SEC OF P_DYu(_V_V_HOB')" USING MULTI-DETECTION METHODS

D.J. Nag}' & D.A. TerwilligerPhysical Analytical Technology Center

Air Products and Chemicals, Inc.Allentown, PA 18195

Introduction

Poly(vinyi alcohol), or PVA, is the largest volume, synthetic,water-soluble polymer resin produced in the world. PVA, a

polyhydroxy polymer, is synthesized commercially by thehydrolyszs of poly(vinyl acetate), or PVAc. Due to keto-enoltautomerism, vinyl alcohol monomer does not exist in the freestate and only traces have been detected (1,2,3). PVA wasdiscovered in 1924 by Herrmann and Haehnel who added alkali

to a clear solution of poly(vinyl acetate),)and__ obtained theivory-colored resin, poly(vinyl alcohol) (4

Today, PVA is employed in a wide range of applications whichowe their use to the excellent physical properties of theresin. Primary end-uses of PVA include adhesives, fibers,textile and paper sizing, emulsion polymerization, and theproduction of poly(vinyl butyral). Significant volumes ofPVA are also used in joint cements for building construction;water-soluble films for hospital laundry bags; cold water-soluble packaging for herbicides, pesticides, andfertilizers; temporary protective films; emulsifiers incosmetics; and photoprinting plates. PVA is an excellentadhesive and possesses superb solvent, oil, and greaseresistance. Films of PVA have high tensile strength, goodabrasion resistance, and excellent oxygen-barrier propertiesat low humidity. Because of low surface tension, theemulsification and protective colloid properties of PVA areexcellent. PVA is also biodegradable (15.

Commercial production of poly(vinyl alcohol) from poly(vinylacetate) is carried out via a continuous process. PVAc ispolymerized w_th a free-radical initiator in methanol usuallybetween 55-85-C. Molecular weight is controlled by theresidence time in the reactors, monomer feed rate, solventconcentration, initiator concentration, and polymerizationtemperature. Direct hydrolysis or catalyzed alcoholysisconverts the PVAc into the corresponding PVA (i). The degreeof hydrolysis can be carefully controlled to yield variousgrades of PVA: super-hydrolyzed (> 99 mole %), fully-hydrolyzed (98 mole %), and partially-hydrolyzed (88 mole %5.Annual world-wide capacity of PVA is 750 million pounds.

t

I

.... . : _ .:i _ _

Molecular weight and molecular weight distribution effectmany of the physical properties of poly(vinyl alcohol).These include solution viscosity, tensile strength, blockresistance, water and solvent resistance, adhesive strength,and dispersing power. These effects are well documented(I,5,6,7). Different molecular weight grades of PVA are

co,only described by 4% solution viscosity in water at20 C. However, reliable and accurate methods are required tomeasure and understand the effect of molecular weight andmolecular weight distribution on physical properties andperformance.

The major.emphasis of this paper will be on recent studiesutilizing molecular weight sensitive detectors for aqueoussize exclusion chromatography (SEC) of PVA. These includedifferential viscometry (Dr), low-angle laser lightscattering (LALLS), and multi-angle laser light scattering(MALLS). The major strengths and weaknesses of each methodwill be discussed for fully-and partially-hydrolyzed PVA.Characterization of long-chain branching in the hydrolysis ofPVAc to PVA is also presented.

Historical Background

The history of PVA molecular weight characterizationgenerally follows advances in SEC technology and methods ofdetection. In 1939, Staudinger and colleagues measured theMark-Houwink constants, K and a, for PVA in aqueous solution(8). Beresniewicz reported the K and a values as a functionof hydrolysis in 1959 (9). In the 1960s before the advent oftechnically feasible aqueous SEC, PVA was often reacetylatedback to poly(vinyl acetate) as a means to characterize themolecular weight distribution. SEC of the resultingpoly(vinyl acetate) was carried out using THF (6). Thisprocedure was indirect and cumbersome since it involved aderivitization step prior to the SEC analysis. Dark et alwere the first to report on the successful aqueous SEC of PVAusing deactivated silica column supports (i0). Other reportssoon followed using various supports such as TSK-PW gels(11,12,13). The TSK-PW supports have since been widelyaccepted for the analysis of a variety of water-solublepolymers including PVA. With the advent of on-line, low-angle laser light scattering (LALLS) detection, absolutemolecular weights of PVA were measured(14), including bothfully-and partially-hydrolyzed grades of various molecularweights (15,16). The use of LALLS allowed for molecularweight characterization without recourse to a columncalibration. The recent commercialization of on-line

differential viscometry (DV) detection opened up a whole newdimension for the characterization of PVA, provlding absolutemolecular weights, intrinsic viscosity, and increased

162

sensitivity (17,18,19). The basic theory and background intothe use of these detection methods is found in the citedreferences given in this paper.

