SATO-THERMAL TRANSFORMATION OF BOEHMITE 9

inductive eflcct of the alkoxy group will be predominant, and heat stability is therefore unlikely. This is consistent with the results of DiGiorgio et aL4 in the preparation of di-(t-butoxy)-bis (aminoalkoxy)silanes, and with the stability of di-(t-penty1oxy)-bis-(2-aminobutoxy)silane, observed by Pedlow & Miner.s

Warrington Joseph Croslield 8r Sons Ltd.,

Rcccived 11 August, 1961

References 1 Klein, G., & Nienburg, H., Ger.P. 637,532 6

295-297 (London: Butterworths Scientific 7

Eaborn, C.. 'Organosilicon Compounds', 1960, pp.

Publications)

Chemical Coru.). U.S.P. 2,885,419 Heinfest, S., Adams, R., & Milius, H. (to Berkeley

4 DiGiorgio, P. A.,'.Sommer, L. H., & Whitmore, F. C., J . Amer. chenz. SOC., 1949, 71, 3254

p. 2637 Riclgc, I]., & Todd, M., J . chenz. SOC., 1949, LI

Bradley, D. C., Mehrota, R. C., & Wardlaw, W: J . chem. SOL., 1952, p. 5020

Merrill, R. C., & Spencer, R. W., J . phys. Chem., 1951, 55, 187

Peeler, R. L., & Kovacich, S. A., Industr. Engng Chem., 1959, 51, 749, and references quoted therein

I'edlow, G. W., jun, &Miner,:C.S ,, jun. (toMinnesota Mining & Mfg Co.), U.S.P. 2,566,365

THE THERMAL TRANSFORMATION OF ALUMINA MONOHYDRATE, BOEHMITE

By TAICHI S A T 0

Tlic thermal transformation of boehmite (alumina monohydrate) prepared hydrothermally froin alumina trihydrate (hydrargillite or bayerite) t o a-alumina has been studied by X-ray diffraction and infra-red spectra.

As a result, i t is seen that the thermal transformation of boehmite proceeds in the following sequence :

Boehmite + y-alumina + 8-alumina --f 0-alumina --f a-alumina

Introduction The thermal transformation of boehmite to a-alumina has been studied by many researchers.

Stumpf et a1.l reported that the thermal transformation of boehmite proceeds in the sequence y-, 6-, 0- and a-alumina. Later, Day et aL2 and Tertian et aL3 supported Stumpf's opinion. In contrast, Thibon et aL4 suggested that the calcination of boehmite at successively higher temperatures yields q-, 0- and a-alumina. Thereupon, Brown et aL5 postulated that boehmite decomposes to y- or ?-alumina, depending on the crystallinity of boehmite, and that the q-form may be regarded as an extremely poorly crystalline y-alumina. Prettre et however, proposed that the course of the thermal decomposition of boehmite goes to q-, 0'- (formed in well-crystallised boehmite only), 0- and a-alumina. According to Glemser et U Z . , ~ the thermal transformation of boehmite occurs in the sequence -q-, 8- and a-alumina. In view of thcse dis- crepancies the present study has been made.

Experimental Boehmite was prepared by the hydrothermal treatment of alumina trihydrate (hydrargillite

or bayerite) for 2 h. at 200°.9 Two kinds of alumina trihydrate were used to prepare boehmite. Hydrargillite was prepared by seeded decomposition of sodium aluminate solution at 50°, and bayerite was formed by carbonatation of sodium aluminate solution with carbon dioxide at 30".

Samples were prepared by heating boehmite at given temperatures between 500 and 1300" for 2 h. after heating up to the given temperature at a rate of 4"/min.1° on the basis of the result for the thermal analysis of b0ehmite.O These samples were examined by X-ray diffraction and infra-red spectra, according to the procedure described in a previous paper.ll

J. appl. Chem., 12, January, 1962

Results and discussion Figs. 1-3 and Table I give infra-red and X-ray results for boehmite samples obtained

liydrothermally from hydrargillite or bayerite and their thermal decomposition products. Only representative data are shown in Fig. 3. This figure and Table I show that, for either boehmite sample, the decomposition follows the sequence y- -+ 6- 3 0- --f u-Al,O,.

From Fig. 1, it is observed that the infra-red spectra of boehmite show two OH stretching bands12-15 and two OH bending bands.12 When the boehmite is heated at 500°, however, these OH absorption bands disappear (Fig. Z), while a very broad absorption band is observed below 970 cm.-l and centred at 810 and 720 cm.-l This arises from the formation of anhydrous

( 0 )

H

~ N O

m m : I I I

3600 3200 2800 FREOUENCY, cm?'

