• Title/Summary/Keyword: anhydrous ER suspensions

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The Effect of the Activation of Phosphoric Ester Cellulose Particles on the Electrotheological Properties of Anhydrous ER Fluids (인산 에스테르 반응 셀룰로오스 미립자의 활성화가 비수계 ER 유체의 전기유변학적 특성에 미치는 영향)

  • 안병길;최웅수;권오관;문탁진
    • Tribology and Lubricants
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    • v.14 no.3
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    • pp.7-16
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    • 1998
  • The electrorheological (ER) behavior of suspensions in silicone oil of phosphoric ester cellulose powder (average particle size: 17.77 $\mu$m) was investigated at room temperature with electric fields up to 2.5 KV/mm. For development of anhydrous ER suspensions using at wide temperature range, we aimed to know the effect of activation of phosphoric ester cellulose particles on the ER activities. As a first step, the anhydrous ER suspensions mixing with the phosphoric ester cellulose particles which were treated with 2M phosporic acid and 4M urea were measured. After activating the anhydrous ER suspensions at 12$0^{\circ}C$, not only the analysis of dispersing cellulose particles which were reacted by phosphoric ester but also the electrorheological characteristics of ER suspensions such as dielectric constant, current density, electrical conductivity and rheological properties were studied. From the experimental results, the activation of phosphoric ester cellulose particles had an influence on the ER properties of anhydrous ER suspensions. As the activation time went by, the size and number of dispersing particles, the electrical properties and the initial apparent viscosity $(η_0)$ of ER suspensions were increased till the activation time passed 5 hours. Also, it was possible, the electrorheological effect $($\tau$/$\tau$_0)$ of ER fluids was grown by the activation of phosphoric ester cellulose particles.

Electrorheological Properties of Anhydrous ER Suspensions Based on Phosphated Cellulose (인산처리 셀룰로오스를 첨가한 비수계 ER 유체의 전기유변학적 특성)

  • 안병길;최웅수;권오관;문탁진
    • Tribology and Lubricants
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    • v.14 no.2
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    • pp.1-9
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    • 1998
  • The electrorheological (ER) behavior of suspensions in silicone oil of phosphated cellulose particles (average particle size 17.77 ${\mu}{\textrm}{m}$) was investigated at room temperature with electric fields up to 2.5 KV/mm. In this paper, for development of anhydrous ER suspensions using at wide temperature range, we would like to know fundamental understandings on the ER activity. As a first step, the anhydrous ER suspensions dispersed the phosphated cellulose particles were measured, and not only the electrical characteristics such as dielectric constant, current density and electrical conductivity but also the rheological properties on strength of electric field and quantity of dispersed phase were studied. From the experimental results, the anhydrous ER suspensions dispersed phosphated cellulose particles showed a stable current density and very high performance of ER effect $(\tau/\tau_0=1030)$ on the 2.5 KV/mm and the dynamic yield stress $(\tau_y)$ was in exponential proportion to the strength of electric fields.

The Effect of Surfactant on the Electrorheological Properties of Phosphoric Ester Cellulose ER Fluids (인산 에스테르 셀룰로오스 ER 유체의 전기유변학적 특성에 대한 계면활성제의 영향)

  • 안병길;최웅수;권오관
    • Tribology and Lubricants
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    • v.15 no.3
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    • pp.240-247
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    • 1999
  • The electrorheological (ER) behavior of suspensions in silicone oil of phosphoric ester cellulose particles (average particle size : 18$\pm$1${\mu}{\textrm}{m}$) coated with octadecylamine ( $C_{18}$ $H_{37}$ N $H_2$) as surfactant was investigated at room temperature. For development of anhydrous ER suspension using at real application, it should be researched how can reduce deposition of ER particles in ER suspension. Anhydrous ER suspensions mixing with phosphoric ester cellulose particles coated with octadecylamine were measured. As increasing the coating concentration of octadecylamine, not only analysis of electrical properties such as dielectric constant, current density and electrical conductivity but also rheological properties of ER suspensions were studied. From the experimental results, coating concentration of surfactant had large influence to ER properties of anhydrous ER suspension. Current density, conductivity and electrorheological effect ($\tau$/$\tau$$_{0}$) of ER suspension were linearly reduced with increasing the coating concentration of octadecylamine. But ER suspensions dispersed the phosphoric ester cellulose particles coated with octadecylamine showed reducing deposition of ER particles and could be redispersed easily.

