Alpha-Celluloses from Different Wood Sources Ross AIKEN GORTNERAND JOHNJ. ILICNAIR University of Minnesota, University Farm, St. Paul, Minn. 2 kg. of chips and 10 liters of Eight diflerent woods were cooked with both cooking liquor. All woods were lose’’ has b e e n i n use sodium hydroxide and sodium sulfite, and the pulped with both sodium hydroxsince a t least 1895, for resulting pulps, after bleaching, were subjected ide and neutral sodium sulfite, Cross and Bevan (4) note that, to a series of successive alpha-cellulose deterthe concentration of these chemiwhen cellulose is treated with cals in the cooking liquors being minations. Each subsequent alpha-cellulose halogens and alkaline solutions, equal t o 25 and 45 per cent, re“the cellulose thus isolated is treatment indicated a lowered alpha-cellulose spectively, of the weight of the not homogeneous b u t is made content. V’hen plotted on coordinate paper, the bone-dry chips. The temperau p of a more resistant alphapercentages of alpha-cellulose in the pulp and ture was slowly raised to the and a less resistant beta-cellupulp residues f r o m successiae treatments fell on cooking temperature (170 ” for lose.” Sumerous methods (1, the hydroxide cooks and 183” approxima fely straight lines. The slope of these 3, 8, 11-13, 16, 17) have been C. for the sulfite cooks) over a proposed for the determination lines was characteristic of each pulp, indicating period of 2 hours, the relief valve of alpha-cellulose. The method that each pulp has its own characteristic angle being cracked a t 15-minute inused in these studies is essenof degradafion. The tangent of the angle of tervals to release gases and pretially t h a t recommended by degradation is proposed as a criterion of the vent the formation of a false Bray ( 2 ) , except t h a t a very pressure. The cooking temperaease of peptization of the cellulose micelles in dilute solution of ammonia was ture was maintained for 5 hours used for the final washing of the the pulp. Apparently both the botanical source in the case of the sulfite cooks alpha-cellulose r e s i d u e . The of the wood and the cooking procedure affect the and for 3 hours in the case of reason for this modification will tangent of fhe angle of degradation. The alphathe hydroxide cooks. (Since the be noted later. cellulose determination as used in the pulp and flax was already in the form of Practically no work has been retted fibers, i t was cooked for done on the effect of repeated paper industry is an empirical procedure, f o r only 2 hours a t 147” C.) At treatments of a pulp with 17.5 two pulps may show identical initial alpha-celluthe completion of the COO$ per cent sodium hydroxide solulose contents and yet be characterized by very the contents of the digester tion. Lenz, Pleus, and Muller different angles of degradation. were blown into a cyclone, and (9) have studied the effect of the resulting- -pulp reDeated t r e a t m e n t s on the - washed on amount and constitution of the beta-cellulose recovered and screens, that portion being retained which passed a 20-mesh find, in the case of cotton, a fairly constant yield after the and was retained on a 60-mesh screen. Following washing, first treatment and, in the case of soda pulps, a fairly con- the pulp was pressed to remove excess wash water and substant yield after the fifth treatment. However, they did jected to multiple-stage bleaching, using sufficient calcium hypochlorite bleach liquor a t each stage to equal 6 per cent not work with the alpha-cellulose residues. Most of the authorities seem to feel, with Hawley and Wise of the oven-dry weight of the pulp as available chlorine. ( 7 ) , that “the question (the identity of alpha-cellulose from Bleaching vias carried out at 40” C., allowing 30 minutes for wood and normal cellulose from cotton) is still a n open one each treatment. Bleaching treatments were continued until with preponderating experimental evidence in favor of the a thoroughly white pulp was obtained, thus insuring a nearly chemical identity of the larger part of the substance of alpha- complete removal of lignin residues. The thoroughly washed, cellulose of mood with alpha-cellulose isolated from cotton.” bleached pulps were then dried a t 65” C. to a moisture conWhile this is true, the question arises: Are they physically tent not exceeding 6 per cent, and Ftored for use. DETERMIK.4TIOS OF ALPHA-CELLULOSE. It was found identical, either in size of micelle or strength of secondary impossible to secure concordant results for successive alphavalences? cellulose determinations with either the standard method recommended by the Alpha-Cellulose Committee of the EFFECTOF SODIUMHYDROXIDE TREATMEXTS AMERICAS CHEhfICAL SOCIETY (11)or the method described by The purpose of this investigation was to deter- Bray ( 2 ) . Using either method, the initial alpha-cellulose PROBLEM. mine the effect of repeated