NBSIR 80-1970

The Cellulose-Water Interaction

in Rag and Wood Pulps

Polymer Science and Standards Division

Center for Materials Science

National Bureau of Standards

Washington, D.C. 20234

Progress Report Covering the Period

Oct. 1, 1978 through September 30, 1979

February 1 980

Prepared for Bureau of Engraving and Printing

U.S. Department of the Treasury

Washington, D.C. 20401

E. L. Graminski and E. E. Toth

NBSIR 80-1970

THE CELLULOSE-WATER INTERACTION

IN RAG AND WOOD PULPS

E. L. Graminski and E. E. Toth

Polymer Science and Standards Division

Center for Materials Science

National Bureau of Standards

Washington, D.C. 20234

Progress Report Covering the Period

Oct. 1, 1978, through September 30, 1979

February 1 980

Note: This document has been prepared for the use of the

Bureau of Engraving and Printing. Responsibifity for its further use rests with that agency.

Prepared for Bureau of Engraving and Printing

U.S. Department of the Treasury

Washington, D.C. 20401

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

O X

Contents

Page

I. Summary 1

II. Introduction 2

III. Experimental Details 4

A. Fiber Saturation Point

B. Determination of Bound Water

C. Pulp Samples

IV. Results and Discussion 7

V. Conclusions 10

VI. Acknowledgement 11

VII. Bibliography 12

I. Summary

The interactions of water with cellulose are of fundamental importance

in papermaking and it is essential to know such basic information as how

much water is inside the cell wall, how the amount changes throughout the

various papermaking stages, and what changes occur in the cell wall structure.

It has only been about 10 years since some basic information on the cellulosewater interaction has been acquired, however, the studies have been conducted

almost entirely on wood and wood pulps.

The mechanical properties of paper are determined in large part by its microstructure which, in turn, is influenced by the cellulose-water interaction during

the pulp preparation stages in papermaking. Rag papers frequently have superior

mechanical durability to wood pulp papers and it is possible that the difference

in durability between rag and wood pulp papers is derived from differences in

microstructure. The development of basic information on the cellulose-water interaction of rag and wood pulps could result in the identification of the parameters

affecting the durability of paper. This information would be valuable in the

design of durable papers from less expensive, readily available papermaking pulps.

Two different cellulose-water interactions were measured: 1) bound water

which is a measure of the accessibility of water to cellulose and 2) the fiber

saturation point (FSP) which is the total amount of water within pulp fibers

in equilibrium with excess water. Bound water was determined by the non- freezing water technique on a sensitive differential scanning calorimeter.

The FSP was determined by the solute exclusion principle using dextran, having

a narrow molecular weight range of 2 x 10°. The difference between the FSP

and bound water was considered to be free or bulk water. The ratio of free

to bound water was considered to be a measure of fiber swelling.

Water has a much greater accessibility to wood pulps than to cotton. In

addition, the free water to bound water ratio (F/B ratio) is much lower for cotton

than for wood pulps indicating a much lower fiber swelling in cotton. On beating,

the bound water in wood pulps remains unchanged, but an appreciable increase

is observed in cotton. An increase in FSP occurred during beating for all the

pulps investigated. The F/B ratio for beaten cotton is considerably lower

than the F/B ratio for unbeaten wood pulps. The F/B ratio for fractionated

currency machine stock varies with each fraction, being lowest with the longest

fiber fraction and highest in the shortest fibers.

The accessibility and affinity of water for cellulose in cotton appears

to be much lower than in wood pulps. This implies that interfiber bonding

in cotton paper should be much lower than in wood papers. Nevertheless, the mechanical

properties of rag papers are frequently superior to those of wood pulp papers

suggesting that the mechanical properties are derived from a quite different

microstructure. This unique microstructure could be responsible for the

excellent durability of currency paper.

Development of basic information on the cellulose-water interaction of

wood pulps would be very useful in establishing the criteria for paper durability.