R_perimental

The following conditions were employed for aqueous SEC ofPVA:

SEC System: Waters/Millipore 1:98_'@PC

Columns: Toyo Soda TSK-PW, 7.5 mm I.D. X 30 cm, set of1000A, 2000A, 3000A, 4000A, 5000A, 6000A

Mobile Phase: 0.05 M NaNO_ for L_T.T.S and M_TI.S

0.i0 M NaNO_, 0.i0 M NaNO_/CH_CN (80/20,vol/vol), H20/CH3CN (80/20, v_i/vol) for DV

Temperature: 35°C for DV; 27°C for LALLS, MALLS

LALLS: LDC CMX-100 (serial configuration with 150C)

M_T.T.S: Wyatt DAWN F (serial configuration with 150C)

Viscometer: Viscotek Model I00 (parallel configurationwith 150C)

Flow Rate: 1.0 ml/min (nominal)

Inj. Volume: 0.200 ml

Software: Viscotek GPC-LS Version 3.01 (LALLS)Viscotek UNICAL Version 3.02 (DV)Wyatt ASTRA Version 2.0 (M_T.T._)

Standards: Poly(ethylene glycol), Poly(ethylene oxide),Poly(acrylamide), American Polymer StandardsCorporation; Poly(saccharide), PolymerLaboratories

PVA Grades: Fully-Hydrolyzed (FH) and Partially-Hydrolyzed (PH) grades, Air Products andChemicals, Inc.

PVA SamplePreparation: 90°C for 30 minutes in aqueous mobile phase,

prefiltered through 0.45 micron Millex-HVfilter

The specific refractive index increment, dn/dc, and polymeroptical constant, K, used in the LALLS and MALLS analyses for

163

." '. .-i k -_ _ ._ • " -" : _/ "

T

fully-hydrolyzed and partially-hydro_yzed PVA, have beenpreviously reported by us (15) at 27 C in 0.05 M NaNO 3 and632 nmwavelength:

FH PVA, dn/dc = 0.150 ml/g, K = 1.631E-07 mol-cm2/g 2

PH PVA, dn/dc = 0.143 ml/g, K = 1.478E-07 mol-cm2/g 2.

Results and Discussion

Characterization of Fully-Hydrolyzed PVA:

Our previous work with aqueous SEC-LALLS, has shown that oneobtains excellent chromatography of PVA on TSK-PW columnsupports (15,16). This lead us to the examination of aqueousSEC-viscometry for absolute molecular weight characterizationof PVA as a complementary method to light scattering.

For SEC-viscometry analysis, our TSK-PW columns werecalibrated using a mobile phase of 0.i0 M NaNO_ with fourwater-soluble standards: poly(ethylene glycol_, or PEG;poly(ethylene oxide), or PEO; poly(saccharide), or PSC; andpoly(acrylamide), or PAA. The molecular weight ranges ofthese standards are summarized in Table i. A universalcalibration plot of log(intrinsic viscosity*molecular weight)versus retention volume was constructed and is shown inFigure 1. It can be seen that the four polymer types fall ona single curve indicating the validity of universalcalibration conditions. This demonstrates that separation isby a true size exclusion mechanism. This calibration was usedfor subsequent molecular weight calculations by DV. Universalcalibration using TSK-PW columns has also been verified usingan aqueous mobile phase with acetonitrile as an organicmodifier (17).

Concentration, DV, and LAT,T.Schromatograms are shown inFigure 2 for a medium molecular weight grade of PVA. Theconcentration chromatogram was obtained using the 150Cdifferential refractive index (DRI) detector. Several spikesfrom particulates are readily apparent in the LALLS response(a 0.22 micron pre-filter was used for the LAT.T.Sdetector).The L_LtS chromatogram also shows a small peak prior to themain distribution. This is probably due to some aggregatedor incompletely dissolved PVA. The DV response, whichoverall exhibits a cleaner signal, is not sensitive to thiscontaminant.

