ANALYTICAL EDITION
August 15, 1942
and ignite to indium oxide for gravimetric determination. For potentiometric titration, dissolve indium hydroxide in dilute hydrochloric acid and dilute the solution so that it is not more than 0.04 N in hydrochloric acid. Determine the aluminum in the usual way by precipitating aluminum hydroxide and igniting to aluminum oxide for weighing gravimetrically. INDIUM-TIN ALLOYS. Treat 0.1 to 0.2 gram of the alloy sample with concentrated nitric acid, and remove the major portion of the tin as metastannic acid. Dissolve this metastannic acid and reprecipitate t o assist removal of any occluded indium solution. Now add atrates and washings from both precipitations, precipitate indium as the hydroxide with 2 N sodium hydroxide (4, and then redissolve by addition of an excess. Boiling the solution, or addition of ammonium chloride causes reprecipitation of indium hydroxide; tin is not precipitated under these conditions. As this separation is not complete, neutralize the filtrate with hydrochloric acid and boil, causing 0.1 per cent of dissolved material to precipitate. Repeat this procedure two or three times for best separations. Repeated solution and reprecipitation of indium precipitate, however, still left more than 1 per cent of tin which could not be removed from the indium. Determine indium and tin aa the oxides. In attempting to locate a suitable means of separation of indium and tin for accurate quantitative analyses, many types of separation were studied and tested. The volumetric determination of tin (11) with iodine in the presence of indium gave poor results, as did the determination of indium potentiometrically with potassium after distillation of stannic chloride from indium solution. The precipitation of indium by means of 8-hydroxyquinoline (6) and also by 8-oxychinolate (3) likewise proved unsatisfactory.
Summary Available methods for indium alloy analysis were investigated and the most accurate and efficient chosen by means of analytical tests. For rapid determinations of indium, the
639
potentiometric titration of Bray and Kirschman using POtassium ferrocyanide was used. Satisfactory procedures for indium-lead, indium-zinc, and indium-aluminum were determined, but no precise method for indium-tin alloys could be found which permitted a determination of greater than 1 per cent accuracy. I n the case of indium-lead, indium-zinc, and indium-aluminum alloys, however, an accuracy of 0.1 to 0.2 per cent was attainable.
Acknowledgment The Bristol-Myers Company, New York, N. Y., and the Sun Tube Company, Hillside, N. J., have sponsored the research program of which this investigation is a part.
(1) Bray, V. B.,
Literature Cited and Kirschman, H. D., J. Am. Chem.
SOC.,49,
2739-44 (1927). (2) Dennis, L. M., and Bridgman, J. A.,Ibid., 40, 1549 (1918). (3) Eineoke, E.,and Harms, J., Z. anal. Chem., 98, 429-46 (1934). (4) Erametsl, Olavi, Suomen Kemistilehti, 13B, 17-18 (1940). (5) Geilman, W., and Wrigge, F. W., Z. unorg. allgem. Chem., 209, 129-38 (1932). (6) Hope, H. B,, Skelly, J. F., and Ross, Madeline, IND. ENQ. CHEM.,ANAL.ED.,8, 51-2 (1936). (7) Mathers, F. C., J. Am. Chem. SOC.,30, 209 (1908). (8) Mathers, F. C.,and Prichard, C. E., PTOC. Indiana A d . Sei., 43,125-7 (1934). (9) Moser, Ludwig, and Siegmann, Friedrich, Monats. 55, 14-24 (1930).
(10) Nizhnik, 0.T., Zapiski Inst. Khim., Akud. Nauk U.S. 8.R.,6, NO. 3-4, 265-87 (1940). (11) Scott, W. W.,“Standard Methods of Chemical Analysis”, 5th ed., Vol. I, pp. 969-70,New York, D.Van Nostrand Co., 1939.
Viscosity Determination of Polymer Solutions D. W. YOUNG, Standard Oil Company of New Jersey, AND E. H. MCARDLE, Standard Oil Development C o . , Elizabeth, N. J.
A new set of bubble tubes extends the Gardner-Holdt series to viscosities of 1000 poises, and thus adapts this rapid method to the measurement of viscosities of high polymers in volatile solvents. The eleven tubes in the set are numbered from 1/2 to 10, and cover the range from 50 to 1000 poises in steps of 100. To minimize effect
I
h’ CONNECTION with recent work (2) requiring the
rapid and precise determination of polymer solution viscosities, the necessary accuracy was found obtainable with the Gardner-Holdt rising air bubble viscometer (1). Results are duplicable, since no solvent is lost, as in using the majority of other viscometers. Further, by inverting the standard tubes at their designated temperature (25’ C.) alongside a water bath maintained a t a different temperature, and containing the sample tubes arranged on a hinged mounting, it is possible to take measurements a t a series of temperatures with speed and with a n accuracy sufficient for most purposes. The highest viscosity available in a closely related GardnerHoldt series is the Z6 tube of the “heavy bodied series” (148
of temperature, each tube is filled with a mixture of a 105 viscosity-index lubricating oil and a polybutene of 12,000 molecular weight. Diameter of tubes is 21.3 mm., double that of the regular Gardner-Holdt series. Length is the same. These dimensions make for ease in filling, and save 80 per cent of the measuring time.
