Comparison of Electrorheological Characteristics Obtained in Two Geometrical Arrangements:

Parallel Plates and Concentric Cylinders

Petra Peer1, a), Petr Filip1, b), Martin Stenicka2, c) and Vladimir Pavlinek2, d)

1Institute of Hydrodynamics, Acad. Sci. Czech Rep., Pod Patankou 5, 166 12 Prague, Czech Republic 2Centre of Polymer Systems, University Institute, Tomas Bata University in Zlín,

Nad Ovčírnou 3685, 760 01 Zlín, Czech Republic

a)Corresponding author: peer@ih.cas.cz b)filip@ih.cas.cz

c)stenicka@ft.utb.cz d)pavlinek@ft.utb.cz

Abstract. The electrorheological characteristics of suspensions of PANI powders suspended in silicone oil measured by a rotational rheometer Physica MCR 501 (Anton Paar Co.) are compared for two different geometrical arrangements – parallel plates and concentric cylinders. The individual differences in the results of the measured parameters are discussed.

INTRODUCTION

The general validity and reproducibility of rheological measurements in various laboratories is neither simple nor obvious in spite of the permanent development of new sophisticated rheometers. There is a coincidence of ‘classical’ rheological characteristics (such as, e.g., shear viscosity) measured for common classical materials. However, for more complicated characteristics and materials the results are quite often different. This can be documented from the examples of M1 and A1 projects carried out in a considerable number of prominent laboratories round the world (Sridhar [1], Hudson and Jones [2]). The non-coincidence of elongational viscosity is remarkable. As the materials used were identical, it proves that other complementary attributes connected with rheological measurements substantially participate in the proper analysis of the studied materials. Generally, among other things, it is possible to mention the process of the preparation of the measured samples, the adequacy of their volume for an applied geometrical arrangement, the materials of which contact surfaces are made, the stability of rheometers, etc. The same problems concern not only measuring the rheological characteristics of the same material in different laboratories, but also measuring the same material at the same laboratory using different rheometers (Rides et al. [3]) or the same rheometer but with various geometrical arrangements (Modigell and Pape [4]).

The literature describing and analysing this discrepancy is very scarce and does not correspond to the significance of the problem, which is further emphasized with the onset of a new generation of so-called smart materials such as those now appearing in magneto- or electro-rheology.

Electrorheological (ER) fluids quickly and reversibly change their structure under the application of an external electric field. The formation of a chain-like structure occurs due to particle polarisation in the direction of an electric field. A number of studies of this mechanism have been summarized in several review papers (Block and Kelly [5], Jordan and Shaw [6], Block et al. [7], Parthasarathy and Klingenberg [8], See [9], Hao [10,11], Sheng and Wen [12]). Most commercially available rheometers can be equipped with ER cells making full use of the functionality of the host instruments. In principle, these devices differ according to the geometry applied – with either parallel plates or concentric cylinders.

Novel Trends in Rheology VIAIP Conf. Proc. 1662, 040005-1–040005-8; doi: 10.1063/1.4918893

© 2015 AIP Publishing LLC 978-0-7354-1306-1/$30.00

040005-1

In the protational parallel plmaking a u

An eleg.mol-1) wconcentrativacuum ova scanning

The DCdeterminedPANI samp

A rotatarrangemenused were the inner aselected teplate for thwire adhersupply off.The intens(F.u.G. Elethe conditi

To prevFig. 2.

present study, trheometer are ates or concen

unique interpre

ctrorheologicawith silicone oions. PANI poven to a constan electron microC conductivityd by a four-poples attained 7

tional rheometents, parallel plas follows: P-P

and outer diamemperature (allhe parallel plaring to an uppe. The rheometeity of the electektronik GmbHon that the elecvent the vibrati

the experimentused, were co

ntric cylindersetation of the rh

al suspension woil (Lukosiol Mwder was grount weight. Figuoscope VEGA

y of PANI baseoint method in.72 x 10-9 S.cm

F

er Physica MClates and concPTD200/E para

meter 16.6 mm l measurementte arrangemener shaft compler itself was fultric field was vH, Rosenheim,ctric current diions caused by

tal data (flow compared. The . As documen

heological char

EXPE

M

was prepared bM200, Chemiund, sieved to oure 1 illustrates3 (Tescan, Cz

e particles pres a van der Pau

m-1.

FIGURE 1. SEM

CR 501 (Antoncentric cylindeallel plates of dand 18 mm, r

ts were carriednt and the cup leted a circuit lly isolated fro

varied through , Germany). Itid not exceed 1y the surroundin

characteristics)only change

nted below, evracterisation of

ERIMENTA

Material

by mixing PAical Works Koobtain particle s the morpholoech Republic).ssed into pelleuw setup (Stej

M pictures of PA

Device

Paar Co.) equers, was emplodiameter 50 mmrespectively. Ed out at 20°C)

in the concentloop, and openm an electric can external DC

t provided an e1 mA (otherwisng influences,

) when the samwas in the ap

ven in this casf the chosen m

AL

ANI powder (Solin, Czech Rsizes smaller t

ogy and wide d. ets (13 mm in jskal and Gilb

ANI powder.

uipped with twoyed. The dimm, C-PTD200/

Each geometry was controlled

ntric cylinder gning the hood current by an inC high voltageelectric field sse voltage was the rheometer

me electro-rheopplied geometrse it is necessaterial.