treatments with 17.5 per cent determination on the original pulp was easily carried out and sodium hydroxide solution on pulps from different sources. duplicate determinations were concordant. When, however, MATERIAL.Eight woods were chosen: white birch the residues from these initial determinations were combined (Betula papyrifera), aspen (Populus treniuloides?, balsam fir and subjected to a second alpha-cellulose treatment, it was (Abies balsamea), tamarack (Lariz laricina), white spruce found that the pulps in the mercerizing solution in many in(Picea glauca), jack pine ( P i n u s banksiana), Xorway pine stances were gummy, and filtered and washed slowly, and (Pinusresinom), and white pine ( P i n u s strobus ). Enzyme- that the weights of the residues were not concordant. The retted flax fiber was also used in order to include a cellulose gummy consistency of the mokt residues and the discrepancies between duplicates increased with each successive alphafrom some qource other than the lignocelluloses. P R E P A R A TOFI O PULPS. ~ The various n-oods were chipped cellulose treatment. Typical results of repeated alphain a commercial chipper and the chips \%-erecarefully screened cellulose determinations are recorded in Table 11. to remove all sawdust, knots, dirt, and oversized chips. Several experiments were undertaken to ascertain what They were then pulped in a jacketed, indirect-steam, semi- factors might be responsible for the irregular results, and i t commercial digester. The charge consisted of approximately was finally found that incomplete removal of adsorbed acetic
T
HE term “alpha-cellu-
505
I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R k'
506
8 to 10 drops of concentrated ammonia. The fiber suspension was again filtered through the crucible, washed with 500 cc. of cold water, dried for 9 hours a t 105' C., cooled, and weighed. The alpha-cellulose residues from the first treatment were
0 I\
0
.
-
B/rch
0
i
Vol. 25, No. 5
/
No A/phs-Ce//u/ose
2
3
4
Teahen/&
5
6
done in the laboratories of the Northwest Paper Company. CROSS AKD BEVAN CELLULOSEDETERMIXATIONS. In order to determine whether there was any correlation between
acid from the cellulose fiber in the final washing was r e s p o n s i b l e . Although the final wash waters were neutral to m e t h y l r e d , and although further washing with hot water did not remove additional acetic acid, nevertheless traces of acetic acid remained adsorbed on the fibers, and, in the drying p r o cess, this acid brought about a pronounced degradation of the cellulose, resulting in the formation of gums in the mercerizing solution. If, after washing with hot water, the alphacellulose residues were given a final washing with water rendered FIGURE2. EFFECT OF REPEATEDALPHACELLULOSE TREATMENTS ON PULPSFROM Soslightly alkaline with DIUM HYDROXIDE COOKS ammonia, no difficulty Data graphed on pulp recovery. was exDerienced with gum formation, and successive alpha-cellulose determinations gave concordant results. Figure 1 shows graphically the effect of this ammonia treatment on repeated alpha-cellulose determinations. The following method was finally chosen for the alphacellulose determinations: One gram of oven-dry pulp was placed in a beaker and triturated with 25 cc. of 17.5 per cent sodium hydroxide solution until the mass was homogeneous. It was then allowed to stand for 30 minutes. The contents of the beaker were then filtered by suction through a No. 3 fritted-glass Jena crucible (porosity 5-7). When all of the liquor had been removed, the mat was broken up with a glass rod and washed first with 50 cc. of 4 per cent sodium hydroxide solution, followed by washing with 300 cc. of cold water. The pad was then further washed with 7 5 cc. of hot 10 per cent acetic acid followed by 300 cc. of hot water. The pulp was removed from the crucible, the pad thoroughly disintegrated, and the fibers stirred with 500 cc. of water containing
of cooks (the pulps with the lowest and highest rates of alpha-cellulose degradation and one with a rate near the average) were analyzed for Cross and Bevan cellulose according to the method given by Bray ( 2 ) . A minimum of 98.82 per cent Cross and Bevan cellulose was found in Norway pine pulp cooked by sodium sulfite, the other pulps tested ranging from 99.07 to 99.44 per cent Cross and Bevan cellulose. EXPERIMENTAL D A T ~ . The experimental data are given in Tables I t o V and shown graphically in Figures 1 to 5, inclusive. All alpha-cellulose determinations were made with the final ammonium hydroxide wash, unless otherwise designated. Table I gives the cooking data, as well as the yields of pulps of the various cooks. Table I1 gives the data obtained on treating
Woods .&/ped W / A Ns
Oh'
-
\f/sx
Aspen
e
/
No. o f Testmenfa
2
3
4
-
5
FIGURE3. EFFECT OF REPEATEDALPHACELLULOSE TREATMENTS ON PULPSFROM SODIUM SULFITE COOKS Data graphed on pulp recovery.
