AU670404B2

AU670404B2 - Homogeneous electroviscous liquids

Info

Publication number: AU670404B2
Application number: AU28380/95A
Authority: AU
Inventors: Tobias Carstensen; Peter Finmans; Hans-Dieter Grasshoff; Dieter Jakubik; Harald Kohnz; Dietrich Pirck; Wilfried Weber; Dieter Winkler
Original assignee: RWE Dea AG fuer Mineraloel und Chemie; RWE Dea AG
Current assignee: Wintershall Dea International AG
Priority date: 1991-11-28
Filing date: 1995-08-04
Publication date: 1996-07-11
Anticipated expiration: 2012-11-30
Also published as: KR100209184B1; AU658949B2; CZ130994A3; JPH07501357A; DE59208255D1; EP0624185B1; EP0624185A1; ATE150480T1; WO1993011209A1; CA2122718A1; DE4294095D2; RU2114904C1; CA2122718C; DE4139065A1; AU2940892A; BR9206842A; AU2838095A; CZ287038B6; JP3236296B2

Abstract

Homogeneous electro-viscous liq. contain or consist of Al soaps obtd. by reaction of (un)satd., monomeric, oligomeric and/or polymeric 3-32C polycarboxylic acid(s) with 1 or more COOH gps., or anhydrides and/or semi-esters in which the alcohol component is an (un)branched, 1-12C mono- or poly-alcohol and/or oligomer, with an Al alcoholate in which the alcohol component is an (un)branched 1-18C aliphatic mono- or poly-alcohol. The Al soaps are pref. obtd. by reaction of a 3-18C (12-18C) polycarboxylic acid, anhydride or semi-ester, esp. a 5-18C (12-18C) alkenylsuccinic acid and/or semi-ester, partic. polycarboxylic acids, anhydrides or semi-esters with free OH gps.. The alcohol component of the semi-ester is a 1-6C (2-5C) di-, tri- or tetra-ol or an oligomer. In the Al alcoholates, the valency of the Al is (partly) the same. The electro-viscous liqs. contain (a) 2-50 (10-35) wt.% of the Al soap, in homogeneous soln., (b) 50-98% (65-90%) of a conventional hydraulic base fluid, and (c) 0-10% (0.1-2%) of soluble known hydraulic oil additive.

Description

6 r a3 S F Ref: 271095 S F Ref: 271095DI

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: RWE-DEA Aktiengesellschaft fur Mineraloel und Chemie Uberseering D-2000 Hamburg

GERMANY

Dietrich Pirck, Hans-Dieter Grasshoff and Harald Kohnz Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Homogeneous Electroviscous Liquids The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845 1A Homogeneous Electro-Viscous Fluids Technical Field This invention relates to homogeneous electro-viscous fluids (EVF).

Background Art Electro-viscous fluids have been known for some time in the form of finely divided, hydrophilic solids dispersed in hydrophobic fluids. The special features of such fluids are that their flow characteristics and, thus, their viscosities can be changed within a large range by subjection to an electrical field, thereby providing a great variety of applications. Electro-viscous fluids are particularly intended for use in the field of industrial and vehicle hydraulics, e.g. for machine and engine bearings or dampers, for positioning work-pieces, for levelling out, cushioning and damping vehicles, for hydrodynamic power transmission and automatic clutches.

The compositions of known electro-viscous fluids for said applications may be rather different. Usually, electro-viscous fluids comprise three components: a dispersed phase containing silicates, zeolites, titanates, semiconductors, polysaccharides or organic polymers; an electrical, non-conducting hydrophobic fluid as liquid phase; a dispersant.

In DE 35 36 934 Al electro-viscous fluids have been described the dispersed phase of which comprises aluminium silicates having a water content of from 1 to 25 wt. and an Al/Si atomic ratio on its surface of between 0.15 and 0.80.

20 However, since all heretofore known electro-viscous fluids are emulsions they have the disadvantage of requiring a considerable amount of additional dispersive components to reduce the material-related tendency to sedimentation. Therefore, for use I in modern hydraulic aggregates most of the known products have proved to be unsatisfactory, especially when used over long periods. In particular, conventional 25 dispersions manifest techno-hydraulic disadvantages some of which are listed in the following: tendency to very high abrasion evaporation of water of crystallisation nonfilterability (no separation of foreign matter) presence of components which are critical under toxicological and safety aspects incompatibilities with elastomeric sealants.