Figure 3 directly compares the DV and LALLS response for asuper low molecular weight grade of PVA. The same sampleconcentration and injection volume was used in both cases.

164I

Table 1

Polymer Standards used for Universal Calibration

Polymer Type Molecular Weight Range

Poly(ethylene glycol) 200 - 18,000Poly(ethylene oxide) 20,000 - 800,000

Poly(saccharide) 6,000 - 850,000Poly(acrylamide) 8,000 - 725,000

The L_T.T.S chromatogram exhibits poor sensitivity for thismolecular weight (approximately i0,000 daltons). Thiscomparison illustrates the superior sensitivity of viscometryto L_TT.S for low molecular weight material. Typically forLAT.T.S, low molecular weight or super low molecular weight PVArequire increased sample concentration in order to providereasonably good signal-to-noise ratio (15). For lowmolecular weight PVA, viscometry is about three to five timesmore sensitive than L_T.TS. The advantage of using DV forbetter detection of low molecular weight fractions in adistribution becomes obvious.

Let's turn our attention to the other end of the molecularweight spectrum by examining super high molecular weight PVA.This type of PVA is often difficult to analyze by LAT.tSbecause of sample entrapment of some of the polymer on anormal 0.22 micron filter. Lower molecular weight grades ofPVA do not present this problem. _ The use of a larger 0.45micron pre-filter eliminates the sample loss problem butintroduces excessive noise and particulate spikes. This iscommon to low angle detection. However, this problem iseliminated by the use of a M_T_.S detector and higher

scattering angles. Figure 4oShOWs DRI (labeled as RI) andMALLS (labeled as angle = 90 ) chromatograms for a super highmolecular weight PVA. It is important to note that the MALLSchromatogram was obtained without the use of a pre-filter.

Absolute molecular weights for fully-hydrolyzed PVAcalculated by viscometry and LALLS are summarized in Table 2.Data from MALLS is also included for a medium molecular

weight PVA. The DV results were obtained with the samemobile phase, 0.i0 M NaNO_, used for universal calibration.Data for L_T.T.S was obtained in 0.05 M NaNO_ (16). There isexcellent agreement between these two methods for super low,low, medium, and high molecular grades. Our estimated

precision for DV and LALLS is about 5% for Mw and 8% forThe peak parameters (detector offset, sigma, tau[v], and Mn"

165

Table 2

Comparison of Molecular Weights for Fully-Hydrolyzed PVA

PVA Type M n Mw [_]

High Mol. Wt.

DV (0.I0 M NaNO.) 55,000 149,000 1.05

LALLS (0.05 M NaNO_) 66,000 139,000 *i.00

Medium Mol. Wt.

DV (0.i0 M NaNO_) 44,000 i00,000 0.85LALLS (0.05 M NaNO_). 48,000 97,000 *0.82

MALLS (0.05 M NaNO_) 68,000 107,000 ....

Low Mol. Wt.

DV (0.10 M NaNO_) 10,000 26,000 0.41

LALLS (0.05 M NaNO_) 14,000 28,000 *0.40

Super Low Mol. Wt.

DV (0.i0 M NaNO_) 5,900 19,000 0.31LALLS (0.05 M NaNO_) i0,000 20,000 *0.33

*[_] at 35°C in 0.10 M NaNO 3 by Ubbelohde viscometry

tau[c]) required by the Viscotek Software for molecularweight calcualtions, were calculated from a poly(ethyleneoxide) standard of molecular weight 80,000.

Also included in Table 2, is intrinsic viscosity data fromDV and Ubbelohde viscometry. There is excellent agreementwith the intrinsic viscosity determined by DV and off-linewith Ubbelohde viscometry.

It should be noted that the number-average molecular weightsfrom LALLS (and M_TT.S) are biased slightly high compared tothose from viscometry. This type of effect has beenpreviously reported (16). This illustrates the decreasedsensitivity of light scattering compared to viscometry forlow molecular weight material. The resulting polydispersityfrom viscometry reflects this fact, as these values will beslightly higher than that from LALLS (or MALLS).

