for HAAKE CaBER 1 - Anamed

1

for HAAKE CaBER 1

Publications

Contents

Application Notes

V-204 Optimization of the filling process of shampoo sachets with the HAAKE CaBER 1

V-206 The influence of thickeners on the application method of automotive coatings and paper coatings – HAAKE CaBER 1

V-208 Correlation of misting during printing with extensional rheological investigations on offset printing inks with the HAAKE CaBER 1

V-211 Optimizing and forecasting the filling behavior of coatings with the HAAKE CaBER 1

V-212 HAAKE CaBER 1 – molecular weight distribution Polystyrene, blends of standards, same MW, different MWD

V-213 HAAKE CaBER 1 – polymer solutions Polystyrene, Mw= 1.8 Mio g/mol in styrene oligomers at very low concentrations

V-214 HAAKE CaBER 1 – binary polymer mixtures

V-215 HAAKE CaBER 1 – reproducibility

V-219 Cellulosic Derivatives in Capillary Break-up - Influence of the MWD and Gel Particles

V-235 Investigating the processing properties of instant release film-coating polymers in aqueous solutions by means of extensional rheology

V-236 Investigating the influence of colouring agents on the rheological characteristics of a film-coating dispersion

V-256 Enhanced Oil Recovery and Elongational Flow – The Thermo Scientific HAAKE CaBER 1

References

1

Optimization of the filling processof shampoo sachets with theHAAKE CaBER 1 Rheometer

Application NoteApplication NoteApplication NoteApplication NoteApplication NoteV-204V-204V-204V-204V-204

Kevin Barber, Thermo Electron Stone, UKDr. Alexandra Ewers, Jint Nijman,Thermo Fisher Scientific, Karlsruhe, Germany

AbstractAbstractAbstractAbstractAbstract

With certain shampoo formulations,‘strings’ of shampoo are formedwhen filling sachets during produc-tion. This causes the product to spillacross the sachet seam area. As aconsequence, the sachet cannot beproperly sealed. Using the HAAKECaBER 1 extensional rheometer‘string forming’ shampoo formula-tions were easily and quickly distin-guished from ‘well performing’samples. Rotational rheometers werenot able to provide this information.

Introduction

While most commercial rheometersare capable of generating only shearflows, in many industrial processesand applications the flow is predom-inantly extensional in nature.Typical examples of this type of floware fiber spinning, paper coating, ex-trusion and filling food or toiletriesin bottles. This paper describes theoptimization of filling shampoo intosachets. With certain shampoo for-mulations, ‘strings’ of shampoo areformed when filling the sachets,which causes the product to spillacross the seam area. As a conse-quence, the sachet cannot be properlysealed. This failure is expensive as itwill result in the disposal of manyimproperly sealed sachets. Using classical rotational oroscillatory shear experiments, nodiscernible differences could be ob-served between the five shampo oformulations investigated. The useof the HAAKE CaBER 1 (CapillaryBreakup Extensional Rheometer)however, allowed the characteriza-tion of the formulations’ extensionalproperties in a quick and easy ex-periment, thus providing a solutionto the problem. Shampoos consist of 80 -90%water with more then 2% detergent,foaming agents and about 1% fra-grances and preservatives [1]. Often

Figure 1: Comparison betweenextensional flow (a) and shear flow (b).

b)

Key Words:Key Words:Key Words:Key Words:Key Words:

••••• ShampooShampooShampooShampooShampoo••••• fillingfillingfillingfillingfilling••••• elongationalelongationalelongationalelongationalelongational

viscosityviscosityviscosityviscosityviscosity••••• stringinessstringinessstringinessstringinessstringiness••••• HAAKE CaBERHAAKE CaBERHAAKE CaBERHAAKE CaBERHAAKE CaBER

shampoos contain antistatic agents,thickeners and conditioners [2].Current health and beauty trendsmake it important to stabilize special-effect particles in gels, body washesor shampoos, hence the addition ofthickeners to prevent the sedimenta-tion of these particulate phases [3].A problem with thickeners, however,is that they can be the cause ofunwanted extensional properties,i.e. they can cause string formation. These unwanted rheologicalproperties can manifest themselvesin an unpleasant and ”slimy” feel-ing while using the product. Theycan also cause string formation dur-ing the high speed filling of shampoointo sachets or bottles, resulting inimproper sealing of the sachet ormessy bottles. Slowing down the fill-ing speed would solve the problem,but that has implications for thethroughput capability of the pro-duction line. A far better solutionwould be to modify the formulationof the shampoo in such a way thatthe highest filling speed can be used. In this investigation five shampooswith different formulations weretested to find out which formula-tion could be filled into the sachetssuccessfully at a high filling speed.All formulations were previously

tested on a high speed packing linewith differing degrees of success.Some exhibited the string formationproblem that resulted in failure ofthe sachet seams.

Experimental

The measurements were carried outwith the HAAKE CaBER 1extensional rheometer. The CaBERexperiment gives a quick insight intothe material properties under anextensional deformation which occur,for example, during the sachet filling.It impossible to determine theextensional properties of a fluidusing a traditional rotational rheo-meter. In an extensional flow the stream-lines converge and the velocityincrease (i.e. the acceleration) is inthe direction of the flow (Figure 1a).This in contrast to the situation in ashear flow where the streamlines areparallel and the velocity increase isperpendicular to the direction ofthe flow (Figure 1b).

a)

2

The principle of the CaBERexperiment is simple. A small quan-tity of sample (less than 0.2 ml) isplaced between two parallel plates(diameter e.g. 6 mm). The fluid isthen exposed to a rapid extensionalstep strain by moving the upperplate upwards, thereby forming afluid filament (Figure 2). The filament evolution as a func-tion of time is controlled by thebalance of the surface tension andthe viscous and elastic forces.The surface tension is trying to“pinch off” the filament while theextensional rheological propertiesof the fluid are trying to prevent that.A laser micrometer measures themidpoint diameter of the gradually

Figure 2: Sequence of a CaBER measurement.

Figure 4: Shear viscosity curves of shampoos 1-5.

Figure 3: Principle of the CaBER experiment.

thinning fluid filament after the up-per plate has reached its final posi-tion (Figure 3).From the measured data, whichdescribes the evolution of the fila-ment diameter as a function of time(Figures 2a, 2b and 2c), the filamentbreak-up time (Figure 2d), theextensional deformation and defor-mation rate and extensional viscositycan be calculated.

Results and Discussion

Five different shampoo sampleswere measured. Two of the samples(samples 1 and 2), performed wellin the sachet filling equipment; thethree other samples (samples 3, 4and 5) did not perform well. When measured in a rotationalrheometer, the five samples did notshow any differences in the flowcurves that could explain their dif-ferent during the filling of the sachets(Figure 4). In contrast, when measured inan extensional flow using the

HAAKE CaBER 1 rheometer, themeasured diameter versus timecurves (see Figure 5) of the fivesamples nicely rank according totheir filling behavior: the shorterthe filament lifetime in the CaBERexperiment, the better the fillingproperties. The 5 samples clearly differenti-ated in extensional flow. The filamentlifetimes of shampoos 1 and 2 arerelatively short. These shampooscan be filled into sachets without anyobvious problems. For shampoos3, 4 and 5, the filament lifetimes aresignificantly longer, which leads toproblems in sachet filling. Stringformations prevented the sachetssealing, a problem which can onlybe resolved by slowing down thefilling process. The graph of the extensionalflow curves (see Figure 6) showsthat the extensional viscosities ofsamples 1 and 2 (which performedwell) are clearly lower then those ofsamples 3 and 5 (which did notperform well). The lower extensional

D = f (t)

3

References

[1]http://www.hairshampoo.com

[2]Laba D. (ed.): Rheological properties of cosmetics and toiletries -Cosmetic science and technology series vol. 13. Marcel Dekker, New York (1993).

[3]Henning T., Milbradt R., Miller D.: Stabilising special-effect particles, Cossma 3 (2003), 48-49.

Figure 5: Filament diameter decay of shampoos in the CaBER experiment.

Figure 6: Extensional flow curves of shampoos 1-5.

viscosity leads to a higher strain rateand shorter break-up time (filamentlife time) in the CaBER experimentand in the filling equipment.

Conclusions

The HAAKE CaBER 1 extensionalrheometer is capable of an easy-to-handle and quick way of distin-guishing between different shampoosand of predicting filament lifetimesfor production and quality control.Shampoos 3 - 5 will need to bereformulated to solve the seriousfilling problems. In this way it ispossible to optimize the quality ofthe shampoos and the productionprocess.

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V-204_5.02.07

© 2007/01 Thermo FisherScientific· All rights reserved ·This document is for informationalpurposes only and is subject tochange without notice.

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1

The influence of thickeners on the applicationmethod of automotive coatings and papercoatings – rheological investigations with theHAAKE CaBER 1


Spraying automotive coatings andthe application of paper coatings areindustrial processes, in which elon-gational flows play an important role.As a result, the application behaviourof these fluids often cannot be suffi-ciently characterised with traditionalshear experiments. Products withsimilar shear viscosities can have ve-ry different elongation properties.With the HAAKE CaBER 1 exten-sional rheometer, a liquid filament iscreated that is stretched under theinfluence of surface tension. Using thedecrease in the filament diameter asa function of time and the life of thefilament, it is possible to characterisethe elongational behaviour of low-viscosity to pasty liquids in a simpleway. The rheological properties oftypical water-based automotive coa-

Rheology Application Notes

Dr. Norbert Willenbacher,Richard BenzBASF Aktiengesellschaft,Ludwigshafen, GermanyDr. Alexandra Ewers,Jint Nijman,Thermo Fisher Scientific,Germany

tings and paper coatings are deter-mined by the thickeners used andtheir interactions with the other recipecomponents. In the CaBER experi-ment, different types of thickener dis-play a characteristic decrease in thefilament diameter as a function oftime. Different break-up times are de-sirable, depending on the applica-tion. When automotive coatings aresprayed, short break-up times areadvantageous in order to obtain thefinest possible drop distribution.When paper coatings are applied withrollers, spraying and „misting“should be prevented as much aspossible, which means that formu-lations with long break-up timesare advantageous.