I N D U S T R I A L .4ND E K G I N E E R I N G C H E M I S T R Y
&lay, 1933
507
-1 b
,
No,Subsequenf 2 3
Zeahi7enf5 4 5
z
FIGURE5. EFFECT OF REPEATEDALPHACELLULOSETREATMENTS ON PULPSFROM SoDIUM SULFITECOOKS
FIGURE4. EFFECT OF REPEATEDALPHACELLULOSE TREATMENTS ON PULPS FROM S O DIUM HYDROXIDE COOKS D a t a graphed on alpha-oellulose recovery.
Data graphed on alpha-cellulose recovery.
birch, aspen, and jack pine sodium sulfite pulps with a series of alpha-cellulose treatments without the ammonium hydroxide wash. Figure 1shows the results obtained with birch and aspen pulps, with and without the ammonirt treatment. Tables I11 and I V together with Figures 2 and 3 give the results of the repeated treatments of the different pulps with 17.5 per cent sodium hydroxide solution. Figures 4 and 5 show the data obtained when the yields were calculated on the basis of the first alpha-cellulose being 100 per cent. The data were calculated thus to determine the effect of repeated treatments on alpha-cellulose itself rather than on original pulps.
Table V gives the pulps in order of decreasing alpha-cellulose content in the original pulps, in comparison with decreasing resistance to repeated alpha-cellulose treatments and the corresponding maximum bursting strength and tear resistance of experimental sheets. The resistance of each pulp was found by determining the angle formed by its curve, in Figure 2 or 3, with the horizontal. The tangents of the angles were determined by the method of least squares as given by hIellor (IO). Table I1 and Figure 1 show that there is pronounced degradation of the cellulose when the alpha-cellulose pads are dried following treatment with acetic acid. This degradation
DATAAXD YIELDSOF PULPS TABLEI. COOKING
-
-TIME-
NaOH AS
TazCOaa
To reach cooking temp. Hours 2 2
-TIME-
At
cooking temp. Hours 3 3 3 3 3 3 3 3
COOKING TEMP.
AS
YIELD^
NazCOP
%
C. 170 170 170 170 170 170 170 170 147
Hours
38.12 35.80 36.40 27.30 32.40 38.95 37.95 33.70 68.33
38 38 38 38 38 38 40 38 15.75
2 2 2
2 2 2
2,
Birch
TREATMEIT 1 % ..
2 % .. 72.25 71.50 64.70
1st 72.79 2nd 71.41 3rd 64.42 4th 40.94 ... Aspen 1st 73.12 73.04 2nd 55.52 55.84 3rd 57.54 57.37 4th 70.26 ... Jack pine 1st 81.22 80.84 2nd 24.10 32.50 a Crucibles plugged because of gums formed.
3
4
5
RECOVERY 6
7
%
%
%
7%
72.14 71.15
72.84 71.75
72.71
72.33
... ...
... ... ...
... ...
... ... ...
72.91 55.26 56.83
73.05 55.97
73.24 55.78
73.19 55.71
73.01
...
80;81
81.08 35.90
... ...
...
.... ..
... ...
