• Title/Summary/Keyword: 유화중합

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Preparation of Monodisperse Blue-colored Polymeric Particles with High Zeta-potential (높은 제타전위를 갖는 단분산의 블루착색 고분자미립자의 제조)

  • Lee, Ki-Chang;Nam, Sang-Yong
    • Journal of Adhesion and Interface
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    • v.13 no.3
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    • pp.109-115
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    • 2012
  • Monodisperse blue-colored poly(styrene-co-acrylic acid) latices were successfully prepared by seeded emulsion polymerization. Blue-colored latices with carboxyl anionic charge on the surface were synthesized at the second stage with the introduction of Blue 606 dye, acrylic acid, and 0.21 ${\mu}m$-polystyrene seed. All the blue-colored latices synthesized in this study were in the size range of 0.25~0.42 ${\mu}m$ and all uniform with less than 1.01 in PSD. The particle size increased with the addition of acrylic acid being delayed and colloidally stable latices were obtained over 30 min after its addition. The blue-colored latex with 20 wt% acrylic acid showed -145 mV of zeta-potential and $-9.4{\times}10^{-6}\;cm^2/Vs$ of electrophoretic mobility, and with 25 wt% of DVB showed high $T_g$ at 396.7 K.

Study on the Properties of Polystyrene and Styrenic Copolymer Containing Carbon Nanotubes and Nanoclay (탄소나노튜브와 나노클레이를 포함하는 폴리스티렌 및 스티렌계 공중합체 나노복합재료의 물성에 관한 연구)

  • Lee, Kyung Hoon;Kim, Young Doo;Lee, Minho;Min, Byong Hun;Kim, Jeong Ho
    • Applied Chemistry for Engineering
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    • v.20 no.5
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    • pp.493-499
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    • 2009
  • The properties of polystyrene and styrenic copolymer nanocomposites containing carbon nanotubes (CNT) and nanoclays were studied. Polystyrene and styrenic copolymer containing styrene and vinylbenzyl trimethylammonium chloride (SVTAC) were synthesized by emulsion polymerization. Polystyrene/CNT/clay and SVTAC/CNT/clay nanocomposites with various concentrations of CNT and different types of clay were prepared via mixing of polystyrene emulsion and clay. SVTAC/CNT nanocomposites showed a better electrical conductivity than PS/CNT nanocomposites. Nanocomposites with more surfactant during polymerization showed a better electrical conductivity than the ones with less surfactant. These indicated the positive effect of comonomer and surfactant on the electrical conductivity. Transmission electron microscopy (TEM) was used to analyze the state of CNT dispersion. TEM results showed that CNT loading, comonomer composition and amount of surfactant affected the final dispersion of CNT in nanocomposites. In order to confirm the effects of CNT loading, comonomer composition and the amount of surfactant on the thermal and dynamic mechanical properties, DSC and DMA analyses were conducted.

A Study on the Preparation of NBR/Polypyrrole Conducting Composites and Their Electrical Properties (Poly(acrylonitrile-co-butadiene) Rubber/Polypyrrole 전도성 복합체의 제조와 전기적 성질에 관한 연구)

  • Jung, Mi-Ok;Huh, Yong-Il;Lee, Wan-Jin
    • Elastomers and Composites
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    • v.35 no.3
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    • pp.188-195
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    • 2000
  • The conducting composites were prepared by emulsion polymerization with poly (acrylonitrile-co-butadiene) (NBR) as a matrix and polypyrrole (PPY) as a conducting polymer. Among several surfactants, the electrical conductivity of the composite which was polymerized by dodecyl sodium sulfate (DSS) was the best. The film of composite was prepared by compression molding. The electrical conductivity was measured by 4 probes method as a function of PPY and temperature. When the content of PPY was 25 wt%, the electrical conductivity of composite was increased up to 1.17 S/cm. The percolation threshold showed at the vicinity of 15 wt% PPY content.