Sigma Aldrich,Republic) in 5than 45 μm, an

distribution of P

diameter, 1 mbert [13]). The

wo ER cells in dmensions of the

/E a bob and cwas covered wd by Peltier el

geometry were automatically

nsulator insertee power supplystrength up to proportionallywas accommo

ological materirical arrangemsary to be care

, USA, base, 55, 10, and 15 nd dried at 80°PANI particles

mm in thicknese conductivity

different geome measuring syup arrangemenwith a hood, alements. The bgrounded. A switched the

ed in the uppery unit HCP 14-12.5 kV.mm-1

y reduced). odated as sketc

ial and ments –

eful in

50,000 wt.%

°C in a s using

s) was of the

metrical ystems nt with and the bottom spring power

r shaft. -12500

under

ched in

040005-2

FIGURE

For a mfor PP geo

Due to measurememeasureme

A basicmeasuremebetween thshaft). Theapparent. Thood. As ethe range 1

E 2. Sketch of th

more adequate cmetry adjustedthe presence

ents merely in ent of a studied

FIGUR

c introductory ent is documenhe spring wire e 'non-homogeTherefore, all mexpected, the m1-100 s-1.

he rheometer supbo

comparison, ind). Prior to the of friction betwair (see Figs.

d material. In th

RE 3. Measurem

Measureme

comparison onted in Fig. 5. and shaft), an

eneous' influenmeasurements measurements

pport (each ‘leg’oard, 70 tennis b

R

n all the measurmeasurementsween the sprin3 and 4). Thenhe following, a

ment of shear visc

ents of Silic

of both geomeMeasurements

nd at the bottomnce of the sprcarried out in of the shear vi

’ consists of a steballs, and iron bo

RESULTS

rements a gap both experime

ng wire and upn this value haall the measure

cosity in differen

cone Oil with

tries was carris on the top wm with an opering wire on the absence ofiscosity of the

eel box, sieved soard (75 kg)).

of 0.7 mm waental geometriepper shaft, it wad to be subtraced data were pr

nt geometries wi

h No Electr

ied out with awere carried ouen hood (no cothe viscosity f electric field

e Newtonian si

sand (0.6 ≈ 0.8 m

s held out (for es were calibra

was first necesscted from the rocessed in this

ith the 'empty' ce

ric Field

a carrier liquidut with a closedontact between

values for smstrength were

ilicone oil wer

mm, 400 kg), pla

CC geometry ated. sary to carry odata obtained s way.

ell.

d - silicone oild hood (with c

n the spring wimall shear rate

taken with thee almost ident

astic

given,

out the during

l. This contact ire and es was e open tical in

040005-3

Stsh

Asw

Frsw

FIGURE 4.

FIGURE 5

teady hear

Amplitude weep

requency weep

Measurement o

5. Flow curve of

TABLE

Shear rate Duration Voltage Shear rate Strain Duration Voltage Shear rate Frequency Duration Voltage

of storage and lo

f the silicone oil

E 1. Measureme

Mixing 10 s-1 30 s 0 V 10 s-1 30 s 0 V 10 s-1 30 s 0 V

oss moduli in dif

l (E = 0 kV.mm-

ent parameters in

Pause 0 s-1 30 s 0 V 0 s-1 30 s 0 V 0 s-1 30 s 0 V

fferent geometrie

1), left: open hoo

n individual mod

0 s-1 60 s xxx V 0 s-1 60 s xxx V 0 s-1 60 s xxx V

es with the 'emp

od, right: closed

des.

Measurement 0.01 - 100 s-1 (00.01 - 100 s-1 (x

0.0001 – 0.01[-]0.0001 – 0.01[-] 0.1-10 Hz / 0.000.1-10 Hz / 0.00

pty' cell.

d hood.

0 V) xxx V)

] / 5 Hz (0 V) ] / 3 Hz (xxx V)

01 [-] (0 V) 006 [-] (xxx V)

040005-4

Electrousing botheach measuand frequeindividual point in thsweep andprolonged

For sheviscosity oparticles. Fshear rate 0become lefrequency suspension

orheological chh ER cells. Theurement. Cons

ency sweep). Tvalues of volta

he steady shead frequency swwith lower val

ear mode, Figsof oil) for both Figure 9 presen0.23 s-1. This lss significant. for both geom

ns with 5 and 1

FIGURE 6. R

FIGURE 7. Re

Rheolog

haracteristics oe samples werequently, comphe courses of tage as indicate

ar flow measurweep) was mealues of the stud. 6-8 compare geometries (PPnts a mutual colower shear ratThe comparis

metries is prese5 wt.% concen

Relative viscosity

elative viscosity

gical Measur

of the suspense stirred mechparisons were the measuremeed in the figurerements as weasured at leastdied characteristhe behaviour