In addition, microscopic investigations of rag and wood pulps would assist in

the identification of structural differences between rag and wood papers. Such

basic information could lead to the design of a paper with less expensive,

readily available, paper pulps.

1
II. Introduction

Pulp fibers are treated mechanically (beating, refining) prior to papermaking in order to obtain paper with a higher density, increased strength,

improved formation and a number of other physical properties. During mechanical

treatment, a number of changes occur in the pulp fibers which contribute to

the modifications of paper properties. Numerous studies, both microscopical

as well as physico-chemical, have been conducted to determine just what

changes occur in the fibers. Of prime interest are the changes which take

place within the cell wall of pulp fibers, however, a lack of experimental

techniques has been an obstacle to progress.

It has been theorized that during beating, lateral bonds between neighboring

lamellae in the cell wall are broken allowing water to enter, enabling the

lamellae to slide past one another and results in increased fiber flexibility

(1). Evidence that some such process occurs is considered to be substantiated

by the fact that during beating, pulp fibers become more flexible, collapse more

easily, and disintegrate into sheet-like films or debris. Unfortunately,

details of the process are lacking. There is great difficulty in examining

the interior of the cellulose-water gel in the presence of water and in the

ability to follow the structural changes during mechanical treatment.

Most methods for examining the structure of a porous system are applicable

only to dry materials. Consequently, fibers were dried by freeze-drying and by

solvent-exchange in order to obtain dry fibers with the same porous structure as

in the water-swollen state. When it was found that the swollen structure

of pulps was only partially preserved by either of the drying methods (2),

a search was made for new methods of investigating the water swollen structure

of pulps in the presence of water.

One method was developed for determining pore size distribution in wet

fibers which evolved from earlier work on "nonsolvent water" (3). The

technique was termed "solute exclusion". The "solute exclusion principle"

consists of equilibrating a sample of wet pulp containing a known quantity

of water with an aqueous solution of polymeric molecules of known hydrodynamic

size and known concentration. The solute molecules then diffuse into all

the water associated with the fibers except for the water contained in pores

of narrower widths than the solute molecules. The solution becomes more

dilute but only to the extent that the solute molecules can diffuse. From

the resultant change in concentration it is possible to calculate the amount

of inaccessible water.

If the polymeric solute material is high in molecular weight and the

hydrodynamic molecular size exceeds the largest pore size of the fibers, then

the total amount of water contained in the fibers can be calculated. For all

intent and purposes dextran, of molecular weight 2 x 10, has the appropriate

molecular size to meet the requirements to be totally excluded from the fiber

pores. Furthermore, dextran is available in a narrow range of molecular

weight fractions. The total amount of water, within pulp fibers in equilibrium

with excess water, is known as the fiber saturation point (FSP).

Part of the water within moist cellulose fibers exhibits properties which

are markedly different from those of the rest of the water and is referred

to as bound water. Apparently bound water is attached to the surfaces of

cellulose by hydrogen bonding and consists of one or more layers of water. The

structure and thermodynamic properties of bound water are significantly different

from free or bulk water. While its existence has been recognized for some time,

quantitative measurement of bound water has led to disagreement as to its

exact quantity in various materials. Numerous methods have been used to determine

2
bound water in cellulose such as solute exclusion, non-solvent water, non- freezing water, rate of cooling, rate of drying, heat of melting, desorption

isotherm analysis and more recently nuclear magnetic resonance. The quantity

of bound water determined appears to be dependent on the measurement method.

The variance in the amount of bound water determined by various methods

should not be surprising as it is likely that the thermodynamic behavior

of bound water molecules includes a wide range of physical properties. There

simply aren't two sharp, well-defined, homogeneous phases of water in the

cellulose-water system each with its own set of unique physical properties.

NMR relaxation studies demonstrate this point clearly since no sharp boundary

exists between bound and free water^ ‘

. The response of the various molecules

of bound water to different measurement techniques will not be alike and as

a consequence, the amount of bound water measured by each technique will vary.

The amount of bound water depends on the accessibility of cellulose to

water. The accessible regions are the amorphous fraction, the partially

crystalline material and the surfaces of the perfectly crystalline fraction.