166

• . .. . •

A comparison of molecular weights between viscometry andM_LT.S for the super high molecular weight PVA discussed

above, is summarized in Table 3. The agreement with the Mwis within the expected precision of the two methods.However, we see once again that the number-average value fromlight scattering is biased high compared to viscometry. Thisreflects the decreased sensitivity of the MALLS to the lowmolecular weight material in the distribution. Both methods,however, are still an excellent choice for characterizationof this type of PVA.

Viscometry measurements allow for the calculation of theMark-Houwink constants under conditions used for the

analysis. The K and a values for PVA over the range of

molecular weights from super high to super low are given inTable 4 at 35 C in 0.i0 M NaNO_. The a values are withinthe expected range of 0.5 to 0T8 for random-coil polymers,and are essentially constant over the whole range ofmolecular weights. The super low molecular weight PVA showsa slightly lower value which may reflect the change inhydrodynamic volume at low molecular weights. This is thefirst reported use of aqueous SEC-viscometry for determiningthe Mark-Houwink constants for PVA.

The significance of knowing these values lies in the factthat molecular weight distribution data can be directlycalculated using one of two methodologies: (1) the Mark-Houwink method which requires prior knowledge of K and avalues for PVA and the calibration standards such as PEG andPEO, and (2) the intrinsic viscosity distribution, or IVD,method as reported by Yau (20). The former is a calibrationdependent procedure, and Mark-Houwink constants for thestandards are readily obtained from calibration/viscometrymeasurements. These have been reported for PEG and PEO (15).For the latter method, however, a simple ratio of specificviscosity signal to the concentration signal in a DVanalysis, yields the IVD (peak parameters, mass injected, andviscometer inlet pressure must be known). The IVD method isa calibration independent procedure. By inputing the Mark-Houwink values, molecular weights can be calculated using theMark-Houwink relationship. Since this procedure iscalibration independent, it may hold significant value forquality or process control.

Characterization of Partially-Hydrolyzed PVA:

Concentration, LALLS, and viscometry chromatograms for a highmolecular weight, partially-hydrolyzed (88 mole %) PVA areshown in Figure 5. Both the LALLS and viscometry exhibitexcellent signal response. A few particulate spikes areseen in the LALLS chromatogram, which was acquired using a0.22 micron prefilter on the CMX-100.

167

Table 3

Comparison of Molecular Weights for Super High Mol. Wt. PVA

Mn Mw [_]

DV (0.i0 M NaNO_) 91,600 249,000 1.40

MALLS (0.05 M NaNO;) 135,000 264,000 ....

Table 4

Mark-Houwink Constants for Fully-Hydrolyzed PVA

(0.i0 M NAN03, 35°C)

Molecular We_gh_ a Loa_K_

Super High 0.570 -2.899High 0.567 -2.870

Medium 0.560 -2.863Low 0.569 -2.902

Super Low 0.517 -2.687

Molecular weights calculated from viscometry for variousmolecular weight grades of PH PVA using the same conditionsas for FH grades, results in low values of 20 to 30 percent(compared to LALLS). This was not surprising since PH PVAis more hydrophobic than the corresponding FH PVA. It issuspected that secondary, nonsize exclusion effects result ina retardation of the polymer, longer elution times, and lowermolecular weights. Similar types of hydrophobic interactionsusing TSK-PW columns have been reported for other water-soluble polymers (13). The addition of an organic modifierto the aqueous mobile phase is a way to minimize or eliminatethis effect (19).

Two mobile phase compositions of HgO/CH3CN (80/20, vol/vol)and 0.i0 M NaNO_/CH_CN (80/20, volTvol) were used forSEC-viscometry _f partially-hydrolyzed grades. PEO, PEG, andPSC were used for column calibration and universal calibra-tion was observed (17). Molecular weights were compared tothose from LALLS. These data are summarized in Table 5 forhigh, medium, low, and super low molecular weights. Closeragreement with LALLS is seen with the H_0/CH_CN mobile phase.It is suspected that the non-salt mobil_ phase does a betterjob eliminating the hydrophobic interactions and maximizing

168

Table 5

Comparison of Molecular Weights for Partially-Hydrolyzed PVA

PVAType Mn Mw [_]

High Mol. Wt.