P 50 and CC 1omparison of fte value was chson concerningented for 10 wntration is analo

y in dependence

in dependence o

rements of E

ion (shear vishanically and thmade for threeents (time interes), range of mell as in the smt three times. stics. of relative vis7) consequentlflow behaviouhosen intentiong the dependenwt.% concentraogous.

on shear rate of

on shear rate of P

ER Suspens

scosity, storagethen placed in e different modrvals, electric f

measured pointmall-strain oscThe time of m

scosity (ratio oly for 5, 10, an

ur for the abovnally, as for hignce of viscoelaation in Figs. 1

f PANI suspensio

PANI suspensio

sions

e and loss moan ultrasonic

des (steady shefield strength (ts) are summarcillatory tests measurement w

f the viscosity nd 15 wt.% conve-stated concegher values theastic moduli o10 and 11. Th

on (5 wt.% conc

on (10 wt.% conc

oduli) were obbath for 30 s ar, amplitude s

(xxx V stands frised in Tab. 1(dynamic amp

was correspon

of suspensionncentrations of entrations at coe studied diffe

on strain and ahe flow behavi

entration).

centration).

btained before sweep, for the . Each plitude

ndingly

n to the f PANI onstant erences angular iour of

040005-5

FIGURE 9

The exThis fact isusing extru

There i- different - different - differenc- more com- anti-shoc- different - possible

in combi- the way o- different

FIGURE 8. Re

9. Flow behavio

xperimental dats not surprisingusion rheometeis a series of regeneration of flow condition

ce in contact sumplicated (trimck balancing ingeneration of appearance of nation with poof calculating rsedimentation

elative viscosity

our of different c

ta obtained forg: cf. e.g. Rideers (the same measons for this dflow; ns for suspendeurface; mming) placemn the laboratoryan electric fielwall slip (Mod

ossible sedimenrheological cha

n times of ER fl

y in dependence o

concentrations ofat fixed s

DIS

r the two geomes et al. [3], whmanufacturer) indeviation:

ed particles;

ent of suspensiy (significant fod (radial vs. pldigell and Papentation); aracteristics frofluids in differe

on shear rate of

f PANI powder shear rate (0.23

SCUSSION

metrical arrangho compared shncluding an in

ion into paralleor lower valueslan-parallel, seee [4], Barnes [1

om raw data geent geometries.

PANI suspensio

in silicone oil ins-1).

ements exhibithear viscosity

nstrumented inj

el plate geomets of independee Fig. 12); 14]) (+ differen

enerated by eith

on (15 wt.% conc

n dependence on

t some degree results obtaineection mouldin

try; ent variables);

nt manifestatio

her geometry;

centration).

n electric field str

of non-coincied at high sheang machine.

on in either geo

rength

dence. ar rates

ometry

040005-6

FI

FIG

F

IGURE 10. Sto

GURE 11. Stora

FIGURE 12. Ra

orage and loss m

age and loss mod

adial and plan-pa

moduli in depend

duli in dependen

arallel orientatio

dence on strain o

nce on frequency

on of an electric f

of PANI suspens

y of PANI suspen

field generated i

sion (10 wt.% co

nsion (10 wt.% c

in the individual

oncentration).

concentration).

l geometries.

040005-7

ACKNOWLEDGMENTS

The authors wish to acknowledge the RVO: 67985874.

REFERENCES

1. T. Sridhar, J. Non-Newtonian Fluid Mech. 35, 85-92 (1990). 2. N. E. Hudson and T. E. R. Jones, J. Non-Newtonian Fluid Mech. 46, 69-88 (1993). 3. M. Rides, A. L. Kelly and C. R. G. Allen, Polym. Test. 30, 916-924 (2011). 4. M. Modigell and L. Pape, Solid State Phenomena 141-143, 307-312 (2008). 5. H. Block and J. P. Kelly, J. Phys. D: Appl. Phys. 21, 1661-1667 (1988). 6. T. C. Jordan and M. T. Shaw, IEEE Trans. Electr. Insul. 24, 849-878 (1989). 7. H. Block and J. P. Kelly, A. Qin and T. Watson, Langmuir 6, 6-14 (1990). 8. M. Parthasarathy and D. J. Klingenberg, Mater. Sci. Eng. R 17, 57-103 (1996). 9. H. See, Korea-Austr. Rheol. J. 11, 169-195 (1999). 10. T. Hao, Adv. Mater. 13, 1847-1857 (2001). 11. T. Hao, Adv. Colloid Interface Sci. 97, 1-35 (2002). 12. P. Sheng and W. Wen, Ann. Rev. Fluid Mech. 44, 143-174 (2012). 13. J. Stejskal and R. G. Gilbert, Pure Appl. Chem. 74, 857-867 (2002). 14. H. A. Barnes, J. Non-Newtonian Fluid Mech. 56, 221-251 (1995).

040005-8

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