In wood pulp, hemi-cel lulosic materials are also accessible to water but the

exact manner in which it interacts with water is unknown.

Determination of bound water and the fiber saturation point would be very

useful in studies on the beating of pulps. Increases in the fiber saturation

point are presumably due to fiber swelling but the exact mechanism for fiber

swelling is unknown. An increase in the FSP is caused either by a decrease

in crystallinity or simply by an expansion of the lamella. If the increase

in FSP is the result of decreased crystallinity, new surfaces would be

generated and the amount of bound water would increase. If the increase was

due to an expansion of the lamella, no change in bound water would be expected

The procedure for determining the fiber saturation point has been developed

adequately and is discussed extensively in a recent publication by Scallan (4).

No acceptable method has been developed for determining bound water although

attempts have recently been made by NMR (5,6) and by differential scanning

calorimetry (7-9). For all intent and purposes, the methods are empirical

in nature as they involve numerous assumptions. Of the two methods, the

mi crocalori metric method appeared to be the more useful because of the relative

simplicity of the method and ease of sample preparation. A common failing

with the microcalorimetric methods was the uncertaintly of the exact amount

of water and anhydrous fibers in each specimen. It was assumed that each

specimen had the same ratio of fiber and water as the bulk sample.

The purpose of this investigation was to develop a microcalorimetric

method for the quantitative determination of bound water and to determine

the effect of beating on bound water in wood and rag pulps.

3
Ill

was

500

. lr

. Experimental Details

A. Fiber Saturation Point

A stock solution of dextran (M.W. 2 x 10 ) at a concentration of 20.000 q/dm pr^paredas follows. The solute (20.000 g) was dissolved in approximately

cm distilled water at the boil. The solution was cooled to ambient

temperature and then transferred quantitatively to a liter volumetric flask. Additional distilled water was added, sufficient to make a liter of solution.

The dextran solution was then filtered through a medium glass frit filter

into a screw cap polyethylene bottle and stored in a refrigerator.

A calibration curve for the dextran solution was prepared by dilutinq weighed amounts of the stock solution (approximately 20 g) with 0-5 grams of distilled water. Ten different solutions were prepared. The optical rotation of these solutions was measured on a sensitive polarimeter capable of measurinq the optical rotation to the nearest five thousandth of a degree. A plot of

grams dextran/gram solution against the degree of rotation was prepared.

Pulp samples, approximately 50 g, were soaked in one liter of distilled water for one hour, then filtered through a coarse glass frit. After beinq washed according to this procedure three times, the pulp was soaked for a minimum of 18 hours in distilled water. The following day the pulp suspension

and weiqhed

d

n dl Vlded TMto eight specimens of approximately equal weight (6-7 g)

?

n ff screw

1 analytical balance to the qearest tenth of a millaqram in a cap polyethylene bottle having a 50 cm-' capacity. Approximately 20 q of the stock solution of dextran, weighed on an analytical balance to the nearest tenth of a milligram was added to each bottle. The bottle caps were screwed on hoTMs

y aThe

a fonowinn°H^

Sha

!$ er and Stated for a minimum of 18 ours. The following day the liquid was decanted from the specimen into a clean, dry centrifuge tube and the excess liquid in the pulp mass was removed by pressing the mass with a spatula. The centrifuge tube was stoppered and centrifuged at 1000 g's until the liquid appeared completely c <^r (approx 5-30 minutes) After cjntrlfugation the clear supernatant liquid was decanted into a clean, dry, 30 cm

J

glass stoppered flask.

aecancea

., The

^°]] d re sidue in the centrifuge tube and the pulp mass in the poly- ethylene bottle were transferred Quantitatively to a one liter beaker and suspended in approximately 500 cm distilled water for 3-4 hours The susDpnsinn

