ELECTRORHEOLOGICAL BEHAVIOR OF CHITOSAN DERIVATIVE SUSPENSIONS

2001 ◽  
Vol 15 (06n07) ◽  
pp. 1025-1032 ◽  
Author(s):  
Ung-su Choi ◽  
Byeng-gil Ahn ◽  
Oh-kwan Kwon
Keyword(s):  
Electric Field ◽  
Volume Fraction ◽  
Silicone Oil ◽  
Flow Behavior ◽  
Chitosan Derivative ◽  
Shear Yield Stress ◽  
Bingham Flow ◽  
Shear Yield ◽  
The Difference ◽  
Er Fluid

The electrorheological (ER) behavior of chitosan and chitosan phosphate suspensions in silicone oil was investigated. Chitosan and chitosan phosphate suspensions showed a typical ER response (Bingham flow behavior) upon application of an electric field. However, chitosan phosphate suspension exhibited excellent shear yield stress compared with chitosan suspension. The difference in behavior results from the difference in the conductivity of the chitosan and chitosan phosphate particles due to their degree of the polarizability. The shear stress for chitosan and chitosan phosphate suspensions showed a linear dependence on the volume fraction of particles. The values of structure factor, A s obtained 1 and 3~4 for chitosan and chitosan phosphate suspensions and it may be due to the formation of single-row chains and multiple chains upon application of the electric field. Throughtout the experimental results, chitosan and chitosan phosphate suspensions were shown to be an ER fluid.

ELECTRORHEOLOGICAL BEHAVIOR OF CHITOSAN DICARBOXYLATE SUSPENSIONS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2501-2506 ◽  
Author(s):  
UNG-SU CHOI ◽  
YOUNG-GUN KO
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Silicone Oil ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Polar Group ◽  
Shear Yield Stress ◽  
Shear Rates ◽  
Shear Yield ◽  
Er Fluid

The electrorheological (ER) behavior of chitosan dicarboxylate suspensions in silicone oil was investigated by varying the electric fields, volume fractions of particles, and shear rates, respectively. The chitosan dicarboxylate susepnsions showed a typical ER response caused by the polarizability of an amide polar group and shear yield stress due to the formation of multiple chains upon application of an electric field. Of these, chitosan malonicate suspension represented slightly higher rheological performance than any other suspensions due to dependent upon the carbon chain length. The shear stress for the suspension exhibited a linear dependence on an electric field power of 1.88. On the basis of the results, the newly synthesized chitosan dicarboxylate suspensions were found to be an anhydrous ER fluid.

Measurement of Interaction Forces at Small Distance under Electric Field in a Smectite Dispersed Silicone Oil Based ER Fluid

2001 ◽  
Vol 15 (06n07) ◽  
pp. 811-816 ◽  
Author(s):  
Toyohisa FUJITA ◽  
Toshio MIYAZAKI ◽  
Toshiharu TANAKA ◽  
Ke Jun Liu ◽  
Eiich KUZUNO ◽  
...  
Keyword(s):  
Electric Field ◽  
Silicone Oil ◽  
Small Distance ◽  
Surface Forces ◽  
Attraction Force ◽  
Interaction Forces ◽  
Repulsive Energy ◽  
Inflection Points ◽  
Dc Electric Field ◽  
Er Fluid

The apparatus to measure interaction forces under an electric field at small distance between a conductive hemisphere and a flat plate has been developed. The surface forces at small distance sandwiched ER fluid dispersing ultrafine smectite particles (20 to 50 nm thickness) in silicone oil has been measured. This fluid shows 0.7 kPa of apparent yield stress by applying 2.5 kV/mm of DC electric field. When an electric field applies to this ER fluid, the repulsive energy curves shows inflection points at about 0.2 μ m distance periodically at small distance of less than 1 μ m because the repulsion force decreases for a vacancy of particles after the particles are pushed out and the dipole attraction force acts between hemisphere and plate. On the other hand, when the electric field becomes off and it passes enough time, the inflection points is observed more shorter distance of about 0.15 μ m periodically. The coagulated particle size is estimated about 0.15 μ m under no electric field and becomes larger by applying electric field.

