Introduction

Polysaccharides are natural polymers from renewablesources. Chief among polysaccharide characteristics istheir ability to modify the properties of aqueous envi-ronments, that is their capacity to thicken, chelate,emulsify, stabilize, encapsulate, flocculate, swell andsuspend, or to form gels, films and membranes. Textileprinting is one of the largest exploitations of the thick-ening properties of carbohydrate polymers. Thickenersare used in textile printing to modulate the rheologicalproperties of the printing pastes during application andto obtain sharp, clean drawing patterns by preventingdye migration. Alginates, guar gum and its derivatives

are excellent thickeners for this applications (Lapasinand Pricl 1995). Alginates are the most widely usedthickeners in cellulose printing among polysaccharides;however, their unstable price and quality as well as theirunreliable supply have made other polysaccharides, inparticular guar gum and their derivatives quite inter-esting alternative thickeners. On the other hand, guarthickeners need to be modified since they have many freehydroxyl groups tending to react with reactive dyes.Indeed, due to their different chemical nature, types anddegrees of derivatization, thickeners can display quitedifferent conformations in aqueous media, which reflectin the structural features of the polymer solution(topological constraints, interchain interactions) and,

Marija Oblonsek

Sonja Sostar-Turk

Romano Lapasin

Rheological studies of concentrated guar gum

Received: 26 August 2002Accepted: 5 February 2003Published online: 12 April 2003� Springer-Verlag 2003

Abstract Polymers and surfactantsare essential ingredients of theprinting paste. Polysaccharides areused commercially to thicken, sus-pend or stabilise aqueous systems.Also they are used to produce gelsand to act as flocculates, binders,lubricants, to serve as modifiers offilm properties, and have a functionas adjusters of rheological parame-ters. Surfactants, on the other hand,perform numerous functions actingas dispersants, wetting agents,emulsifiers and antifoaming agents.The rheological properties of

polysaccharide thickeners (guargums with different substitutionlevels and different producers) atdifferent concentrations and tem-peratures and, second, the effectsproduced by the addition of non-ionic surfactants (polyoxyethylene

stearyl alcohols with different num-bers of EO groups) have been stud-ied under linear and nonlinear shearconditions. Experimental data havebeen correlated with the differentmodels: flow curves with the Cross,Carreau and Meter-Bird model, andmechanical spectra with the gener-alized Maxwell model and Friedrich-Braun model. The surface tensionsof aqueous systems containingpolysaccharide and/or surfactantshave been determined over extendedconcentration ranges in order todetect the CMC conditions and toprovide a better understandingabout the polysaccharide-surfactantinteractions.

Keywords Rheology Æ Visco-elasticity Æ Polysaccharide ÆSurfactant Æ Textile printing

Rheol Acta (2003) 42: 491–499DOI 10.1007/s00397-003-0304-0 ORIGINAL CONTRIBUTION

M. Oblonsek Æ S. Sostar-Turk (&)Institute of Textile Chemistry,Ecology and Colorimetry,Faculty of Mechanical Engineering,University of Maribor, Smetanova, 17,Maribor, SloveniaE-mail: sonja.sostar@uni-mb.si

R. LapasinDepartment of Chemical, Environmentaland Raw Materials Engineering, Universityof Trieste, piazzale Europa 1, I 34127Trieste, Italy

consequently, into its rheological properties (Oblonsek

et al. 2000; Sostar-Turk and Schneider 1999; Kokol andSostar-Turk 1998).

The surfactants are characterized by the presence oftwo moieties in the same molecule, one polar and theother nonpolar. The polar group may carry a positive ornegative charge, giving rise to cationic or anionic surf-actants, respectively, or may contain ethylene oxidechains or sugar or saccharide-type groups, as in the caseof nonionic surfactants (Kunjapu 1999; Goddard andAnathapadmanabhan 1993).

The surfactants are added to printing pastes and theycould perform numerous functions acting dispersants,wetting agents, emulsifiers and antifoaming agents(Kunjapu 1999).

