SYNTHESIS AND VISCOELASTIC BEHAVIORS OF POLY(ANILINE-CO-O-ETHOXYANILINE) PARTICLES SUSPENDED ELECTRORHEOLOGICAL FLUID

2001 ◽  
Vol 15 (06n07) ◽  
pp. 649-656 ◽  
Author(s):  
H. J. CHOI ◽  
J. W. KIM ◽  
M. S. SUH ◽  
M. J. SHIN ◽  
K. TO
Keyword(s):  
Particle Size ◽  
Silicone Oil ◽  
Loss Modulus ◽  
Chemical Oxidation ◽  
Steady Shear ◽  
Rheological Parameters ◽  
Linear Viscoelastic Region ◽  
Linear Viscoelastic ◽  
Er Fluids ◽  
Poly Aniline

Copolyanilines are synthesized by a chemical oxidation of aniline and o-ethoxyaniline with various molar ratios in an acidic media, and then characteristics of these polymers such as chemical structure, particle size and the particle size distribution were examined by using FT-IR, SEM and particle size analyzer, respectively. Suspensions of copolyaniline containing ethoxy group, namely poly(aniline-co-o-ethoxyaniline), in silicone oil have been investigated as one of many potential candidates for dry-base electrorheological (ER) fluid systems. Rotational rheometer (Physica) equipped with a high voltage generator was used to characterize the rheological properties of ER fluids from both steady shear and dynamic tests. From the steady shear experiment, we obtained flow properties and found that ER fluids exhibited the yield phenomenon. On the other hand, viscoelastic property was also obtained from the dynamic experiment. Since viscoelastic properties for ER fluids are mainly dominated by the particle chain structure, the state at different time scale was analyzed from the rheological parameters such as storage modulus (G'), loss modulus (G'') and tan δ. We conducted a strain amplitude sweep at 1 Hz under an applied electric field to determine a linear viscoelastic region first. The G' and G'' were then measured by a frequency sweep from 0.1 to 100 Hz in the linear viscoelastic region.

EFFECT OF IONIC AND NONIONIC SUBSTITUENTS ON THE ELECTRORHEOLOGICAL CHARACTERISTICS OF POLYANILINE DERIVATIVES

2001 ◽  
Vol 15 (06n07) ◽  
pp. 988-995 ◽  
Author(s):  
H. J. CHOI ◽  
M. S. CHO ◽  
J. W. KIM ◽  
R. M. WEBBER ◽  
M. S. JHON
Keyword(s):  
Silicone Oil ◽  
Experimental Results ◽  
Dielectric Spectra ◽  
Er Fluids ◽  
Ionic Copolymer ◽  
Poly Aniline

We report our experimental results on the electrorheological (ER) characteristics of ER fluids consisting of suspensions of semiconducting polyaniline and copolyaniline particles in silicone oil. Ionic sodium diphenylamine sulfonate and nonionic o-ethoxyaniline were introduced to synthesize copolyanilines, i.e. N-substituted copolyaniline and poly (aniline-co-o-ethoxyaniline), respectively. ER fluids using these particles were compared. ER fluids, which contain the ionic copolymer, showed the highest ER performance among polyaniline and its copolymer systems. This result was interpreted in terms of the conductivities of the particles and their dielectric spectra.

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.

The Effect of Activation Time of Phosphoric Ester Cellulose Particles on the Electrorheological Properties of Anhydrous ER Fluids

2001 ◽  
Vol 15 (06n07) ◽  
pp. 1009-1016 ◽  
Author(s):  
B. G. Ahn ◽  
U. S. Choi ◽  
C. H. Kim ◽  
O. K. Kwon
Keyword(s):  
Particle Size ◽  
Electric Fields ◽  
Silicone Oil ◽  
Average Particle Size ◽  
Constant Current ◽  
Average Particle ◽  
Activation Time ◽  
Constant Current Density ◽  
Phosphoric Ester ◽  
Er Fluids

The electrorheological (ER) behavior of suspensions in silicone oil of phosphoric ester cellulose powder (average particle size: 17.77 μm) was investigated at room temperature with electric fields up to 2.5 kV/mm. For development of anhydrous ER fluids using at wide temperature range, it was sought the effect of activation time of phosphoric ester cellulose particles on the ER activities. Anhydrous ER fluids based on the phosphoric ester cellulose particles made from cellulose particles treating in chemical solution of 2M phosphoric acid and 4M urea and heating at 150°C were measured. After activating the phosphoric ester cellulose anhydrous ER fluids at 120°C, not only analysis of dispersing cellulose particles but also electroroheological characteristics of ER fluids such as dielectric constant, current density, electrical conductivity and rheological properties were studied. Activation time had a large influence to ER properties of anhydrous ER fluids based on phosphoric ester cellulose. As the activation time went by, particle size and number of dispersing particles, electrical properties, dynamic yield stress on electric field, initial apparent viscosity (η0) and electrorheological effect (τA/τ0) of phosphoric ester cellulose ER fluids increased with increasing activation time at 120°C till activation time over 5 hours.

