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Paper Engineering Senior Theses Chemical and Engineering

4-1995

Effect of Retention Aids on AKD Size Response and Permanence

Jeremy Matthews Western Michigan University

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Recommended Citation Matthews, Jeremy, "Effect of Retention Aids on AKD Size Response and Permanence" (1995). Paper Engineering Senior Theses. 306. https://scholarworks.wmich.edu/engineer-senior-theses/306

This Dissertation/Thesis is brought to you for free and open access by the Chemical and Paper Engineering at ScholarWorks at WMU. It has been accepted for inclusion in Paper Engineering Senior Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact wmu- [email protected]. EFFECT OF RETENTION AIDSON AKD SIZE RESPONSE AND PERMANENCE

by

Jeremy Matthews

A Thesis Submitted inPartial Fulfillment of the Requirements forthe Degree of Bachelor of Science

Departmentof Paper andPrinting Science andEngineering WesternMichigan University Kalamazoo,Michigan April, 1995 Table of Contents

PageNumber

Introduction 1

Problem Statement 4

ExperimentalProcedure 5

Results and Discussion 5 Conclusions 11

LiteratureCited 12

Figures,Tables, Charts 14 Abstract

Poor size responseand size reversion have been major concernswith the useof an dimer (AKD)sizing system. Poor retentionof calciumcarbonate fillersand fiberfines are believed to be the cause of poorsize response. A number of materials, includingcarbonate fillers, promotersand retentionaids are believedto contributeto size reversion. The focusof this study was to determinethe effectivenessof retentionaids in obtaining good size response. Size permanencewas also studied The performanceof the retention aides were studied by preparing handsheetsat fivedifferent zeta potentials. It wasdetermined that when no retentionaid wasadded to the system, size responsewas not dependenton zetapotential. It was dependenton theamount of polyethyleneimine(PEI) present in the system. Low sizing levels in the absence of PEI indicate poor retention of the size molecules. When cationicpolymers were added to the stock, sizing levels showed a dramatic increase. This increase was do to superiorretention of the fiberfines. As zeta potential wasincreased to highly cationic,size levels droppeddue to poorretention of the sizing chemical. Cationic polymerwas not observedto contributeto size reversion. Size responsewith the addition of an anionic polymerwas highly dependenton the presence of a cationic fixative. When no PEI waspresent in the stock, the anionic polymerwas ineffective. Small amountsof PEI provided cationicsites forthe anionic polymerto bridge the fibers. Contraryto previous literature studies, the anionicpolymer did not contributeto size reversion. When PEI wasadded to the system, largeincreases in sizing levels were observed PEI promotes excellent retentionof the fiberfines. Good finesretention will increasesizing levels. Not only did PEI promote the reactionbetween AKD and cellulose, no size reversion wasobserved when it wasused Introduction/LiteratureAnalysis

Alkalinepapermaking has seen a surge in popularityover thepast decade. In

1991, 26% of printing andwriting paperswere produced by alkaline processes (1). By

1995, that percentagehad increasedto · 65% andis expectedto increaseto 9()0/oby the end of the century(2). Alkaline produced paperhas advantages over acid systemsthat include: improved sheet strength,substitution of calciumcaroonatc for and improved paperstability on aging. Calcium caroonatefillers arc much more inexpensive than titanium dioxide. Therefore, aslong asstrength and runability requirements can bemet, more fillercan besubstituted at the samecost Calcium carbonatefillers increase opacity, brightness, and print quality(3).

Sizing is definedas the abilityof paperto reducethe rateof fluidpenetration. All sizingagents must achieve fourrequirements to develop sizing. First, they mustreduce fiber wetability, which is accomplished by introducinghydrophobic groups at the surface of thesheet. The size must alsobe retained on the fiber, distributedevenly over the fiber surface andbe anchored to the cellulose toprovide goodwater repellency (4).

Acid paperis sizedusing the traditional rosin andalum system. Thissystem is not efficientat neutralto alkaline pH,so analternative sizing system must be used. The most popularalkaline sizing agent is alkylketene dimer (AKO). AKDis a synthetic. long-chainorganic molecule that reactsdirectly with cellulose hydroxylgroups to form (5). A portionof the AKDremains unbound,but it also contnbutesto sizing (6).