Polymer-surfactant interactions, which are akin toprotein-surfactant interactions, have attracted muchattention owing to their industrial applications, e.g. inpaints, coatings, cosmetics, tertiary oil recovery etc. aswell as in biological systems (Saito 1987; Goddard andAnathapadmanabhan 1993). The polymer surfactantinteractions have been studied by various methods(Goddard 1986; Cabane and Duplessix 1987; Chari et al.1994). All these studies indicate that polymers interactwith surfactants by inducing micellization of surfactantson the polymer chain and after polymer gets saturatedwith the micelles the excess surfactants form free micelles(Biggs et al. 1992). These polymer-bound micelles havehigher solubilizing power as well as viscosity in com-parison to individual polymer or micelle (Saito 1987).Figure 1 presents the schematic diagram of the polymer-surfactant complex (Goddard and Anathapadmanabhan1993).

The reactive printing paste contains many compo-nents like thickener, reactive dye, surfactant, urea, so-dium carbonate, water and reduction substance. Therheological properties of printing pastes depend on thethickener used, its concentration and its interactionswith other components of the printing paste, which canaffect the viscous and the elastic properties, too. Dur-ing the printing process, i.e. the action of the squeegeeon the printing screen, the printing paste undergoeshigh deformation rates and stresses and, consequently,marked changes in the rheological parameters occursuch as viscosity drop and increased elasticity, whichall together give the printing paste the capability topenetrate into the fabric (Oblonsek et al. 2000; Sostar-Turk and Schneider 1999; Kokol and Sostar-Turk1998).

The behaviour of polymer and polymer-surfactantmixtures has been studied rheologically by using arotational controlled stress rheometer HAAKE RS150,equipped with cone and plate C60/1 and parallel platePP35 TI sensor system.

Experimental part

Used polymers and surfactants

Polymers Four different polymers from different producers havebeen used: nonsubstituted guar gums and substituted guar gumwith the substitution level DS=1.1. Table 1 presents their com-mercial names, substitution levels, abbreviations, molecularweights, polydispersities and the producers of used thickeners.

The chemical structure of guar gum consists of linear mainchains of mannose units linked by 1,4-b glycosidic bonds. Everysecond mannose monomer carries a galactose residue by the 1,6-aglycosidic bonds. The esterification of free hydroxyl groups withethanoic acid in SGG increases the hydrophilic character of thepolymer. The primary chemical structures of nonsubstituted andsubstituted guar gums are presented in Figs. 2 and 3.

Surfactants We used non-ionic stearyl alcohol surfactants withdifferent numbers of EO groups (Brij 76 with 10 EO and Brij 78with 20 EO) from Fluka Chemie AG, GmbH Germany. Primarychemical structures of stearyl alcohols are presented in Figs. 4 and5. Their molecular weights, HLB values, critical micellar concen-trations (CMC) at temperature 25 �C, EO percentage in the mol-ecule, melting points, commercial names and abbreviations arecollected in Table 2.Fig. 1 Schematic diagram of polymer-surfactant complex

Table 1 Commercial names, substitution levels, abbreviations, molecular weights, and polydispersities of used thickeners

Guar gum DS (-) Mnc (g/mol) Mw

c (g/mol) Mw/Mn (-) Abbreviation Commercial name

Nonsubstituted 0 54.542 149.260 2.737 GNa Lameprint DX-9Nonsubstituted purifiedd 0 177.840 297.290 1.672 GPa –Nonsubstituted 0 149.650 237.370 1.586 Fb –Substituted 1.1 54.917 145.370 2.642 SGGa Lameprint L-22733

aThe producer is Cognis GmbH, GermanybThe producer is Fluka Chemie AG, GmbH, GermanycThe molecular weights was measured by Size Exclusion Chromatography at the Institut fur Textilchemie, Denkendorf, GermanydNonsubstituted guar gum GN was purified by extraction method from producer (Cognis GmbH, Germany)

492

Preparation of the samples

The defined quantity of polymer was added progressively into thedemineralised water and stirred to get a homogeneous solution.The prepared mother solution was left in a refrigerator overnight toattain complete swelling. The lower concentrated polysaccharidesolutions were prepared by dilution of the mother solution.