SYNTHESIS AND ELECTRORHEOLOGICAL CHARACTERIZATION OF POLYANILINE AND NA+-MONTMORILLONITE CLAY NANOCOMPOSITE

2001 ◽  
Vol 15 (06n07) ◽  
pp. 657-664 ◽  
Author(s):  
J. W. KIM ◽  
S. G. KIM ◽  
H. J. CHOI ◽  
M. S. SUH ◽  
M. J. SHIN ◽  
...  
Keyword(s):  
Silicone Oil ◽  
Dynamic Tests ◽  
X Ray Diffraction ◽  
Aniline Monomer ◽  
Nanocomposite Particles ◽  
X Ray ◽  
Linear Viscoelastic ◽  
Er Fluids ◽  
Er Fluid

Polyaniline- Na +-montmorillonite nanocomposite particles were synthesized using an emulsion intercalation method, and electrorheological (ER) fluids were produced by dispersing the synthesized nanocomposite particles in an electrically-insulating silicone oil. The emulsion of an aniline monomer with dodecyl benzenesulfonic acid was inserted into the layers of clay, and polymerization was processed by adding the oxidant initiator solution. DBSA as a emulsifier and a dopant took a important role for polyaniline clay nanocomposite. This insertion of polyaniline was confirmed by X-ray diffraction. To observe its ER properties, we measured the shear viscosity and the shear stress by controlling shear rate. Furthermore, we conducted dynamic tests to investigate the viscoelastic properties of the ER fluid under an electric field in the linear viscoelastic region.

Viscoelastic analysis of oat grain within linear viscoelastic region by using dynamic mechanical analyzer

2020 ◽  
Vol 16 (4) ◽  
Author(s):  
Nan Zhao ◽  
Bo-wen Li ◽  
Ying-dan Zhu ◽  
Dong Li ◽  
Li-jun Wang
Keyword(s):  
Moisture Content ◽  
Storage Modulus ◽  
Heating Temperature ◽  
Loss Modulus ◽  
Creep Recovery ◽  
Dynamic Mechanical Analyzer ◽  
Frequency Sweep ◽  
Dynamic Mechanical ◽  
Linear Viscoelastic Region ◽  
Linear Viscoelastic

AbstractThe stress relaxation, creep-recovery, temperature, and frequency sweep tests were performed within the linear viscoelastic region by using a dynamic mechanical analyzer to investigate the viscoelastic characteristic of oat grain. The result showed that 5-element Maxwell and Burgers model were able to describe viscoelastic behaviors better. The relaxation stress decreased with the increasing moisture content from 6.79 to 23.35%, while the creep strain increased as well as the final percentage recovery decreased from 58.61 to 32.50%. In frequency sweep, storage modulus increased with the increasing frequency. In temperature sweep, there was a clear turning point in storage modulus, loss modulus, and tan delta curves with increasing temperature. The turning value of 167.47, 147.44, 134.27, 132.41, 110.28, and 92.62 °C detected in the tan delta were regarded as the best glass transition temperatures. This temperature was found to be lower than gelatinization heating temperature and decrease with the increase of moisture content. The crystalline structure of oat exhibited a typical A-type pattern and corresponding crystallinity increased from 22.03 to 31.86% with increasing moisture content. The scanning electron microscopy (SEM) micrograph of oat section was found that the size and adhesive effect of starch granules increased due to hydration.

Rheological Study of Steady Shear and Linear Viscoelastic Characteristics of Polyethylene and Polycarbonate Nanocomposites

2007 ◽  
Author(s):  
Michael P. Lalko ◽  
Leela Rakesh ◽  
Stanley Hirschi
Keyword(s):  
Critical Strain ◽  
Uv Light ◽  
Loss Modulus ◽  
Steady Shear ◽  
Functionalized Carbon Nanotubes ◽  
Polymer Properties ◽  
Oscillatory Rheometry ◽  
Linear Viscoelastic ◽  
Viscoelastic Characteristics ◽  
Strain Storage