The glass

HTcer centrifugation, the optical rotation of the clear suoernatant

polarimeter

extran solution was measured on the precision polarimeter. ’Before the cell was filled for the optical rotation measurement the cell

the

S

s ! tlon

TM

\

of ?? solutio" t0 be TMeas“en miediith

? 1 ce?l t

r

h eTMos?ated

raatlo°r

th® solub

i on

, to «»» into equilibrium with

; ,

1 ! to ten

tnermostated at 20 C. The optical rotation was then measured dv times at one minute intervals and the average of the readies was considered

solution

to be the optical rotation of the solution. The concentration of was determined from the calibration curve and the"? o?

the

water diluting the stock solution calculated as follows
t where

W

n = weight of water diluting stock dextran solution

3 || g. = concentration of stock dextran solution

gl = concentration of diluted dextran solution

p = weight of stock dextran solution

The fiber saturation point was then determined as follows

FSP = ^ W

T

‘ W

D^

f

d

I where

W

T

= grams of water in specimen

wi = grams of water diluting stock dextran solution

f|j = grams of dry fibers in specimen

B. Determination of Bound Water

Samples of unbeaten and beaten pulp were washed three times by soaking

in distilled water for one hour and decanting the supernatant liquid. After

the final wash the excess water was removed by pressing the pulp mass with a

I spatula. The sample was then soaked for at least 18 hours in excess distilled

water. The following day the water was removed by decantation and the excess

water removed once again by pressing the wet pulp mass with a clean spatula.

Approximately 3-6 mg of wet pulp was placed in previously weighed aluminum

sample holders and sealed hermetically. The sample holders and covers were

dried at 105°C for one hour in a vacuum oven and cooled to ambient temperature

before weighing on a microbalance. The sealed sample holders were then weighed

on a microbalance to the nearest microgram. Before the sealed specimens were

placed in the differential scanning calorimeter (DSC) on the following day they

were weighed on a microbalance once again. If the second weight changed by

more than 2-3 ug, the sample holder was considered improperly sealed and

was discarded.

The sealed samples were placed in the sample holder of the DSC and

allowed to stand for five minutes before cooling to 240°K. The cooling rate was 5°/min. Following cooling, the samples were heated at 5°C/min. up to 290°K.

The cooling and heating procedure was repeated a second time for each specimen.

Following measurement on the DSC each specimen was weighed once again. If

the weight did not change by more than 2-3 ug, the specimen was considered to

be adequately sealed, otherwise the sample was discarded. If the specimen

was sealed satisfactorily, the cover of the specimen holder was pierced with

a sharp mandrel and dried in a vacuum oven at 105°C for one hour, cooled to

ambient temperature in a desiccator and weighed on a microbalance. As cellulose is

hygroscopic, and as the specimen was exposed to the atmosphere, the weight of

the specimen and holder was measured every 15 seconds for three minutes. A

plot of weight as a function of time was prepared and extrapolated to zero time to estimate the true anhydrous weight of the specimen. After a considerable

number of specimens were weighed in this manner, it was recognized that the

weight obtained within the first 30 seconds was within one microgram of the

extrapolated weight. The specimen was redried, cooled and weighed repeatedly

until the difference between consecutive weighings was no greater than 2-3 ug.

The DSC was calibrated with weighed specimens of distilled water. The water

specimens were cooled to 240°K at 5°C/min then heated to 290°K at 5°C/min.

The area under the melting curve was determined with a planimeter as suggested

by Flynn (10). Using the value of 79.71 cal/g as the heat of fusion for ice, a

5
calibration constant was calculated. The amount of ice formed in each pulp specimen was calculated from the area under the curve and the calibration constant.

The difference between the total weight of water in the specimen and the weight

of ice formed was defined to be the amount of water bound to the cellulose.

C. Pulp Samples

Two kraft wood pulps and a virgin cotton were investigated. The

wood pulps were prepared from single logs of Norway Spruce and Slash Pine.

The Norway Spruce was pulped to a yield of 47.5% and a Kappa No. of 41.8.

The Slash Pine was pulped to a yield of 44.9% and had a Kappa No. of 45.7.