Nonionic surfactants are solid at ambient temperature, so theywere melted at 45 �C and then the defined surfactant quantity wasadded to demineralised water. Such a system was then mixed andheated at about 100 �C until the solution became clear.

During the following cooling down, the defined quantity ofpolymer was progressively added to the surfactant solution andstirred to get a homogeneous polysaccharide-surfactant solution.

The reactive printing paste was prepared by stirring the poly-saccharide matrix added with all the other components.

Apparatus and procedures

The rotational controlled stress rheometer HAAKE RS150,equipped with cone and plate (C60/1) and plate and plate (PP35 TI)sensor systems was used to carry out the rheological tests. Tem-perature was controlled by circulator HAAKE TC500.

Polysaccharide and polysaccharide-surfactant solutions havebeen investigated under steady and oscillatory shear conditions.Shear stress ramps and stepwise procedures with sequential changesof shear stress have been applied in order to study shear dependentbehaviour under destructive shear conditions. The extension of thelinear viscoelastic regime has been determined from stress sweeptests under oscillatory shear conditions at constant frequency(1 Hz). Frequency sweep experiments have been carried out atconstant strain amplitude in the range of 100–0.01 Hz.

Tensiometer Kruss K12 with Wilhelmy measuring plate wasused to measure the surface tension of surfactant solutions, poly-saccharide-surfactant systems and reactive printing pastes.

Results and discussion

Rheological properties of polysaccharide systems

The flow curves for the SGG system are typical for or-dinary polymer solutions, since the first Newtonianplateau is generally attained at low shear stresses andshear rates. This is not the case of GN systems; a slightdivergence is observed from the Newtonian behaviour inthe same stress region (Figs. 6 and 7).

The flow curves of GP and F systems show not onlythe first Newtonian plateau at low shear stress and shearrate but also the tendency to the second Newtonianplateau at high shear rate. It could be mentioned here,that the concentrations considered for GP and F systemsare ten times lower that the concentrations of SGG andGN systems in order to lie in the same viscosity range

Table 2 Molecular weights, HLB values, critical micelle concentration (CMC) at temperature 25 �C, the percent of EO in the molecule,melting point, commercial name and abbreviation of used surfactants

Commercial name Abbreviation M (g/mol) HLB CMC25 �C (wt%) Tmelt. EOa (%)

Brij 76 B 710 12.4 4·10–3 38 62.0Brij 78 C 1150 15.3 9.5·10–4 42–43 76.5

aHLB is calculated with equation (definite from producer):HLB ¼ E5, where E is the weight percent of EO in the surfactant

Fig. 2 Primary structure of nonsubstituted guar gum

Fig. 3 Primary structure of substituted guar gum

Fig. 4 Primary structure of stearyl alcohol with 10 EO

Fig. 5 Primary structure of stearyl alcohol with 20 EO

493

and this is the reason why we did not prepare moreconcentrated GP and F systems (above 2%).

The experimental data have been correlated withdifferent models suitable to describe the shear thinningbehaviour of the systems. An example is reported inTable 3. From the comparison between the parametersdescribing the quality of fitting (the objective function,the average percentage deviation and the number ofruns) we can conclude that the Cross model provides thebest fitting so that it can be profitably used for com-paring the shear properties of all the systems. Among theCross parameters we see that, as expected, both the zeroshear viscosity g0 and the characteristic time k increasewith increasing polysaccharide concentration.

The dependence of the Cross parameters g0 and k onpolymer concentration is described by similar scalinglaws for all guar systems (Fig. 8). GP and F havehigher molecular weights and, hence, higher intrinsicviscosities than SGG and GN polymers and this is thereason why the lines relevant to GN and SGG areshifted to higher values along the concentration axis. Itshould be noted that, if the polymers belong to thesame family and have similar conformation, the samezero-shear-rate viscosity can be attained for differentcombinations of molecular weight and concentration,on condition that the product concentration·intrinsicviscosity is constant. The overlap concentration mark-ing the boundary between dilute and concentratedsolutions, c*, was determined for system GP and isaround 0.17 dl/g.