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Semi-continuous Emulsion Polymerization of n-Butyl acrylate/Methyl metacrylate using Environmental-Friendly LE-Type Nonionic Surfactant (환경친화적 LE-형 비이온계면활성제를 사용한 반연속식 말브틸-아크릴레이트/메틸메타-아크릴레이트 유화중합에 관한 연구)

  • Kim, Chul-Ung
    • Clean Technology
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    • v.11 no.1
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    • pp.41-50
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    • 2005
  • In this study, semibatch emulsion copolymerization of n-BA as adhesive component and MMA as coagulant component were carried out for the stable acrylic polymer latex in aqueous phase for polymer cement using LE-type nonionic surfactant as environmental friendly surfactant. The stable polymer emulsion was obtained with the increases of chain length(n) of this surfactant. The effect on the amount of LE-50 as nonionic surfactant were showed that the concentration of polymer latex were increased by increasing the amount of LE-50, whereas the average particle size were decreased by increasing the amount. The addition of functional monomer in initial reactor charge showed a significant effect on the final polymer concentration and the latex particle size. The single polymerization of each n-BA or MMA showed a very low concentration of polymer latex and very big particle size due to coagulation. In the polymerization composed of mixed monomer with MMA and n-BA, the larger the ratio of MMA to n-BA in the copolymers, the greater the amount of coagulum produced. It was found that a stable copolymers were obtained in the range of 15-35 % of n-BA. Moreover, incorporation of some functional monomers in addition to of main monomers became more stable polymer latex. Through DSC and IR analysis, the final polymer latex was composed by MMA/n-BA/AA/AM with a single Tg depending on the reaction conditions. As a result, the conditions of this acrylic polymerization could also be effectively controlled to get the desired final products.

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Influence of Graphene Oxide and Graphite Nanoplatelets on Rheological and Electrical Properties of Polystyrene Nanocomposites (산화 그래핀과 나노 흑연이 폴리스티렌 나노복합재료의 유변물성 및 전기적 물성에 미치는 영향)

  • Yeom, Hyo Yeol;Na, Hyo Yeol;Lee, Seong Jae
    • Polymer(Korea)
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    • v.38 no.4
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    • pp.502-509
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    • 2014
  • Carbon-based nanoplatelets such as graphene oxide (GO) sheets and graphite nanoplatelets (GNPs) are frequently used as conductive nanofillers for polymer nanocomposites. In this study, polystyrene (PS)/GO and PS/GNP nanocomposites were prepared through a latex technology and investigated to compare the effect of nanofillers on rheological and electrical properties of the PS nanocomposites. PS particles were prepared by emulsifier-free emulsion polymerization and GO was synthesized by using the modified Hummers' method from graphite. Hydrophilic GO was dispersed in aqueous PS suspension, but hydrophobic GNPs were dispersed with the help of a surfactant. In comparison with PS/GO nanocomposites, the rheological properties of PS/GNP counterparts were not too high because GNP existed in aggregates of graphene layers. Conducting pathways of PS/GO and PS/GNP nanocomposites were achieved at the electrical percolation threshold of 0.50 and 5.82 wt%, respectively. The reason for enhanced electrical conductivity in PS/GO nanocomposites is that GO was thermally reduced during molding.

Effect of Latex Particle Size on Rheological and Electrical Properties of Polystyrene/Multi-Walled Carbon Nanotube Nanocomposites (라텍스 입자 크기가 폴리스티렌/탄소나노튜브 나노복합재료의 유변물성 및 전기적 물성에 미치는 영향)

  • Kang, Myung-Hwan;Noh, Won-Jin;Lee, Seong-Jae
    • Polymer(Korea)
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    • v.35 no.5
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    • pp.451-457
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    • 2011
  • The effect of latex particle size on rheological and electrical properties of latex-blended polystyrene (PS)/multi-walled carbon nanotube (MWCNT) nanocomposites was investigated. Mono-dispersed PS particles synthesized either by emulsifier-free emulsion polymerization or by dispersion polymerization were mixed with MWCNTs under ultrasonication, and freeze-dried to prepare the nanocomposites. As the MWCNT content increased, storage modulus, complex viscosity and electrical conductivity were substantially increased. The increase of storage modulus and complex viscosity was higher for larger PS particles. The effect of particle size on electrical properties was different depending on MWCNT content. With lower MWCNT content, the nanocomposite prepared by smaller PS particles showed higher electrical conductivity, but the opposite result was given as the content increased.

Waterborne Core-shell Pressure Sensitive Adhesive (PSA) Based on Polymeric Nano-dispersant (고분자 분산제를 이용한 Core-shell 수성 감압점착제)

  • Lee, Jin-Kyoung;Chin, In-Joo
    • Journal of Adhesion and Interface
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    • v.17 no.3
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    • pp.89-95
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    • 2016
  • An environmentally friendly water-based pressure sensitive adhesive (PSA) was designed in an attempt to replace the solvent-based adhesive for dry lamination used in flexible food packaging films. Instead of using a low molecular weight surfactant, which may have variable material properties, a high molecular weight dispersant was used for emulsification. A polymeric nano-dispersant (PND) was synthesized using solution polymerization, and it was used as a micelle seed in the surfactant, resulting in the synthesis of a core/shell grafted acrylic adhesive. The shell and core exhibited different $T_g$ values, so that the initial adhesion strength and holding power were complemented by the film's flexibility, which is required to provide good adhesion of thin films. Results showed that the PSA designed in this study using the PND instead of traditional low molecular weight surfactant had adhesive properties applicable to the flexible packaging with appropriate tack.