AKD alsoreacts withwater to forma 13-ketoacid whichdecomposes to aketone. This side reactionis undesirablesince the doesnot contnbuteto sizing(7). The reactionsof AKD shownare in Figure_t 2

Two major differencesbetween AKD and rosin and alumsizing systems have beenobserved. The firstdifference is in the shapeof the size responsecurves (see Figure

2). In anacid system, rosin is precipitated on the fiberswith alum. Sizing is developed in the dryersection when the rosin is melted andanchored to the fibers. This system is robustand has a fairly constant sizeresponse, even at low additionlevels.

Inalkaline sizing systems, a covalent bond is formedto providea stronglink betweensize and fiber. AKDis emulsifiedwith dispersantsand stabilizers to allow preliminarydistnbution to fibersin the stock. This impartsa net cationiccharge to the size which permitsa weak electrostaticbonding with cellulose fibersat the wet end.

During drying,size is redistributed over thefiber surface andforms covalent bonds with the hydroxyl groupson cellulose molecules. Initial retention is criticalsince the initialelectrostatic link is weak andthe fullcovalent bond does not formuntil the drying cycle. Poor initialretention will result in hydrolysis of the AKD molecule (8). At low

AKDaddition levels, emulsion particleshave a moredifficult time in spreadingto cover the entirefiber surface. Thisaccounts for differencesin theresponse curves of acid and alkaline sizing systems, and explainswhy alkaline sizingis moredifficult to control.

Anotherdifference between the two sizingsystems is permanence. Rosin and alumsizing maintainsits effectiveness over time. However, AKDsizing hashad many problems with"size reversion,"a loss in sizingover time. The most extremecase of size reversion,where sizing is completely lost, is called fugitivesizing (16). Both typesof sizing loss have beenobserved under many conditions. 3

As mentionedearlier, unbound AKD contributes to the hydrophobicityof the

sheet However, this material stillpossesses a potentialfor hydrolysis. If the unreacted

size is hydrolyzed, it no longer contributesto sizing. Researchdone by Patton (9)

determinedthat up to 85% of theretained A.KOis unbound Marton(7) determinedthat about50% of retained AKD is unbound Both these figuresrepresent the largepotential

forthe size to behydrolyzed, causing size reversion.

Size reversionhas been observedunder many conditions. Water hardness,

alkalinity, promoters, retentionaids and carbonatefillers have all beenaccused of causing sizereversion (10). The focus of researchhas beenon fillersand fiber fines (11).

Carbonatefillers and fiber fines have been found to adsorba disproportionate

amount of size material due tohigh surfacearea. Filler chemistrydoes not provide an opportunityfor bonding with AKO. Therefore, any AKD which is adsorbedby the carbonateis unbound

The key to obtaininggood initial sizing values andpreventing size reversion is to maintain high firstpass retention (12). Good firstpass retention provides two main benefitsto sizing: it preventsAKD hydrolysis in the white water and contributessizing from thefines fraction of thestock. In addition,good firstpass retention is criticalto maintainingthe economic advantageof using calcium carbonatefillers (13).

Retentionaids areused to increaseretention of finematerials such ascalcium carbonateand fiberfines. Betterretention of theseparticles increases sizinglevels. With highermachine speeds being used today,there is a need to formfloes which areresistant 4

higher machine speedsbeing used today, there is a need to formfloes which are resistant

to shear. Most of these retentionaids have a high molecularweight and are

polyacrylamide-based. An excellent review of retentionaids wasdone by Hubbe(14).

Thereare several other advantages to using retentionaids. By increasing

drainage,they increasewet-web strengthwhich canre.duce the numberof wet-web

breaks. In addition,better wet-web strength allows papermakersto usea greateramount

of recycled fiberin the product (15).

Retentionaid perfonnance is highlydependent on the zetapotential of the solids

in the system ( 17). Zetapotential is a measureof the potentialof a particleat its shear

plane. Zetapotential is controlledon thepapermachine to maximizeretention of fibers,

fillers, finesand dyes(17). Cellulose fibersare anionicallycharged due to carboxyl

groups on the hemicelluloses anddue to lignosulfonates. Theaddition of cationic materialto the fibrous system will affect zeta potentialby adsorbingon thesurface of the particle. Therefore,by addinglow molecularweight, highly cationicmaterials such as alumor polyethyleneimine(PEI), the zeta potentialof thecellulose fibersincreases from negativeto positive.