The addition of nano-sized particles into a polymer matrix is an excellent way to manipulate polymer properties. Our current efforts try to understand how a material’s properties are influenced by parameters such as temperature, particle size, and particle concentrations of additives. This paper presents the rheological behavior of polycarbonate (PC) and low density polyethylene (LDPE) containing at least 2.5% and 5% weight fractions of functionalized and un-functionalized carbon nanotubes (CNTs). These materials were investigated using steady shear and oscillatory rheometry over a range of processing temperatures. The properties examined through rheological experimentation include: viscosity, critical strain, storage modulus (G′), and loss modulus (G ). The nanocomposites samples were examined using scanning electron microscopy (SEM) and UV light microscopy.

scholarly journals Viscoelastic and Deformation Characteristics of Structurally Different Commercial Topical Systems

Pharmaceutics ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1351
Author(s):  
Maryam Dabbaghi ◽  
Sarika Namjoshi ◽  
Bhavesh Panchal ◽  
Jeffrey E. Grice ◽  
Sangeeta Prakash ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Loss Modulus ◽  
Polymer Network ◽  
Zero Shear Viscosity ◽  
Potential Implication ◽  
Pharmaceutical Equivalence ◽  
Linear Viscoelastic Region ◽  
Oil In Water ◽  
Linear Viscoelastic ◽  
Oil Emulsions

Rheological characteristics and shear response have potential implication in defining the pharmaceutical equivalence, therapeutic equivalence, and perceptive equivalence of commercial topical products. Three creams (C1 and C3 as oil-in-water and C2 as water-in-oil emulsions), and two gels (G1 and G2 carbomer-based) were characterized using the dynamic range of controlled shear in steady-state flow and oscillatory modes. All products, other than C3, met the Critical Quality Attribute criteria for high zero-shear viscosity (η0) of 2.6 × 104 to 1.5 × 105 Pa∙s and yield stress (τ0) of 55 to 277 Pa. C3 exhibited a smaller linear viscoelastic region and lower η0 (2547 Pa∙s) and τ0 (2 Pa), consistent with lotion-like behavior. All dose forms showed viscoelastic solid behavior having a storage modulus (G′) higher than the loss modulus (G″) in the linear viscoelastic region. However, the transition of G′ > G″ to G″ > G′ during the continual strain increment was more rapid for the creams, elucidating a relatively brittle deformation, whereas these transitions in gels were more prolonged, consistent with a gradual disentanglement of the polymer network. In conclusion, these analyses not only ensure quality and stability, but also enable the microstructure to be characterized as being flexible (gels) or inelastic (creams).

SYNTHESIS AND ELECTRORHEOLOGY OF MESOPOROUS PARTICLS SUSPENSIONS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2514-2520 ◽  
Author(s):  
HYOUNG J. CHOI ◽  
MIN S. CHO ◽  
WHA-SEUNG AHN
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Silicone Oil ◽  
Linear Viscoelastic ◽  
Static Yield ◽  
Viscosity Enhancement ◽  
Er Fluids ◽  
Elasticity Measurement ◽  
Static Yield Stress ◽  
Mcm 41

Electrorheological (ER) properties of a fluid composed of mesoporous MCM-41 particles suspended in silicone oil under high electric field were investigated. Typical properties of ER fluids such as viscosity enhancement and viscoelasticity under applied electric fields in MCM-41/silicone oil suspensions were observed. In the dynamic and static yield stress measurements, a strain hardening effect was also observed and subsequently confirmed by elasticity measurement as a function of time under a linear viscoelastic condition.

Impact of high-pressure homogenization on the microstructure and rheological properties of citrus fiber

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Dianbin Su ◽  
Xin-Di Zhu ◽  
Yong Wang ◽  
Dong Li ◽  
Li-Jun Wang
Keyword(s):  
Particle Size ◽  
High Pressure ◽  
Rheological Properties ◽  
Binding Capacity ◽  
Loss Modulus ◽  
High Pressure Homogenization ◽  
Carreau Model ◽  
Hydration Properties ◽  
Water Binding ◽  
Water Holding

Abstract Citrus fiber dispersion with different concentrations (5–25 g/kg) was treated by high-pressure homogenization (90 and 160 MPa) for two cycles. The particle size distribution, hydration properties of powders, morphology and rheological measurements were carried out to study the microstructure and rheological properties changes by high-pressure homogenization (HPH). In conclusion, the HPH can reduce the particle size of fiber, improve the water holding capacity and water binding capacity. Furthermore, fiber shape can be modified from globular cluster to flake-like slices, and tiny pores can be formed on the surface of citrus fiber. The apparent viscosity, storage modulus and loss modulus were increased by HPH whereas the activation energy was reduced. The Hershcel–Bulkley model, Carreau model and Power Law mode were selected to evaluate the rheological properties.

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