IntroductionIntroductionIntroductionIntroductionIntroduction

Elongation flows occur in many in-dustrial production and working pro-cesses, especially where product flowsexperience cross section changes orare diverted, and determine thesesignificantly. Spraying, coating, pum-ping or filling processes are typicalexamples that are relevant in almostall branches of industry. The charac-terisation of elongational propertiesin product development and qualityassurance is therefore essential in or-der to optimise product properties

or production processes. In a shear flow, the flow lines runparallel – in an elongational flow theyconverge (figure 1). Elongationalflows and elongation properties ofsubstances therefore cannot be simu-lated and analysed with rotationalrheometers. Materials that displaya similar rheological behaviour inthe shear experiment may displayvery different properties in elonga-tional flows.This article discusses the rheologi-cal results of elongational and shearexperiments of various thickenersand formulations, to which such

thickeners have been added.

b)

a)

Figure 1: Comparison between exten-sional flow (a) and shear flow (b).

Material and MethodsMaterial and MethodsMaterial and MethodsMaterial and MethodsMaterial and Methods

With the HAAKE CaBER 1 exten-sional rheometer (Capillary Break-up Extensional Rheometer) it ispossible in a simple experiment toexamine quickly and without com-plications the rheological propertiesof liquids in an elongation flow. A drop of liquid is placed betweentwo parallel plates in the HAAKECaBER 1. The upper plate is thenmoved up very quickly (in 50 ms),during which the sample is elon-gated, producing a liquid filament.The necking and breakage of theliquid filament provides valuableinformation about the product andprocess properties of the substancebeing examined (Figure 2).The measuring principle shown inFigure 3 is simple: A laser micro-meter measures the decrease in thesample diameter D as a function ofthe time t after the upper plate hasarrived in its final position. The re-lative elongational viscosity is cal-culated from the measurementresult (D = f(t)).If the surface tension of the sampleis known, the absolute elongationalviscosity can be determined. The

decrease in the string diameter as a

Key words:Key words:Key words:Key words:Key words:

• Paper coatingsPaper coatingsPaper coatingsPaper coatingsPaper coatings• Automotive coatingsAutomotive coatingsAutomotive coatingsAutomotive coatingsAutomotive coatings• MistingMistingMistingMistingMisting• Elongational viscosityElongational viscosityElongational viscosityElongational viscosityElongational viscosity• Roller applicationRoller applicationRoller applicationRoller applicationRoller application• HAAKE CaBER 1HAAKE CaBER 1HAAKE CaBER 1HAAKE CaBER 1HAAKE CaBER 1


2

Results of aqueous thickener solu-Results of aqueous thickener solu-Results of aqueous thickener solu-Results of aqueous thickener solu-Results of aqueous thickener solu-tions and correlation with thetions and correlation with thetions and correlation with thetions and correlation with thetions and correlation with theapplication processapplication processapplication processapplication processapplication process

Three different classes of thickenerswere examined with the HAAKECaBER 1 and a rotational rheo-meter:

- CMC thickener (CarboxyMethylCellulose)

Fig. 2: Sequence of a CaBER measurement: filament formation (a), filament necking (b,c) and filament break-up (d)

Figure 3: Functional principle of theHAAKE CaBER 1

Laser micrometer

Sample

Measurement D = f (t)

function of time is determined bythe competing physical effects ofsurface tension, viscosity, elasticity

and mass transfer.

- Acrylate thickener

- Associative thickenerIn addition to the traditional acry-late-based synthetic products, theassociative thickeners include claymineral suspensions and DNA so-lutions. The former because of theirassociative house of cards structure,the latter because of the strong inter-molecular interactions. CMC andacrylate thickeners are widely usedin the paper industry. Associativethickeners are used in areas such asformulations of cosmetics and auto-motive coatings. Figure 4 shows theresult of the elongational and shearexperiments with these thickeners. The viscosity curve in the shearspeed range of 10-2 to 103 s-1 wasmeasured with the rotational rheo-meter. Figure 4b shows a log-logdepiction of the relationship betweenthe viscosity and the shear speed.The shear-thinning behaviour (dec-rease in viscosity as the shear speedincreases) is at its most pronouncedin the case of the associative thicke-ners; the viscosity curves of the ac-rylate and CMC thickeners bothdisplay a significantly lower dec-rease in viscosity. In elongation experiments, the va-rious thickeners displayed characte-

ristic differences. The filament break-up time is very short in the case ofthe associative thickeners. The rea-son for this is that the pronouncednetwork structure is destroyed veryquickly in the elongational experi-ment and cannot rebuild itself duringthe elongation experiment.The acrylate thickeners and associa-tive thickeners (Figure 4a) displayan exponential decrease in the fila-ment diameter as a function of time,and thereby the typical elongationalbehaviour of an elastic fluid. TheCMC solutions display the elonga-tional behaviour of a more viscousfluid, i.e. the filament diameter dec-reases according to a power law.The thickeners that have zero visco-sity in the shear experiment displaya longer string life than the associa-tive thickeners, the shear viscosityof which increases in the low-shearrange.The differences in the CaBER experi-ment that were found for associa-tive and non-associative thickenerscorrelate with the spray coating pro-perties of water-based automotivecoatings: Smaller droplets are formedin the case of the formulations con-taining associative thickeners.These display a lower elongationalviscosity than formulations based

Figure 4: Comparison of CaBER experiment (a) and shear experiment ofdifferent aqueous thickeners

a) b) c) d)

3

on non-associative thickeners, evenwhen the shear viscosity functionsare almost identical in a wide shearrate range (1).In the case of paper finishing, thecoating is in most cases applied viarollers. When the coating is trans-ferred to the raw paper, unwanteddrop formation can occur, the so-called „misting“. In case of this phe-nomenon, the elongational viscosi-

ty also plays a decisive role (Fig. 5).

Figure 5: Schematic depiction of thefilament and droplet formation whenapplying paper coatings via rollers.

The time curve for the filament dia-meter in the CaBER experiment fortwo paper coatings that differ onlyby the addition of a thickener isshown in Figure 6. It is apparent herethat the filament break-up times ofthe coating with acrylate thickener issignificantly longer than in the caseof the recipe containing CMC. Thiscorrelates with practical experiencein machine experiments. Coatingsthickened with acrylate tend to sprayand mist more rarely than those con-taining CMC.

Results of aqueous thickener solu-Results of aqueous thickener solu-Results of aqueous thickener solu-Results of aqueous thickener solu-Results of aqueous thickener solu-tions and correlation with thetions and correlation with thetions and correlation with thetions and correlation with thetions and correlation with theapplication processapplication processapplication processapplication processapplication process

An acrylate thickener was used tomake different paper coatings withthe same mixture of clay mineral

Figure 6: Comparison of two differently thickened coatings

and calcium carbonate pigments, butwith different binding agents. In the CaBER experiment, it wasapparent that the pure thickener hasa clear tendency to form filament.The filament break-up time variesbetween 0.5 s and 100 s, dependingon the polymer concentration. The results from elongational andshear experiments on the investiga-ted paper coatings are shown in Fi-gure 7. The coating formulations withoutthickener display no filament forma-tion at all. However, if the formula-tion contains only 0.35% of this ac-rylate thickener, string formationcould be observed in the experiment.This is related to the interaction bet-ween the dissolved thickener mole-cules, pigments and binder particles.Type A binders have a different par-ticle surface (charge, steric stabilisinggroups and tensides) and thereforea different affinity to the thickenerthan the Type B binders. It can be seen that the filamentdiameter for all paper coating com-pounds decreases by mathematicalpower quantities (Figure 4a). In con-trast, the pure thickener displays anexponential decrease in the filament

diameter (Figure 7a).

Figure 7: Comparison of CaBER experiment (a) and shear experiment (b)of different paper coatings

In the shear experiment, it was bare-ly possible to differentiate betweenthe different mixtures of the papercoatings (Figure 7b), which meansthat it is not possible to draw conclu-sions from this data about the app-lication behaviour during the coa-ting process. A water-based automotive coatingand an aqueous solution of an asso-ciative thickener used in this formu-lation as a rheological additive wereexamined in the elongational and

shear experiment. The results of thesemeasurements are compared in Fi-gure 8. In the elongational experiment, thedecrease in the filament diameter as afunction of time again as expecteddisplays the exponential curve for thepure thickener, while the completeformulation follows the pattern ofthe power law function.Surprisingly however, the filamentbreak-up time for the auto-motivecoating is significantly longer thanfor the pure thickener, even thoughthe shear viscosity of the purethickener up to a speed of 100 s-1 isapproximately one decade abovethat of the automotive coating.

SummarySummarySummarySummarySummary

In the CaBER experiment, the acry-late thickeners display an exponen-tial decrease in the filament diame-ter as a function of time, while theCMC solutions display power lawbehaviour. The thicke-ner solutionsexamined have similar shear visco-sities but in the elongation experi-ment it was apparent that the fila-ment break-up time for the CMCthickener is shorter than for the ac-rylate thickener.The long filament break-up timecorrelates with the reduced misting

4

Figure 8: Comparison of the CaBER experiment (a) and shear experiment(b) of a pure thickener (red circles) and an automotive coating (black squares)containing this thickener

during roller application, e.g. ofpaper coatings. On the other hand,very short filament break-up timesindicate excellent properties for spray-

ing, e.g. automotive coatings. The elongational and shear expe-riments on paper coatings and auto-motive coatings indicate that the be-haviour of these substances cannotbe predicted by the simple charac-terisation of the pure thickener. Theproperties of these complex formu-lations are controlled by the balan-ce of the interactions between thedissolved thickener polymers andthe pigments or the binder. The shear viscosities often do notpermit any clear conclusions to be

drawn about the application beha-viour. Elongational experiments canoften better differentiate betweenvarious products and allow corre-lations with the process behaviourwith regard to the coating processesdescribed above.

ReferencesReferencesReferencesReferencesReferences

(1) Dirking, T., Willenbacher, N.,L. Boggs, Elongational FlowBehavior of AutomativeCoatings and its Relation toAutomatization and MottlingProg. Org. Coatings, 42 (2001),59-64

V-206_01.07.04

© 2004/07 Thermo Fisher Scientific·All rights reserved · This document isfor informational purposes only and issubject to change without notice.