Furthermore, it is known that a great number of high-polar fluids, too, change their flow characteristics in a high-voltage field. But since these effects are only weak, no technical use can be made thereof.

Object of the Invention Therefore, it is the object of this invention to provide homogeneous electroviscous fluids which comply with the technical requirements made on a modern industrial IN:\LIBZ00422:CB hydraulic fluid and which do not have the foregoing disadvantages, but rather manifest a high electro-viscous effect.

Summary of the Invention According to the present invention, the problem is solved by providing a homogeneous electro-viscous fluid comprising an aluminium soap produced by reacting one or more saturated and/or unsaturated monomeric, oligomeric and/or polymeric

C

3 to C 3 2 polycarboxylic acid(s) having one or more carboxylic group(s), the anhydrides and/or semi-esters thereof wherein the alcohol component(s) is (are) linear or branched, monohydric or polyhydric C 1 to C 12 alcohols and/or the oligomers thereof with one or more of reactive aluminium compound(s) selected from the group consisting of aluminium alcoholate(s), the alcohol component(s) thereof comprising one or more aliphatic straight or branched, mono- or polyhydric C 1 to C 1 8 alcohols; aluminium alkyls; aluminium oxoalkyls; aluminium hydroxycarboxylates; aluminium oxocarboxylates; aluminium oxoalcoholates; aluminium alkoxycarboxylates; aluminium oxides and aluminium oxyhydrates.

In a preferred form of the invention, the reactive aluminium compounds are aluminium alkyls and aluminium oxoalkyls having linear or branched C 1 to C6 alkyl residues; aluminium hydroxycarboxylates and aluminium oxocarboxylates having linear or branched aliphatic or unsaturated C 2 to C 3 0 carboxylic acids; aluminium oxoalcoholates having linear or branched aliphatic C 1 to C 6 alcohols; aluminium alkoxycarboxylates having linear or branched aliphatic C 1 to C 6 alcohols and linear or branched aliphatic or unsaturated C 2 to C 30 carboxylic acids; aluminium oxides and aluminium oxyhydrates of the general formula A1 2 0 3 25 nH20 (n 0 to or S aluminium alcoholates, the alcohol components of which have 2 to 8, more preferably 2 to 5 carbon atoms.

It was surprisingly found that by doping with aluminium a great electrorheological effect is attained. The resultant products are completely homogeneous.

Detailed Description of the Invention The aluminium soaps used according to this invention are the products obtained by the reaction of polycarboxylic acids, anhydrides or semi-esters with the reactive aluminium compounds, all or part of the valences of the aluminium having been converted.

In a preftrred embodiment, those aluminium soaps are used which have been obtained by reacting polycarboxylic acids, the anhydrides and, particularly, the semiesters thereof which comprise one or more free OH group(s) with aluminium alcoholates.

In particular, the aluminium soaps are produced by reacting one or more alkenyl succinic IN:\LIBZ100422:CB

I

3 acid(s) and/or the semi-esters thereof with 5 to 18 carbon atoms, preferably 12 to 18 carbon atoms.

It is preferred that the electro-viscous fluids according to the invention comprise the following components: component 2 to 50 wt. preferably 5 to 40 wt. particularly 10 to 35 wt. of the aluminium soap, in homogeneous solution with component 50 to 98 wt. preferably 60 to 95 particularly 65 to wt. of a conventional hydraulic base fluid, and additionally component 0 to 10 preferably 0 to 5 particularly 0.1 to 2 wt.% of soluble hydraulic additives known as such, each referring to the total composition.

Component consists of oligomeric complex aluminium soaps based on reaction adducts of polycarboxylic acids or olefin carboxylic acids, the anhydrides, semi-esters or oligomers thereof with the reactive aluminium compounds. Saponification takes place, wholly or in part, for example by controlled partial hydrolysis yielding hydroxyl soap structures.

By polycarboxylic acids are meant carboxylic acids obtained by reaction of unsaturated carboxylic acids with each other or with olefins. The oligomers thereof used S*i: are compounds consisting of 2 to 10 units, preferably 2 to 6 units.