DV (HoO/CH_CN , 80/20) 59,000 151,000 1.13DV (0.10_M Na/qO_/CH_CN, 80/20) 59,000 144,000 1.17

LALLS (0.05 N NaNO3) 88,000 160,000 *0.96

Medium Mol. Wt.

DV (H?O/CH_CN, 80/20) 53,000 123,000 0.78DV (0.10-M NaNO_/CH_CN, 80/20) 48,000 i03,000 0.94

LALLS (0.05 N Na/_O3) 63,000 118,000 ,0.81

Low Mol. Wt.

DV (H_O/CH_CN, 80/20) 12,000 39,000 0.47DV (0.10-M NaRO3/CH_CN , 80/20) 14,000 33,000 0.46

L_LTIS (0.05 N NAN03) 18,000 37,000 *0.42

Super Low Mol. Wt.

DV (HgO/CH_CN , 80/20) 4,700 18,000 0.34DV (0.10"M NaNO_/CH_CN, 80/20) 9,100 18,000 0.30

LALLS (0.05 H Na/_O3) 9,500 20,000 *0.30

*[_] at 35°C in H20/CH3CN (80/20) by Ubbelohde viscometry

the size exclusion mechanism. Intrinsic viscosity valuescalculated from DV for the two acetonitrile mobile phase

compositions and from Ubbelohde viscometry in H20/CH3CN , arealso summarized in Table 5.

In general, the characterization of partially-hydrolyzed PVAneeds further investigation to better understand the impactof hydrophobic interactions. The use of other organic,mobile phase modifiers such as N-methyl pyrrolidine (NMP) ordimethyl sulfoxide (DMSO) is a possible approach.

Branching in the Hydrolysis of PVAc to PVA:

The molecular wSight of PVAc (the precursor to PVA) can bereliably measured in THF using SEC-viscometry (21). The use

169

of differential viscometry and LALLS provides a means toexamine long-chain branching in the hydrolysis of PVAc toPVA. It is suspected that the hydrolysis results in the lossof hydrolyzable, long-chain branches. These branches extendfrom the ester to the main PVAc backbone (7). Of course,branches formed by chain transfer to a carbon atom in themain chain are non-hyrolyzable and will remain.

Our examination of branching utilized fully-hydrolyzed PVAand the fact that PVA can be reacetylated in pyridine back toPVAc. The reacetylated PVA could be thought of as the"linear" PVAc and the starting PVAc (referred to as PVAcpaste) as.the "branched" analog.

Figure 6 includes an overlay of the molecular weightdistributions of the PVAc paste and reacetylated PVA.Molecular weight and viscosity data are snmmarized in Table6. It is readily apparent that the reacetylated PVA is lowerin molecular weight. Virtually all of the molecular weightis lost from the high molecular weight end of the

distribution. This is attributed to the loss of lon_-chainbranches from the PVAc paste during hydrolysis, and is seenas a lower value for the polydispersity of the reacetylated

PVA. The M w and intrinsic viscosity values also reflect thisdifference. It is also interesting to point out that thechange in Mark-Houwink constants from 0.63 for the PVAc pasteto 0.73 for the reacetylated PVA is another indicator of theloss of long-chain branches. The branched PVAc paste wouldbe expected to have the lower value for intrinsic viscosity(21). The molecular weight of the PVA which was reacetylatedto PVAc is also listed in Table 6. These molecular weightswere obtained from SEC-LALLS, and are consistent with thoseof the two PVAc types obtained from SEC-viscometry.

Figure 6 also includes an overlay of the Mark-Houwink curvesfor the PVAc paste and reacetylated PVAc. The curve for thePVAc paste deviates slightly from linearity, indicating thepresence of branched pol_mer. The loss of long-chainbranches in the hydrolysls and the corresponding decrease inmolecular weight of the PVAc, is reflected in this smalldifference in the Mark-Houwink plot.