Thermo Fisher ScientificThermo Fisher ScientificThermo Fisher ScientificThermo Fisher ScientificThermo Fisher ScientificProcess InstrumentsProcess InstrumentsProcess InstrumentsProcess InstrumentsProcess Instruments









1

Correlation of misting during printing withextensional rheological investigations on offsetprinting inks with the HAAKE CaBER 1


The tendency for misting on offsetprinting inks was examined on twosamples using the rotational rheo-meter HAAKE RheoStress 600 andthe extensional rheometer HAAKECaBER 1.The results for the amplitude andfrequency curve, the creep and reco-very test and the flow curve measu-rement with the rotational rheometerdo not correlate with misting duringprinting.With the rotational rheometer, it waspossible with the aid of the filamentbreak-up time to easily and quicklydraw distinctions between differenttendencies for misting with offset

printing inks.


Offset printing is the most widelyused method in the printing industry.A thin film of printing ink is appliedonto the printing form via a systemof rollers. In one hour, it is possibleto print approximately 10,000 sheetsusing this method. Factors that arecrucial to printing quality include theprinting inks used with regard totheir wettability, gradation, sheen anddrying.Offset printing ink consists of the 3components pigment, binding agentand additives. It is a suspension withcomplex rheological properties thatare influenced by the componentsused.In the printing process, it is requiredthat smooth and sharply definedtear-off edges are obtained and thatscumming (misting) of the ink is a-voided. When the ink is transferred


Dr. Eberhard Pietsch

Thermo Fisher Scientific, Germany

to the printing plate and when thelatter is moistened, water dropletsare formed in the printing ink.When there are such droplets in anink string that forms in the gap bet-ween the printing roller and the rub-ber blanket, the ink can spray.In practice, relative terms such asstickiness (short, long) and rigidityare often used to describe the pro-perties of a printing ink. In addition,besides rheological variables the tackvalue (stickiness) is defied as a re-lative value. A forecast regarding thetendency of printing inks to foamand to spray is desirable for inkdevelopment and for their use inthe printing machine.

Material and methodsMaterial and methodsMaterial and methodsMaterial and methodsMaterial and methods

Two offset printing inks were exa-mined at a temperature of 40°C withregard to their tendency to mist.The inks were available in their un-modified (sample A) and modified

form (sample B). The rotational rheo-

meter HAAKE RheoStress 600 withair bearings permits all the usual rhe-ological examinations such as flowcurve measurements, flow limit mea-surements, creep and recovery, defor-mation jump and oscillation tests, aswell as normal force measurements.


• CoatingCoatingCoatingCoatingCoating• Elongational viscosityElongational viscosityElongational viscosityElongational viscosityElongational viscosity• MistingMistingMistingMistingMisting• Offset printing inkOffset printing inkOffset printing inkOffset printing inkOffset printing ink• HAAKE CaBER 1HAAKE CaBER 1HAAKE CaBER 1HAAKE CaBER 1HAAKE CaBER 1

Figure 1: Amplitude curve in CS mode

Comparison of offset printing inks


2

A cone/plate measuring unit consis-ting of a Peltier temperature controlunit and measuring cone C35/1° wasused. Rheometer control and evalu-ation of the measured data were per-formed with the software HAAKERheoWin.Using the extensional rheometerHAAKE CaBER 1, a low sample vo-lume of 6 mm diameter and 3 mmheight was extended to a height of10 mm by way of abrupt extension(50 ms). An extension flow formedfor a short time in a liquid. The re-duction in the filament diameter upuntil the point of breakage was mea-sured as a function of the time (1, 2).

Figure 2: Creep test curve of the compliance J(t) in the creepage phase (t = 1 Pa) and in the recovery phase (t = 0 Pa)

Rotational rheometer resultsRotational rheometer resultsRotational rheometer resultsRotational rheometer resultsRotational rheometer results

An amplitude sweep measurementwas carried out first in the oscilla-tion mode with a defined shear stress(CS) in order to determine the linear-visco-elastic range (LVB). Two minuteswas selected as the temperature adjus-tment time. There was no noticeabledifference between the two samples(Figure 1). For measurements withinthe LVB, a shear stress of 10 Pa anda deformation of 1% should not beexceeded. The slight rise in the sto-rage and loss module indicates thatthe sample was still relaxing duringthe measurement.

Figure 3: Frequency curves of the storage modulus (open symbols) and loss modulus (closed symbols)

Comparison of offset printing inks

Comparison of offset inks

A creep and recovery test was carriedout in the next step. The tempera-ture equilibration time was two mi-nutes. The applied shear stress of 1 Pawas held for a period of 300 s andthe recovery was observed. Cleardifferences were apparent betweenthe two samples (Figure 2; Table 1). The modified sample B has agreater elastic deformation and reco-very at low shear stresses. The zero

viscosity η0 is almost the same onboth samples, However, there aredifferent retardation times λi. Theseresults are relevant to all stages inthe printing process that occur atlow shear stresses, for example thegradation of the ink after printing.In addition, the necessary informa-tion is obtained about how long itis necessary to wait after thesample filling until the start of themeasurement, and also the necessa-ry measurement time for the creepageand recovery phase. Three times therecovery time – in this case approx.20 to 30 minutes – applies as a ruleof thumb.In another measurement, the reac-tion to different excitation frequen-cies was examined with a frequencysweep for both samples. This measu-rement was performed in the linearvisco-elastic range (LVB) with a de-formation of 1%.The curves for both samples are si-milar (Figure 3). They show the ty-pical pattern for offset printing inks.For slow stresses, the storage modu-lus G’ is much bigger than the lossmodulus G’’, and in this range thesamples are extremely elastic. Theloss modulus G’’ predominates forrapid stresses, and the viscous compo-nent prevails. The intersection pointof G’ (w) and G’’ (w) – also designa-ted as the crossover point – repre-sents a characteristic variable in thefrequency curve (Table 1).For sample B, the crossover point isat a lower cycle frequency w and themodule values are lower. The sampleis „softer“. This could be an indica-tion of reduced mist formation.

Table 1: Zero viscosity η0,retardarion time λi, crossovermodulus and crossover frequency

Probe AProbe AProbe AProbe AProbe A Probe BProbe BProbe BProbe BProbe B

η0 [Pas] 118.000 117.000

λi [s] 460 590

Gc‘ = Gc‘‘ [Pa] 1194 731

ωc [rad/s] 13.8 8.5

3

However, the deformations occur inthe roller gap outside the LVB, whilethe measurement was made insidethis range.In the rotation test, the flow curvesof both samples were measured (Fi-

gure 4). Here, problems arose through

the gap emptying at high shear speedsand through shear heating at highshear speeds. At a shear speed of140 s-1, the viscosity curves displayonly a slight difference. For sampleA, the interpolation provides with14.3 Pas a slightly higher (dynamic)

Fig. 4: Rotation test-breakage curve (open symbols) and viscosity curve (closed symbols)

viscosity than for sample B at 12.7Pas. This means that no clearsample differentiation is possiblewith regard to the question„misting during printing“.

Extensional rheometer resultsExtensional rheometer resultsExtensional rheometer resultsExtensional rheometer resultsExtensional rheometer results

Figure 5 shows semi-logarithmicallythe decrease in the thread diameterreferred to the starting diameter forsample A and sample B over the pe-riod up until breakage. Three repeatmeasurements were performed in eachcase, with a slight scatter in the fila-ment break-up times. The reason forthis was the type of sample fillingand different waiting times up untilthe measurement. However, greatdifferences can be found in the ave-rage thread breakage time betweensample A at 148 seconds and sampleB at 33 seconds. Due to the signifi-cantly longer thread breakage time,sample A tends to mist formation,while sample B displays this tenden-cy less.

Figure 5: Decrease in the relative filament diameter

Figure 6: Apparent extensional viscosity as a function of the extension

Comparison of offset inks

Sample ASample B

Sample B

Sample A

4

A great difference between bothsamples can also be found in the ap-parent elongational viscosity thatcan be calculated with the aid ofmodel assumptions (Figure 6)., wheresample A displays a value up to 10times greater than sample B.

SummarySummarySummarySummarySummary

The tendency towards misting withoffset printing inks could be diffe-rentiated quickly and easily by mea-suring the filament break-up timeon two samples with the extensio-nal rheometer HAAKE CaBER 1.With a high-performance rotationalrheometer, a differentiation with re-gard to this criterion was not possib-le with any clarity, even with compre-

hensive rheological measurements.

ReferensesReferensesReferensesReferensesReferenses

[1] Tripathi A., Spiegelberg S.,McKinley G. H.:Studying the extensional flow andbreakup of complex fluids usingfilament rheometers,Proceedings of the XIIIth Inter-national Congress on Rheology,Cambridge,UK (2000), 3-55 - 3-57.

[2] Mönch G.:Newtonsche Standardflüssigkeitenim Dehnrheometer HAAKECaBER 1,Thermo Electron Rheologie-Applikationsbericht V-205 (2003).










V-208_01.06.04


1

Optimizing and forecasting the fillingbehavior of coatings with the HAAKECaBER 1


Two coatings, which showed differentstringing behavior when filled into con-tainers during a production process,have been investigated with the HAAKECaBER 1 extensional rheometer. It wasshown that the filament lifetime asmeasured by the CaBER correspondsdirectly with the behavior seen in theproduction process. By changing theprocessing temperature, the behaviorof the problematic sample could beoptimized.


When filling coatings into containers inindustrial processes, the stringiness of theproduct may cause problems by leavingexcess material on the packaging. In thefilling process considered here, the pro-cess temperature is 60°C. At this tem-perature product A can be filled intothe containers without problems, whereasduring the filling of product B the fluidjet will not break-up quickly enoughafter the filling has stopped. This slowbreak-up causes strings of coating mate-rial spill over the container.

This phenomenon, which iscaused by the extensional properties ofthe samples, can be monitored with theHAAKE CaBER 1 (Capillary BreakupExtensional Rheometer) instrument.


Figure 1: Filament diameter as a function of time for products A and B at a temperature of 60°C.