Position Control of a Cylinder Using a Hydraulic Bridge Circuit With ER Valves

1997 ◽  
Vol 122 (1) ◽  
pp. 202-209 ◽  
Author(s):  
Seung-Bok Choi ◽  
Woo-Yeon Choi
Keyword(s):  
Electric Field ◽  
Position Control ◽  
Bridge Circuit ◽  
Silicone Oil ◽  
Network Control ◽  
Operational Parameters ◽  
Pressure Drops ◽  
Feedback Error Learning ◽  
Feedback Error ◽  
Er Fluid

This paper presents the position control of a double-rod cylinder system using a hydraulic bridge circuit with four electro-rheological (ER) valves. After synthesizing a silicone oil-based ER fluid, a Bingham property of the ER fluid is first tested as a function of electric field in order to determine operational parameters for the ER valves. On the basis of the level of the field-dependent yield stress of the composed ER fluid, four cylindrical ER valves are designed and manufactured. Subsequently, step responses for pressure drops of the ER valve are empirically analyzed with respect to the intensity of the electric field. A cylinder system with a cart is then constructed using a hydraulic bridge circuit with four ER valves, and its governing equation of motion is derived. A neural network control scheme incorporating the proportional-integral-derivative (PID) controller is formulated through the feedback error learning method, and experimentally implemented for the position control of the cylinder system. Both regulating and tracking position control responses for square and sinusoidal trajectories are presented in time domain. In addition, a tracking durability of the control system is provided to demonstrate the practical feasibility of the proposed methodology. [S0022-0434(00)00701-2]

INFLUENCE OF PARTICLE SIZE ON THE DYNAMIC STRENGTH OF ELECTRORHEOLOGICAL FLUIDS

1994 ◽  
Vol 08 (20n21) ◽  
pp. 2835-2853 ◽  
Author(s):  
YUNG-HUI SHIH ◽  
HANS CONRAD
Keyword(s):  
Particle Size ◽  
Electric Field ◽  
Volume Fraction ◽  
Low Voltage ◽  
Silicone Oil ◽  
Particle Surface ◽  
Dynamic Strength ◽  
Columnar Structure ◽  
Particle Surface Area ◽  
Polarization Component

The electrical properties, rheology and structure of model ER fluids consisting of glass beads in silicone oil were investigated as a function of electric field E (0–4 kV/mm ), particle size D (6–100 µ m ) and shear rate [Formula: see text]. The conductivity of the suspensions was 3 orders of magnitude greater than that of the host oil at E ⋝ 1 kV/mm ; their low-voltage d.c. permittivity was about 1.35 times larger. The flow stress of the suspensions was given by [Formula: see text] where τE is the polarization component and τ vis the viscous component. The linear dependence of τE on E was attributed to dipole saturation. The observed opposing effects of D and [Formula: see text] on τE were concluded to result from their respective influence on the strength of the columnar structure normally produced by the electric field and its fragmentation during shear. The constant C1 was in agreement with the Einstein equation for the effect of volume fraction of particles on the viscosity of suspensions. The parameter C2/D was concluded to reflect either the effect of particle surface area on viscosity or a polydispersion effect. The present results did not correlate with the Mason number as normally formulated, but did when it was appropriately modified.

Effect of Particle Size and Distribution on the Viscosity of a Model Electrorheological (ER) Fluid

1999 ◽  
Author(s):  
Ying Chen ◽  
Hans Conrad
Keyword(s):  
Particle Size ◽  
Reasonable Agreement ◽  
Volume Fraction ◽  
Silicone Oil ◽  
Zero Field ◽  
Effect Of Particle Size ◽  
Er Fluids ◽  
Er Fluid ◽  
Modified Equation ◽  
Single Size