As alcohol components of the polycarboxylic acid semi-esters linear or branched S. monohydric or polyhydric alcohols are used. It has proved to be advantageous if the carbon number is determined by the base fluid in order to ensure that the corresponding reaction products are soluble.

Examples of component are partial ester/aluminium soap adducts based on alkenyl succinic anhydrides, particularly n-hexenyl succinic anhydrides, diisobutenyl succinic anhydrides, tetrapropenyl succinic anhydrides, dodecenyl succinic anhydrides and polyisobutenyl succinic anhydrides. Also suitable are e.g. olefin addition products of itaconic, citraconic and mesaconic acid.

Furthermore, copolymerisates of unsaturated carboxylic acids, e.g. of maleic, fumaric, acrylic or methacrylic acid are appropriate. Polyesters containing carboxyl groups which are based on saturated or aromatic dicarboxylic acids, such as adipic acid or phthalic acid, are also suitable.

The alcohol components of the aluminium alcoholates used are lower straight and branched alcohols, particularly such with 1 to 6 carbon atoms. The alcohols are set -free during reaction and are eliminated. If the reaction is performed with anhydrides, straightchain or branched alcohols with up to 18 carbon atoms can be used as the alcohol component. Since these alcohols add to the molecule, most of them remain in the reaction product.

IN:\LIBZ]00422:CB Suitable aluminium alcoholates are e.g. aluminium triisopropoxides, aluminiumtri-sec-butoxides or complex mixed alcohols and partial chelates, such as DOROX D DOROX D 300, and DOROX D 310 (commercial products of CONDEA Chemie GmbH, Hamburg).

Preferably, those aluminium alcoholates are used all the aluminium bonds of which carry alcoholate groups. Also suitable are aluminium alcoholates one or two aluminium bonds of which carry hydroxyl groups.

Component comprises hydraulic media, such as conventional mineral oil selective raffinates, hydrocracking products, hydrogenates, poly-alpha-olefins or synthetic o1 esters.

The viscosities of the aforesaid fluids are selected in dependence on the intended use of the end product.

Examples of component are: Spindle oil raffinate 6/20 of DEA, Hamburg Kinematic viscosity (40 4.2 mm 2 /s Density (15 840 kg/m3 Solvent raffinate SN 45 of DEA, Hamburg Kinematic viscosity (40 6.5 mm 2 /s Density (15 842 kg/m3 Hydrocracking product VHVI-light of DEA, Hamburg Kinematic viscosity (40 30.4 mm 2 /s Density (15 854 kg/m3 Hitec 162, PAO of Ethyl, St. Louis Kinematic viscosity (40 5.0 mm2/s Density (15 800 kg/m3 Priolube 3958 of Unichema, Gouda Kinematic viscosity (40 10.5 mm 2 /s Density (15 921 kg/m3 Component comprises customary hydraulic additives for optimising the hydraulic product characteristics, such as wear resistance, resistance to ageing, friction characteristics, resistance to foaming, corrosion resistance and low-temperature characteristics.

Examples of component are: Additin RC 3212 of Rhein-Chemie, Mannheim 2-Ethylhexyl-Zn-dithiophosphate Irganox L 107 of Ciba-Geigy, Basel 2,6-di-tert-butylphenol IN:\LIBZ100422:CB Viscoplex 1-300 of R6hm, Darmstadt Polymethacrylate, 70 solution in neutral raffinate.

In a preferred process for producing electro-viscous fluids a dilute carboxylic acid semi-ester is placed into a vessel and blended with the aluminium carrier component in the absence of moisture. After the chemical reaction is complete, a sufficient amount of component is added to adjust the viscosity to the rated value, and component is added as required.

In a voltage field of from about 500 V/mm field strength, the fluids thus prepared show a significant increase in viscosity as the field strength increases. Optimum response is reached between 3 and 8 kV/mm field strength, the aluminium content being preferably 0.1 to 0.5 The initial viscosity of the electro-viscous fluid may be in the range of from 15 to 6,000 mPa-s at 40 oC.

Brief Description of the Drawings Figure 1 is a tabulation of measurements of yield stress at various shear rates and field strengths on the product of Example 6 described below.

S Figure 2 is a graphical representation of some of the measurements in Figure 1.