81027
5
0.25
TABLE11. RESULTSO F REPEATED ALPHA-CELLULOSE DETERMINATIONS ON S O D I C M PULP
At cpoking temp. Hours 5 5 5 5 5 5 5
To reach cooking temp,
NazS01
Total % Hours Aspen 33 5 Spruce 33 5 7 5 J a c k pine 33 7 5 Balsam 33 Birch 33 2 5 White pine 33 2 5 3 Tamarack 35 5 Norway pine 33 2 5 2 2.25 Flax 13.25 0.25 0 Calculated on basis of oven-dry weight of chips. %IlTERlaL
SODICMSULFITECOOKS
SODIUM HYDROXIDE Cooxs
70
...
2
SCLFITE
8
%
...
...
...
...
... ... ... 72.86 ... ... ...
80.97 38.56
80.84
80.96
...
...
...
...
Total Hours 7 7 7 7 7 7 7 7 2.25
PULPS, 9
%
... ... ...
...
72.90
... ... ...
.... ..
COOKING TEMP.
YIELDO
c.
%
183 183 183 183 183 183 183 183 147
41.90 36.75 36.00 42.40 37.95 52.85 37.95 36.10 76.67
AMVONIA
WITHOUT
PBRCENTAGE ORIGINAL PCLP
. OF
$yerage
% 72.51 71.45 64.56 40.94 73.04 55.68 57.25 70.26 81.00
...
72.51 51.81 34.10 13.96 73.04 40.67 23.28 16.36 81.00
...
I N D U S T R I A L A N D E S G I S E E R I N G C H E M I S T R I'
508
Vol. 2 5 , No. 5
TABLE111. RESULTS OF REPEATED ALPHA-CELLULOSE DETERMINATIOXS ON SODIUM HYDROXIDE PULPS PULP TREATMEXI Birch
Jack pine
Flax
Spruce
Aspen
Tamarack
Balsam
Norway pine
White pine
let 2nd 3rd 4th 5th 6th 1st 2nd 3rd 4th 5th 6th 1st 2nd 3rd 4th 5th 6th 1st 2nd 3rd 4th 5th 6th 1st 2nd 3rd 4th 5th 6th 1st 2nd 3rd 4th 5th 6th 1st 2nd 3rd 4th 5th 6th 1st 2nd 3rd 4th ,5th 6th 1st 2 nd 3rd 4th 5th 6th
--1
~
~
~
2
3
4
%
%
%
%
72.68 85.36 91.13 91.53 90.77 92.33 80.48 94.90 95.30 96.12 97.01 97.41 86.71 94.97 96.40 96.62 95.24 97.61 76.65 93.77 95.80 96.63 96.42 97.14 80.37 93.18 96.76 95.41 96.29 92.11 85.01 90.65 94.00 95.60 95.54 95.70 73.67 89.28 92.31 94.16 95.44 96.53 78.86 94.45 95,39 97. 16 97.09 96.82 65.30 91.03 94.72 97.22 96.79 97.22
72.44 86.42 90.62 92.20 90.26
72.54 86.53 90.86 92.32
72,63 86,06 90.95
...
... ...
80.42 94.03 95.74 96.95 97.40
80.82 94.12 96.05 96.62
RECOVERY 5
~
7
8
%
%
%
%
%
72.52 86.14
71.93
72.54
72.57
...
..
... ...
... ... ...
...
81.12 94.32 95.83
80.73 94,59
80.84
...
... ...
...
72.46 86.10 90.89 92.02 90.52 92,33 80.75 94.39 95.73 96.56 97.21 97.41 86.92 95.60 96.75 96.77 95.11 97.61 76.50 93.63 95.85 96.93 96.61 97.14 80.13 93,27 96.38 95.06 96.34 92.11 84.39 90.44 94.26 95,55 95,79 95.70 72.35 89.53 92.79 94.33 95.66 96.53 78.62 94.39 95.65 96.82 97.15 96.82 65.59 91.52 95.07 97.00 96.83 97.22
...
...
...
...
...
...
...
... ...
80 83
...
... ... ...
. .
...
87.27
87.23
... . .
...
...
76.14
76,49
... ...
...
... ...
86,53 95.77 96.95 96.74 94.98
86.54 95.74 96.78 96.95
86.69 95.94 96.86
87.44 95.57
...
... ...
... ... ...
... ... ...
... . . ... ...
76.95 93.73 96.39 97.23 96.80
76.40 93,51 95,38 96.92
75.82 93.59 95.84
77.03 93,55
...
... ... ...
... ... ... ...
... ... ... ... ...