Problem Statement

Under certainconditions, AKO size responseis poorand is lost over time.

However, themechanism of poorsize response andsize reversionhas not been established. Thisstudy attemptedto determinethe effect of retentionaids on the initial size responseand the permanence of AKDsizing. 5

Procedure

Figure 3 is a summaryof the experimentaldesign. A blend of 75% hardwood and

25% softwoodwas refinedin a Valley beater to a Canadianstandard freenessof 450 mL.

Polyethyleneimine(PEI) wasadded to a portionof stock at0.025, 0.05, 0.10, 0.15, 0.20 and0.25% w/w based on oven-dryfiber. Zeta potentialwas measured after each addition of PEI. The graphicalrelationship betweenzeta potential and PEI concentrationwas used to producehandsheets fromfurnishes at zeta potentialsof-20, -10, 0, 10 and20 millivolts.

For each retention aid,five handsheets weighing 2.50 ± 0.30 gramswere prepared at eachzeta potential. The handsheets were allowed to conditionovernight and then were testedfor Hercules sizing (T 530 pm-89) at1, 3, 6 and9 dayintervals. AKDsizing

(Hereon 70) addition level washeld constant at 0.20%, andeach retentionaid wasadded at0.25% w/w based on dryfiber.

To determinethe effect of PEI on siu responseand permanence, PEI wasadded to stockat 0.0015,0.0030, 0.0060and 0.0120%. Five handsheetsweighing 2.50 ± 0.30 gramswere prepared for each level of PEI additionand tested for Hercules sizingat 1, 3,

6 and 9 day intervals. Hereon70 wasadded at 0.20% based on dryfiber.

Resultsand Disc11.SSion

PEI wasadded to thefibers to modify their zetapotential. Thefibers themselves bad zetaa potential of about-16 millivolts. As PEI was toadded thestock, the zeta potentialinitially rose sharply. The graphicalrelationship between PEI additionand zeta potentialis shownin Figure4. At higher zetapotentials, larger amounts of PEI badto be 6

added to achieve the same incrementalchange in zeta potential. The results correlated

very well with results obtainedby Miyanishi(19).

Size Response

Size responseof the controlnui did not behaveas expected. Figure5 shows that

as zeta potentialincreases from -20 to +20 millivolts, sizing levels initiallyincreased,

then leveledoff from -10 to + 10 millivolts and then increasedmarkedly at +20 millivolts

zeta potential. A bell-shapedcurve was expected for the controlsince only a minimum

of retentionaid is present Size responseis usuallyhighest aroundzero zetapotential becausethe repulsive forcesbetween particles is at a minimum. Size response appeared to beproportional to the amountof PEI in the stock. At 20 millivolts zetapotential, size responseshould have beenpoor. Since the sizematerial is slightly cationicand since there wasvery little retention aid present,retention of thesize should havebeen poor because of largerepulsive forces. However, sizinglevels were highestat 20 millivolts zetapotential. Thisis also where theconcentration of PEI is atits highest level. The role of PEI willfurther be discussed in following sections.

The additionof a polyacrylamide(PAM) based cationic polymer to the system caused a dramaticincrease in sizinglevels at all zeta potentials. However,it appearsthat zeta potentialhad very little effecton size response. Errorbars on Figure6 show that sizing levels were statistically equivalent for all zeta potentials. The excellent size response wasthe result of excellent retention of the emulsion particlesand fines. As mentionedearlier, disproportionate amounts of size materialare adsorbed by the fines.

Cationicpolymers such asthe one usedin thisexperiment "tie" the fines to thelonger .. 7

fiberby electrostaticattraction. In addition,they causethe fibersto flocculatewhich also

aids in fineparticle retention (15). This will increasethe size retentionwhich, in turn,

will increase size response.

Increasing zeta potentialto high levels should 1:µlvecaused sizing levels to

decrease. As the system becomesincreasingly cationic, repulsion between cationic

retentionaid andcationic size emulsion particles should havedecreased sizing levels.