The effects of temperature on the flow behaviour aresimilar at different polymer concentrations so that all theflow curves can be reduced to a single master curvethrough a double shift procedure, more conveniently ina log viscosity-log shear stress plot. Figure 9 reports anexample of the master curve obtained for the SGGsystems. As we can observe in Fig. 10, no appreciablechange is observed for the exponent b of the scaling lawdescribing the dependence of the zero shear rate vis-cosity on polymer concentration, whereas the preexpo-nent a changes in accordance with the Arrheniusequation (log a is a linear function of 1/T).

For SGG (diamonds: 15�C, squares: 25�C, Triangels:35�C).

From stress sweep tests the upper limit of the linearviscoelastic behaviour was determined, also resorting tothe Soskey-Winter equation, which provides good fittingof the experimental data (Fig. 11). The Soskey-Winterequation could be used for description of viscoelasticmoduli vs deformation (Soskey and Winter 1984):

G�

G�0ðcÞ ¼ 1

1þ acbð1Þ

where G* is the complex modulus, G0* is the complexmodulus in the linear viscoelastic regime, c is the strainand a and b are adjustable parameters. The border of theupper linear viscoelastic regime is arbitrarily set in cor-respondence with G*/G0*=0.95.

Looking at the parameter, which rules the rate ofdecrease of elastic and viscous moduli with increasingstrain, we can remark more evidently that the elasticmodulus decreases with strain more rapidly than theviscous one. As expected, both moduli increase withincreasing polysaccharide concentration. Critical straindoes not change significantly with polysaccharide con-centration, since its value is generally between 25 and40%. This is typical of ordinary polysaccharide andother polymer solutions. We could mention here that forweak gels the critical strain is generally lower and inseveral cases markedly lower than 10%.

Fig. 6 Flow curves for SGG system at 35 �C (3% squares, 6%circles, 9% diamonds)

Fig. 7 Flow curves for GN system at 15 �C (3% squares, 6%circles, 9% diamonds)

494

The mechanical spectra of SGG systems show thetypical shape of ordinary polymer solutions (Fig. 12).This means that at higher frequencies the elastic mod-ulus is predominant, whereas at low frequency (terminalzone) the viscous modulus is higher than the elastic oneand the curves tend asymptotically to the usual limiting

slopes for both moduli. The crossover frequency (be-tween the profiles of elastic and viscous moduli) de-creases with increasing concentration of polysaccharideas a consequence of increasing relaxation times. Con-versely, the mechanical spectra of GN (Fig. 13) andF guar gums are qualitatively different from thoseof ordinary polysaccharide solutions and partially

Table 3 Model parameters (g0,g¥,kand n) and parameters of fitting quality for SGG systems at 35 �C

Model Crossd Meter-Birde Carreaug

wt% 3.0 6.0 9.0 3.0 6.0 9.0 3.0 6,0 9.0g0 [Pa s] 1.030 13.039 131.139 0.917 10.633 114.762 0.904 11.376 111.024g¥ [Pa s] 0.001 0.001 0.001 0.001 0.016 0.001 0.001 0.001 0.001k [s]f 0.057 0.188 1.167 0.087 0.019 0.018 0.156 0.334 2.690n 0.656 0.750 0.720 1.415 2.618 1.436 0.490 0.36 0.394O.F.a 0.0021 0.1187 0.0036 0.1243 1.8219 1.4115 0.1930 0.4555 1.6394APDb 0.56 0.95 0.81 5.88 7.77 14.10 7.29 5.73 17.10no. runsc 7 4 5 3 4 2 3 4 2

aThe objective function O.F. is given by O:F : ¼PN

i¼1 ð1�gi;cal

gi;expÞ2 where gi cal is calculated from the model and gi exp is the experimental value

bThe average percentage deviation APD is given by APD ¼PN

i¼1 1� gi;cal

gi;exp

���

��� � 100N

cThe number of runs is given by no. runs ¼XN

i¼2

signðgi;cal � gi;expÞ � signðgi�1;cal � gi�1;expÞ2

����

����

The models used are:dThe Cross model g ¼ g1 þ g0�g1

1þðk _ccÞneThe Meter-Bird model (Meter and Bird 1964) g ¼ g1 þ g0�g1

1þðksÞnfLambda parameter has the inversion dimension of a stress and then it must be expressed in Pa–1, when the Meter-Bird equation is usedgThe Carreau model g ¼ g1 þ g0�g1