The purified cotton sample was received from the Southern Regional Research

Center and was obtained from the Mississippi Delta region (Delta Pine, smooth

leaf variety). The cotton was purified by a modification of the Conrad

method (11) with the addition of an 8 hour boil in 1% NaOH under N~ atmosphere,

washed successively with distilled water, 1% acetic acid, 1% NH.Of-rand finally

distilled water. It was then dried in a vacuum oven at 60°C. All of the

specimens were placed in polyethylene bags, inserted in metal cans which were

sealed and stored in a freezer. The wood pulp samples were never dried.

Beating was done in a laboratory mill at a 10% consistency with distilled

water for 5000 revolutions at a relative velocity of roll to bedplate of 6 m/sec

at a force of 3.4 kilograms.

Currency stock was obtained from Crane and Company, Inc. The stock was obtained after the beater, but before passing through the refiners and jordan.

The consistency of the currency stock was approximately 1-2% when received.

Excess water was removed by filtration on a large Buchner funnel. After

filtration, the consistency was approximately 25%.

6
IV. Results and Discussion

The legitimacy of determining the FSP and bound water is dependent on the accuracy of several assumptions. In determining the FSP, it is assumed

that the hydrodynamic diameter of dextran, molecular weight 2 x 10°, is

greater than the diameter of most of the pores in swollen cellulose.

Furthermore, it is implied that water, bound to the surface of cellulose

and in contact with the dextran solution, behaves as free water and will take

part in the dilution of the dextran solution. The validity of the latter

assumption has never been proven. If water, bound to the surfaces of pulp

fibers, does not participate in the dilution of dextran, the errors in calculating FSP would be expected to be small except in cases where the surface

area is high. The determination of FSP for very fine cellulosic material

as fines and debris or of highly fibri Hated fibers could lead to spuriously

high results.

In determining bound water by the nonfreezing water technique it is

assumed that only bound water does not freeze and that the heat of fusion of

the frozen water is identical to that of bulk water. It is likely that the

nonfrozen water not only involves water firmly bound to cellulose, but also

loosely bound water and water whose structure is affected by surfaces, as in very fine

capillaries. The free water in fibers is the difference between the FSP and

the bound water.

Two factors, 1) drying of the sample holders, and 2) the quantitative

determination of the water and dry fibers in each specimen, were important

in measuring bound water. If the sample holders were not previously dried

both the mean and standard deviation were affected as shown in Table 1. If

the quantity of water in each specimen was assumed to be identical to the

bulk of the sample, the standard deviation was affected as shown in Table 2.

The bound water content of cotton is approximately one half that found

in both wood pulps. It is quite obvious that bound water is a function of

accessibility and not crystallinity. Two cellulosic materials, with an identical

amount of amorphous material, but different crystal size, would have different

amounts of bound water. As the crystal size and/or the crystal perfection decreases

the number of hydroxyls lying at the surface, increases. Therefore, increasing

the crystal surface to volume ratio increases the amount of bound water.

The FSP for wood pulps is approximately 2.5 times greater than it is for

cotton. Not only is cotton less accessible to water, it cannot accommodate free

water as does wood pulp. This is indicated very well by the free water to bound

water (F/B) ratio. The F/B ratio for wood pulp is approximately 1.5 times greater

than it is for cotton.

Beating has no effect on the bound water content of wood pulp, but a substantial increase is observed in beaten cotton. Presumably, new surfaces are generated during beating. The manner by which the new surfaces are generated is

not known, but cotton does fibri 11 ate readily during beating and large amounts

of debris are formed. In any event, the disparity in bound water between wood

pulp and cotton decreases during beating.

Increases in FSP occur during beating for both wood pulp and cotton. Even

though the percent increase in FSP is larger in cotton than in the wood pulps,

the increase in the F/B ratio is much greater in wood pulp than in cotton. This

indicates that cotton does not swell as much as does wood pulp during beating.

In fact, the F/B ratio for beaten cotton is lower than the F/B ratio for unbeaten

wood pulp. Apparently, the lamella in cotton do not separate as much as they do

in wood pulps.