79.93 92.90 95.88 94.80 96.39
79.86 93.40 96.10 95.07
80,73 93.29 96.78
79.81 93.56
80.13
80.10
...
...
... ...
84.25 90,77 94.39 95,38 96.03
84.83 89.89 94.03 95.66
83.76 90.40 94,62
84.23 90.49
...
...
...
...
...
...
...
...
...
...
...
...
...
,..
...
... ,
.
... ... ... ,..
... ... ...
...
... ... ... ...
...
,..
...
...
83.95
. .
... ... ...
... ... ...
... ... ...
72.26
73,07
. .
... . .
... ...
... ,..
73.06 89.94
...
... ...
...
... . .
, . .
...
...
78.96 94.30 95.76 96.41 97.21
78.66 94.15 95.79 96.89
i8.95 94.58 95.65
78.52 94.48
7S.41
78.28
...
66.97 92.04 95.08 97.22 96.86
69.46 89.47 92.85 94.53
... ...
65.10 91.53 95.99 96.55
... ,
.
...
,..
...
...
...
...
... ... ...
...
65.63 91.49 94.48
65,23 91.52
... . . . .
appears to be caused by a very sinal1 amount of acetic acid remaining adsorbed upon the fibers and being held so firmly t h a t it cannot be removed by washing with hot water. A final washing with slightly ammoniacal water neutralizes this acid and prevents its harmful action. K h e n , therefore, the residue of a n alpha-cellulose treatment is to be retained for further studies, or whenever a pulp has received an acid treatment of a n y kind, i t would appear to be advisable to wash the pulp with very dilute ammonia before drying. When this investigation was begun, it was thought that each pulp would lose diminishing amounts on repeated treatments until finally a practically insoluble residue would result. This would give a parabolic curve rather than a straight line. Figures 2 and 3 show that, except for experimental variation, straight lines are obtained. This seems to dispose of two theories: (1) t h a t alpha-cellulose is insoluble in l i . 5 per cent sodium hydroxide solution, and (2) that alpha-cellulose is less and less soluble until finally an insoluble residue is obtained. From these data, moreover, we have an indication that alpha-cellulose from different sources is not the same, since the slopes of the various curves differ. This is shown more clearly by Figures 4 and 5 , giving the losses suffered by alpha-cellulose after repeated treatments. I n these figures the curves are farther apart, and it is obvious that the slopes differ greatly. It may be argued, however, that more than one alpha-cellulose treatment is necessary to remove the soluble material; this is true, especially in the case of the sodium hydroxide pulps. A study of the data
,..
...
. . ...
. .
84.68
73.60 90.46 92.89
71.36 88.51 93.12 94.29 95.87
--
6
...
... ... ...
...
. , ,
...
..,
... ... ...
... ... ...
... ...
65.83
65. 09
,.. , . .
. .
...
...
Average
PERCEXTAGE OF ORIGIXAL PULP
72.46 62.39 511.71 52.18 47.23 43.61 80.75 26.22 13.97 71.47 69.43 67.63 86.92 83.09 80.39 27.79 13.99 72.22 76.50 71.63 68.66 66.55 64.30 62.46 80.13 74.73 72.03 68.47 65.97 60.76 84.39 76.32 71.94 68.74 65.84 63.01 72,35 64,78 60.11
56.70 54.24 52.36 78.62 74.37 71.13 68.87 66.91 64.78 65.59 60.03 57.07 55.35 53.59 52.10
sho~vsthat, in the case of sulfite pulps, one alpha-cellulose treatment is sufficient to remove the soluble material, and the rest of the treatments show practically the same yield; the hydroxide pulps, however, require two treatments to remove the soluble material, indicating that the sodium hydroxide has a much more destructive action on the cellulose. The angles formed with the horizontal by the curves in Figures 2 and 3 may be taken as a measurement of the resistance to degradation. The tangents of angles are given in Table T'. I n each series of pulps the largest angle (showing the greatest amount of degradation) is a t least twice the magnitude of the smalled. This fact alone may be considered a proof t h a t alpha-cellulose from different sources is not reacting in an identical fashion. A further study of the data s h o m t h a t there is no relation between fiber dimensions and either the original alpha-cellulose content of the pulp or the extent to Tvhich the cellulose is degraded by successive alpha-cellulose treatments. Instead of the alpha-celluloses from different mood sources having the same resistance to mercerizing solutions, each alpha-cellulose has its own characteristic angle of degradation which may or may not coincide with that of another. This is somewhat analogous to protein peptization (5, 6, 14, 15) and indicates that the alpha-cellulose procedure not only removes impurities (beta- and gamma-celluloees) but either that it degrades a part of the true cellulose micelles, forming further amounts of hydrocelluloses, oxycelluloses, etc., which are removed when the system is given a further alpha-cellulose treatment, or that
I N D U S T R I A L AN D E N G I N E E R I N G C H E M IST R Y
Mal-, 1933
TABLE IV.