Figure 1 shows the results of two fila-ment break-up experiments. Product Ahas a filament lifetime of 0.62 s whereasproduct B needs 0.8 s before breakingup. This time is obviously too long forthe process considered here.

ExperimentalExperimentalExperimentalExperimentalExperimental

The principle of the CaBER measure-ment is simple. A small quantity ofsample (less than 0.2 ml) is placedbetween two parallel plates (diameter6 mm). The fluid is then exposed to arapid extensional step strain by movingthe upper plate upwards, therebyforming a fluid filament (Figure 2).The filament evolution as a functionof time is controlled by the balance ofthe surface tension and the viscous andelastic forces. The surface tension istrying to „pinch off“ the filament whilethe extens-ional rheological propertiesof the fluid are trying to prevent thisprocess. A laser micrometer measuresthe midpoint diameter of the graduallythinning fluid filament after the upperplate has reached its final position.

From the measured data, whichdescribe the evolution of the filamentdiameter as a function of time, thefilament break-up time, the extensionaldeformation, the deformation rate andthe extensional viscosity can be calcu-lated (2).

The temperature of the samples can becontrolled with an accuracy of +/- 0.1 Kusing a circulator (in this case a HAAKE

Phoenix).

Dr. Dirk Eidam; Jint Nijman, Thermo Fisher Scientific, Process Instruments, Karlsruhe, Germany

Keywords:Keywords:Keywords:Keywords:Keywords:

• Coatings• Coatings• Coatings• Coatings• Coatings• Filling Process• Filling Process• Filling Process• Filling Process• Filling Process• Extensional Viscosity• Extensional Viscosity• Extensional Viscosity• Extensional Viscosity• Extensional Viscosity• Filament Lifetime• Filament Lifetime• Filament Lifetime• Filament Lifetime• Filament Lifetime• T• T• T• T• Temperatureemperatureemperatureemperatureemperature Dependence Dependence Dependence Dependence Dependence• Stringiness• Stringiness• Stringiness• Stringiness• Stringiness• HAAKE CaBER 1• HAAKE CaBER 1• HAAKE CaBER 1• HAAKE CaBER 1• HAAKE CaBER 1

2

Results and DiscussionResults and DiscussionResults and DiscussionResults and DiscussionResults and Discussion

In order to optimize the filling pro-cess of product B, it was measuredin the HAAKE CaBER 1 at diffe-rent temperatures. Figure 3 showsthat the filament lifetime decreaseswith increasing temperature. At a temperature of 80°C, thefilament lifetime is reduced to 25%of the original value. The filamentlifetime of sample B at a tempera-ture of 65°C is 0.66 s. For sampleB, a temperature increase to 65°Cwould be sufficient to make it per-form like sample A at 60°C, there-by solving the filling problems.

ConclusionConclusionConclusionConclusionConclusion

With the CaBER experiment theproperties of coatings that are impor-tant during the filling of the coatingin containers can be analyzed quan-titatively. The filament life time is adirect measure of the stringiness ofthe product, as observed in the fillingprocess. By changing the processingtemperature the behavior of the prob-lematic sample could be optimized.The capillary break-up experiment isa valuable tool for forecasting thebehavior of the investigated coatingsin the filling procedure.

Figure 2: Sequence of a CaBER measurement [1].

Figure 3: Filament diameter as a function of time at different temperatures for product B at T = 60°C, 65°C and 80°C and product A at T = 60°C.


[1] Willenbacher N., Benz R., Ewers A., Nijman J.: Einfluss von Verdickern auf das Applikationsverhalten von Auto- lacken und Papierstreichfarben - Rheologische Untersuchungen mit dem HAAKE CaBER 1, Thermo Fisher Scientific Rheologie- Applikationsbericht V-206 (2003).

[2]Tripathi A., Spiegelberg S., McKinley G. H.: Studying the extensional flow and breakup of complex fluids using filament rheometers, Proceedings of the XIIIth Inter- national Congress on Rheology, Cambridge, UK (2000), 3-55 - 3-57

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V211_21.08.2007

© 2007/08 Thermo FisherScientific· All rights reserved ·This document is for informationalpurposes only and is subject tochange without notice.

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HAAKE CaBER 1 – molecular weightdistributionPolystyrene, blends of standards, same MW, different MWD

CaBER test resultCaBER test resultCaBER test resultCaBER test resultCaBER test result

In extensional flow differences inmolecular weight distribution(MWD) can be differentiated.

In shear flow differences in MWD

cannot be detected.


The CaBER measurement is highlysensitive towards high molecular

components in mixtures.

Practical applicationsPractical applicationsPractical applicationsPractical applicationsPractical applications

Industrial processes where highmolecular polymer fractions

influence application behaviour.


Clasen/ University of Hamburg

RheoFuture 2004


1.843.0

1.662.0

1.361.5

1.111.2

1.061.1

1.00 - 1.051.0

(Mw/Mn)Blends(Mw=const)

1.843.0

1.662.0

1.361.5

1.111.2

1.061.1

1.00 - 1.051.0

(Mw/Mn)Blends(Mw=const)


2










V212_07.04.

© 2004/07 Thermo Fisher Scientific ·All rights reserved · This document isfor informational purposes only and issubject to change without notice.

1


0 10 20 30 40 50 60 7010-3

10-2

10-1

100

101

Konzentration/ ppm:

0.00 0.371.202.504.407.5014.025.042.079.0140250

d / m

m

t / s

HAAKE CaBER 1 – polymer solutionsPolystyrene, Mw= 1.8 Mio g/mol in styrene oligomersat very low concentrations

10-2 10-1 100 101

2x101

4x1016x1018x101102

concentration / ppm:

0.00 14.0 0.37 25.0 1.24 42.0 2.50 79.0 4.40 140 7.50 250

shea

r vis

cosi

ty /

Pas

shear rate / s-1


In extensional flow the effect ofsmallest concentrations of polymers(ppm range) can be measured

quantitatively.

In shear flow differences betweensmall concentrations cannot be

detected.


CaBER measurement detects smallamounts of polymers in extensional

flow.


Industrial polymer systems whereextensional flow appears

(Filling, spraying, coating, ...)



RheoFuture 2004


2










V213_07.04.


1

HAAKE CaBER 1 – binary polymer mixturesPolystyrene, blends of standards,Mw= 1.8 Mio g/mol + Mw= 13 Mio g/mol


At a constant concentration of250 ppm in Boger fluids binarymixtures can be differentiated in

extensional flow.

In shear flow differences between

in mixing ratio cannot be detected.


The influence of molecular weightof polymers is more sensitive in the

CaBER measurement.


Industrial processes where smallchanges in polymerization processor recipe may influence application

behaviour.



RheoFuture 2004



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V214_07.04.


1

E6000 #2 2.09 E6000 #3 2.09

E40000 #1 13.4 E40000 #2 13.0

Break up time/ s

E6000 #1 2.08

HAAKE CaBER 1 – reproducibilityNewtonian Test fluids E6000 and E40000

TTTTTest fluidsest fluidsest fluidsest fluidsest fluids

Newtonian Standard fluidsE6000 (η = 6000 mPas, 20 °C)E40000 (η = 40000 mPas, 20 °C)


CaBER test resultsCaBER test resultsCaBER test resultsCaBER test resultsCaBER test results

1. CaBER data (break up times) can be measured with high reproducibility

2. Extensional viscosity of Newtonian Standard fluids follows Trouton ratio ( = 3x shear viscosity value)

Fig. 1: Diameter as a function of time (break up time) for 2 different Newtonian fluids E6000 and E40000

(multiple measurements with new filling)

Fig. 2: Extensional viscosity as a function of deformation for 2 different Newtonian fluids

(calculated from data shown in fig. 1)


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V215_12.04.


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• HAAKE CaBER1• HAAKE CaBER1• HAAKE CaBER1• HAAKE CaBER1• HAAKE CaBER1• Elongational Rheology• Elongational Rheology• Elongational Rheology• Elongational Rheology• Elongational Rheology• Cellulosic Derivatives• Cellulosic Derivatives• Cellulosic Derivatives• Cellulosic Derivatives• Cellulosic Derivatives• Thickeners• Thickeners• Thickeners• Thickeners• Thickeners• Polymer Solutions• Polymer Solutions• Polymer Solutions• Polymer Solutions• Polymer Solutions• MWD• MWD• MWD• MWD• MWD

Cellulosic Derivatives in Capillary Break-up - Influence of the MWD and Gel Particles

Rheology Application Notes Jan Philip Plog, Ph.D. Thermo Electron Corporation Newington, NH 03801 USA

Abstract

Application note V-219 showed that the CaBER1 extensional rheometer is able to detect slight differences in the MWD (molecular weight distribution) of blended polystyrene standards. However, the question remains if these results obtained on a standard system can be transferred to more complex polymers in solution like cellulosic derivatives?

In order to control the adaptability of this method, commercially available, blended methylhydroxyethyl celluloses (MHEC, e.g. used as thickener agent in construction materials) were characterized by uniaxial elongation in capillary break-up experiments with the CaBER1 extensional rheometer. The determined break-up- and relaxation times t resp. were then correlated with the blending composition of the methylhydroxy-ethyl celluloses and hence with the high molar mass fraction of the sample.

Introduction

The MHECs characterized here are amongst other applications utilized as thickening- and water retention agents in plasters. As plasters are more than often applied by spraying, strong elongational forces are implied. These elongational forces again may induce flow anomalies like spattering (or misting, roping in other applications), which are directly related to the elasticity of the polymer and hence the high molar mass fraction of the incorporated polymer.

To describe the high molar mass fraction of a polymer, the weight-average molar mass Mw alone

is not satisfactory; the molecular weight distribution and hence the polydispersity has to be taken into account also. However, the detection of the influence of the polydispersity on the rheological properties is not easily to achieve quantitatively.

This applies particularly for cellulosic derivatives, because native polymers naturally show very broad molar mass distributions. The processability of these cellulose derivatives depend strongly on their MWD, which in turn depends on the origin of the specific cellulose [1]. Therefore in technical applications cellulose samples are usually blended to broaden the MWD and hence minimize the effect of the MWD of a single sample. However, already the initial molar mass distribution of the sample that is to be blended is not easy accessible and the “right” mixing ratio is often chosen on empirical tryouts of the material properties of the different mixing ratios [1,2].