Figure 3 is a tabulation of measurements of yield stress at various shear rates and i field strengths on the product of Example 7 described below.

Figure 4 is a tabulation of measurements of yield stress at various shear rates and S' 20 field strengths on the product of Example 8 described below.

Figure 5 is a graphical representation of measurements of yield stress at various shear rates and field strengths on the product of Example 8 described below.

Examples In the following Examples, Example 1 is based on a polycarboxylic acid not 25 reacted with a reactive aluminium compound." The acid proved to be ineffective.

Example 2 is based on a reaction with Li-alcoholate. The electro-rheological effect of the product is extremely weak and only detectable in a static test.

Examples 3 to 8 describe reaction products of the invention. The corresponding electro-rheological measurement results are shown in the Table hereinbelow and in Figures 1 to Example 1 (Comparison) 100 grams of a tetrapropenyl succinic acid semi-ester having the following characteristics Density (15 985 kg/m3 Kinematic viscosity (40 1,750 mm 2 /s Viscosity (100 31 mm 2 /s Flash point P.M. 175 °C IN:\LIBZ]00422:CB Mineral oil content 37 wt.-% Acid number 144 mg KOH/g Hydroxyl number 43 mg KOH/g were diluted with 100 g of a naphthenic mineral oil cut.

0.1 of a commercially available demulsifier and 0.1 of a commercially available defoamer were added to this mixture.

The final mixture had a viscosity of 39 mm 2 /s at 40 °C and an acid number of 72 mg KOH/g.

When testing the aforesaid mixture in a high-voltage rotary rheometer, no increase in yield stress was detectable up to a field strength of 8 KV/mm at a shear rate of D 1/100.

Example 2 (Comparison) 100 grams of the final mixture as described in Comparison Example 1 were blended with a dispersion of 1 gram of lithium-sec-butylate in 5 ml of light oil by intensively stirring over a period of 30 minutes in the absence of moisture. The temperature was slowly increased to 80 OC over a period of 60 minutes where it was Smaintained for 90 minutes.

After cooling, the reaction product was diluted with 100 ml of petroleum ether and Swashed four times with 60 ml of 20 After filtration and vaporisation of the petroleum ether, 73 grams of a product having a viscosity of 160 mm 2 /s at 20 °C and a lithium content of 0.11 were obtained.

When testing the aforesaid mixture in a high-voltage rotary rheometer, no increase in yield stress was detectable up to a field strength of 8KV/mm at a shear rate of D 1/100.

25 Example 3 Reaction of an Aluminium Oxoalkyl grams of the tetrapropenyl succinic acid semi-ester as described in Example 1 were dissolved in 150 ml of toluene, cooled to -30 oC and made inert. 33 ml of a 10 solution of methyl aluminium oxide (product of Witco company) were injected with a syringe. The temperature was gradually increased to room temperature whereby gas was formed. After the evolution of gas was complete, the temperature was raised and maintained at 80 "C for 2 hours to complete reaction. The toluene was eliminated on the rotary evaporator and 50 ml of a naphthenic white oil were added as hydraulic base oil.

The product then was examined.

IN:\LIBZ100422:CB Example 4 Reaction of an Aluminium Oxocarboxylate A mixture comprised of 10 g of the tetrapropenyl succinic acid semi-ester described in Example 1, 6 g of aluminium-oxo-2-ethyl-hexanoate (DOROX® D 490 of CONDEA Chemie), 15 g of 2-ethylhexanoic acid and 130 g of naphthenic white oil as hydraulic base oil was heated to 120 °C during one hour. After cooling the product was examined.

Example Reaction of an Aluminium Oxide Hydrate A mixture comprised of 10 g of the tetrapropenyl succinic acid semi-ester described in Example 1, 2.5 g of aluminium oxide hydrate (Disperal® of CONDEA Chemie), 15 g of pelargonic acid and 130 g of naphthenic white oil as hydraulic base oil was heated to 120 OC during one hour. Filtration by means of a press filter was performed at 80 100 OC. After cooling the product was examined.

Example 6 The procedure was the same as described in Example 2, the difference being that the reaction was performed with a solution of 2.5 grams of aluminium-sec-butylate in ml of light oil.

