• Title/Summary/Keyword: Core-shell

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Polymerization and Effect of Organic/Organic Core Shell Binder (Organic/organic Core Shell 바인더의 중합과 처리영향)

  • Sim, Dong-Hyun;Ban, Ji-Eun;Kim, Min-Sung;Seul, Soo-Duk
    • Polymer(Korea)
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    • v.32 no.5
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    • pp.470-477
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    • 2008
  • Core shell binder of organic/organic pair that has two different properties within a particle were prepared by a step emulsion polymerization of methacrylate (MMA), styrene (St), ethyl acrylate (EA), butyl acrylate (BA), and 2-HEMA by using an water soluble initiator(APS) in the presence of an anionic surfactant (SDBS). Unwoven tensile strength of the core shell binder after processing and measuring the PSt/PMMA/2-HEM core shell with the binder is a value represents the highest was $10.75\;kg_f$/2.5cm, elongation measurements PEA/PBA core shell binder showed the highest value was 120.00%. In conclusion, using the core shell binders were able to control the mechanical properties such as tensile strength and elongation.

Manufacture of PMMA/PBA and PBA/PMMA core Shell Composite Particles - Effect of emulsifier - (PMMA/PBA와 PBA/PMMA Core Shell 복합입자의 제조 - 유화제의 영향 -)

  • Seul, Soo Duk
    • Journal of Adhesion and Interface
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    • v.11 no.3
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    • pp.112-119
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    • 2010
  • Poly(methyl methacrylate)/poly(butyl acrylate) PMMA/PBA core-shell composite particles were prepared by the emulsion polymerization of MMA and BA in the presence of different concentration of sodium dodecyl benzene sulfonate (SDBS). The following conclusions are drawn from the measured conversion and particle size distribution, morphology, average molecular weight distribution, observation of film formation and particle formation, glass transition temperature and physical properties of polymerized core-shell composition particles for using adhesive binder. When the concentration of 0.03 wt% surfactant, the conversions of PMMA and PBA core polymerization are excellent as 95.8% for PMMA core and 92.3% for PBA core. Core-shell composite particles are obtained 90.0% for PMMA/PBA core-shell composite particles and 89.0% for PMMA/PBA core-shell composite particles. It is considered that the core and shell particles are polymerized to be confirmed FT-IR spectra and average molecular weight measured with a GPC, formation of the composite particles is confirmed by the film formation from normal temperature, and composition of inside and outside of the composite particle is confirmed by TEM photograph. The synthesized polymer has two glass transition temperatures, suggesting that the polymer is composed of core polymer and shell polymer unlike general copolymers. It is considered that each core-shell composite particle can be used as a high functionality adhesion binder by the measurement of tensile strength and elongation.

Plasma Treatment Effect of Organic/Organic Core-Shell Acrylic Adhesive Binder (II) (Organic/Organic Core-Shell 아크릴 접착바인더의 플라즈마 처리영향 (II))

  • Seul, Soo-Duk
    • Polymer(Korea)
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    • v.34 no.2
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    • pp.89-96
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    • 2010
  • Adhesive binders with core-shell structure of organic/organic pair were prepared by emulsion polymerization of acrylic monomers, such as methyl methacrylate(MMA), ethyl acrylate(EA), n-butyl acrylate(BA), and styrene(St). Ammonium persulfate (APS) was used as an water soluble initiator in the presence of an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS). Non-woven fabric and leather were impregnated with the adhesive binder. The surface of the impregnated fabric and leather were treated with plasma technique and then kinetics analysis and mechanical properties were measured. The conversions of the polymerization of core-shell binder (MMA/EA, MMA/BA) were greater than 90%. When the core-shell binder was prepared at equimolar conditions, the increasing effect of the core-shell binder on the state peel strength of the impregnated and plasma-treated non-woven/non-woven fabric has the order of MMA/St, EA/BA, BA/MMA, EA/St, and EA/MMA. When the core-shell binder was prepared at non-equimolar conditions, the increasing effect of the core-shell binder on the state peel strength of the non-woven fabric/leather has the order of MMA/BA, BA/EA, MMA/EA, St/MMA, and EA/St.

