• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.212-217
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• 2010

In this study, suspension polymerized toners were prepared by using poly(vinyl alcohol)(PVA) as an organic suspending agent. Styrene and butylacrylate monomers were used simultaneously with carbon black to prepare microspherical polymerized toners with a narrow-particle size distribution. Preliminary particles without carbon black were polymerized first to optimize suspension polymerization conditions. The preliminary particles were prepared at various polymerization conditions and their characteristics were compared to each other to determine an optimized polymerization condition. The black polymerized toner prepared at the optimized polymerization condition showed reasonable particle size and shape, and good thermal and printing characteristics by showing its glass transition temperature at $53.6^{\circ}C$.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.457-460
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• 1998

일반적인 리빙중합의 정의는 개시반응과 사슬의 성장반응만이 있으며 사슬이동반응이나 종결반응 등의 부반응은 일어나지 않아서 중합반응 후에도 사슬의 성장활성이 오랫동안 유지되는 중합반응계를 말한다. 이러한 리빙중합은 여러 가지의 중합방법에 의해서 시도되어졌는데 가장 대표적이고 성공적인 방법으로서 이온중합에 의한 방법을 그 예로 들 수 있다. 그러나 이온중합에 의한 방법은 그 리빙성이 매우 우수한 반면에 중합가능한 단량체의 종류가 국한되어 있고 중합조건이 아주 까다로워서 실용성이 없다는 단점이 있다. (중략)

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.477-486
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• 2008

Acrylic resin is widely used in dental practice. However, the residual monomer in acrylic resin could act as a negative biocompatability on human body. The aim of this study was to evaluate the amount of the monomer elution from polymerized orthodontic acrylic resin. Orthodontic acrylic resin was used in the study. The curing condition of the resin was controlled by temperature, pressure, aquatic and atmospheric environment. The duration and amount of monomer elution and timedependent plot was recorded by high performance liquid chromatography. The result showed that the only monomer eluted from the resin was methyl methacrylic acid. And the amount of the monomer elution has diminished considerably by time progress especially within 24 hours. Furthermore, elution of the residual monomer was significantly lower in group of pressure, moisture and elevated temperature than control (p<.05). According to this study, it was thought that the elution of residual monomer might be influenced by curing environment.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.1
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• pp.17-21
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• 2003

5원환 고리아세탈 화합물인 4-methylenes(4,5)을 합성하고 저온조건 하에서 중합반응을 조사한 결과, 선택적인 개환중합이 일어났다. 보통의 양이온 개시제를 사용한 결과 $-78^{\circ}C$에서 가교체가 얻어졌으며, $CH_3SO_3H$를 개시제로 사용하면 같은 조건에서도 주사슬과 곁사슬에 이중결합을 가지는 개환중합체가 얻어진다. 이 중합체는 반응성을 가지는 불포화기를 포함하고 있으므로 prepolymer로써 널리 사용될 수 있다.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.17-20
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• 1998

1. 서론 : 계면중합은 제조에 따른 박막의 성능 조절이 가능한 이유로 해서 역삼투용 복합막의 주요 제조 방법으로 제시되어 왔다. 계면중합을 응용하여 제조된 복합막의 성능은 반응 단량체의 종류, 용재의 종류, 단량체의 농도, 반응시간, 열처리 유무 및 온도와 시간 등에 의해 변한다. 한편 위의 변수에 절대적인 영향을 받고 아울러 단량체간의 몰 비가 성립하지 않음으로 해서 최적의 막 성능으로 제시되는 조건을 만족하기 위하여 주로 시행착오에 의한 방법을 동원하여 여러 변수에 다른 제조 막의 성능 고찰을 실시하여 왔다. (생략)

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.676-680
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• 2011