509
RESULTS OF REPEATED ALPHA-CELLCLOSE DETERMINATIOXS ON SODIUM SULFITE PULPS PERCENTAOE O F
Aspen
Birch
Jack pine
Spruce
Tamarack
White pine
1st 2nd 3rd 4th 5th 1st 2nd 3rd 4th 5th 6th 1st 2nd 3rd 4th 5th 6th 1st 2 nd 3rd 4th 5th 6th
1st 2nd 3rd 4th 5th 6th 1st 2 nd 3rd 4th 5th 6th
1
2
3
4
5
6
7
8
Average
%
%
%
%
%
%
%
%
%
74.11 92,99 93.04 93.11 89.23 73.94 96.15 95.53 95,06 93.89 91.88 80.78 96.28 97.07 96.47 96,60 96. 85 82.63 96,75 96.83 9 i . 07 96.96 96,85 87.55 95.66 96.40 95.34 96.45 94.90 72.63 94.14 94.35 93.64 95.24 92.94 81.60 95.13 96,20 95,24 94.92 94.58 77.78 94.37 95,68 94.27 95.17 94.74 73.21 91.26 92.25 92.00 93.08 93.34
73.64 92.55 93.17 93.28
74.05 92.17 93.49
73.62 92.83 92.83
73,78 92.25
i3.69
74.08
73.73
...
... ... ...
73.56 96.12 94.62 94.04 93.10
73.41 95.41 95.24 94.51
73.68 96.25 95.37
73.69 95.37
...
... ...
... ... ...
81.43 96.02 96.97 96.83 95.88
81.33 96,06 97.17 97.06
81.03 95.19 97.14
...
...
82.36 96.51 96.69 97.03 97.03
73.84 9 2 . 56 93.13 93.20 89.23 73.59 95.86 95.19 94.54 93.50 91.88 81.04 95.84 97.09 96.79 96.24 96.85 82.79 96.65 96.53 97.22 97,OO 96.85 87.66 95.56 96.50 95.55 96.59 94.90 72.86 94.25 93.95 93.91 95.31 92.94 81.76 95.34 95.75 95.84 94.86 94.58 77.64 94.71 95.28 94.89 95.21 94.74 74.46 91.78 93.12 92.34 93.06 93.34
...
... ...
...
... ...
.,.
...
80.89 95.63
...
...
,
.
I
... ...
... ...
...
...
73.19
73.60
73.65
, . .
...
, . .
... ...
... ... ... ... ...
...
...
...
SO. 88
80.93
... 82.77
...
... ...
... ...
... ... ...
... ... ... .,.
82.35 96.63 96.86 97.57
83.14 96.73 95.74
83.06
83.24
...
... ...
...
...
...
...
...
... ...
... ... ...
87.71 95.62 96.51 95.32 96.72
87.61 95.43 96.65 95.99
87.55 95.01 96,45
87.66 96.09
87.57
87.95
...
72.77 94.11 94.04 94.23 95.37
...
...
81.50 95.15 95.61 96.32 94.80
81.83 95.58 95.53 95.97
81.84 95.49 95.67
... ...
... , . . ...
77.66 94.83 95.33 95,03 95.25
78.01 95.01 95.20 95.36
77.34 94.81 94.90
...
...
...
...
...
...
...
...
... ...
...
...
... ... ...
... ... ... ...
... ...
72.88 94.07 94.05 93.91
72.49 94.46 93.37
72.67 94,45
72.92
...
...
...
...
... , . . ...
... ... ... ...
...
, . .
...
... ,..
... ... ... ...