TCC behavior of a shell phase in core/shell structure formed in Y-doped BaTiO3: an individual observation (Yttrium이 첨가된 BaTiO3에서 형성된 core/shell 구조에서 shell의 TCC 거동: 독립적 관찰)

  • Jeon, Sang-Chae
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.30 no.3
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    • pp.110-116
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    • 2020
  • Grains in the BaTiO3, which is used for a dielectric layer in MLCC(Multi-Layer Ceramic Capacitor) are necessary to form core/shell structure for a stable TCC(Temperature Coefficient of Capacitance) behavior. The shell property has been deduced from the whole TCC behavior of core/shell structure due to its tiny size, ~ few ㎛. This study demonstrates the individual TCC behavior of the shell phase measured by micro-contact measurement in a temperature range between 35 and 135℃. Pt electrode pairs deposited on an enlarged core/shell structure in a diffusion couple sample made the measurement possible. As a result, the DPT (Diffusion Phase Transition) behavior of the shell phase was revealed as a different TCC behavior from that of the core: a broad peak with Tm at 65℃. This would be also useful experimental data for a modelling that depicts dielectric-temperature behavior of core/shell structure.

Manufacture of Core-Shell Composite Polymer Materials for Nonwoven binder (부직포 바인더용 Core-Shell 복합소재의 제조)

  • Lee, Sun Ryong;Lim, Jae Keel;Seul, Soo Duk
    • Journal of Adhesion and Interface
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    • v.3 no.4
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    • pp.27-36
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    • 2002
  • The organic/organic core-shell composite polymer for nonwomen binder were synthesized by stage polymerization of methyl methacrylate and styrene with ammonium persulfate after preparing monomer pre-emulsion in the presence of anionic surfactant. We study the effect of initiator concentration, $0.79{\times}10^{-3}{\sim}3.16{\times}10^{-3}mol/L$ for core polymer, $2.0{\times}10^{-4}{\sim}8.0{\times}10^{-4}mol/L$ for shell polymer, sulfactant concentration, $1.45{\times}10^{-5}{\sim}4.15{\times}10^{-5}mol/L$ for core polymer, $0.73{\times}10^{-5}{\sim}2.91{\times}10^{-5}mol/L$ for shell polymer on core-shell structure of polymethyl methacrylate/polystyrene and polystyrene/polymethyl methacrylate. Emulsion stability was major test method, particle size and particle size distribution were measured using particle size analyzer and the morphology of the core-shell composite polymer was determined using transmission electron microscope, glass temperature was also measured using differential scanning calorimeter.

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Preparation of Methyl Methacrylate-Styrene System Core-Shell Latex by Emulsion Polymerization (유화중합에 의한 Methyl Methacrylate-Styrene계 Core-Shell 라텍스 입자 제조에 관한 연구)

  • Kim, Nam-Seok;Kim, Duck-Sool;Lee, Seok-Hee;Park, Keun-Ho
    • Journal of the Korean Applied Science and Technology
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    • v.22 no.2
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    • pp.96-105
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    • 2005
  • Core-shell polymers of methyl methacrylate-styrene system were prepared by sequential emulsion polymerization in the presence of sodium dodecyl benzene sulfonate(SDBS) as an emulsifier using ammonium persulfate(APS) in an initiator and the characteristics of these core-shell polymers were evaluated. Core-shell composite latex has the both properties of core and shell components in a particle, whereas polymer blends or copolymers show a combined physical properties of two homopolymers. This unique behavior of core-shell composite latex can be used in various industrial fields. However, in preparation of core-shell composite latex, several unexpected matters are observed, for examples, particle coagulation, low degree of polymerization, and formation of new particles during shell polymerization. To solve this matters, we study the effects of surfactant concentrations, initiator concentrations, and reaction temperature on the core-shell structure of PMMA-PSt and PSt-PMMA. Particle size and particles distribution were measured by using particle size analyzer, and the morphology of the core-shell composite latex was observed by using transmission electron microscope. Glass temperature was also measured by using differential scanning calorimeter. To identify the core-shell structure, pH of the composite latex solutions was measured.

[Retraction] Preparation of Methyl methacrylate/styrene Core-shell Latex by Emulsion Polymerization ([논문 철회] 유화중합에 의한 Methyl methacrylate/styrene계 Core-shell 라텍스 입자 제조에 관한 연구)

  • Kang, Don-O;Lee, Nae-Woo;Seul, Soo-Duk;Lee, Sun-Ryong
    • Elastomers and Composites
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    • v.37 no.1
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    • pp.21-30
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    • 2002
  • Core-shell polymers of methyl methacrylate/styrene pair were prepared by sequential emulsion polymerization in the presence of sodium dodecyl benzene sulfonate(SDBS) as an emulsifier using ammonium persulfate(APS) as an initiator. The characteristics of these core-shell polymers were evaluated. Core-shell composite latex has the both properties of core and shell components in a particle, where as polymer blonds or copolymers show a combined properties from the physical properties or two homopolymers. This unique behavior of core-shell composite latex can be used in many industrial fields. However, in preparation of core-shell composite latex, several unexpected phenomina are observed, such as, particle coagulation, low degree of polymerization, and formation of new particles during shell polymerization. To solve the disadvantages, we studied the effects of surfactant concentrations, initiator concentrations, and reaction temperature on the tore-shell structure or PMMA/PSt and PSt/PMMA. Particle size and particle size distribution were measured by using particle size analyzer, and the morphology of the core-shell composite latex was observed by using transmission electron microscope. Glass transition temperature($T_g$) was also measured by using differential scanning calorimeter. To identify the core-shell structure, pH of the composite latex solutions were measured.