Abstract The zero-field viscosity of model ER fluids consisting of glass beads in silicone oil was determined as a function of average particles size (D¯ = 3–75 μm), volume fraction (ϕ = 0.1–0.3) and bimodal mixtures of two sizes. The viscosity increased with ϕ and decreased with D¯. The viscosity of the suspensions ηs in all cases was described reasonably well by the following relation:ηs=ηs,o(ϕ)+b(ϕ)D¯2/D¯3 where ηs,o(ϕ) and b(ϕ) are constants which increase with ϕ. Reasonable agreement with the Mooney crowding equation occurred for the single size particles, giving for the crowding factor k = 1.3 + 1.5/D¯. For ϕ < 0.2 the viscosity of the bimodal mixtures could be described by a modification of the Mooney equationηsηo=exp(2.76ϕ11-k1ϕ1)exp(2.76ϕ21-k2ϕ2) where ηo is the viscosity of the silicone oil, ϕi the volume fraction of each particle size Di and ki the normal crowding factor for that size. At ϕ = 0.3 the measured values of ηs for the bimodal mixtures became appreciably larger than those calculated from the modified equation. The decrease in particle size leads to both an increase in surface area of the particles per unit volume of the suspension and to a decrease in spacing (crowding); both factors probably contributed to the increase in ηs.

ELECTRORHEOLOGY OF DISPERSIONS OF BaxSr(1-x)TiO3 IN SILICONE OIL UNDER AC OR DC ELECTRIC FIELD

2012 ◽  
Vol 26 (14) ◽  
pp. 1250081 ◽  
Author(s):  
GLAUBER M. S. LUZ ◽  
ANTONIO J. F. BOMBARD ◽  
SILVIO L. M. BRITO ◽  
DOUGLAS GOUVÊA ◽  
SHEILA L. VIEIRA
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Electric Field ◽  
Silicone Oil ◽  
Ferroelectric Materials ◽  
Dc Electric Field ◽  
Ac Fields ◽  
Er Fluid ◽  
Constant Shear Rate

Electrorheology (ER) of ferroelectric materials such as nanometric BaTiO 3 is still not fully understood. In this paper, nanoparticles of Ba x Sr (1-x) TiO 3 (where x = 0.8, 0.9 or 1.0) were synthesized using the method of Pechini, calcinated at 950°C, and after, lixiviated under pH 1 or pH 5. A controlled stress rheometer (MCR-301) was used to make the ER characterization of dispersions made of Ba x Ti 1-x O 3 in silicone oil (30% w/w), where (a) shear stress as a function of DC electric field (under constant shear rate) or (b) shear stress as a function of shear rate (under constant AC or DC electric field) were measured. We observed that electrophoresis occurred under electric field DC, creating a concentration gradient which induced phase separation in ER fluid. On the other hand, under AC fields above 1 kV/mm, the ER effect is stronger than for DC field, and almost without electrophoresis. Furthermore, there is an AC frequency, dependent on the disperse phase, where the ER effect has a maximum.

Investigation into Electrorheological Fluid-Assisted Polishing Optical Glass

2011 ◽  
Vol 110-116 ◽  
pp. 1099-1106
Author(s):  
Yun Wei Zhao ◽  
De Xu Geng ◽  
Xiao Min Iu ◽  
Jin Tao Zhang
Keyword(s):  
Electric Field ◽  
Silicone Oil ◽  
Optical Glass ◽  
Electrorheological Fluid ◽  
Abrasive Particles ◽  
Micro Tool ◽  
Ultra Precision ◽  
Aspherical Lenses ◽  
Field Lines ◽  
Er Fluid

Electrorheological (ER) fluid-assisted polishing process is the ultra precision finishing technologies for micro-aspherical lenses and dies. The principle of ER fluid-assisted polishing (ERP) is to use ER effect as a result of the application of electric field. The ER particles and abrasive particles suspended in silicone oil are polarized in which ER particles strongly attract each other and aggregate into chain like structure along the electric field lines, and the abrasive particles may adhere to the ER chain. The force acting on ER particles and abrasive particles in an electric field is calculated. Furthermore, experiments of polishing optical glass with Al2O3 are carried out to find the influential regularities of polishing time, rotational speed of micro-tool, voltage, the density of abrasives in ER fluid on the surface roughness.

