removed, examined, pressed between blotters, and dried a t room temperature. The choice of buffers did not seem to influence the results at any given pH. To study the effect of pH, boiling tests were carried out a t various pH values with the acetylated nonaluminum reel fibers described in Table IA. The appearance and feel of the fibers after the boiling tests are described in Table V. The differences in resistance were marked. These results have been duplicated many times. At all pH values other than 4 and 5, the untreated materials became gelatinous and disintegrated. At pH 4 and 5, however, a hard mass devoid of all fibrous structure resulted on drying. I n contrast to the untreated fiber, the fiber of 1.2% acetyl content did not disintegrate a t any pH value listed but became brittle when dry. This fiber was most resistant a t pH 4 to 6. The fiber of 6.3% acetyl content was extremely resistant over the pH range 2.9 to 7.0,and appeared normal after drying, but at higher pH values this fiber powdered somewhat when dried and rubbed. When the three samples were boiled in distilled water, the results were substantially the same as when they were boiled in buffer solutions of pH 5 to 6. Boiling tests at different pH values were also made with the aluminum fibers of 0, 1.0, and 5.2% acetyl content described in Table IB. The effects of pH were the same as those with the nonaluminum fibers. I n general, however, observation of the results of many experiments showed that the acetylated fiber containing aluminum salt waa more resistant to boiling and did not feel so harsh after the boiling treatment. DYE UPTAKE AND ACETYL CONTENT
Much has been written about the extreme affinity of casein fiber for dyes, and acetylation has been advocated as a method of reducing the dye affinity of casein fiber to approximately that of wool ( 1 ) . With a series of fibers of increasing acetyl content, the relation was easily demonstrated. Results with two types of fibers and with two different dyes are shown in Table VI. Since the pH of the dyeing solution has such a marked influence on dye uptake, preliminary tests were made to obtain a dyeing rate slow enough to permit comparisons between the entire set of acetylated samplw. With both the dyes used, a pH of 4.5 was satisfactory. All the results make apprtrent the decrease in dye affinity with increased acetyl content. The large decrease in percentage dye exhaust with introduction of small amounts of acetyl can be explained by the initial action of acetylation treatment, mainly, masking of the basic groups. Thus the protein groups responsible for combining with most of the colored anion of the dye at this pH can be masked by relatively little acetylation. That these are not the only groups participating is evident from the fact that acetylation over and above that necessary to cover the basic groups still decreased the dye uptake. From these results it also seems that the nonaluminum fiber takes up less dye than the aluminum fiber of similar acetyl content.
December, 1944
INDUSTRIAL AND ENGINEERING CHEMISTRY ACKNOWLEDGMENT
The authors are especially grateful to R. Petemon and T.p. Caldwell of this Laboratory for the preparation of several large samples of caaein fiber, without which this investigation could not have been made; they also wish to acknowledge msistance given by Clare M. McGrory of this Laboratory.
117s
Kise, M. A., and Carr, E. L., Taztile Rasearch. 7 , 103-9 (1936); Carr, Edward, Il@., 8, 125-33 (1938). (8) McMeekin, T. L.,and Warner, R. C., J . Am. Chm. sot., 64, (7)
2393-8 (1942); A S T M Bull. 125, 19-21 (1943).
(9) Millson, H.E., Cdco Tech.Bull. 667, (1942). (10) Rath, H., and Essig, A., Klepzig’s Teztil-Z., 41, 463-6 (1938). (11) Sakami, W., and Toennies, G., J . BioE. Chem., 144, 203-5 (1942). (12) Sheppard, S. E., and Newsome, P. T., J. Phgs. Chem., 33, 1817-
.----,
36 _ - f 1928).
LITERATURE CITED
a
Atlantic Research Associates, Brit. Patent 536,841 (May 29, 1941); Atwood, F. C., U. 8.Patent 2,342,634 (Feb. 29, 1944). Carr, Edward, Teztile Research, 8, 399-405 (1938). Elliott, G. H., and Speakman, J. B., J . SOC.Dyers Colourists, 59, 186-91 (1943).
Gebhard, K., 2.angew. Chem., 27, 302-4 (1914). Gordon, W. G., et al. (in course of preparation). Hendrix, B. M.. and Paquin, F., Jr., J . Biol. C h m . , 124, 136-45 (1938).
Sutermeister, Edwin, and Browne, F. L., “Casein and Its Industrial Applications”, A.C.S. Monograph 30, 2nd ed., p. 158, New York. Reinhold Pub. Corp,, 1939. (14) Traill, David (to Imperial Chemical Industries), Brit. Patent, (13)
492,895 (Sept. 26, 1938). (16) Ibid., 496,332 (Nov. 10, 1938). (16) Worrnell, R. L. (to Courtauld’s Ltd.), Ibid., 495,885 1938).
(Nov. 22.
PRXISXINTED before the Division of Industrial and Engineering Cbemistry a t the 107th Meeting of the AMERICAN CHEMICAL SOCIETY, Cleveland, Ohio.
Carbon TetrachlorideTetrachloroethvlene Svstern J
J
VAPOR PRESSURE AND LIQUID-VAPOR COMPOSITION HUGH J. McDONALD AND WILLIAM R. McMILLANl Illinois Institute of Technology, Chicago, Ill.
The liquid-vapor composition for the binary system carbon tetrachloride-tetrachloroethylene has been determined. The vapor pressure data are obtained by determining the boiling points at four different pressures of nine samples covering the binary diagram. The boiling points of the system at 1 atmosphere pressure and the vapor pressure at 60”C. are given.
twice to the original sample, and the procedure was repeated. The temperature-pressure data thus obtained make up the first four lines in each section of columns 1 and 2, Table 11. A similar procedure WM followed with carbon tetrachloride as the initial sample. Tetrachloroethylene was added five times. These data make up the first four lines in each section of columna 5 and 0 and of 9 and 10. The system waa covered with a total of thirty-six vapor pressure measurements on nine samples. The
I
N T H E course of investigations on liquid mixtures in this laboratory, the industrially important system carbon tetrachloride-tetrachloroethylene was studied. It was felt that data gathered on this mixture would be of interest to handlers of commercial solvents, especially to those who manufacture tetrachloroethylene from carbon tetrachloride and therefore have a separation problem. The preparation and quality of the carbon tetrachloride and tetrachloroethylene and the method of analysis of samples were reported previously (8). The apparatus for determining the vapor composition (1, 9) and the vapor pressure have already been described (4). T o obtain the liquid-vapor composition, samples of approximately 50 ml. were made up by weight at exactly 0.1 mole fractions and were allowed to come to boiling equilibrium before being distilled (2). A few drops were then distilled, and the analysis of this distillate waa taken as the vapor composition for each sample. The results are given in Table I and Figures 1 and 2. To obtain the vapor pressure, representative mixtures were made up and boiled with efficient reflux at four different pressures (4). This was done first on pure tetrachloroethylene, and a sample waa withdrawn to check the composition by refractive index. Then small amounts of carbon tetrachloride were added 1
Present address. Mine Safety Appliances Company. Pittsburgh, Pa.
70
o
0.1 0.2
rn
0.t as 0.6 0.7 Nccl+ IN CC12:CC12
0.8 0.9
Figure 1. Liquid-Vapor Composition Diagram for Carbon TetrachlorideTetrachloroethylene
1.0
I