The end product had a viscosity of 330 mm 2 /s at 40 'C and an aluminium content 20 of 0.24 The product showed a pronounced electro-viscous effect, as illustrated by the results in Figures 1 and 2.

Example 7 The procedure was the same as described in Example 2, the difference being that 25 the reaction was performed with a solution of 1.7 grams of aluminium-sec-butylate in 8 ml of light oil.

The end product had a viscosity of 826 mm 2 /s at 40 OC and an aluminium content of 0.17 The product showed a pronounced electro-viscous effect, as illustrated by the results in Figure 3.

Example 8 The procedure was the same as described in Example 2, the difference being that the reaction was performed with a solution of 1.2 grams of aluminium-sec-butylate in ml of light oil.

The end product had a viscosity of 800 mm 2 /s at 20 OC and an aluminium content of 0.14 IN:\LIBZ]00422:CB 8 The product showed a pronounced electro-viscous effect, as illustrated by the results in Figures 4 and IN:\LI13ZI00422:CB

TABLE

ELECTRORHEOLOGICAL

MEASUREMENTS

Tension Power Shear Yield ERF Yield ERF Rate Stress Stress Factor u I kV mA 1/s Pa Pa Example 3 600 103 0.08 600 116 13 1.12 0.12 600 142 39 1.37 0.24 600 213 110 2.06 0.32 600 341 236 3.31 8 0 0.42 600 547 444 5.30 Example 4 17.7 27 0.00 17.7 36 9 1.33 0.00 17.7 53 27 2.00 0.01 17.7 82 56 3.09 4.0 0.01 17.7 ill 84 4.17 Example 5 17.7 0.00 17.7 34 9 1.36 2.0 0.01 17.7 50 25 2.00 3.0 0.01 17.7 74 49 2.96 4.0 0.02 17.7 103 1 78 1 4.12

S

S.

S

[N:%11BZ00422:CB

Claims

1. A homogeneous electro-viscous fluid comprising an aluminium soap produced by reacting one or more saturated and/or unsaturated monomeric, oligomeric and/or polymeric C 3 to C 3 2 polycarboxylic acid(s) having one or more carboxylic group(s), the anhydrides and/or semi-esters thereof wherein the alcohol component(s) is (are) linear or branched, monohydric or polyhydric C 1 to C 12 alcohols and/or the oligomers thereof with one or more of reactive aluminium compound(s) selected from the group consisting of aluminium alcoholate(s), the alcohol component(s) thereof comprising one or more aliphatic straight or branched, mono- or polyhydric C 1 to C 18 alcohols; aluminium alkyls; aluminium oxoalkyls; aluminium hydroxycarboxylates; aluminium oxocarboxylates; aluminium oxoalcoholates; aluminium alkoxycarboxylates; aluminium oxides and aluminium oxyhydrates.

2. An electro-viscous fluid according to claim 1 wherein the reactive aluminium compound is selected from aluminium alkyls and aluminium oxoalkyls having linear or branched C 1 to C 6 alkyl residues.

3. An electro-viscous fluid according to claim 1 wherein the reactive aluminium compound is selected from aluminium hydroxycarboxylates and aluminium S: oxocarboxylates having linear or branched aliphatic or unsaturated C 2 to C 30 carboxylic 20 acids.

4. An electro-visous fluid according to claim 1 wherein the reactive aluminium compound is selected from aluminium oxoalcoholates having linear or "branched aliphatic C 1 to C 6 alcohols. S.

5. An electro-viscous fluid according to claim 1 wherein the reactive aluminium compound is selected from aluminium alkoxycarboxylates having linear or branched aliphatic C 1 to C 6 alcohols and linear or branched aliphatic or unsaturated C 2 to C 3 0 carboxylic acids.

6. An electro-viscous fluid according to claim 1 wherein the reactive aluminium compound is selected from aluminium oxides and aluminium oxide hydrates of the general formula A1 2 0 3 nH20 (n 0 to 6).

7. An electro-viscous fluid according to claim 1 wherein the reactive aluminium compound is selected from aluminium alcoholates, the alcohol component(s) thereof comprising one or more aliphatic straight or branched mono- or polyhydric C 1 to C 6 alcohols.