However, Figure 6 shows that sizing values were at least1800 secondsfor each zeta

potential. The shapeof the size responsecurve may have differedfrom expected results

becauseof the natureof the cationicpolymer. Zeta potentialwas used to influencethe

performanceof the polymers. However, zeta potential is much less usefulin predicting

retentionby bridge formation. The bridges extend beyondthe electrical double layer

used to measure zetapotential ( 18). This may be acause of the unexpectedsize

response.

Size response of anionic retention aids washighly dependent on the presenceof

PEI. Figure7 shows therelationship between zetapotential and sizeresponse with the useof an anionic retentionaid At a zetapotential of -20 millivolts,there was almost no size response. Thisis because therewas no PEI presentin the system. Anionicpolymers formbridges between fibersin the presence of highly cationicmaterials such asPEI and alum. When PEI andalum are not present, there areno cationicsites on the fibers to bondwith the anionicpolymer. However, when thesematerials are present, anionic· polymers areable to bondwith the fiber. The resultingbridge is strongand veryresistant to shear(12). Retention of fines,fillers and fibers is greatlyimproved Since a large 8 fraction of the AKOsize is adsorbedon these materials, their retentiongreatly improves sizing. At zeta potentialsabove -20 millivolts, where PEI waspresent, sizing levels were very high( about2000 seconds). The shape of the size responsewas consistent with expectedresults. Withouta low molecularweight, high charge density materialsuch as alum or PEI, size responsewas poor. However, when these materials were present even in small amounts,size responsewas much higher.

Size response of the controlrun appeared to behighly dependenton the presence of PEI. Additional sheetswere preparedto investigateits effecton size response. The results areshown in Figure 8. The size response of AKO wasfound to behighly dependenton PEI addition. When no PEI was addedto the stock, sizing values were only about30 seconds. Small additionlevels of PEI (less than .02%) causedsizing levels to increaseto over 1000 seconds. There appearedto be aminimum criticalconcentration of

PEI necessaryto achievehigh sizing levels. Afterthis amount is present,a dramatic increasein sizing is observed. IncreasingPEI concentrationbeyond the minimum critical concentrationdoes not appearto provide much additionalbenefit

PEI is knownfor excellent fines retention ( 15) andsmall addition levels appeared to dramaticallyincrease sizing levels. The largeincrease in sizinglevels withthe use of

PEI was probably due to anincrease in finesretention.

SizePermanence

Sizinglevels weremaintained over time forthe controlrun. The effectof adding no retention aid to the system on size permanenceis shownin Figure 9. Afterthe final testinginterval, the sizing values werestatistically equivalent to the initial sizing values. 9

However, it appearsas though there wasadditional curing takingplace over the 9-day testinginterval. No size reversionwas observedfor the controlrun. 1bisis expected since none of the materials suspectedof causing size reversion were present in the system.

No size reversion wasnoticed with the use of the cationicpolymer. Figure 10 showsthat sizelevels remainedalmost constantover time at each zetapotential. It appears asthough sizing levels in the sheetsmade at zetapotentials of +20 and-20 millivolts fluctuated over time. However, the sizinglevels of all the sheetsare statisticallythe same at each testing interval. However, any increasein sizing over time would likely bedue to additionalcuring of the unboundAKD. Rende andDumas (10) foundthat "coagulants"do not contributeto size reversion. However, theyalso mention highinitial sizing levels tend to prevent size reversion. Therefore,although no size reversionwas observed with the useof cationic polymer,sizing loss may have been preventedby high initialsizing values.

Researchdone by Patton(9) has shownthat anionic PAM contributes to size reversion. She believes that theanionic polymeragglomerates AK.D size particlesand when theyare deposited on the fibers,they rearrange over timeand eventually hydrolyze.