16'. 1 . (abuvc) I j r u - r e d cpertru o j bochirrzle prepnvrd Iiydvothi~Ymally /ram uliminn

Ira hydrate (a) 01% stretching (h) OH bending

region region JioeliiiiiLe prepared from (H) hydrargillite,

(B) bayerite

+ 1000 8 0 0 1000 8 0 0

FREOUENCY, cm.-l

J. appl. Chem., 12, January, 1962

11

I 1 I I I I I f I 30 40 5 0 6 0 70

z e, DEGREES

1;ig. 3. X-ruy dtJfruction diugrams o f thc products derived f r o m boehmite (prepured hydrothcrvnu~~~~ /rum hydrargillite) heutcd at vari0u.s temperatures

Table I X-ray diffraction results of aluminas derived from

boehmite heated at various temperatures Boehmite prepared hydrothermally from (H)

hydrargillite or (B) bayerite Phases detected

Tenipemture, H I3

500 600 700 800 900

1000 1100 1200 1300

With boehmite prepared from hydrargillite (Fig. 2a), the shape of the broad band below 970 cm.-1 is almost the same in the temperature range between 500 and 700" because of the formation of y-alumina. But, a t 800°, the absorption at 880 cm. -1 which is contained within the

J. appl. Chem., 12, January, 1962

12 THOMPSON-DRAINAGE RATES OF HIGH-EXPANSION FOAMS

broad band below 970 cni:.' becomes slightly sharp because of the formation of 8-alumina in addition to y-dumina. Owing to the disappearance of y-alumina, a t 900" the absorptions at 880, 810, 755 and 725 cm. -I bcconie sharper. When the sample is heated at 1000" the absorption at 815 cni. -1 becomes stronger on account of tlie formation of 0-alumina in addition to 6-alumina. At 1100" the absorption at 880 cm. -I caused by the presence of 8-alumina disappears, and the absorptions at 815, 760 and 720 cm. -I become sharp because of thc increase of 0-alumina. With further lieating the broad band below 970 cm.-l is shifted to a lower frequency : the broad bands of thc products heated at above 1200" are observed below 910 c m . 3 The absorption a t 720 c m . 3 of alumina obtained by heating at 1300" is sharper than that a t 1200", because the small amount of 0-alumina present in the 1200" product has disappeared at 1300". Thus, it is evident that the results of infra-red spectra are in good agreement with those of X-ray diffraction and show the characteristic patterns which correspond to the formation of different aluminas. Furthermore, from Fig. 2b it is found that the thermal transformation of boehmite obtained from bayerite is similar to that of boehmite prepared from hydrargillite.

Hence, it is concluded that boehniite prepared hydrothermally from hydrargillite or bayerite transforrns to a-alumina through the following sequence :

Uoehmite --f y-alumina + 8-alumina -.+ 0-alumina - t a-alumina 1 he transformation tcmperature of each stage is influenced by tlie particle propcrtics of boelimite used as sample.

,.

Government Chrnical Industrial l<csearch Institute, I lonniaclii, Shibuya-ku,

Tokyo, Japan licceivetl 12 May, 19Gl ; aiiiciicled iiiaiiuscript 31 J u l y , 1961

References ' Stumpf, H . C., liussell, n. S., Ncwsonie, J . W., Ji

Tucker, C. M., f m h t r . Engng C h m t . , 1951), 42, 1398

7 Inielik, H., l'ctitjcan, M.. & I'rettre, M . , C. fr'. Acrid.

8 Glemser, 0.. & Rieck. G.. z 4 ~ z ~ ~ c w . Chcm.. 1955, 67, Sci., Paris, 1953, 236, 1278

l h y , hl. I<. U . , & Hill, V. J., J . phys. Chenz., 1953,

a 'l'crtian, R., & I'apck, L)., C. li. Acud . Sci., Paris,

Tliibon, I{., Charricr, J . , & 'l'crtian, K., Bull. SOC.

Brown, J . P., Clark, D., & Elliott, W. W., J . chem.

I'rcttrc, M . , Inielik, U., 13lancliin, l , . , Ji I'etitjean, ill.,

57, 946

1955, 241, 1575

ch im . Fv,, 1951, p. 384

Soc., I9S3, 1'. 84

z4qqcw. Chcm., 1953, 65, 549

. . 652

Sato, T., J . up@. Chem., 1960, 10, 414 l o Sato, T., J . uppl. Chcm., 1959, 9, 331 l1 Sato, T., J . appl. Chem., 1961, 11, 207 l2 Frederickson, I,. D., jun., Anal?/l. Chem., 1954, 26,

13 Glemscr, O., & Hartcrt, E., Z . unorg. Chcm., 1956, 1883

283, 1 1 1 Ibcrg, R., Helv. chim. Actu, 1957, 40, 102

l5 Sliipko, 1;. J . , & Haag, K. M., U . S . i l l . Enirgy Commission, 1957, KAPI,-1740

MEASUREMENT OF DRAINAGE RATES OF HIGH-EXPANSION FOAMS

By W. THOMPSON

.A i i i(! t l iocl lor mt~asin-in~ tlic drainage rates of single liquid films by the ~ii~ivcnic:iit ( I [ ilitcrlcreiico fringcs is tltwxilxd. I t is sliowii that the cross-section of a fast draining film is wctlgr-shaped ancl so its average tliickness equals the thickness at its mid-height. Various tlc.grces of water hardness produced changes in the drainage rate uf a single film that were consistent with the changes produced in tlic drainage rate of high-expansion foam.

Introduction The standard laboratory methods for measuring the drainage rates of foams entail measuring

at intervals the quantity of liquid which collects beneath a sample of foam. These methods are

J. appl. Chem., 12, January, 1962