Our work has shown that both aqueous SEC-viscometry, L_I.LS,and MALLS are excellent methods for characterization offully-hydrolyzed PVA. Viscometry is more sensitive to lowmolecular weight material, but requires the adherence touniversal calibration for calculation of absolute molecularweights. We have demonstrated that universal calibrationbehavior is observed using TSK-PW columns in a mobile phase

170

Table 6

Molecular Weight and Viscosity Data forPVAc Hydrolysis to PVA

PVAc Paste pVAc Reacet_lated PV__AA

Mw 323,000 195,000 I00,000

Mn 106,000 91,000 49,000

Mw/M n 3.0 2.1 2.1

[_] 1.00 0.83 ---

a 0.63 0.72 ---

Log(K) -3.44 -3.84 ---

of 0.i0 N NaNO_. Mark-Houwink constants have been determinedunder these conditions over a full range of molecular weightsfor fully-hydrolyzed PVA. Both L_TIS and MALLS require priorknowledge of dn/dc constants for molecular weight analysis.Viscometry and M_T.TS work well for super high molecularweight PVA of approximately 250,000.

Characterization of partially-hydrolyzed PVA by viscometry iscomplicated by secondary, hydrophobic interaction effects.These effects can be minimized by using a suitable aqueousmobile phase with an organic modifier such as acetonitrile.

Long-chain branching can be characterized by SEC-viscometry(in THF) of the starting PVAc used for the hydrolysis toPVA.

Acknowledgment

The authors wish to thank Air Products and Chemicals, Inc.for permission to publish this work.

171

Literature Cited

1. F.L. Marten, Vinyl Alcohol Polymers, in Encyclopedia ofPolymer Science, Volume 17, John Wiley & Sons, Inc., NewYork, 1989, p. 167.

2. J.M. Hay and D. Lyon, Nature 216, 790 (1967).

3. B. Capon, D.S. Watson, and C. Zucco, J. Am. Chem. Soc.103, 1761 (1987).

4. Get. Pat. 450,286 (1924), W. Haehnel and W.O. Herrmann(to Consort. f. elecktrochem. Inc. GmbH).

5. Airvol_Polyviny I Alcohol, Product Bulletin 1990, AirProducts and Chemicals, Inc., Allentown, PA.

6. I. Sakurada, Polyvinyl Alcohol Fibers, Marcel Dekker,Inc., New York, 1985.

7. C.A. Finch, Polyvinyl Alcohol, Properties andApplications, John Wiley and Sons, New York, 1973.

8. H. Staudinger and J. Schneider, Liebigs Ann. 541,261 (1939).

9. A. Beresniewicz, J- Polym. Sci. 39, 63 (1959)

i0. W.A. Dark, K.J. Bombaugh, and J.N. Little, Anal. Chem.,41, 10, 1337 (1969).

ii. R.V. Vilvilecchia, B.G. Lightbody, N.Z. Thimot, andH.M. Quinn, J. Chromatogr. Sci., 15, 424 (1977).

12. T. Hashimota, H. Sasaki, M. Aiura, and Y. Kato, J.Polym.Sci., Polym. Phys. Ed. 16, 1789 (1978).

13. Y. Kato, T. Matsuda, and T. Hashimota, J. Chromatog. 332,39 (1985).

14. M. Fukutomi, M. Fukuda, and T. Hashimota, Toyo SodaKenkyu Hokoku 24, 33 (1980).

15. D.J. Nagy, J. Polym. Sci., Part C: Polym. Lett., 24, 87(1986).

16. D.J. Nagy, Proceedings of 1987 International GPCSymposium, Waters/Millipore Corp., Chicago, IL, May 1987.

17. D.J. Nagy, J. Liq. Chromatog, 13, 677 (1990).

172

18. D.J. Nagy and D.A. Terwilliger, Viscotek CorporationUser's Group Mtg., 1990 Pittsburgh Conference, New York,March 1990.

19. D.J. Nagy, First International GPC-Viscometry Symposium,Houston, Texas, April 1991.

20. W.W. Yau and S.W. Rementer J. Liq. Chrom. 13, 627 (1990).

21. B.D. Lawrey, First International GPC-Viscometry Symposium,Houston, Texas, April 1991.

173

Figure I. Universal calibration curve for _queous SEC-viscometry in 0.10 M NaNO3 at 35 C with TSK-PWcolumns.