The hydrolysis reactioncauses a largeloss in sizing. However, in thisstudy, no size reversionwas observed with the use of anionicpolymer (see Figure 11). Testingresults fromthe ninthday showed a 20% decreasein sizing levels forsheets producedat -10 and

0 millivoltszeta potential. However, when thecoefficient of variationis takeninto consideration, thereis verylittle difference between these sheets and the sheets produced 10 at-20, + 10 and +20 millivolts. In addition, the sheets produced at-10 and 0 millivolts zeta potentialwere tested a month later and showed no additionalloss in sizing. Anyloss in sizing was probably due to the inaccuracy of the Hercules size test instrument. Once again, size reversion may have beensuppressed by high initialsize levels. Butanionic polymers did not appearto contributeto size reversioa

Over time the sizing levels of the PEI sheets remainconstant (Figure 12). It can be concluded that not onlydoes PEI greatlyimprove size response, it also does not cause size reversion. However, the effectsof PEI on size responseand reversion should be studiedin greater detailto betterdetermine its usefulnessin sizing. In this experiment, it appearedto behighly beneficial.

Test results from the varioustesting intervals showedlarge fluctuations in sizing levels. However, theresults remainedconstant from a statisticalstandpoint They show that fromday to daythe reliability of theHercules size test machines canbe suspect 11

Conclusions

1. Preliminarystudy done to determinethe effectof PEI additionon pulp zeta potential wasin good agreementwith published values. In this experiment,the electromobility meter was an accurate predictor of zeta potential.

2. Size responseof controlrun did not correlatewith zeta potential. However, it appearedto bedirectly related to PEI concentration. No size reversion wasobserved within the 9 daytesting period.

3. Sizeresponse of the cationicpolymer was high at all zetapotentials. Thepolymer effectivelyretained the size emulsion which resulted in high sizinglevels. Cationic polymers did not appearto contributeto size reversion.

4. The size responseof anionicpolymers is highlydependent on the presence of cationic materials such asPEI and alum. Anionicpolymers must have cationicsites to form bridges between itselfand the fibers. Contraryto previousstudies, nosize reversion was observed with the useof anionic polymers. However, veryhigh initialsizing levels may have suppressed the possibility of observingsize reversion.

5. A studywas done to determine the effectof PEI concentrationon size responseand permanence. It wasdetermined that very small additions of PEI drasticallyincreased size response becauseof excellent finesretention. No sizingloss wasobserved over a 9 day testing period The additionof PEI to stock may be beneficial in promoting SlZl.Dg. 12

Literature Cite

1. Crouse, B. E. and Wimer, D. G., "Alkaline Papennaking: An Overview'', Tappi Journal 74(7): 152(1991).

2. Zhuang,J. andBiermann, C. J., "Neutralto AlkalineRosin Soap Sizing With Metal Ions and Polyethyleneimineas Mordants", TappiJournal 78(4): 155(1995).

3. Fairchild, G. H., "IncreasedFiller Levels in Alkaline PaperUsing PCC Technology",TAPP! 1992 PapermakersConference Proceedings, TAPP! PRESS, Atlanta,p. 521.

4. Dumas,D. H., "An Overview of Cellulose-ReactiveSizes", TappiJournal 64(1): 43(1981).

5. Marton,J., "Practical Aspectsof Alkaline Sizing",Tappi Journal 73(11): 139(1990).

6. Adamsky,F. A., Gibbon,D. L., Simon,G. C. andWilliams, R H., "Retention MechanismsUsing a UniqueDual Polymer Approach", TAPPI 1991 Papermakers Conference Proceedings,T APPi PRESS, Atlanta,p. 469.

7. Marton,J., ''PracticalAspects of Alkaline Sizing: AlkylKetene Dimer in Mill Furnishes",Tappi Journal 74(8): 187(1991).

8. Hennessy, T. J., "Conversion to Alkaline System RequiresExtensive Testing", SouthernPulp andPaper 46(4): 18(1983).

9. Patton,P. A, "On theMechanisms of AKD Sizingand Size Reversion", TAPPI 1991 PapermakersConference Proceedings, TAPP! PRESS, Atlanta,p. 415.

10. Novak, R W. and Rende,D. S., "Size Reversionin Alkaline Papermaking", TappiJournal 76(8): 117(1993).

11. Strutz,M D., "Sizing and NaturalGround Calcium Carbonate", TAPP! 1992 SizingShort Course, TAPPI PRESS, Atlanta, p. 81.