7
Since cotton swells less than wood pulp during beating, the cotton fibers

should be less flexible and should not form interfiber bonds as readily as wood

pulps. The strength, durability, and other mechanical properties, dependent

on interfiber bonding, ought to be superior in wood pulp papers. However, high

grade rag papers such as currency paper, have superior strength and mechanical

durability to that found in high quality wood pulp papers. Since high quality

rag papers are strong and durable, indicating the presence of strong bonding,

it must be assumed that the mechanical properties of rag papers are derived

from a microstructure quite different from that found in wood pulp papers.

The bound water, FSP, and F/B ratio varied for each of the four different

fiber length fractions, being lowest for the longest fiber fraction and highest

for the shortest fiber fraction. It was interesting to note that the F/B ratio

of the longest fiber fraction was identical to that found in unbeaten cotton.

Apparently, the long fibers do not swell when beaten. As mentioned previously,

a large amount of debris is generated during beating. This debris probably has

a much larger surface area than the long fiber fraction. It would be of interest

to determine whether the surface area of the fines is responsible for the increased

bound water and FSP.

In a previous study on fractionated wood pulps (11) it was found that the

FSP for similar fractions was lower than for the unfractionated pulp, but that

the FSP for the material passing through a 100 mesh screen was considerably higher

(3.9 to 5.8gH

? 0/g. fiber). In this study, the finest screen used was 150 mesh

and since the material passing through that screen was not recovered, the FSP

could only be estimated (Fraction V). There is a very great difference between

the determined FSP of the fines in wood pulp and the calculated FSP for the fines

in currency stock. However, it is not known whether the apparent cellulose-water

interaction of the fine material differs depending on whether it is combined

with the whole pulp or separated from it. It will be necessary to check

this point further.

Previous studies on fractionated currency stock (12) and on fractionated

wood pulps (13) indicate that bonding in handsheets, made from individual

fractions, is much greater in wood pulp than'in currency stock. Furthermore,

the difference in the strength of handsheets, made from the unfractionated pulp

and those made from the individual fractions is quite high for currency stock

but minimal for wood pulp, indicating that the bonding mechanism in wood pulp

is similar in all the fiber length fractions, but not in currency stock. Evidently,

the manner by which currency paper derives its mechanical properties is very

different from the manner wood pulp properties are derived. This suggests two

entirely different microstructures are operative.

8

V. Conclusions

The cellulose-water interaction in rag pulps is considerably different

from that in wood pulps. Apparently, the long fiber fractions of rag pulp

do not swell as extensively as do wood pulps and consequently, do not form

many or very strong interfiber bonds. The excellent mechanical properties of

rag paper must originate with a microstructure considerably different from

that in wood pulps. Additional data on the cellulose-water interaction in

the various fractions of currency machine stock will be necessary in order

to determine more fully the specific differences in wood and rag pulp papers.

10
VI. Acknowledgement

The authors wish to thank Professor Renata Marton, Syracuse University,

for supplying the two wood pulps prepared from single logs. Dr. Ralph J.

Berni of the Southern Regional Center for supplying the sample of purified

cotton, Dr. A. M. Scallan, for determining the fiber saturation point for

unbeaten cotton and Mr. Fred Crane, Jr. of Crane and Company, Inc. for

providing the sample of currency machine stock.

11
VII. Bibliography

1. Emerton^ H. W., Fundamentals of the Beating Process, Marshal Press,

London, 1957.

2. Stone, J. E. and Scallan, A. M., In Consolidation of the Paper Web,

F. Bolam, E., Tech. Sect. Brit. Paper and Board Makers' Assn., London,

Vol . 1, 1965, 145-174.

3. Aggerbrant, L. G. and Samuelson, 0. J., J. Appl . Polym. Sci . , 1964,

8 (6), 2801-2812.

4. Scallan, A. M., In Fiber-Water Interactions in Paper-Making, Fundamental

Research Committee Ed. Technical Division, The British Paper and Board

Industry Federation, London, Vol. 1, 1977, 9-27.