ð1þðk _ccÞ2Þð1�nÞ=2 where g1 is the infinite-shear-rate viscosity, g0 is the zero-shear-rate viscosity, k is

the characteristic time, n is an exponent _cc is the shear rate, and s is the shear stress

Fig. 8 Parameters from Cross equation vs polysaccharide concen-tration at 25 �C (g0: filled symbols, k: open symbols, GP diamonds,F squares, GN circles, SGG triangles)

Fig. 9 Parameters from Cross equation vs polysaccharide concen-tration at different temperature. For SGG (diamonds: 15 �C,squares: 25 �C, triangles: 35 �C)

495

resembles the weak gel behaviour, particular in the ter-minal zone, where the divergence of moduli from thecanonical slope could be ascribed to the presence ofimpurities (usually proteins for guar gums) and theirinteractions with the polysaccharide.

Two mechanical models were taken into consider-ation for fitting the experimental data: the generalizedMaxwell model with four elements and a fixed scaling ofrelaxation times and, alternatively, the Friedrich-Braunmodel, which is based on fractional derivatives and can

represent a parsimonious solution (only five adjustableparameters) to achieve a satisfactory data correlation.This is particularly convenient for analysing experi-mental data of differently structured fluids. In its generalform the Friedrich-Braun model is given by

sþ kcDc s���� ¼ Ge D0 c

����

�þkcDc c

�����þ DGkdDd c

���� ð2Þ

where c is the deformation tensor, s is the stress tensor,k is a characteristic relaxation time, Ge is the equilibriummodulus, DG is a parameter which rules the magnitudeof the viscoelastic response and c and d are the deriva-tion orders of fractional derivatives Dc and Dd.

Fig. 12 Mechanical spectra of SGG system at 25 �C (G¢: filledsymbols, G¢¢: open symbols; 3% circles, 6% triangles, 9% squares)

Fig. 11 Stress sweep data of 9% SGG at 25 �C and correlationwith the Soskey-Winter equation (G¢: filled symbols, G¢¢: opensymbols)

Fig. 10 Parameters a and b from Power-law model vs 1/T for SGGsystem (b: circles, a: diamonds)

Fig. 13 Mechanical spectra of GN system at 15 �C (G¢: filledsymbols, G¢¢: open symbols; 3% circles, 6% triangles, 9% squares)

496

In oscillatory shear conditions the elastic and viscouscomponents can be calculated as

G0ðxÞ ¼ Ge þ DGðkxÞd cosðd p

2Þ þ ðkxÞc cosððd � cÞ p2Þ

� �

1þ 2ðkxÞc cosðc p2Þ þ ðkxÞ2c

ð3Þ

G00ðxÞ ¼ DGðkxÞd sinðd p

2Þ þ ðkxÞc sinððd � cÞ p2Þ

� �

1þ 2ðkxÞc cosðc p2Þ þ ðkxÞ2c ð4Þ

where G¢ is the storage modulus, G is the loss modulusand x is the angular frequency. The limits ofparameters of the Friedrich-Braun model are presentedin Table 4. The limiting behaviour at high frequenciesof both module in the limit is reported in Table 5(Pricl et al. 1997; Friedrich and Braun 1992). For thesystem examined the equilibrium modulus Ge can beset equal to zero, so reducing the number of adjust-able parameters.

In both cases the differences between the linear vis-coelastic properties of the polymer systems can be easilyhighlighted. If we refer to the results of data fitting usingthe generalized Maxwell model and compare the relax-ation spectra (gi=f(ki)) of SGG systems at three differ-ent concentrations (Fig. 14), we can recognize again thecanonical profiles for polysaccharide solutions withincreasing contribution of higher relaxation times forincreasing polymer concentration. The profiles ofrelaxation spectra for GN systems show a differentshape, more similar to the power law behaviour typicalof weakly structured systems or of sol/gel transitionstate (Fig. 14).