The Effect of Compressing ER Electrode on Electrorheological Properties of Anhydrous ER Fluids (ER 유체용 압축전극이 ER 유체의 전기유변학적 특성에 미치는 영향)

  • Ahn, Byeng-Gil
    • Tribology and Lubricants
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    • v.18 no.1
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    • pp.16-23
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    • 2002
  • For increasing the yield stress of ER fluids, the compressing ER electrode was developed and the compressing electrorheological (ER) behavior of anhydrous ER fluids in silicone oil of phosphorous ester cellulose powder was investigated. Under constant electric field, not only the current density but also the yield stress of anhydrous ER fluids were studied as varying the compressing length of ER electrode distance. From the experimental results the compressing of ER electrode had a large influence to the ER properties of anhydrous ER fluids. The current density was proportional to the compressing length of ER electrode under constant electric field and volume fraction also tile compressing yield stress was proportional to the volume fraction of dispersed particles under constant electric field and compressing length. When the ER electrode was compressed with 150mm after charging the electric field, 4 kV, tile yield stress of phosphoric ester cellulose ER fluids increased to thirteen times comparing with the yield stress measured at normal electrode.

Electrorheological Properties of Phosphoric Ester Cellulose ER Fluids on the Elevated Temperature (온도 변화에 따른 인산 에스테르 셀룰로오스 ER 유체의 전기유변학적 특성)

  • 안병길;오경근;최웅수;권오관
    • Tribology and Lubricants
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    • v.15 no.1
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    • pp.8-16
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    • 1999
  • The electrorheological (ER) behavior of suspensions in silicone oil of phosphoric ester cellulose powder (average particle size : 18$\pm$1 ${\mu}{\textrm}{m}$) was investigated on the elevated temperature up to 10$0^{\circ}C$. For development of anhydrous ER fluids using at wide temperature range, it should be researched to how the effect of temperature on the ER activities. As a first step, the anhydrous ER suspensions mixing with the phosphoric ester cellulose particles which were made from the phosphoric ester reaction of cellulose were measured. As increasing the temperature, not only the analysis of electrical properties such as dielectric constant current density and electrical conductivity but also the rheological properties of ER fluids were studied. From the experimental results, the temperature had a large influence to the ER properties of anhydrous ER fluids. The current density, conductivity and elecoorheological effect ($\tau$$_{A}$$\tau$$_{0}$) of phosphoric ester cellulose ER fluids were proportional to the temperature with power law. And the shear stress of them was closely related with the square of dielectric constant mismatch parameter ($\beta$$^2$) under constant shear rate and electric field.d.

Synthesis and Electrorheological Effect of the Suspensions Composed of Nano Sized Hollow Polyaniline Derivatives

  • Choi Ung-Su
    • KSTLE International Journal
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    • v.7 no.1
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    • pp.18-21
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    • 2006
  • The electrorheology of hollow PANI derivative suspensions in silicone oil was investigated by varying the electric fields and shear rates, respectively. The hollow PANI derivative susepnsions showed a typical electrorheological (ER) response caused by the polarizability of an amide polar group and shear yield stress due to the formation of chains upon application of an electric field. The shear stress for the hollow PANI succinate suspension exhibited an electric field power of 0.67. On the basis of the experimental results, the newly synthesized hollow PANI derivative suspensions were found to be an anhydrous ER fluid.

Electrical and Rheological Behavior of the Anhydrous ER Fluids Based on Chitosan Derivatives as the Dispersion Phases

  • Choi Ung-su;Sung Bo-hyun
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2004.11a
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    • pp.323-329
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    • 2004
  • The electrical and rheological properties pertaining to the electrorheological (ER) behavior of chitosan derivatives, chitosan, chitosan ammonium salt and chitosan phosphate suspensions in silicone oil were investigated. Chitosan derivative suspensions showed a typical ER response (Bingham flow behavior) upon application of an electric field. However, chitosan phosphate suspension exhibited an excellent shear yield stress compared with chitosan and chitosan ammonium salt suspensions. The difference in behavior results from the difference in the conductivity of the disperse phases due to the difference of their polarizability. The shear stress for the chitosan, chitosan ammonium salt and chitosan phosphate suspensions exhibited a linear dependence on the volume fraction of particles and 1.18 ,1.41 and 1.67 powers of the electric field. On the basis of the experimental results, the newly synthesized chitosan derivative suspensions found to be an ER fluid.