poises), and hence the choice of polymers and their solution concentrations was delimited a t that value. It was also found diffcult to fill sample tubes of 10.65-mm. inside diameter with highly viscous solutions of polymers in volatile solvents, without losing appreciable solvent. I n addition, were it attempted to extend the viscosity range with the small diameter tubes, the time of bubble ascent would become excessive (Figure 1). A series of four experimental tubes, of the same length (11.4 cm.) but of progressively larger diameter, was accordingly constructed from regular Pyrex tubing. Carefully made flat bottoms permitted standing perfectly upright on a horizontal surface, without the aid of a holder. Times of bubble
I N D U S T R I A L AND E N G I N E E R I N G CHEMISTRY
I
I
100 200
300 400 500 600 700 STOKES (UBBELOHDE) AT 25’C.
800 900
FIGURE 1
ascent, from the moment of inversion to the incipient flattening of the bubble against the cork, are shown in Figure 2.
Tube Size and Contents It was found that the tube of largest inside diameter-21.3 mm. (double the Gardner-Holdt size)-averaged approximately one fifth the time for bubble ascent throughout the range (cf. Figures 1 and 3). the 1000-poise tube requiring 4 minutes and 20 seconds as compared with Z6 (148 poises) 3 minutes and 8 seconds. Eleven tubes were chosen to make up the set. Ten cover viscosities. in steps of 100 stokes, from 100 to 1000, and are num-
Val. 14, No. 8
bered 1 to 10. Tube has 50 stokes’ viscosity. Table I shows the values as determined in a No. 4 Ubbelohde tube at 25” C. Since the two ingredients used to make the blends have respective densities at 25” C. of 0.93 for the 12,000 molecular weight polybutene, and 0.87 for the 105 viscosity-index lubricating oil, stokes and poises are herein used interchangeably. (Gardner-Holdt ‘LpoiseB’J refer to the petroleum oils contained in the standards tubes. Since, however, most varnishes and resin cuts possess similar densities at 25” C., no great error is involved.) Relative bubble dimensions, in the present eleven-tube set, correspond to those in the Gardner-Holdt “varnish series”. Bubble height was chosen at 35 mm., providing a length approximately twice the diameter. When three tubes were “filled” with the 200-stoke blend, times of ascent for bubbles respectively 42, 35, and 28 mm. long were 41, 43, and 44 seconds. Hence, as stated in the directions for using the Gardner-Holdt viscometer, “slight variations of the bubble size do not affect the determination, provided the length of the bubble is greater than its width”.
To test the relative accuracy of the set, four solutions of 80,000 molecular weight polybutene were made in ordinary rubber solvent, with concentrations of 140, 160, 180, and 200 grams per liter. Results are plotted in Figure 3. It appears that 20 to 40 per cent solutions of 12,000molecular weight polybutene in light petroleum lubricating oils behave substantially as Newtonian liquids at such low rates of shear as occur in a rising air bubble viscometer, since no suggestion of “tail” is visible a t the bottom of the rising bubble in any tube in the set. Instead, the bottom is as rounded as the top, exactly as in the bubble in a straight petroleum bright stock. I
260-
*I0
POLYMER SOLUTION VISCOMETER (213 MM DIAMETER TUBES)
4
TABLEI. B-CBBLE ASCEKTV a ~ m s Ubbelohde Stokes at 2 5 O C.
Tube NO.
Bubble Ascent, Seconds
Tube No.
Ubbelohde Stokes a t 25’ C.
Bubble Ascent Second;
TEST
100 EFFECT OF TUBE DIAMETER
1
OVER-ALL RATIO :
I
I
200 300 400 500 600 700 STOKES ( UBBELOHDE ) AT 25’C.
1
800 900
FIQURE 3
It is believed that choosing blends of 12,000 molecular weight polybutene and a highviscosity-index straight petroleum oil provides for minimum temperature effects when measuring viscosities of polymer solutions. Acknowledgment Opportunity is taken to thank W. A. Schaefer, of the Esso Laboratories, who constructed the tubes.
W
z
i-
100
Literature Cited (1) Gardner, H. A., and Sward, G. G., “Physical and Chemical Examination of Paints, Varnishes, Lacquers and Colors”, 9th ed., p. 216, Washington, Institute of Paint and Varnish Research, 1939. (2) McArdle, E. H., and Robertson, A. E., “Solvent Properties of Isomeric Paraffins”, Division of Paint, Varnish, and Plastics Chemistry, A. C. S. Meeting, Memphis, 1942.
80
TUBE DIAMETER: MM.
FIGURE 2
PRESENTED before the Division of Paint, Varnish, and Plastics Chemistry SOCIETY, Memphis, Tenn. a t the 103rd Meeting of the AMERICANCHEMICAL
