INDUSTRIAL AND ENGINEERING CHEMISTRY
July 1954
r
’
.I.j
s too
i
90
/
-
. 80
-
-
0
I
1
70 60 50 40 30 P E S D L ~ L CELLULOSE ~PERCENTI
PO
IO
0
Figure 5. Moisture Adsorption of Three Cellulosic Materials a s a Function of Extent of Hydrolysis At 27’ C. and 68.5% relative humidity. Asterisks indicate point at which all easily hydrolyzable material has been removed, as determined from Figure 2.
Davidson (5) and Nickerson and Habrle (16) previously observed the drop and rise in moisture adsorption short of the point at which limiting moisture uptake is reached. These workers explained the initial rapid fall in adsorption as being due to the removal of the more hygroscopic amorphous cellulose. Nickerson (16)then postulated that hydrolysis proceeds by lateral attack on the crystallites. This leads to FI dilemma in that such a mechanism requires a continuous increase in ratio of surface to volume with a corresponding continuous increase in moisture adsorption. Lateral attack can therefore explain the observed experimental data only to the point a t which about one half of the starting material has been removed. Crystallite size then appears to remain constant. Ranby (18, 19) has recently shown by electron micrograph studies that hydrolysis does result in an apparent limiting crystallite diameter of about 70 A. A partial explanation of the progress of the heterogeneous hydrolysis of cellulose can be formulated from the preceding facts. B s hydrolysis proceeds, amorphous material is rapidly removed, leaving the resistant portion in the form of more or less uniform crystallites. Further hydrolysis progresses by lateral attack until a definite crystallite size, characteristic of the starting material, is reached. When this limiting size is reached, further hydrolysis causes disruption of the crystallite. Hydrolytic attack is thus similar to enzymatic attack, where it has been shown that degradation goes to completion once attack is initiated ($4). Closer examination of Figure 5 , however, brings out the fact that all the celluloses studied have very nearly the same limiting moisture adsorption and hence apparently equal ratios of surface to volume, in spite of the fact that hydrolysis rates may vary as much as sevenfold. In addition, the hydrolysis rate for an individual material remains constant throughout the hydrolysis of the entire resistant portion, which would be unlikely if the changing mode of attack postulated above were followed. It thus appears that no simple concept of the progress of heterogeneous hydrolysis is adequate to explain all the data obtained in these experiments. LITERATURE CITED (1) Battista, 0. A., IND.ENG.CHEM.,42,502 (1950). (2) Bonner, W. D., and Branting, B. F., J . Am. Chem. SOC.,48, 3098 (1926). ENG,CHEM.,37, 592 (3) Conrad, C. C.,and Scroggie, A. G., IND. (1945).
1497
(4) Conrad, C. M., Tripp, V. W., and Mares, T., J . Phys and Colloid Chem., 55, 1474 (1951). (5) Davidson, G. F., J . Teztile Inst., 32, T132 (1941); 34, T87 (1943). (6) Foster, D. H., and Wardrop, A. B., Australian J . Sct. Research, A4, 412 (1951). (7) Foulk, C. W., and Hollingsworth, nl., J . Am. Chem. SOC., 45, 1220 (1923). (8) Hermans, P. H., and Weidinger, d.,J . Polymer Sci., 4, 317 (1949). (9) Howsmon, J. A., Teztile Research J . , 19, 152 (1949). (10) Ingersoll, H. G., J . A p p l . Phys., 17, 924 (1946). (11) Jorgensen, L., Acta Chem. Scand., 4, 185 (1950). Lovell, E. L., and Goldsohmid, O., IND.ENG.CHEDI.,38, 811 (1946). Mehta, P. C., and Pacsu, E., Textile Research J., 18, 387 (1948); 19, 699 (1949). Nelson, M.L., and Conrad, C. AI., Ibid., 18, 149 (1948). Sickerson, R. F., IND. ENG.CHEM.,33, 1022 (1941); 34, 85, 1480 (1942). Nickerson, R.F., and Habrle, J. A,, Ibid., 37, 1115 (1945).
Philipp, H. J., Nelson, 1cI. L., and Ziifle, H. M., Textile Research J., 17, 585 (1947). Ranby, B. G., Inaugural Dissertation, Stockholm, Sweden, 1952.
Ranby, B. G., TAPPI, 35,53 (1952). Roseveare, W. E., IND.ENG.CHEM.,44, 168 (1952). Roseveare, W. E., Waller, R. C., and Wilson, J. S . , Textile Research J., 18, 114 (1948). Saeman, J. F., IND.ENG.CHEW 37, 43 (1945). Saeman, J. F., Millett, M. A., and Lawton, E. J., Ibid., 44, 2848 (19521.
Siu, R. G. H., “Microbial Decomposition of Cellulose,” New York, Reinhold Publishing Corp , 1951. Staudinger, H., and Sorkin, N., Ber., 70B, 1565 (1937). Technical Association of Pulp and Paper Industry, Paper Trade J., 124-1,37 (1947). Ward, K., Jr., Tertile Rescarch J . , 20,363 (1960). RECEIVED for review October 16, 1853. ACCEPTED April 6, 1954. Presented before the Division of Cellulose Chemistry a t the 122nd Meeting of the AMERICANCHEMICAL SOCIETY, Atlsntio City, N . J. Work supported in part by Army Ordnance.
Equilibrium Temperatures and Compositions behind a Detonation W ave-Correction In the article on ‘‘Equilibrium Temperatures and Compositions behind a Detonation Wave’’ [IND.ENG.CHEM.,46, 1056 (1954)], several equations are in error. They should read:
PH20
=
Knpf;Po
PCO
=
Kispcpo
(17) (19)
PHZ= KzoP8 PO^ P C O ~=
(20)
K ~ I P ~ K~ZPCP$
I n the Nomenclature, the three definitions following P sure should read:
(21) (22) =
pres-
PH = defined in Equation 23
PO = defined in Equation 24 PO = defined in Equation 25 ALEXANDERWEIR, JR. RICHARD B. MORRISON