12. Honig, D. S., ''RetentionAid Requirements for Alkaline Papermaking", TAPP! 1989 Papermakers Conference Proceedings, TAPP!PRESS, Atlanta, p. 161.

13. Gill, RA, ''PrecipitatedCalcium Carbonate (PCC) Fillersand the Sizing of Alkaline ",TAPP! 1992 Sizing Short Course, TAPP! PRESS, Atlanta,p. 75. 13

14. Hubbe, M. A, "How Do RetentionAids Work?", TAPPI 1989 Papermakers Conference Proceedings, TAPPI PRESS, Atlanta,p. 389.

15. Allen, L. RandYaraskavitch, I. M, "Effectsof Retention andDrainage Aids on PaperMachine Drainage: a Review'', TappiJournal 74(7): 79(1991).

16. Colasurdo,AR and Thorn, I., "The Interactionsof AKD With Other Wet-End Additives",TAPPI 1992 PapermakersConference Proceedings, TAPPI PRESS, Atlanta,p. 135.

17. Pietschker,D. A, "PracticalApplication of Zeta Potential", TappiJournal 68( 4): 84(1985).

18. Stratton,RA and Swanson,J. W., ''Electrokineticsin Papennaking", Taopi Journal64(1): 79(1981).

19. Miyanishi, T., "On-Line Zeta PotentialAnalyses of a Fine PaperMachine and a Newsprint PaperMachine", TaopiJournal 78(3): 85(1995). l'

a Hydrolysis and cellulose reactions of alkyl ketene dimer (I)

R

Cellulose -0 - C- CHI - C - CH2 -R II II Cellulose - 01/ 0 0

/Sizing

R-CH=C-CH -R I I o-c=o

\ H20 Hydrolysis \

R-CH2-C-CH - R-R-CH2-C-CH2-R+C02 I I II o c=o 0 I OH R = C12 to C20 �-Keto acid Ketone

fi5ure. 2.. I Performance response profiles for acid and alkaline sizing ( 1)

w Cl) z. 0 a. C/l, w a:.

SIZE ADDED .... Figure 3: 15

Runs Prepared to Examine the Effectof R.A. 's on Size Response and Reversion

Cationic Polymer Anionic Polymer Zeta Potential Hercules 1232 Hercules 1523H Size Response Size Response -20mV ++ -10mV + 0mV + + + 10mV + +20mV ++

Zeta Potential Control AKO addition Size Response 0.19% -20mV 0 Added to stoc -10mV + at .15% cnsistenc 0mV + + 10mV +20mV

Runs Prepared to Determine the Effect of PEI on Size Response and Reversion

PEI addition (% on dr fber) 0.000 0.0015 0.0030 0.000 0.0120

.. 16

Table1: Summar Table of Data For Dteining the Efe o [PEI] on Zeta Potential

PE % Zeta Potential m 0 -15.9 : 3.0 0.025 -10.6 :1.2 0.05 -5.0 :0.4 0.1 4.0 :2.1 0.15 8.6: 1.8 0.2 13.1±1.3 0.25 15.1± 1.2

Table 2: Summar Table of Data For Deterining te Ef of Control on Size Respons

Zea Potential HST {snds} (mV) Day1 Day3 Day6 Day9 -20 3± 26 57±51 9 ±5 71 : 93 -10 924: 9 123±39 1137± 203 1149 :259 0 69 ±226 8± 14 95 ±220 93± 137 10 519± 259 597± 19 597±24 63± 226 20 1472±69 1769±497 1757± 282 1624: 33

Table 3: Summar Table of Data For Deterining the Ef of Caioic Polymer on Size Respns

Zeta Potential HST {snds} (mV) Dav1 Dav3 Day6 Day9 -20 1821± 15 19: 93 195: 93 1870± 119 -10 193± 18 19±4 198± 5 20±20 0 20±20 199±24 20±20 20±20 10 20±20 20 ±20 20 ±20 20±20 20 181 : 38 18±285 181: 310 1955: 10