Preparation and Physical Properties of Poly(Styrene/Acrylate) Core-Shell Latex Particles (Poly(Styrene/Acrylate) Core-Shell 라텍스 입자의 제조와 물성에 관한 연구)

  • Lee, Kyoung-Goo;Park, Keun-Ho
    • Journal of the Korean Applied Science and Technology
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    • v.20 no.1
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    • pp.27-32
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    • 2003
  • The core-shell latex particles were prepared by sequential emulsion polymerization of alkyl methacrylate and styrene(ST) by using an water-soluble initiator(APS) after preparing monomer pre-emulsion in the presence of an anionic surfactant(SDBS). In organic/organic core-shell polymerization, the pre-emulsion method, which minimized required quantity of sulfactant, has been used to increase the conversion rate and the stability of core-shell latex particles as well as to reduce the formation of secondary particle that cause problems of soap-free emulsion during shell polymerization. We used several methods to observe the core-shell structure. The core-shell structure was studied by measuring pH change during hydrolysis by NaOH, glass transition temperature($T_g$) by differential scanning calorimeter(DSC), morphology of latex by transmission electron microscope(TEM) and change of particle size and distribution by a particle analyzer.

Pt@Cu/C Core-Shell Catalysts for Hydrogen Production Through Catalytic Dehydrogenation of Decalin

  • Kang, Ji Yeon;Lee, Gihoon;Jeong, Yeojin;Na, Hyon Bin;Jung, Ji Chul
    • Korean Journal of Materials Research
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    • v.26 no.1
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    • pp.17-21
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    • 2016
  • Pt@Cu/C core-shell catalysts were successfully prepared by impregnation of a carbon support with copper precursor, followed by transmetallation between platinum and copper. The Pt@Cu/C core-shell catalysts retained a core of copper with a platinum surface. The prepared catalysts were used for hydrogen production through catalytic dehydrogenation of decalin for eventual application to an onboard hydrogen supply system. Pt@Cu/C core-shell catalysts were more efficient at producing hydrogen via decalin dehydrogenation than Pt/C catalysts containing the same amount of platinum. Supported core-shell catalysts utilized platinum highly efficiently, and accordingly, are lower-cost than existing platinum catalysts. The combination of impregnation and transmetallation is a promising approach for preparation of Pt@Cu/C core-shell catalysts.

Sol-gel 법을 이용한 ZnO-$TiO_2$ Core-shell 나노입자의 합성

  • Yang, Hui-Su;Nam, Sang-Hun;Jo, Sang-Jin;Jeong, Won-Seok;Bu, Jin-Hyo
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.366-366
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    • 2011
  • 이성분 산화물인 ZnO/$TiO_2$ core-shell 나노입자는 core-shell 구조의 특성과 이성분 산화물의 상호작용에 의해서 염료감응형 태양전지의 효율향상을 기대할 수 있다. Znic acetate($Zn_2(CH_3COO)$)와 Titanium(IV) butoxide($Ti(OBu)_4$)를 이용하여 ZnO 나노입자를 수열합성하고 그 주의에 $TiO_2$을 가수분해 반응을 이용하여 둘러싸는 core-shell형태의 물질을 합성하였다. 그 이후 결정성 및 유기물 제거를 위해서 4시간 동안 고온에서 소성하였다. SEM 결과에 따르면 소성 온도를 600도까지 증가시키면 ZnO의 경우 나노입자의 크기가 증가하는 경향을 확인하였다. 하지만 core-shell의 경우는 ZnO의 뭉침현상을 $TiO_2$이 방해하여 초기합성된 크기와 동일한 크기를 유지하는 것을 확인하였다. 또한 XRD 결과에 따르면 주변에 형성된 $TiO_2$ 이외에 $Zn_2TiO_4$의 spinel 구조를 가지는 물질이 합성되는 것을 확인할 수 있었다. 합성된 core-shell 구조의 나노입자는 약 40~50 nm의 크기를 가지고 600도에서 소성된 입자의 경우 산소 정공이 거의 없는 약 3 eV의 밴드갭을 가지는 물질로 합성이 되었다. Core-shell 나노입자의 경우 염료 감응형 태양전지의 반도체 물질로 응용 가능할 것으로 판단된다.

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