The Cox-Merz rule was tested for SGG and GNsystems and we could conclude again that SGG behaveslike ordinary polysaccharide solutions owing to theproximity of both curves (complex viscosity and con-tinuous shear viscosity vs frequency and shear rate,respectively), whereas this is not the case of GN systems.

Flow curves and mechanical spectra at differenttemperatures and at the same concentration of poly-saccharide can be shifted to draw a common master flowcurve or master mechanical spectra, in accordance withtime-temperature superposition principle.

Rheological properties of polysaccharide-surfactantsystem

Polymers and surfactants are often used together inindustrial formulations to take advantage of their pe-culiar properties. When both components are present,they can interact to provide beneficial effects or causeunwanted problems. Such interactions can occur in bothaqueous and nonaqueous systems. Information aboutthe conformational changes of polymer moleculesresulting from their interactions with a surfactant hasbeen mainly obtained from viscosity measurements(Goddard and Anathapadmanabhan 1993).

The effects of surfactant addition on the rheologicalproperties of polysaccharide solutions depend on severalfactors: polymer substitution and concentration, sur-factant type and concentration, temperature.

The comparison of the Cross parameters of SGGsystems with different concentrations of added surfac-tant shows a slight decrease of the zero-shear-rate vis-cosity for small surfactant additions, as shown inFig. 15. Then the zero shear viscosity increases withincreasing surfactant concentration for surfactant B,whereas it remains nearly constant for surfactant C(Fig. 15). Similar effects are observed for the charac-teristic time k. The initial decrease in viscosity could be

Fig. 14 Relaxation spectra of SGG systems (open symbols) and GNsystems (filled symbols) at 25 �C (9% circles, 6% diamonds, 3%triangles)

Table 4 The limits of parameters of Friedrich-Braun model

Parameter Limit

Ge ‡0DG ‡0k ‡0c, d 0 £ c £ d

Table 5 The limiting behaviour of the viscoelastic moduliaccording to the Friedrich-Braun model

c, d G¢ (x) G¢¢ (x)

d>c G¢ (x) fi ¥ for x fi ¥ G¢¢ (x) fi ¥ for x fi ¥d=c G¢ (x) fi Ge+DG for x fi ¥ G¢ (x) fi 0 for x fi ¥

497

ascribed to surfactant-induced intramolecular interac-tions and, consequently, to slight conformational chan-ges of polymer chains, whereas at higher surfactantconcentrations the intermolecular connections promotedby micelles can prevail depending on micelle confor-mation and interactions, so leading to a moderate in-crease in viscosity and characteristic relaxation times.This is in line with viscosity effects observed for semi-dilute solutions as a function of surfactant concentration(Goddard and Anathapadmanabhan 1993).

The surfactants are added to the reactive printingpastes to preclude chemical reaction of the guar gumwith the other components of the reactive printing paste(especially reactive dye). The result of this chemicalreaction of guar gum with the other components of thereactive pastes in the process of printing is fabric stiff-ness.

When surfactant addition is contained at sufficientlylow levels, only slight but different changes are observedfor linear viscoelastic properties (Fig. 16).

Fig. 15 Parameters from Cross equation vs surfactant concentra-tion for SGG system at 25 �C (B: filled symbols, C: open symbols,g0: triangles, k: circles)

Fig. 16 Dynamic moduli (at 0.01 Hz) vs surfactant concentrationfor 6% SGG system at 25 �C (B: filled symbols, C: open symbols,G¢: circles, G¢¢: squares)

Fig. 17 Surface tensions ofsurfactant and polysaccharide-surfactant systems vs surfactantconcentration at 25 �C (surfac-tants: filled symbols, polysac-charide-surfactant systems:open symbols, B: triangles, C:circles)

498

Surface tension measurements

The surface tension measurements for surfactant andpolysaccharide-surfactant system were measured. Sur-factant B shows a steeper decrease of surface tension(from 70 to 40 mN/m) with increasing concentrationthan surfactant C owing to different energetic contri-butions. The CMC for surfactant B is 4·10)3 wt%and for surfactant C is 9.5·10)4 wt%. For polysac-charide studied, the CMC in the presence of polysac-charide is essentially equal to the CMC of the puresurfactant, indicating slight or negligible interactions(Fig. 17).