Tale4: Sumar Tale o Data For Dterining te Ef of Aionic Polymer on Size Respnse

Zeta Potetial HST !s} (mV) Da1 Day3 Day6 Day9 -20 5± 7 4±4 4±6 3 :4 -10 187: 192 19: 159 1871: 28 1593 : 4 0 19: 57 20±20 1921± 113 1659 ±47 10 20±20 20±20 2±20 20±20 20 200 ±20 20±20 200 ±20 200 ±20

Table5: Summar Table of Dat to Dine te Ef o [PEI] o Siz Re

[PEI] HST !sds l (%) Day1 Oay3 Oay6 . Oay9 0.0 3±26 57 :51 69±5 71 ±93 0.0015 113±25 10± 43 10±25 91 ±133 0.030 139±257 112± 10 139±23 1020 ± 142 0.00 1210 :155 1259 ±47 139 :28 9±20 0.0120 1533±288 1225± 18 1575± 9 1215± 121 Figure 4: 17 Efect o( PEI Concentrtion on ZetaPotential

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Efect of Zet Potential on Size Response of Shet Made With Anionic Retention Aid 2000 ...... :::::::::::::::::::::::::::!i!ii:::i!i???!??!ii?!i?!i??!!?/ii\i!i!lt;:====:: ...... ::: ... ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::;:::::::::::::::::; ·················•··•·····•····································································································••··••······················ ··········•··································································•••·•·······································•································••···························

1800 ··············•···············•··•·····························································•···•····················•······················································································ ! llillllllillil!illllllllil!Jjjjjjjjjjjjjjjj 1800 :ti!il!lll!illllllll!il!il!illlll!illllllllllllllll�llllll![[!ilil!illl mm,,,\,,, 1:iii!lllll!llllllllllll!!!!!!!�!�!!!!:;;;;::::�llll!ll!ll!llll!lllll

1200

800 : :, il!!lllliiiiiillilllll!l:lllllllll!lill!illi!liilillililiiilliilliliiil!!ll! lliiiliiiW::m:m::::m:m::::::::::: : mmm : I !��111���1I !![l�l l�l! Iii !�l !�[! ![l !I[! Ill!�! I� l�l l li l 11 l II I I11 ii11 I 11 I. .. ��!l�l !�! ......

::::::::::::::::...... ::::::.. ·:::············:::1::::::···:::::::::::::::::::::····················:::··:::::···· ......

200 :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::::::::::::::::::::

111111 i�1H11mi111111111!1!11!111i�rn1�11�1rn��111�1irn�m�rnrn11111i1111�111�11!11!1�11!1111i11i��1�r-··--·--·--...... i1!l!!lll!l!lllll!!l!l!!!I!::: !l!!l!!ll!!l!llllll!!ll!!l!!!!!!!!!!!!!ll!llllllllllll!l!l!lll!l!!l!l!!l!l!!!ll!lll!!l!l!lll!l! m11 ttitttittttiititiiii··········· 0 ,:::::m:::,,,::m:::mm:::::::::::m::::,::::::::,::::::::,•,:::,::::::rn::m::::::;,,gg, ·····-'"'······•······""··· .... ············'"""""""." ...... -2 -15 -10 - 0 5 10 15 2 • · z.-Paanllal(mV). Figure 8: 21

Ee o PE on Si Repn

-• ,,C -•§

�E (% on d fb Figue 9: 22

Efect of Time on Size Peranence of Shet Made Without Retntion Aids

15

�-2mV

--10mV - -0mV ::c �+10mV -•2mV 10

Tlme(days). . Figue 10: 23

Efect of Time on Size Permanence of Sheet Made With Cationic Retention Aid

20 ::::::::::::::::::::::

''.:'°:''::':::::':'::::: .. ·""; ::;;;;:;;;;:;;;;;;;;;;;;:;;;;;:;:;;;;:::::::::::::::::::::::::::::::::::::: :

......