Aim of this contribution is therefore to correlate the relaxation times, determined via capillary break-up extensional rheometry with a Haake CaBER1, of blended methylhyroxyethyl celluloses with the MWD of the samples.

Materials and Methods

The methylhydroxyethyl celluloses (MHEC) used were made available from a company involved in MHEC chemistry. Preparation of the samples was achieved by solving the respective amount of polymer in 2 wt% NaOH. Homogenization was achieved by permanent agitation over a period of time not shorter than 3 days at RT. Filtrating of this solvent was achieved with a cellulosic filter of a pore size of 0.1 m (Sartorius GmbH, Germany) Elongational characterization was achieved on a Haake CaBER1 extensional rheometer. Determination of the molar mass and its distribution of the MHECs was achieved using a combined method of size exclusion chromatography (SEC), multi-angle laser light scattering

(MALLS) and differential refractometer (DRI).

Results and Discussion

The investigated MHECs were specifically blended from 3 different celluloses with different intrinsic viscosities ([ ]cellulose3 < [ ]cellulose2 < [ ]cellulose1) by the supplier to obtain different MWDs but almost the same Mw. This is usually done to tune the flow properties of a specific sample to a specific application. The blended samples were hydroxyethylated afterwards.

In Tab. 1 the different blending ratios and the DS (degree of substitution for the methyl group at one glucose monomer unit) and MS (molar degree of substitution for the hydroxyethyl group because of multiple substitutions) of the investigated MHECs are summarized. In addition to this the intrinsic viscosities of the pure cellulose samples are listed.


Jan Philip Plog, Ph.D.Thermo Fisher Scientific,Newington, NH 03801 USA

Jan Philip Plog, Ph.D.Thermo Fisher Scientific,Newington, NH 03801 USA

2

The determined mean values for the distribution and the polydispersities for the MHECs are listed in Table 2 together with the recovery rates of the SEC. The recovery rate is the fraction of polymer that reaches the differential refractometer based on the amount of polymer that was originally injected.

Figure 1 shows that the investigated MHECs do not show significant differences in terms of their shear viscosity, as required by the producer; only the sample MHEC 2 gives a slightly higher zero shear viscosity than the other two samples. Via fitting of the experimental data to the modified Carreau model one can determine the longest relaxation time 0 of steady shear flow.

0 1n

b b

o (1)

with b being a transition parameter and n being the slope of the flow curve. These calculated relaxation times, listed in table 3, show no quantitative differences. Still these samples show a different behaviour in the practical application as in droplet break-up, filament formation and nozzle extrusion. A method to quantitatively access these properties is via extensional flow. Figure 2 shows the results for uniaxial elongation determined with the CaBER experiment for the same MHEC solutions shown in Fig. 1.

From Fig. 2 one can see very clearly that the MHEC solutions show pronounced differences in filament break-up. The sample MHEC 3 shows a considerably higher break-up time then the blending composition of this sample would suggest, since its MWD is the narrowest over all.

Polymer Mw

105 g/mol

Mw / Mn

Mz

105 g/mol

Recovery Rate

/ %

MHEC 1 3.41 3.5 7.38 74 MHEC 2 3.23 2.9 6.55 79 MHEC 3 2.94 2.5 5.77 72

Table 2: Molecular parameters of investigated MHECs 1-3, determined via combined methods of SEC/MALLS/DRI.

Polymer Cellulose 1

1738*

Cellulose 2

925*

Cellulose 3

356*

Mw / Mn DSM MSHE

MHEC 1 50 - 50 broad 1.78 0.33 MHEC 2 37.5 25 37.5 intermediate 1.75 0.31 MHEC 3 25 50 25 narrow 1.76 0.30

(*Intrinsic viscosities of the raw cellulose samples in cm3/g as provided by manufacturer) Table 1: Blending composition, DS (degree of substitution for the methyl-group) and MS (molar degree of substitution for the hydroxyethyl-group) of the investigated MHECs 1-3.

10-2 10-1 100 101 102 10310-1

100

101

102 MHEC 1 MHEC 2 MHEC 3 Carreau Fit for MHEC 1 Carreau Fit for MHEC 2 Carreau Fit for MHEC 3

/ Pa

s

g / s-1

Fig. 1: Filament diameter versus time for the MHECs 1-3, 2 wt% in NaOH (2 wt %) at 25°C.

Shear rate / s-1

3

As shown in table 2, the ratios of recovery for the light scattering experiments indicate a rather large amount of not molecularly dispersed sample that is separated

from the solution by filtration and the following pre-columns. To adjust the sample preparation for the CaBER experiments to the

sample preparation for the light scattering measurements the MHEC solutions were centrifuged and again examined via CaBER measurements. The results are shown in Fig. 3.

In contrast to Fig. 2 the centrifuged samples show the order in break-up times expected from the distributions determined

with light scattering. Sample MHEC 1 with the broadest MWD shows the longest break-up time sample MHEC 3 with the narrowest MWD the shortest break-up time. The results of the CaBER experiments and the results of light scattering can thus be correlated with the same sample preparation, because in both cases only the molecularly dispersed fraction of the sample is characterized. The relaxation times evaluated from Fig. 3 via

0

13

30 004

tG D

D D e (2)

[3] are also listed together with the relaxation times of the non-centrifuged samples in Table 3. As the concentrations used for the MHEC solutions are relativly high (2 wt%) structure buildup via hydrogen bonding is an issue. These aggregates may have great influence on the elongational behaviour of the MHEC solutions even in the centrifuged state and superpose the results obtained for the single polymer coil.

Summary

The longest relaxation times 0 obtained by CaBER experiments for blended celluloseethers yield information on the MWD of these polymers. In comparison to shear tests this method is faster and more sensitive. The results could then be correlated with the absolute molar mass distributions obtained via means of SEC/ MALLS/ DRI. Uniaxial elongation in CaBER experiments is a more sensitive method for the detection of the molecular weight distribution then steady shear flow for samples with similar weight-average molar mass and

10-2

10-1

100

6420

MHEC 1 Fit to Eq. 2 MHEC 2 Fit to Eq. 2 MHEC 3 Fit to Eq. 2

D /

D0

t / s Fig. 2: Filament diameter versus time for the samples MHECs 1-3, 2 wt% in NaOH (2 wt %) at 25°C.

Polymer

/ Pas 0

Carreau

/ s

b n 0 CaBER / s

centrifuged

0 CaBER / s

Non centrifuged MHEC 3 7.9 0.17 0.53 -0.61 1.14 1.12 MHEC 2 12.8 0.18 0.53 -0.70 1.08 0,92 MHEC 1 9.3 0.17 0.53 -0.65 0.98 1.85

Table 3: Carreau parameters and longest relaxation times of elongation for the investigated MHECs 1-3.

10-2

10-1

100

2 640

MHEC 1 ___ Fit to Eq. 2

MHEC 2 ----- Fit to Eq. 2

MHEC 3 ....... Fit to Eq. 2

D /

D0

t / sFig. 3: Filament diameter versus time for the centrifuged samples MHECs 1-3, 2 wt% in NaOH (2 wt %) at 25°C.

4

V-219_03.2006











therefore similar flow properties in steady shear flow experiments. CaBER experiments also allows for a sensitive detection of non molecularly dispersed fractions of the investigated native cellulose derivative and can thus predict the processability of these polymers in elongational flows.

References

[1] Clasen, C. and W.M. Kulicke, Determination of viscoelastic and rheo-optical material functions of water-soluble cellulose derivatives. Progress in Polymer Science, 2001. 26(9): p. 1839-1919. [2] Schittenhelm, N. and W.M. Kulicke, Producing homologous series of molar masses for establishing structure-property relationships with the aid of ultrasonic degradation. Macromolecular Chemistry and Physics, 2000. 201(15): p. 1976-1984. [3] Anna, S.L. and G.H. McKinley, Elasto-capillary thinning and breakup of model elastic liquids. Journal of Rheology, 2001. 45(1): p. 115-138.

1

Investigating the processing properties of instantrelease film-coating polymers in aqueoussolutions by means of extensional rheologyT. Agnese and T. Cech, BASF SE, European Pharma Application Lab, Ludwigshafen, GermanyW. Dejan, Glatt AG, Application Lab, Pratteln, SwitzerlandN. W. Rottmann, BASF SE, Pharma Ingredients & Services Europe, Ludwigshafen, GermanyF. Soergel, Thermo Fisher Scientific, Material Characterization, Karlsruhe, Germany

PurposePurposePurposePurposePurposeThe application of an instant releasefilm-coating polymer onto the surfaceof a substrate such as a tablet or apellet is a standard process in thepharmaceutical industry. In this realm,recent polymers such as polyvinylalcohol (PVA) and in particularKollicoat® IR (PVA-PEG graft copo-lymer) offer low viscosities of theiraqueous solutions. This propertyenables high solid matter contentsleading to short and economical film-coating processes [1, 2].Furthermore, high solid matter con-tents influences the rheological charac-teristics of an aqueous polymer solu-tion. Even if the resulting dynamicshear viscosity is found to be low, poorextensional rheological propertiescan cause severe problems duringthe atomisation of the film-coatingdispersion (Fig. 1).This work was intended to investigatethe extensional rheological propertiesof several instant release film-coatingpolymers and to deduce a recommen-dation for their processability (theinfluence of colouring agents wasstudied separately [3]).

Materials and MethodsMaterials and MethodsMaterials and MethodsMaterials and MethodsMaterials and MethodsMaterialsThe following instant release polymerswere investigated: Kollicoat® IR andKollicoat® Protect – both BASF SE,Ludwigshafen Germany; Pharma-coat® 603 (HPMC 3 mPas) andPharmacoat® 606 (HPMC 6 mPas)– both Shin-Etsu Chemical Co. Ltd.,Tokyo, Japan; Klucel® EF (HPC EF)– Ashland Aqualon, Wilmington,U.S.A.MethodsAqueous polymer solutions of variousconcentrations (concentrations areindicated in Table 1 and the differentcharts respectively) were prepared.Both extensional properties and dy-namic shear viscosity were measuredat a temperature of 25 °C.Extensional viscosityFor extensional testing, the ThermoScientific HAAKE CaBER 1 (Thermo


Fig. 1: “Cobweb“ caused by filament formation.