Conclusions

The flow curves and mechanical spectra for SGG guargum are typical for ordinary polymer solution. This isnot the case for GN systems. The presence of impuritiescan significantly change the rheological behaviour ofpolysaccharide (GN) and polysaccharide-surfactantsystems, because there are strong interactions between

surfactant and impurities (proteins in our case). We haveto emphasize again that we deal with concentratedpolysaccharide solution and with surfactant solutionabove CMC.

The surface tensions of the reactive printing pastehave also been measured and we found out that thesurface tensions of the reactive printing paste was lowerwithout surfactant (41.64 mN/m) than with surfactant B(3.75 wt%) 56.30 mN/m and surfactant C (1.5 wt%)47.12 mN/m and (3.5 wt%) 42.87 mN/m. Because thesurface tension of reactive printing paste with addedsurfactants is higher than without surfactants, we couldconclude that interactions occur with the other compo-nents of the reactive printing paste.

These polysaccharides and surfactants have beenused in reactive printing pastes with other componentsand printed on the viscose fibre. Reactive printing pasteswith GP and F guar gums are very elastic and the resultsof printing are not so good, because the reactive printingpaste doesn’t penetrate into the fibre but remains on thesurface. This seems to restrict its use to inkjet printing,where it is recommended for the thickener, that it remainon the surface of the fibre.

References

Biggs S, Selb J, Candau F (1992) Effect ofsurfactant on the solution properties ofhydrophobically modified polyacryl-amide. Langmuir 8:838–847

Cabane B, Duplessix R (1987) Decorationof semidilute polymers solutions withsurfactant micelles. J Phys (Paris) 48:651

Chari K, Antalek B, Lin MY, Sinha SK(1994) The viscosity of polymer-surfac-tant mixtures in water. J Chem Phys7:5294–5300

Friedrich C, Braun H (1992) GeneralizedCole-Cole behavior and its rheologicalrelevance. Rheol Acta 31:309–322

Goddard ED (1986) Polymer-surfactantinteraction, part 1, uncharged water-soluble polymers and charged surfac-tants. Colloids Surf 19:255

Goddard ED, Anathapadmanabhan KP(1993) Interaction of surfactant withpolymers and proteins. CRC Press, BocaRaton

Kokol V, Sostar-Turk S (1998) Rheology ofmodified polysaccharide-ride polymersin reactive printing. In: Proceeding ofthe Fifth European Rheology Confer-ence, Portoroz, Slovenia, pp 568–569

Kunjapu JT (1999) Polymer-surfactant,interactions in ink chemistry. Am InkMarker 77:34–40

Lapasin R, Pricl S (1995) Rheology ofindustrial polysaccharides, theory andapplications. Chapman & Hall, London

Meter DM, Bird RB (1964) Tube flow ofnon-Newtonian polymer solutions.1. Laminar flow and rheological models.AIChE J 10:878–881

Oblonsek M, Sostar-Turk S, Schneider R,Lapasin R (2000) Interactions betweenpolysaccharides and surfactants and theinfluence on the rheological properties.In: Proceeding of the 13th InternationalCongress on Rheology, Cambridge,United Kingdom, vol 4, pp 154–156

Pricl S, Lapasin R, Grassi M (1997)Application of fractional viscoelasticmodels to polysaccharide systems. RheolMater Ind Agro-alimentaires Cosme-tiques Pharm 448–457

Saito S (1987) Polymer-surfactant interac-tions. In: Nonionic surfactants. Surfac-tant Science Series, Marcel Dekker, NewYork, vol 23, p 881

Soskey PR, Winter HH (1984) Large stepshear strain experiments with paralleldisk rotational rheometers. J Rheol28:625–645

Sostar-Turk S, Schneider R (1999) A studyof fabric stiffness with guar gum inreactive printing. Dyes Pigments 41:167–175

499