Micro-mechanical theory of shear yield stress for strongly flocculated colloidal gel

Soft Matter ◽  
2020 ◽  
Vol 16 (7) ◽  
pp. 1801-1809 ◽  
Author(s):  
Saikat Roy ◽  
Mahesh S. Tirumkudulu
Keyword(s):  
Yield Stress ◽  
Constitutive Relation ◽  
Volume Fraction ◽  
Mechanical Theory ◽  
Shear Yield Stress ◽  
Interparticle Potential ◽  
Shear Yield ◽  
Colloidal Gel ◽  
Scale Properties

We derive a constitutive relation for shear yield stress of strongly aggregated colloidal gel as a function of interparticle potential, volume fraction, contact scale properties and gel microstructure.

Electrorheology of Suspension of Sulfonated Styrene-Co-Divinylbenzene Particles — Approach Based on the Dielectric Properties of the Suspension —

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1845-1851 ◽  
Author(s):  
F. Ikazaki ◽  
A. Kawai ◽  
T. Kawakami ◽  
M. Konishi ◽  
Y. Asako
Keyword(s):  
Shear Stress ◽  
Dielectric Properties ◽  
Dielectric Property ◽  
Water Content ◽  
Particle Concentration ◽  
Silicone Oil ◽  
Relaxation Frequency ◽  
Measurement Temperature ◽  
The Difference ◽  
Er Fluid

Effects of particle concentration, water content and temperature on the electrorheology of suspensions of highly sulfonated styrene-co-divinylbenzene (SSD) particles in a silicone oil were investigated. The induced shear stress was measured with a modified rotary rheometer. The electrorheology of the suspension was largely affected by the particle concentration, the water content and the measurement temperature. The induced shear stress for the particle concentration of 40 wt% was about twice as large as that of 20 wt%. The induced shear stress for the water content of 4 wt% was about twice as large as that of 2 wt%. The induced shear stress for the temperature of 80°C was about 15 times as large as that of 20°C. Dielectric properties were measured to elucidate the mechanism of electrorheology. In order for an ER fluid to have large ER effect, relaxation frequency of the ER fluid should be between 100 and 105 Hz and the difference of the dielectric constant below and above the relaxation frequency (Δ∊′) must be large, which we refer to as the dielectric property mechanism. The relation between measured ER effect and dielectric property mechanism was discussed.

Electrorheological Properties of Suspensions Prepared From Polythiophene Conductive Polymer

Materials ◽  
2005 ◽  
Author(s):  
Datchanee Chotpattananont ◽  
Anuvat Sirivat
Keyword(s):  
Shear Flow ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Applied Stress ◽  
Volume Fraction ◽  
Scaling Law ◽  
Oscillatory Shear ◽  
Steady Shear ◽  
Er Fluid

Electrorheological (ER) fluids are typically composed of polarizable particles dispersed in a non-conducting fluid. Upon the application of an electric field, chain-like or fibrillar aggregates of the suspended particles are oriented along the direction of the electric field, thereby inducing viscoelasticity and a drastic increase in viscosity. In our study, Poly(3-thiophene acetic acid), PTAA, has been developed for using as ER material. The rheological properties of this PTAA suspension upon the application of electric field were investigated under various deformations; oscillatory shear flow, steady shear, and creep. We found that PTAA based ER fluid exhibited viscoelastic behavior and showed the excellent responses under an applied electric field. Moreover, the ER response of this PTAA fluid was amplified with increases in electric field strength, particle concentration, and particle conductivity. Under the oscillatory shear, the dynamic moduli, G′ and G″, increased dramatically by 10 orders of magnitude, when the field strength was increased to 2 kV/mm. The suspensions exhibited a transition from fluid-like to solid-like behavior as the field strength increased. While under steady shear flow, the yield stress increased with electric field strength, E, and particle volume fraction, φ, according to a scaling law of the form, τy α Eαφγ. Furthermore, the creep curves of this ER fluid consisted of both elastic and viscous responses and this fluid exhibits partially elastic recovery after the removal of applied stress. The creep properties strongly depended on the magnitude of an applied stress.

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