... 73,66
... ... ... ...
...
... ...
82.18
81.61
... ...
... ... ...
... ... ... ...
77.66 94.55
78.01
77.05
...
... ...
... ...
...
... ... ...
...
... ...
...
. .
...
... ...
... ... ...
... ...
... ...
...
74.17 92.39 93.27 93.06 93.03
74.33 91.13 93.57 91.96
74.49 91.78 93.40
75.16 92.33
74.84
75.01
...
, . .
...
...
... ...
the cellulose micelles differ from wood to wood and from pulp t o pulp in their ease of peptizability in alkaline solution. These studies indicate that alpha-celluloses from different wood sources and prepared from pulps by two different cooking treatments are not physically identical. It is difficult with the data a t hand to say how much of the observed differences is due to the wood source and how much to th(3 pulping process; however, the data do show that either the size of the cellulose micelles or the secondary valences holding the cellulose units together within the micelles differ from pulp to pulp. The authors believe that the tangent of the angle of degradation may he a valuable criterion in evaluating the colloid chemical behavior of a given cellulose sample. The data given in Table V show definitely that there is no correlation between either alpha-cellulose content of the original pulp or rate of degradation due to repeated alpha-cellulose treatments, and strength of pulp as shown by bursting strength and resistance to tear. This indicates that increased alphacellulose content does not necessarily mean increased paper strength, in spite of the fact that claims of that sort have been made. SUMJIARY
Alpha-cellulose determinations, as used in the pulp industry, do not appear to have been subjected to an intensive study having as its aim the question of whether or not alpha-cellulose is a distinct entity and whether or not alpha-celluloses from different woods are identical in chemical and physical properties.
,.
,..
...
...
...
...
... ... ...
...
...
...
... , . . ...
,..
...
...
... ... ...
... ...
... ... ... ... ... ... ...
...
... ...
... ... ... ,.. , . . , . .
... ,.. ... ... ... ... ... ... ... ... ... ... ... ...
...
... ... ...
... ... ,..
ORIGINAL PULP
73.84 68.35 63.66 59.33 52.94 73.59 70.54 67.15 63.48 59.35 54.53 81.04 77.67 75.41 72.99 70.25 68.04 82.79 80.02 77.24 75.10 72.85 70.56 87.66 83.77 80.84 77.24 74.61 70.80 72.86 68,67 64.52 60.60 57.76 53.68 81.76 17.95 14.64 71.54 67.87 64.19 77.64 73.54 70.07 66.49 63.31 59.98 74.46 68.34 63.64 58.76 54.68 51.04
Eight woods-spruce, jack pine, white pine, Sorway pine, tamarack, birch, balsam, and aspen-were pulped with sodium hydroxide and with sodium sulfite cooks under essentially commercial conditions. Flax was included in both series in order to have a cellulose source other than wood. TABLE5'.
COMPARISOS O F .4LPHA-CELLULOSE COSTElr'TS O F ORIGINAL PULPS, ASD TA\GESTO F h G L E O F DEGRADATIOS WITH hhXI>fCM BURSTING STRENGTH ASD TEAR REsIST4NCE O F EXPERIMENTAL SHEETS
COOK
~ZATERIAL
TANGEXT OF XkX. ANGLEOF TEAR PCELLU- DEGRADA- Alax. BURST- HERISTL08E TIOS IXOSTREXGTH h S C E " Points per 15. G'rams % ( p e r ks.)
NaZSOa
NaOH
Flax Spruce Tamarack Jack pine White pine Balsam Aspen Birch S o r w a y pine
1 . 2 0 (0.544) 0 . 6 4 (o.29nj 1 . 2 1 (0.549) 1 . 1 8 (0.535) 0 . 7 6 (0.345) 0 . 6 1 (0.277) 0 . 9 5 (0.431) 0 . 5 2 (0.236)
i40 199 136 216 223 75 114 118
Flax Tamarack Jack pine Aspen N o r u a y pine Spruce Birch Balsam White pine
86.92 0.295 84.39 0.404 0 . 5 4 (0.245) 13'6 0.253 80.75 0.80 (0.363) 183 0.362 80.13 0 . 4 9 (0,222) 112 0.271 78.79 0 . 67 n. 6 5 (0.295) (0.304) 95 (6.50 0.269 154 0.555 72.46 0 . 4 4 (0.200) 147 72.35 0.386 0 . 4 2 (0.191) 140 65.59 0.255 0 . 5 1 (0.231) 95 a Using Elmendorf tearing tests under t h e official conditions [cf. Paper Testing Methods of Technical Association of Pulp and Paper Industry Ti, Y., pu. 68-72 (1928) 1: The results shall he computed in grams per singie sheet of paper b y multiplying t h e reading of t h e instrument by 16 and dividine by t h e number of eheets tested a t one time."