Fisher Scientific, Karlsruhe, Germany)was used. This equipment determinesthe capillary break-up time (filamentlife-time) as a measure for the exten-sional viscosity.Dynamic shear viscosityIn order to measure the dynamic shearviscosity, the Thermo ScientificHAAKE RotoVisco 1 rotationalrheometer (Thermo Fisher Scientific,Karlsruhe, Germany) with liquid tem-perature control for concentric cylin-der measuring geometries was used.

Results and DiscussionResults and DiscussionResults and DiscussionResults and DiscussionResults and DiscussionIn a coating process, a film formingpolymer or a coating formulation(additionally holding pigments, color-ants and further additives) is appliedonto a substrate. In order to do this,the spraying dispersion is atomisedinto small droplets. This is typicallydone by using dispersion and com-pressed air with a two-componentnozzle.Important for a smooth and homo-geneous appearance of the final coatis: firstly, the droplet formation duringatomisation and secondly, the spread-ing of the droplets on the surface ofthe substrate. Hereby, the actualdroplet formation is described byextensional rheology, the spreadingis mainly influenced by dynamic shearviscosity.

The filament life-time (FLT) – whichis actually measured in the extensionalexperiment – indicates the quality ofthe atomisation process. As long asthe FLT is in a specific range, goodresults can be expected, whereas verylong FLTs may result in a spray dryingeffect as shown in Fig. 1. Hereby, bothdroplets and filaments are formed.The ratio of surface to volume is muchhigher for a filament leading to aninstant drying. Finally the dried fila-ments are deposited on mounting partssuch as nozzles or the nozzle-arm –which looks like a cobweb.Systematic investigations showed thatthe basis for an appropriate compa-rison of instant release film coatingpolymers is the same dynamic shearviscosity [4]. For the first set of measu-rements, a viscosity of about 50 mPaswas adjusted for all solutions (Table 1).Hereby, Kollicoat® IR was found withthe highest solid matter content – aboutthree times higher than the two cellulosicderivatives HPC EF and HPMC 6 mPas.

Viscosity Polymer content

[mPas] [%]

Kollicoat® IR 51.7 17 Kollicoat® Protect 52.6 14 HPMC 3 mPas 51.0 10 PVA 47.5 11 HPMC 6 mPas 45.5 6 HPC EF 61.7 6

Tab. 1: Dynamic shear viscosity of polymersolutions and corresponding polymer contents.

2

Fig. 2: Filament life-time of various polymer solutions holding a dynamic shear viscosityof about 50 mPas.

Fig. 3: Filament life-time of various concentrations of HPMC type 3 and 6 mPas.

It was found that the various solu-tions resulted in markedly differentFLTs (Fig. 2). Even though, one mightexpect that a high polymer concentra-tion results in a long FLT, the samplewith the highest content showedthe shortest FLT. This suggests thelowest risk of a cobweb-effect forKollicoat® IR.PVA on the other hand, showed avery pronounced filament formationwith a FLT four times longer thanthe one for Kollicoat® IR. Hence,PVA bears a distinctively higher riskfor the cobweb-effect.In the second set of experiments, solu-tions with various polymer con-centrations were tested (Fig. 3, Fig. 4).Comparing the two HPMC grades,a similar FLT was determined withthe polymer concentrations of 10%HPMC 3 mPas and 5% HPMC 6mPas (Fig. 3). When increasing thepolymer concentration, a higherimpact on FLT could be found forthe 6 mPas grade.A similar effect could be seen for17% Kollicoat® IR and 14% PVA,for both polymers FLT was found tobe similar, whereas at a concentra-tion of 20% PVA yielded a muchlonger FLT (Fig. 4).After describing the atomisationcharacteristics via FLT, the actualspreading of the dispersion can bedescribed by dynamic shear viscosity(Fig. 5). Generally, higher polymercontents led to a distinctive increasein viscosity. The lowest values couldbe found for Kollicoat® IR resultingin the highest processible polymerconcentrations which still leads tosmoothly coated surfaces.

ConclusionConclusionConclusionConclusionConclusionTwo rheological characteristics areof utmost importance for developinga spraying dispersion properly:• Filament life-time is responsible for the atomisation characteristics and consequently for process safety.• Dynamic shear viscosity is describing the spreading and stands for coat quality and process efficiency.Therefore, the best coating processesare achievable with a low viscous po-lymer solution allowing for high solidmatter contents and still yielding shortfilament life-times. The Kollicoat®

products were found to match allthese requirements best. The resultsfor the cellulosic derivatives revealedthat their application lead to a lesseconomical process.

Fig. 4: Filament life-time of different concentrations of Kollicoat® IR and PVA.

Fig. 5: Dynamic viscosity of various instant release polymers as function of polymercontent in an aqueous media.

3

ReferencesReferencesReferencesReferencesReferences[1] T. Cech, F. Soergel: Improvement of the pharmaceutical coating process

by rotational rheological characterization; Application Note V-234; June2007; Thermo Fisher Scientific, Karlsruhe, Germany

[2] T. Cech, K. Kolter: Comparison of the coating properties of Kollicoat®

IR and other film forming polymers used for instant release film-coating;ExcipientFest; June 19-20, 2007; Cork, Ireland

[3] T. Agnese, T. Cech, N. W. Rottmann, F. Soergel: Investigating theinfluence of colouring agents on the rheological characteristics of afilm-coating dispersion; Application Note V-236; June 2011; ThermoFisher Scientific, Karlsruhe, Germany

[4] T. Cech: Benchmarking of instant release film coating polymers; 2007;University of Applied Sciences; Bingen am Rhein, Germany

Presented at the 3rd PharmSciFair; June 13-17, 2011; Prague, Czech Republic

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1

Investigating the influence of colouringagents on the rheological characteristics ofa film-coating dispersionT. Agnese and T. Cech, BASF SE, European Pharma Application Lab, Ludwigshafen, GermanyN. W. Rottmann, BASF SE, Pharma Ingredients & Services Europe, Ludwigshafen, GermanyF. Soergel, Thermo Fisher Scientific, Material Characterization, Karlsruhe, Germany

PurposePurposePurposePurposePurposeCoating a tablet with a non-functionalbut coloured film is a standard pro-cedure in the pharmaceutical industry.During the development and valida-tion of such a film-coating process,a huge variety of data about theprocessability and applicability hasto be gathered.Hereby, the focus is typically set onthe film forming polymer and itsconcentration which are known tohave a strong impact on the coatingresult [1, 2, 3]. However, furtherexcipients are involved which mightinfluence the processability as well.The intention of this work was toinvestigate the influence of colouringagents on the rheological characte-ristics of a ready-to-use film coatingsystem.

Materials and MethodsMaterials and MethodsMaterials and MethodsMaterials and MethodsMaterials and MethodsMaterialsThe polymers Kollicoat® IR andKollidon® VA64 as well as the ready-to-use coatings Kollicoat® IR White II,Kollicoat® IR Sunset Yellow, Kollicoat®

IR Carmine and Kollicoat® IR Red(all BASF SE, Ludwigshafen, Germany)were used.All ready-to-use formulations containKollicoat® IR and Kollidon® VA64as film-formers and the pigmentskaolin and titanium dioxide. The indi-vidual colours are obtained by addingeither an aluminium lake (sunsetyellow, carmine) or an iron oxide (red)to the formulation.MethodsAqueous dispersions of these pro-ducts were prepared in different con-centrations to determine their indivi-dual rheological characteristics.Extensional viscosityFor extensional testing, the ThermoScientific HAAKE CaBER 1 (ThermoFisher Scientific, Karlsruhe, Germany)was used. This equipment determinesthe capillary break-up time (filamentlife-time) as a measure for the exten-sional viscosity.Dynamic shear viscosityIn order to measure the dynamic shear


Fig. 1: Determination of the optimal solid matter content for a film-coating processresulting in the shortest possible spraying time (Kollicoat® IR Carmine) at three differentinlet air temperatures [4].

viscosity, the Thermo ScientificHAAKE RotoVisco 1 rotationalrheometer (Thermo Fisher Scientific,Karlsruhe, Germany) with liquid tem-perature control for concentric cylin-der measuring geometries was used.

Results and DiscussionResults and DiscussionResults and DiscussionResults and DiscussionResults and DiscussionWhen optimising a film-coatingprocess in regard to efficiency, theshortest possible time for applyingthe required weight gain homoge-nously onto the cores has to be de-termined. The main influencing para-meters are spray rate and solid mattercontent of the film-coating dispersion,whereas an increase of one of theseparameters already leads to a shorterprocessing time.By varying the inlet air temperature(50, 60, 70 °C) and spray rate, theshortest total spraying time for differ-ent solid matter contents was deter-mined (Fig. 1). It was found that thespraying dispersion holding 30%solids showed distinctively differentcoating properties resulting in lowerpossible spray rates. This could beexplained by a decisive change of thedispersions’ viscosity. It was suggestedthat the results could only be trans-ferred to formulations showing thesame rheological characteristics [4].Dynamic shear viscosityDynamic shear viscosity is an indi-cator for the spreading behaviour

of the droplets on the core surface.Hence, this value is to be used forestimating the final coat quality inregard to smoothness.All formulations showed a shearviscosity clearly depending on solidmatter content (Fig. 2). However, therewas hardly any difference between thedispersions up to a concentration of25%. At 30% and especially 35%,the flow properties differed markedly.The highest increase was found forKollicoat® IR Sunset Yellow. Thesecond ready-to-use coating contain-ing an aluminium lake (Kollicoat® IRCarmine), yielded a low increase inshear viscosity. Interestingly, Kollicoat®

IR Carmine and Kollicoat® IR Red(which holds an iron oxide) werefound with the same viscosity curves.Extensional viscosityExtensional viscosity is an indicatorfor droplet formation as well as forthe risk of spray drying. In a first test,the general effect of pigments on theextensional parameter filament life-time (FLT) was investigated. In orderto do this, Kollicoat® IR White II dis-persions (25, 30, 35%) were com-pared to polymer solutions containingKollicoat® IR and Kollidon® VA64in exactly the ratio and quantity asthey are present in the dispersion(16.6, 19.9, 23.2%).At 25% solids, there was hardly anydifference between the polymer solu-

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Fig. 2: Dynamic shear viscosity of different Kollicoat® IR based film-coating dispersionsas function of solid matter content measured at 25 °C.