5. Carles, J. E. and Scallan, A. M. , J. Appl. Polym. Sci., 17, 1855 (1973).

6. Froix, M. F. and Nelson, R., Macromolecules, Vol. 8, No. 6, 726 (1975).

7. Karmas, E. and DiMarco, G. R. , Analytical Calorimetry, Vol. 2, 135 (1970).

8. Karmas, E. and Chen, C. C., Analytical Calorimetry, Vol. 3, 489 (1974).

9. Nelson, R. A., J. Appl. Polym. SCi . , Vol. 2, 645 (1977).

10. Flynn, J. H., Thermochimica Acta, 8 (1974) 69-81.

11. Stone, J. E., Scallan, A. M. and Abrahamson, B., Svensk Papperstidn, 71 (19),

687-694 (1968).

12. Graminski, E. L. and Toth, E. E., Durability of Paper, NBSIR 75-978, Dec.,

15, 1975.

13. Graminski, E. L. and Toth, E. E., An Evaluation of Wood Pulp Paper Durability,

NBSIR 78-1417, Feb., 15, 1977.

14. Dehl, R. E., J. Chem. Phys. 48, 831 (1968).

12
Table

1.

The

Effect

of

Sample

Holder

Drying

on

the

Determination

of

Bound

Water

in

Slash

Pine

Pulp

on

s-

<u -a

aja

E

fO OO-Q

a>

•I*s_ Q

an on in .

r^CMooooouocMro OO

<U

(T3

3

O

CQ

Sa; -Q

cn OC\J

cn

on

iaj -o

0)a

E

<T3 <S) -a

<v

•r—S_ *oC

C3

C\J o CO LO oo OO r— oo o oo r— oo CO OO 1 1— on

on oo <=d- oo oo 1 o

C

ra

a;

c

o•1“ -M

fO

r

>

a> a

T3

Sra -ac

fC -MOO

a) s- E CJ

•r- _Q u E

a) 3

Coj oo on oo

oo
Table

2.

The

Effect

of

Determining

the

Water

in

Each

Specimen

on

the

Estimation

of

Bound

Water

in

Norway

Spruce

Pulp

&_

S- O)

aj

+-> -r- rO 4_

-a cn c \3 oO CM

ca nr

s_O) +J

fO c

12 O)

ra u

+-> aj O CL l— CO CM CO i

CO *3- CO o o CO CM 00 CO cn CO C -C o o

cn <3* o

<T3 -a lxj aj10

rO CO

CT5

r- <D

ra 1

4-> Q_

o E

I— ra OO c

o c

T

3

a> s,

1/5 O)

ra +41 CQ ra

COCM

r~. O'* CO CO CO

CO CO C^J cn cn cn CO

CO CO LO cn •^3" o

c

raaj

c

o

I

4—5 ra I>

a> a

-a

sra T3c

ra

+-> oo

c

aj s- E oj

•i— _q u E '— cm co <3- cn co r-- cu o

Q- 2T oo
Table

3.

The

Fiber

Saturation

Point

and

Bound

Water

of

Two

Kraft

Wood

Pulps

and

Purified

Cotton e

<u CO p~- CM CM c +-> CO i3- *3- r— 03 r-. o (O 03 O CO O LD • +-> aj • • • . • p—