_ _
5. 10
1 N D U S T I< 1 A L A X D E N G I N E E R I N G CII E M 1 S T H Y
Following the isolation of the pulps, tlrcy were dried in a uniform manner and then subjected to a st.aiidard treatment for the estimation of the alpha-cellulose content. Seven (or more) initial alpha-cellulose determinations were made. The alpha-cellulose residues from these %-erecombined, and a series of second alpha-cellulose determinations was carried out. The residues from these were coinbined, and a third series of alpha-cellulose determinations wm made, and so on until all of the pulps had been subjected to six successive treatments for alpha-cellulose. The data support the following conclusions: 1. When a pulp is treated with 17.5 per cent sodium hydroxide in the usual dpha-cellulose method, and the find wash water is slightly acidified with acetic acid to insure the removal of the lnst traces of alkali, traces of acetic acid remain adsorbed on the moist cellulose fibers. 2. When such moist cellulose is dried, the adsorbed acetic acid is concentrated in the residual water film and causes a pronounced degradation of the cellulose, so that a second alphacellulme treatment does not indicate the true physical state of the cellulose fibers. ' 3 . A final washing with water, made faintly alkaline with ammonia, neutralizes the adsorbed acetic acid and yields B residual cellulose which does not suffer marked degradation during the drying procees. Such a final washing is recommended whenever oellulose is to be dried, following any acid treatment of the
Vol. 25, KO. 5
9. It is evidont that the single alpha-eeliulose determination as used in the pulp and paper industry is an empirical rocedure. 10. Cellulose from different woads may be idonticarin chemical composition, but the pulps certainly differ greatly in calloidal behavior. 11. The colloidal behavior of the various pulps, in so far as their peptizability is concerned, s u g w t s thst the same colloidal phenomena are operating in the c&se of the cellulose micelle as have been observed in the protein systems previously studied in tliis laboratory. 12. The alpha-cellulose content of ti pulp does not appear to have Q determining influence on the resistance to tes, or the bursting strength of pa er m d e from the pulp. 13. The Cross and %cvan cellulase content of s pulp is not directly related to the alpha-cellulase content. 14. All of the above conclusions were drawn from single cooks of each wood. They are accordingly subject to modification if and when a series of cooks i s studied.
ACXNOWLEDGMENT The authors are indebted to the Northwest Paper Company, Cloquet, Minn., for advice and for the use of their equipment in the chipping, pulping, and bleaching of these experimental cooks.
LITERATGI~E CITED (1)
Herggvist, R..Pulp & Paper Mag. Can., 28, 5lE-16, 548. 5.50
~.""",.
,101"\
( 2 ) Bray, M. W.. Paper Trade J . . 87. No. 25,69-68 (1928). (3) Bray. hf. W.,and Andmws, T.hf., IND.EKO.C ~ E M 15, . , 377-8 (1923) (4) Cross,
C. F.,and Bevan, E. J., "Ceilulose," p. 93, Longmans.
1895.
(5) Gort.ner, It. A,, Hoffman, W. F.. and Sinolair. W. D.. Cere01 Ciiem.. 6 , 1-17 (1920). (6) Gonner. R. A.. Hoffman, W. F..and Sinclair. W. B., Colloid Svmposiunr Munomzph, V, 17WW (1928). (7) Hawiey. I,. F.,and Wise. L. E., "Chemistry 01 Wood," p. 148, Chemicd Catalog, 1026. (8) Jentgen. H., K u m t s l o f f e , 1. 165 (1011). (9)Lenu, F.. Plciis, B., and Moiler, J., J . pmkt. Cheni., 101, 21364 (lV20). (10) . , Melior. .J. XV... "Hiciier .~ Mathematics for Stu