Fig. 3: Filament life-time of polymer solutions in comparison to dispersions ofKollicoat® IR White II.

Fig. 4: Filament life-time of different Kollicoat® IR based film-coating dispersions holdingdifferent colorants as function of solid matter content.

tion and Kollicoat® IR White II disper-sion (Fig. 3). Increasing the solid mattercontent resulted in a longer FLT forboth formulations. However, the pig-ments present in Kollicoat® IR White IIpronounced this effect leading to longerFLTs for the dispersion compared tothe equivalent polymer solution.After considering the general effectsof pigments on FLT, the impact ofdifferent colorants was investigatedin a second set of experiments (Fig. 4).When comparing the three differentcolours White II, Sunset Yellow andRed a similar FLT could be found for

solid matter contents of 25%. How-ever, at higher concentrations markedlydifferent FLTs were found for thedifferent formulations. This suggeststhat surface effects caused by the in-dividual colorants affected the rheo-logical properties of the sprayingdispersion at higher solid mattercontents.Both investigations (shear and exten-sional viscosity) showed that thecolouring agents did not influencethe rheological properties at solidmatter contents of 25%. As soon asthe solid matter content was increased

to 30% or above, a pronouncedeffect of the colorant was observed.This suggests that coating parame-ters can be transferred from one for-mulation to another for sprayingdispersions not higher concentratedthan 25%.

ConclusionConclusionConclusionConclusionConclusionDynamic and extensional viscositywere found to be dependent on thesolid matter content of the sprayingdispersion. As soon as a concentrationof 25% was exceeded the colouringagent had a distinctive influence onboth rheological characteristics.This suggested that coating parame-ters can be used universally and in-dependently of the colorant as longas the basic formulation (in regardto the kind and amount of polymers)is equivalent and a solid matter con-tent of 25% is not exceeded. In regardto higher concentrations, the pigmentsinfluence the coating properties andparameters have to be gathered se-parately for each individual colour.

ReferencesReferencesReferencesReferencesReferences[1] T. Cech, F. Soergel: Improvement

of the pharmaceutical coatingprocess by rotational rheologicalcharacterization; ApplicationNote V-234; Thermo FisherScientific, Karlsruhe, Germany

[2] T. Cech, K. Kolter: Comparisonof the coating properties of instantrelease film coating materials usinga newly developed test method– The Process-Parameter-Chart;3rd Pharmaceutical World Cong-ress; April 22-25, 2007;Amsterdam, The Netherlands

[3] T. Agnese, T. Cech, W. Dejan,N. W. Rottmann, F. Soergel:Investigating the processingproperties of instant releasefilm-coating polymers in aqueoussolutions by means of extensionalrheology; Application Note V-235;Thermo Fisher Scientific

[4] T. Cech, C. Funaro, F. Wildschek:Investigating the influence of inletair temperature and solid mattercontent on the total sprayingtime in a side vented pan coatingprocess; 37th CRS; July 10-14,2010; Portland, Oregon, U.S.A.

Presented at the 3rd PharmSciFair;June 13-17, 2011; Prague,Czech Republic

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Enhanced Oil Recovery and Elongational Flow– The Thermo Scientific HAAKE CaBER1Klaus Oldörp, Thermo Fisher Scientific, Material Characterization, Karlsruhe, Germany

IntroductionIntroductionIntroductionIntroductionIntroductionWhen a new oilfield starts producingoil, the oil is driven up the well by theinternal pressure of the oil deposit.Unfortunately only about 10 % ofthe oil in place can be recovered likethis (primary production). Withsupporting technical methods likee.g. pumping water into the oilfieldto push the crude oil out of the porousstone or sand layer towards the pro-duction well, oil production can beincreased up to approximately 20 –40 % of the oil in place (secondaryproduction). Due to the viscositydifference between water and oilsooner or later so-called fingeringwill occur, where the water injectedwill break through the oil instead ofpushing the oil towards the produc-tion well.To push the total recovery up to 30– 60 %, so-called enhanced oil reco-very (EOR) techniques are utilized(tertiary production). One of thesetechniques is polymer flooding. Herepolymers are used to increase theviscosity of the injection fluid tosuppress the fingering.Unfortunately the standard oilfielddoes not exist. Every oil deposit hasits individual characteristics dependingon a large number of parameters likefor example temperature, pressure,crude oil viscosity, crude oil composi-tion, salinity, and pore size distribution.Consequently, the polymers used forflooding have to be selected or eventailored to perform effectively underthe conditions of the individual oildeposit.Already several decades ago it hasbeen observed that the flow ofpolymer solution through a porousmedium cannot be described basedon shear flow alone [1]. Instead of acontinuous viscosity drop with in-creasing flow rate, polymer solutionscan show an increase in viscosity abovea characteristic flow rate. This effecthas been called “shear thickening“


in earlier works. Currently it is com-monly accepted that extensionaleffects (Fig. 1) are the cause for theviscosity increase observed [2]. Insome cases it is even suspected to bethe key factor to the effectiveness ofpolymer solutions in EOR [3].

As a consequence there is an increas-ing demand for analytical techniquescapable of characterizing the exten-sional properties of low viscouspolymer solutions used in polymerflooding.

ExperimentalExperimentalExperimentalExperimentalExperimentalClassical studies have mostly beendone via flooding real rock materialretrieved from the well or syntheticporous media made of sand or simi-lar materials. These porous mediaare difficult to make, difficult to char-acterize and difficult to maintain dueto absorption of the polymers.For a systematic characterization itis much easier to expose polymer so-lutions to an extensional field directly.The most convenient and time effi-cient approach is using the ThermoScientific HAAKE CaBER 1, the onlycommercially available extensionalrheometer for low viscous fluids(Fig. 2).

Fig. 1: Schematic illustration of the elon-gation and relaxation of a polymer coilduring its flow through a porous medium.The red arrow indicates the direction offlow from the injection well to the produc-tion well.

Fig. 2: The HAAKE CaBER1, the onlycommercially available elongationalrheometer for liquids.

This Capillary Breakup ExtensionalRheometer quickly pulls a smallvolume of a liquid apart to form aliquid filament. It measures thethickness of this filament (Fig. 3a)or, more precisely, how quickly thisfilament collapses. The thickness ofthe collapsing filament is measured atthe mid-point between the two platesand plotted as a function of time(Fig. 3b).In total, the collapse of the filamenthappens because the liquid flowsaway from the centre of the filamenttowards the upper and the lowerplate, which causes its diameter toshrink until it breaks. The centralpoint of the filament is locatedbetween two opposing flows, a so-called stagnation point where theflow speed is zero. Therefore thecentral volume element is exposedto a uniaxial elongational strain(Fig. 4).

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Fig. 3 a: Simplified principle of the HAAKE CaBER 1. The liquid sample is pulled upwards to form a filament (light green). The thickness ofthe filament is measured at its thinnest point with a laser micrometer.b: Schematic depiction of the raw data from a CaBER test. The diameter of the liquid filament is measured in the middle betweenthe two plates and plotted as a function of the time.

From a variety of powder polyacryl-amides for polymer flooding, 2 differ-ent samples have been selected. Accord-ing to the chemical characteristics ofthe oilfield, the tests were done for, asalt solution containing CaCl2 andNaCl that was prepared to simulatethe real-life chemical conditions in thefield. A 5000 ppm polymer solutionhas been prepared from both polymersamples. To prepare each solution, ameasured amount of the salt waterhas been filled into a glass containerwith a screw-on lid. A stirring magnethas been added and the polymer wasintroduced into the vortex of thestirred salt water. The glass was closedwith its lid and carefully sealed witha flexible sealing tape to avoid anychanges in concentration due to eva-poration.After some hours of slow stirring, thepolymer solutions have been testedwith the HAAKE CaBER 1. Due to

a b

Fig. 4: During the collapse of the filamentthe liquid flows away from the centre pointof the filament (red arrows) leaving a cen-tral volume element where the speed iszero. At this so-called stagnation point theliquid is exposed to a uniaxial elongationalstrain.

the low viscosity of the samples the4 mm plates have been selected. Usinga small syringe without needle (!) thesamples have been filled into a 2 mmgap between the plates of the HAAKECaBER 1 at 20 °C. Within 50 ms theupper plate was lifted to 6.5 mmabove the lower plate, which equalsa Hencky Strain of 1.2.Under these test conditions the 2 poly-acrylamides showed a significantdifference in break-up time. Thefilament formed by Polymer 1 wasless stable collapsing after approx.0.01 s whereas the filament ofPolymer 2 lasted for 1.1 s (Fig. 5).

Regarding the curves shown in Fig.5 shows that both collapses happenabruptly. The plot shows the norma-lized filament diameter (DN = actualdiameter divided by initial diameter)as a function of time. Both polymersolutions start with DN-values around0.3, which stay almost constant untilthe break-up occurs. This behaviourindicates that both polymers have anextended coil structure in this kind ofsolvent. The results from the CaBERtests give an insight into the polymer/solvent interaction and the rigidityof the polymer coil in solution [4].Based on the raw data the HAAKECaBER 1 software calculates theapparent extensional viscosity, shownin Fig. 6 plotted against the elon-gational strain. Again the behaviourof the two polymers differs signifi-cantly. While Polymer 1 shows analmost constant viscosity, Polymer2 exhibits a strong viscosity increasearound a strain of 3. For floodingprojects a rather constant viscosityhas the advantage of a more uniform

behaviour independent of the actualstrain, which depends on porediameter and flow speed.