...... 18

---- i --20mV 8 : 16 --10mV

:::: ::::: ::::::::: i:: ::::: : :::::::::: ::: ::::::::: ::::::::::::::::::::::::::::::::::::::::::::::: ' ' ::::: :: : :::: ::::: : :: :::::::::::::: : :::::::;:::::::::::: ::::::::::::: .OmV 1 111 14 mrn === = �11 illlililllillilili::::::::1:1:1:1:::::::::::::::::::::1::11:11:1:1:::::1Iiii:::�:��:�1����������::;::::::::::�:�l���:� �!!�!����!�iiiiiii _J illliiiiilllllllll!!lillllllllllllilllillllliiiilllllllililllillllillilllllllli!l!llillllilliilllltmmmmmmmmmm1i111!!l!J1111111mm11ff::::::::::::::::::::::::::::::::::::::::;::::::::::::::::::::::::::::::::::::::::::::::::===mmm!1m ::m= ""="1::::1:\:::::m1::?i:lilliiilill!iilliiilillllllllllll;;HEmEEHEmHimmmiil!illlllllil mmrnmmmrnmmmmmmmm ._ __

12 S'' lIII 10 ll�!!l!!!��!i!!!�!!!!l!ii!ii!ii�llllliilliiiilllllllll!liii111111111111111t,"i,!!!�!!l�r11�!!!11!!!;;1r1;1:11��!! i!!!�!�llili ,, '' ' il�' !' 0 1 2 3 4 5 8 7 a 9 Tm(d) . . Figure 11: 24

Efect of Time on Size Permanence of Shet Made With Anionic Retention Aid

25

I :: :,

2000 ::,:::: :::: :::;::::: . .. . . ::::: ::::::::: :: . . . ;;::: ::: ,::,:: " J : :.. ... ;::;::: ' ::,Ht' '' ,::, :::::: 1111 Iiililillliillllllllll' : ::::::::::::: " :!llili! .,,,,,, :::: .,., H\:;,,,,,,,,, ""

:::::: ::: ..

···:...... :::: :;:::

15 --2mV ::::::;::::::: :::::: :::::: i!IHI n "" .... ,,,:::;·'" :::::;:: --10mV ...... ::: : :: ; """' : :: ::::::: .... : : ;:;;;;::;::;:: ; _OmV ::: ::,;;::::;:+ ::::: :', :;;; :: ,:: ... �+10mV : en... ii i,i H:" '' :::::::,::;;;;;;::; :: :: :::: ::c -•2mV :::::::::::,,::, ;:;::;:: 10 ;:; : ...... ::: '"'::::::: W T :::::::::::::::./!!: i

::::: ,,. ::::

::::::: :::.:...... ::::::::::::,,,:::;;::; ·····-;::: ::::::::::;··········'"· :::: :::: :: : :: : . : : :;: :::i;;;;;i::: . . ::::::::::::: '"'' ::::: ::: :::::::::c::::::::::::::+rn::: :: : liiiiii!iil!IIIIIIIIIIII ::: :::::: ":::::::::::::::::::: : 5 ·::: ::,,::• ::+ ...... ::: : : ::

::::::: :: ::/{::::; ::: :: : : : : :::·::::: :::::::::: :, , ; ;;; : : . .. :: : ::::::::::'::::: :::: ::g: ;;;;::::::::;;::::;"::::::::::: :: . .... : . ::::::: :::::::······

.... : .... ::::::::::::::: : , : : :: .. ;;:::;:;,,, 0 : :::: : : : 0 1 2 3 4 5 8 7 a 9 Tm (d) Figure 12: 25

Effect of Time on Size Permanence of Shet Made With PEI

160

::::::::::::::::::: :

12 .:.::::::::

-NPE [iiiiiiiiiiiifiiiiiiil �iiili!iiiiiii!iiiiiliili!!ll!lili!ll!ll!ili!! iii!iiiiiiiiiiiif!iiliiilii!i:;;;;;;:mmmmmm-'''''' -.015% f '� .0.03% -0.0 -0.012

; ; i I�ii!Mi;;;:;i::::;;;:;:;:: �:;:::;;;;;;;; : :: : : :::::::::: : :�::i;;:;;�;;;�;'.;:� ::::::::::::ii ii i : :: : - ::::::::::::::::::::::::::::::::: : : ::: : :,:mrnrnm:rnrnmm::

: :::::,::::::::::::,:::,:::::::::,::::::::::::::::::::::::::::,,::::::::�''"::::::::: ,,,,,,,,, ,,,,::::::::

. :::::::::: : : : :; ,- i 0 2 i 3 4 5 8 7 a 9 Tlme(daya)..