Suspension Polymerization of Thermally Expandable Microcapsules with Core-Shell Structure Using the SPG Emulsification Technique: Influence of Crosslinking Agents and Stabilizers (SPG 유화법을 사용하여 현탁중합한 코어-쉘 구조를 갖는 열팽창 마이크로캡슐 제조: 가교제 및 안정제의 영향)

  • Bu, Ji Hyun;Kim, Yeongseon;Ha, Jin Uk;Shim, Sang Eun
    • Polymer(Korea)
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    • v.39 no.1
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    • pp.78-87
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    • 2015
  • With aiming to prepare microcapsules having a particle size of $30-50{\mu}m$, thermally expandable capsules with relatively uniform particle sizes consisting of a n-octane/poly(acrylonitrile-co-methyl methacrylate) core/shell structure were synthesized using SPG membrane emulsification and suspension polymerization. Four steric stabilizers and five crosslinking agents were employed. When poly(vinyl alcohol) as a stabilizer was used, the prepared capsules showed a smooth and regular morphology and the liquid hydrocarbon (n-octane) was well encapsulated in the core. When 1,4-butnaediol methacrylate (BDDMA) was used as a crosslinker, the uniform capsules with the average diameter of $36.8{\mu}m$ were synthesized. The capsules prepared with 0.05 mol% BDDMA showed the best encapsulation efficiency.

Synthesis and Characterization of Cellulose-Hybrid Polystyrene Nanoparticles by Using Reactive Hydroxypropyl Methylcellulose Phthalate (반응형 히드록시프로필 메틸셀룰로오스 프탈레이트를 이용한 셀룰로오스 혼성 폴리스티렌 나노입자의 합성 및 특성 분석)

  • Cheong In-Woo
    • Polymer(Korea)
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    • v.30 no.5
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    • pp.437-444
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    • 2006
  • Reactive hydroxypropyl methylcellulose phthalate (reactive HPMCP) was synthesized by using a stepwise urethane reaction with isophorone diisocyanate (IPDI) and 2-hydroxyethyl moth acrylate (HEMA). Molecular weight, acid number, and critical micelle concentration (CMC) of the synthesized reactive HPMCP and pristine HPMCP were measured and used as a polymeric surfactant in the emulsion polymerizations of styrene. In the preparation of HPMCP-hybrid poly styrene nanoparticles, 6, 9, 12, 18, and 24 wt% of HPMCPs were introduced, and the maximum rate of polymerization ($R_{p,max}$), the average number of radicals per particle (n), particle size distribution were investigated. In addition, core - shell morphology of the nanoparticles were observed by using TEM and their thermal stabilities were measured by using TGA. Reactive HPMCP showed higher $R_{p,max}$, smaller particle size, larger values of n and gel contents as compared with pristine HPMCP, due to the vinyl groups from HEMA, which can be reacted with styrene oligomers, in the reactive HPMCP.

Morphological Study on PNIPAAm Hydrogel Microspheres Prepared by Using SPG Membrane Emulsification and UV Photopolymerization (SPG 막유화 및 UV 광중합법에 의해 제조된 PNIPAAm 하이드로젤 입자의 형태학에 관한 연구)

  • Lee, Yun Jig;Kim, Mi Ri;Cheong, In Woo
    • Journal of Adhesion and Interface
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    • v.16 no.2
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    • pp.76-82
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    • 2015
  • W/O emulsions were prepared from the aqueous solution containing NIPAAm, MBA, and APS in the continuous phase of toluene and mineral oil mixture with HMP and Span80 by using SPG membrane emulsification, and followed by the formation of PNIPAAm hydrogel microspheres through UV photopolymerization. As the ratio of mineral oil to toluene increased in the continuous phase, both particle size of the hydrogel increased and density of PNIPAAm polymer in the hydrogel particle increased, and which significantly affected swelling/deswelling ratio ($V/V_o$) with temperature change around VPTT. When the polymerization temperature was below LCST ($20^{\circ}C$), PNIPAAm hydrogel showed filled particle morphology; however, it was turned out to hollow particle morphology with thick shell layer with $40^{\circ}C$. Both density of PNIPAAm and gel content of the hydrogel increased with the increase in MBA concentration.