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The Effect of phosphoric Ester of Cellulose on the Electrorheological Properties of Anhydrous ER Fluids (셀룰로오스의 인산 에스테르 반응이 비수계 ER 유체의 전기유변학적 특성에 미치는 영향)

  • 최웅수
    • The Korean Journal of Rheology
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    • v.10 no.3
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    • pp.143-151
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    • 1998
  • 실리콘 오일에 인산처리 셀룰로오스 분말을 분산시킨 비수계 전기유변성(ER) 유체 의 전기유변 거동을 상온에서 최대 2.5KV/mm의 전기장하에서 실험하였다. 넓은 온도 영역 에서 사용이 가증한 비수계 ER 유체를 개발하기 위해 셀룰로오스의 인산 에스테르 반응이 ER 유체의 전기유변효과에 미치는 영향을 조사하였다. 먼저 여러 가지의 인산처리 농도로 처리된 인산처리 셀룰로오스 미립자를 분산시킨 ER 유체를 제조한 후 ER 유체의 유전상수, 전류밀도 및 전기전도도 등과 같은 전기적 특성을 측정하였으며 ER 유체의 전기유변 특성 또한 측정하였다. 인산처리 셀룰로오스가 분산된 비수계 ER 유체의 전류밀도는 셀룰로오스 의 인산 에스테르 반응에서의 인산처리 농도에 의해 조절할수 있음을 알수있었으며 셀룰로 오스의 인산처리 농도가 2.5 M과 3.0 M 사이일 때 인산처리 셀룰로오스가 첨가된 비수계 ER 유체의 전기유변효과 ($\tau$/$\tau$0)가 가장 높게 측정되었다.

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Electrorhelological Properties of Monodispersed Submicron-sized Hollow Polyaniline Adipate Suspension

  • Sung, Bo-Hyun;Choi, Ung-Su
    • KSTLE International Journal
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    • v.6 no.1
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    • pp.28-32
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    • 2005
  • The electrorheoloRical (ER) fluids are composed of a colloidal dispersion of polarizable particles in insulating oil, and it's the rheological property changes by the applied electric field. These changed are reversible and occur fast within a fewmilliseconds. The ER properties of the ER fluid such as increment of viscosity and yield stress come from the particle chain structure induced by electric fleld. When formulating the ER fluid for a speciflc application, some requirement must besatisfled, which are high yield stress under electric field, rapid response, and dispersion stability. While this characteristic makes valuable ER fluids in valious industrial applications, their lung term and quiescent application has been limited because ofproblems with particle sedimentation. In an effort to overcome sedimentation problem of ER fluids, the anhydrous ER materials of monodispersed hollow polyaniline (PANI) and adipate derivative respectively with submicron-sized suspension providing wide operating temperature range and other advantage were synthesized in a four-step procedure. The ER fluidswere characterized by FT-lR, TGA, DLS, SEM, and TEM. Stability of the suspensions was examined by an UV spectroscopy.The rheological and electrical properties of the suspension were investigated Couette-type rheometer with a high voltagegenerator, current density, and conductivity. And the behavior of ER suspensions was observed by a video camera attached toan optical microscope under 3kV/mm. The suspensions showed good ER properties, durability, and particle dispersion.

Study on Electrorheological Properties of the Synthesized Chitosan Derivatives (키토산 유도체의 합성과 이의 전기유변학적 특성에 관한 연구)

  • 고영건;임세환;손태일;최웅수
    • Tribology and Lubricants
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    • v.19 no.2
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    • pp.72-77
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    • 2003
  • Chitosan derivatives, Fluorinated chitosan, and N,N,N-Trimethyl chitosan iodide were synthesized as the disperse phases for the electrorheological fluid. The synthesis of these materials were confirmed by Fourier transform infrared spectroscopy (FT-lR). Chitosan derivative suspensions showed ER effect under the electric field. Especially, N,N,N-Trimethyl chitosan iodide suspension showed better electrorheological and electric properties than Fluorinated chitosan. It is due to difference in electron strength of polar groups composed derivatives. N,N,N-Trimethyl chitosan iodide suspension exhibited a linear dependence on an electric field power of 2.07.