8.0

7.0

6.0

A

5.0

O:E 4.04=

_ 3.Oo.J

2.0

1.0 • PEG • PEO • PSC • PAAM

I I | I

30.0 34.0 38.0 42.0 46.0 50.0 54.0RETENTIONVOLUME,ML

174

Figure 2. DRI, LALLS, and DV chromatograms for medium

molecular weight, _ully-hydrolyzed PVA in0.10 M NaNO 3 at 35 C.

S.00 CONCENTRATIONCHROMATOGRAM

4.00

3.00

X> 2.00:E,.i

.<Z 1.000

.000

-- 1.00 i ; , , _ , l , t , t , , I ,_.0 31.0 37.0 43.0 49.0 55.0

s.0o LALLSCHROMATOGRAM

¢_ 4.00+O

X

_> 3.00

Z

1.00 f = 1 I I r l I I I I I I I r

25.0 31.0 37.0 43.0 4g.0 55.0

- 3.00 VISCOSITYCHROMATOGRAM

- 4.00

_- 5.00x

._ - 6.00

-- 7.00U)

- 8.00

-- 9.0.._. 0 31.D 37.0 43.0 49.0 55.0RETENTION VOLUME, ML

175

Figure 3. LALLS and DV chromatograms for super lowmolecular weight PVA. Same conditions as inFigure 2.

110.0 -- 30.0

100.0 - 40.0

=E • t, / _,\-_ LALLS _/'/ '_ ....-VISCOMETRY <

90.0 - 50.0

m .r-.J..j :¢

",-', ,',,,_-',-','_"_' / " "h , --60.080.0 """- ..... '

I I I I i i I I I I I I I |

30.0 36.0 42.0 48.0 54.0 60.0RETENTION VOLUME, ML

176

II

Figure 4. DRI (labeled as RI)90B_ MALLS (labeled asscattering angle = chromatograms forsuper high molecular weight PVA. Sameconditions as in Figure 3.

Peak NuMber: t ] 9B° -----BI ...........

177

Figure 5. DRI, LALLS, and DV chromatograms for highmolecular weight, partially-hydrolyzed PVA in

0.i0 M NaNO3/CH3CN (80/20, vol/vol).

CONCENTRATION CHROMATOGRAM

11.0

-T- 8.000

x

> 6._IE

z_a 2._

| I I I I I I i I | I ° " ' I

1.._25.0nn 31.0 37.0 43.0 49.0 55.0

s.oo LALLS CHROMATOGRAM

4.00X

,_ 3.00

2.00

1.00 l r ; ! I I ! : _ i I I ! i !25.0 31.0 37.0 43.0 49.0 55.0

- 2.00 VISCOSITY CHROMATOGRAM

- 3.00

; -- 4.002x _ 5.00>:S-J -- 6.00,<z

-- 7.00

-- 8.00

-- 9.00 | ; I T I T I I T I I * r25.0 31.0 37.0 43.0 49.0 55.0

RETENTION VOLUME. ML

178

Figure 6. Molecular weight distributions and Mark-Houwink

plots of PVAc paste and reacetylated PVA fromSEC-viscometry in THF.

24.0

22.0

20.0

16.( PVAc.REACETYLATEDFROM PVOHO

(LINEAR)x 14.0

_- M, = 91,000 PVAc PASTE12.0 Mw = 195,000 t_dc" (BRANCHED)C_

o Mw/M. = 2.1 % MN = 106.000

_10.0 I.V. = 0.83 =Mw 323.000

I/ Mw/M, = 3.0

8.00 PVOH MWD. BY LALLS I I.V. = 1.06.00 ME = 49,000 f

Mw = 100,000 %4.00 MwJM. = 2.1 %

%2.00

\

.000 \2.00 3.00 4.00 5.00 6.00 7.00

LOG (MOLECULAR WEIGHT)

6.00

!4.00 [

LINEAR PVAc / //

TOX2.00 (R'_"_-"_'TED FROM P_//--- .000ED PVAco PASTE

O.J

- 2.00

- 4.00

- 6.00 ' T ' 14.04 4.50 5.00 5.50 6.00 6.50 7.00

LOG (MOLECULAR WEIGHT)

179

lib,.. ..... _:. _. ...... L ............. _._._ -..... - "--.L__-- ___...:.s,,,L_-_ • _,,,,..-.:.e,_,.:=-..___" __ ;"_:-_ .._:_._.- _,_4P