+-> CQ o o o O

O ooo<d

•r— c

4— aj

•r— +-> o CO

S- (13 CO CD 3 dJ ld O CO •U" CD

Q- -Q • • CO co 03 CO C O o CM 0 r-. CM 33 • •/ • p— o 0 O

4-J

C

C

0) • T— r-. CM CO 03 vf

+J o CO LD CO S3" CO CO

(13 Q- CO o CO ItfO 03 13- • cu • • S- • • CO

<D CQ

C r— o dJ o O s_ r—

C o CD

*T— • r— (13 +-> Cl. 4-> (13

(13 3 -C c S- -a

CO ai 3 c cu

(13 +j -i-> *3- CD 3 r— CD <D CO r— (13 (13 cn CO o CO 1— S- CD 0

C/0 aj 00 CMO CO CQO u_ CO > J3 • • • • CM C S- r— o o O O ZD <u J3r—

Ll_

C

<D cu on o 03 r-'- CO U +j CO CM LD CO

O 3 (13 o r-'* "O- O r^» CO • S_ a> • • • • CO a. CQ i

o o O 1

C/3>>

(13 2

&_

C o a) s: -M CD (''- CO

O CO

(13 CM CO LD CO 03

a> CO o CO 0 r«- CO • -Q • • • • p— e i

o O 0 0 33 c c o 0 p— CO •1

CO +J c -M S3

(13 <u (13 a>

s_ i

E S- • r— E sa> > •p— dJ > •1

dJ -Q a> JD a> u -Q S-

*r- T3 O) • 1

T3 <D i- -r- S- O) 4— Cl 4— CL CD 4- CD +J •a . co T3 CO +-> 4-J (13 03 u 03 S- (O 03 (13 12

(13 4— \ (13 4— 2 \ 3 o T3 O O T3 O O -O

CMC CM

C O) CM 0)

C

zc (13 • 31 (O • cu 3r a) 3

4->

O +->

O s_ s_

O

03 (/3 c 03 COC 4- 03 u. CQ
Table

4.

The

Fiber

Saturation

Point

and

Bound

Water

for

Fractionated

Currency

Stock coo

fO

S- s_<u J34— C C CD o o "

•r- +J

CO • r— CO o c +-> c CM

(O a) fO a) nr

s_ •i— E s_ •i

E

CL) > • iO) > •r- CD

-Q <u

O -Q ajO S-

•r— T3 aj •r“ -a O) &- s- <v 4— Q. 4- CL aj CD -a CO -a CO +-> +J fO 'CD s_ cn s_ to tO 3 

<0 4- \ tO 4- 2 3: o o o o T3 O T3

CM c CM

C O) a>

C

re tO • CC tO • <u QJ 3

4-> o +J

O s_ S- o

CD CO c CD CO c 4- Ll_ CO

^Estimated
JEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

i. PUBLICATION OR REPORT NO.

NBSIR £0—1970

2. Gov't Accession No. 5. Ractpsent' 4 Accession No. V

' T'

4. TITLE AND SUBTITLE

The Cellulose-Water Interaction in Rag and Wood Pulps

5. Publication Date

V, " 5

7. AUTHOR(S)

E. L. Graminski and E. E. Toth

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, state, zip

)

11. Contract/Grant No.

13. Type of Report & Period Covered

15. SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT (A 200-word or leas factual summary of moat significant information. If document includes a significant bibliography or

literature survey, mention it here.)

The interaction of water with cellulose has been determined for two wood

pulps, a purified cotton and for currency paper machine stock. Two different

interactions were measured, 1) bound water which measures accessibility of

cellulose to water and 2) the fiber saturation point which measures the total

amount of water within cellulose fibers. Bound water was determined by the

non-freezing water technique and the fiber saturation point was determined by

the solute exclusion principle. Wood pulp is more accessible to water than

is cotton. Beating does not increase accessibility to water in wood pulps but

it does increase in cotton signifying the generation of new surfaces in cotton.

Wood pulps swell more extensively on beating than does cotton. Most of the

water interacting with cellulose in currency machine stock is in the short fiber

fraction. There appears to be considerable difference in the interaction of

water with the fines in beaten wood pulp and in beaten cotton.

17. KEY WORDS (six to twelve entries ; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

Bound water; fiber saturation point; fiber swelling; paper microstructure; paper

durability; interfiber bonding; cellulose accessibility.

18. AVAILABILITY OUnlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF

PRINTED PAGES

|~x| For Official Distribution. Do Not Release to NTIS UNCLASSIFIED

1 ! Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

20. SECURITY CLASS

(THIS PAGE)

22. Price

1 1 Order From National Technical Information Service (NTIS), Springfield,

VA. 22161 UNCLASSIFIED

USCOMM-DC