SummarySummarySummarySummarySummaryWith the HAAKE CaBER 1 it is pos-sible to test the elongational behav-iour of even low viscous liquids likethe flooding solutions tested for thisreport. Since the elongational visco-sity of liquids is not accessible usinga rotational viscometer or rheometer,this elongational rheometer is theperfect complement to get the fullinformation needed to understandapplications, which are clearly influ-enced or even dominated by elonga-tional flow effects.Especially when the real applicationcannot be accessed directly and anyerror could cause costly consequences,a reliable lab test, which can be per-formed quickly, is highly recommended.Polymer flooding of an oilfield is oneof those applications where it is essen-tial to gather as much relevant infor-mation as possible in the lab beforetrying something out in the oilfielddeep underground. Regarding thecosts involved in a flooding projectand the financial benefit every im-provement of the flooding efficiencyyields, the investment in a HAAKECaBER 1 is a very reasonable andforemost profitable one.

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Fig. 5: Decrease of the normalized filament diameter over time for the solutions of 2 different polyacrylamides in saltwater.Although having the same concentration both solutions show different break-up times and different curve shapes.

ReferencesReferencesReferencesReferencesReferences[1] Smith, F.W.: The Behavior of Partially Hydrolyzed Polyacryl- amide Solutions in Porous Media, J. Pet. Tech. (1970) 22(2):148- 156[2] Jones, D.M., Walters, K.: The behaviour of polymer solutions in extension-dominated flows, with applications to Enhanced Oil Recovery, Rheol. Acta (1989) 28:482-498

Fig. 6: Apparent elongational viscosities as a function of the elongational strain of 2 different polyacrylamides in salt water. Onepolymer shows a rather constant viscosity, the other one shows a sharp increase of viscosity by a factor of one hundred.

[3] Odell, J.A., Haward, S.J.: Viscosity enhancement in the flow of hydrolysed poly (acrylamide) saline solutions around spheres: implications for enhanced oil recovery, Rheol. Acta (2008) 47:129-137[4] Stelter, M. et al.: Investigation of the elongational behavior of polymer solutions by means of an elongational rheometer, J. Rheol. 46 (2002) 507-527

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List of References

Anna, S., McKinley, GH. (2001). Elasto-capillary thinning and breakup of model elastic liquids. Journal of Rheology, 45(1), 115.

Arnolds, O., Buggisch, H., Sachsenheimer, D., Willenbacher, N. (2010). Capillary breakup extensional rheometry (CaBER) on semi-dilute and concentrated polyethylene oxide (PEO) solutions. Rheologica Acta, 49, 1207-1217.

Bazilevskii, A. V., Entov, V. M. and Rozhkov, A. N. (1990) In Proceedings of the 3rd European Rheology Conference(Ed, Oliver, D. r.) Elsevier, pp. 41-43.

Bazilevskii AV., Entov VM. et al. (1997). Failure of Polymer Solution Filaments. Polym. Sci., A(39), 316-324.

Bazilevskii AV., Entov VM. et al. (2001). Failure of an Oldroyd Liquid Bridge as a Method for Testing the Rheological Properties of polymer Solutions. Polym. Sci., A 43, 1161-1172.

Berg, S., Kröger, R. and Rath, H. (1994) "Measurement of Extensional Viscosity by Stretching Large Liquid Bridges in Microgravity" Journal of Non-Newtonian Fluid Mechanics, 55, 307-319.

Bhardwaj, A., Miller, E. et al. (2007). Filament stretching and capillary breakup extensional rheometry measurements of viscoelastic wormlike micelle solutions. J. Rheol., 51, 693-719.

Bousfield, D., Keunings, R., Marrucci, G. and Denn, M. (1986) "Nonlinear Analysis of the Surface-Tension Driven Breakup of Viscoelastic Fluid Filaments" Journal of Non-Newtonian Fluid Mechanics, 21, 79-97.

Christanti Y, Walker, LM. (2001a). Effect of fluid relaxation time of dilute polymer solutions on jet breakup due to a forced disturbance. Journal of Rheology, 46, 733-748.

Christanti, Y., Walker, LM. (2001b). Surface tension driven jet break up of strain-hardening polymer solutions. Science, 100, 9-26.

Clasen, C., Plog, JP, Kulicke, WM., Owens, M., Macosko, C.W, Scriven, LE., et al. (2006). How dilute are dilute solutions in extensional flows? Journal of Rheology, 50(6), 849.

Eggers, J. (1997) "Nonlinear Dynamics and Breakup of Free-Surface Flows" Review of Modern Physics, 69, 865-929.

Entov, V. M. and Hinch, E. J. (1997) "Effect of a spectrum of relaxation times on the capillary thinning of a filament of elastic liquid." J. Non-Newtonian Fluid Mech., 72, 31-53.

Gaudet, S., McKinley, G. and Stone, H. (1996) "Extensional Deformation of Newtonian Liquid Bridges" Physics of Fluids, 8, 2568-2579.

Kheirandish S., Guybaidullin, I., Wohlleben, W., Willenbacher, N. (2008a). Shear and elongational flow behavior of acrylic thickener solutions. Rheologica Acta, 47(9), 999-1013.

Kheirandish, S., Gubaydullin, I., Willenbacher, N. (2008b). Shear and elongational flow behavior of acrylic thickener solutions. Part II: effect of gel content. Rheologica Acta, 48(4), 397-407.

Klein, C., Naue, I., Wilhelm, M., Brummer, R., Nijman, J., Co, A., et al. (2009). Addition of the force measurement capability to a commercially available extensional rheometer (CaBER). Soft Materials, 7(4), 242-257.

Kolte, M. and Szabo, P. (1999) "Capillary Thinning of Polymeric Filaments" Journal of Rheology, 43, 609-626.

Liang, R. F. and Mackley, M. R. (1994) "Rheological Characterization of the Time and Strain Dependence for Polyisobutylene Solutions" Journal of Non-Newtonian Fluid Mechanics, 52, 387-405.

McKinley, G H., Tripathi, A. (2000). How to extract the Newtonian viscosity from capillary breakup measurements in a filament rheometer. Journal of Rheology, 44(3), 653.

Niedzwiedz, K., Arnolds, O., Willenbacher, N, & Brummer, R. (2009). How to Characterize Yield Stress Fluids with Capillary Breakup Extensional Rheometry ( CaBER )? Appl. Rheol., 19(4), 41969.

Niedzwiedz, K., Buggisch H., Willenbacher N. (2010). Extensional rheology of concentrated emulsions as probed by capillary breakup elongational rheometry (CaBER). Rheol. Acta, 49(11-12), 1103-1116.

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Stelter, M., Brenn, G., Yerin, A., Singh, R. and Durst, F. (2000) "Validation and application of a novel elongational device for polymer solutions" Journal of Rheology, 44, 595-616.

Szabo, P. (1997) "Transient Filament Stretching Rheometer I: Force Balance Analysis" Rheologica Acta, 36, 277-284.

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Tirtaatmadja, V., McKinley, GH., Cooper-White, J.J. (2006). Drop formation and breakup of low viscosity elastic fluids: Effects of molecular weight and concentration. Physics of Fluids, 18(4), 043101.

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About Thermo Fisher Scientifi c

Thermo Fisher Scientifi c Inc. (NYSE: TMO) is the world leader in serving science. Our

mission is to enable our customers to make the world healthier, cleaner and safer.

With revenues of nearly $11 billion, we have approximately 37,000 employees and

serve customers within pharmaceutical and biotech companies, hospitals and clinical

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environmental and process control industries. We create value for our key stakeholders

through two premier brands, Thermo Scientifi c and Fisher Scientifi c, which offer a unique

combination of continuous technology development and the most convenient purchasing

options. Our products and services help accelerate the pace of scientifi c discovery, and

solve analytical challenges ranging from complex research to routine testing to fi eld

applications. Visit www.thermofi sher.com.

Thermo Fisher Scientifi c, one of the pioneers in rheology, successfully supports a wide

range of industries with its comprehensive Thermo Scientifi c material characterization

solutions. Material characterization solutions analyze and measure viscosity, elasticity,

processability and temperature-related mechanical changes of plastics, food, cosmetics,

pharmaceuticals and coatings, chemical or petrochemical products, plus a wide variety of

liquids or solids. For more information, please visit www.thermoscientifi c.com/mc.

Material Characterization

© 2011/07 Thermo Fisher Scientific Inc. · 623-2103 · Copyrights in and to all photographs of instruments, accessories and red fruit jelly are owned by Thermo Fisher Scientifi c. Copyrights in and to all other photographs are owned by a third party and licensed for limited use only to Thermo Fisher Scientifi c by iStockphoto. This document is for informational purposes only. Hastelloy is a registered trademark of Haynes International, Ltd. Ampcoloy is a registered trademark of MatWeb, LLC. Tefl on is a registered trademark of DuPont. Specifi cations, terms and pricing are subject to change. Not all products are available in every country. Please consult your local sales representative for details.

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© 2012/05 Thermo Fisher Scientific Inc. • All rights reserved • Copyrights in and to all photographs of instruments, accessories are owned by Thermo Fisher Scientific. Copyrights in and to all other photographs are owned by a thrid party and licensed for limited use only to Thermo Fisher Scientific by iStockphoto. Hasteloy is a registered trademark of Haynes International, Ltd. Specifications, terms and pricing are subject to change. Not all ptoducts are available in every country. Please consult your local sales representativ for details.

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Thermo Fisher Scientific Inc. is the world leader in serving science. Our mission is to enable our customers to make the world healthier, cleaner and safer. With revenues of $12 billion, we have approximately 39,000 employees and serve customers within pharmaceutical and biotech companies, hospitals and clinical diagnostic labs, universities, research institutions and government agencies, as well as in environmental and process control industries. We create value for our key stakeholders through three premier brands, Thermo Scientific, Fisher Scientific and Unity™ Lab Sevices, which offer a unique combination of innovative technologies, convenient purchasing options and a single solutions for laboratory operations management. Our products and services help our customers solve complex analytical challenges, improve patient diagnostics and increase laboratory productivity. Visit www.thermofisher.com. Thermo Fisher Scientific, one of the pioneers in rheology, succesfully supports a wide range of industries with its comprehensive Thermo Scientific material characterization solutions. Material characterization solutions analyze and measure viscosity, elasticity, processability and temperature-related mechanical changes of plastics, food, cosmetics, pharmaceutical and coatings, chemical or petrochemical products, plus a wide variety of liquids or solids. For more information, please visit www.thermoscientific.com/mc.

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