8. An electro-viscous fluid according to any one of the preceding claims wherein the aluminium soaps used are produced by reacting one or more polycarboxylic acid(s), anhydride(s) or semi-ester(s) having 3 to 18 carbon atoms. [N:\LIBZ]00422:CB

9. An electro-viscous fluid according to claim 8 wherein the aluminium soaps used arc produced by reacting one or more polycarboxylic acid(s), anhydride(s) or semi- ester(s) having 12 to 18 carbon atoms.

An electro-viscous fluid according to any one of claims 1 to 7 'vherein the aluminium soaps used are produced by reacting one or more alkenyl succinic acid(s) and/or the semi-ester(s) thereof having 5 to 18 carbon atoms.

11. An electro-viscous fluid according to claim 10 wherein the aluminium soaps used are produced by reacting one or more alkenyl succinic acid(s) and/or the semi- ester(s) thereof having 12 to 18 carbon atoms.

12. An electro-viscous fluid according to any one of the preceding claims wherein the aluminium soaps used are produced by reacting polycarboxylic acids, anhydrides or semi-esters with the reactive aluminium compounds, all of the valences of the aluminium having been converted.

13. An electro-viscous fluid according to any one of the preceding claims wherein the aluminium soaps used are produced by reacting polycarboxylic acids, the anhydrides or the semi-esters thereof comprising one or more free OH group(s) with said reactive aluminium compound(s).

14. An electro-viscous fluid according to any one of the preceding claims wherein the alcohol component(s) of the semi-esters is (are) dihydric to tetrahydric 20 alcohols having 1 to 6 carbon atoms, or the oligomers thereof.

15. An electro-viscous fluid according to any one of the preceding clallls wherein the alcohol component(s) of the semi-esters is (are) dihydric to tetrahydric alcohols having 2 to 5 carbon atoms, and the oligomers thereof.

16. An electro-viscous fluid according to any one of the preceding claims. 'd fluid comprising 2 to 50 wt. of said aluminium soap in homogeneous solution with 50 to 98 wt.% of a conventional hydraulic base fluid, and additionally 0 to 10 wt. of soluble hydraulic oil additives known per se, each referring to the total composition.

17. An electro-viscous fluid according to claim 16, said fluid comprising 5 to 40 wt. of said aluminium soap in homogeneous solution with 60 to 95 wt. of a conventional hydraulic base fluid, and additionally 0 to 5 wt. of soluble hydraulic oil additives known per se, each referring to the total composition.

18. An electro-viscous fluid according to claim 16, said fluid comprising 10 to 35 wt.% of the aluminium soap in homogeneous solution with 65 to 90 wt. of a conventional hydraulic base fluid, and additionally 0.1 to 2 wt. of soluble hydraulic oil additives known per se, each referring to the total composition. IN:\LIZIO00422:CB 12

19. An electro-viscous fluid comprising an aluiv-iium soap, which soap is substantially as hereinbefore described with reference to any ne of Examples 3 to 8. An electro-viscous fluid substantially as hereinbefore describeL with -reference to any one of Examples 3 to 8. Dated 3 August, 1995 RWE-DEA Aktiengesellschaft fur Mineraloel und Chemie Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON @00 to. of* IN:\LIOZIO04M2CB Homogeneous Electroviscous Liquids Abstract Homogeneous, electro-viscous fluids are provided which comprise aluminium soaps produced by reacting one or more saturated and/or unsaturated monomeric, oligomeric and/or polymeric C3 to C 32 polycarboxylic acid(s) having one or more carboxylic group(s), the anhydrides and/or semi-esters thereof wherein the alcohol component(s) is (are) linear or branched, monohydric or polyhydric C 1 to C 12 alcohols and/or the oligomers thereof with one or more of reactive aluminium compound(s) selected from the group consisting of aluminium alcoholate(s), the alcohol component(s) thereof comprising one or more aliphatic straight or branched, mono- or polyhydric C 1 to C 1 8 alcohols; aluminium alkyls; aluminium oxoalkyls; aluminium hydroxycarboxylates; aluminium oxocarboxylates; aluminium oxoalcoholates; aluminium alkoxycarboxylates; aluminium oxides and aluminium oxyhydrates. The aforesaid fluids manifest a high electro- rheological effect and are completely homogeneous. IN: LIZI100422.C E