Investigated was the effect of the crucial polymerization conditions such as methyl acrylate(MA) mole fraction in feed, polymerization temperature and time on Atom Radical Transfer Polymerization(ATRP) behavior of styrene and methyl acrylate(MA). As MA mole fraction in feed increased, molecular weight(MW) of the resulting copolymer increased. At polymerization time of 3 hrs the composition of MA in the resulting copolymer was shown to have a linear relationship with the mole fraction of MA in feed. MW was increased and the composition of MA in copolymer was decreased as the polymerization time increased, showing the characteristics of ATRP. MW was also increased as polymerization temperature increased, and the composition of MA in copolymer was shown to be increased drastically at polymerization temperature of $110^{\circ}C$.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.276-285
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• 1997

The theoretical and experimental analysis on polyamide used for reverse osmosis thin-film composite membrane had been conducted. The physicochemical properties of polyamide had been varied by preparation recipes which depends on kinds of monomer, solvents and polymerization time. These properties and performance as a reverse osmosis membrane had been calculated by group contribution method. The experimental results has the same trends with theoretical preview.

• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.213-219
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• 1997

The plasma polymerized styrene films were prepared by using an inter-electrode capacitively coupled gas-flow-type reactor, and the effects of plasma polymerization condition on the molecular weight distribution were investigated by Fourier Transform Infrared (FT-IR), Pyrolysis Gas Chromatography(PyGC), Differential Scanning Calorimetry(DSC) and Gel Permeation Chromatography(GPC). From the above results, the very cross-linked films different from chemical characteristics of the starting monomer were taken out, and it is realized that the molecular structure, cross linking density, and molecular weight distribution could be controlled by changing the parameters such as deposition pressure, deposition power and gas flow rate. Accordingly, it is suggested that plasma polymerization method performed by inter-electrode capacitively coupled gas-flow-type reactor has good characteristics for manufacturing the functional organic thin films which can be applied in sensors, opto-electric device, photo-resist by changing the polymerization parameters.

• Journal of the Korean Chemical Society
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• v.20 no.2
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• pp.158-165
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• 1976

The anionic polymerization of ${\varepsilon}$-caprolactam with N,N'-adipyl-bis-${\varepsilon}$-caprolactam as an initiator and potassium hydroxide as a catalyst was studied under various conditions.It was found that concentration of catalyst and initiator was 4.2 and 1.6 mole %, and polymerization temperature of 130$^{\circ}C$C, polymerization time of 1.5 hours was the optimum condition. The intrinsic viscosity and molecular weight of the obtained polymer was over 0.9 dl/g and 12,000. The polymerization was carried out in the presence of N-acyl-${\varepsilon}$-caprolactam as an initiator, it was observed that the reactivity of N,N'-adipyl-bis-${\varepsilon}$-caprolactam was greater than both of the N-benzoyl-${\varepsilon}$-caprolactam and N-acetyl-${\varepsilon}$-caprolactam. In general it was also observed that the intrinsic viscosity and yield of conversion was increased as an increasing of concentration of catalyst and initiator and also highly depend on temperature.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.923-928
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• 2012

Optimizing a water-phase suspending system is very important to manufacture high-quality suspension polymerized toners. Therefore, in this study, the effects of the molar ratio of calcium hydroxide ($CaOH_2$)/phosphoric acid ($H_3PO_4$)(Ca/P), which were used as inorganic suspending agents, and pH of the water-phase on the characteristics of styrene-based suspension polymerized toners were mainly investigated. At first, the water-phase was fixed to neutral condition (pH=7.5) and Ca/P molar ratio was changed from 1.5:1 to 1.76:1. As a result, an ideal calcium phosphate (hydroxyapatite) was prepared at the Ca/P molar ratio of 1.73:1 and polymerized toners prepared at this condition showed good particle size distribution, circularity and charging characteristic. Based on this result, Ca/P molar ratio was fixed to 1.73:1 and pH of the water-phase was changed to weak acidic (pH=5.5) and weak basic (pH=9.5) conditions. As a result, polymerized toners prepared under the weak acidic condition showed very good particle size distribution, circularity and charging characteristic along with excellent printing quality. High-quality suspension polymerized toners could be prepared via optimizing Ca/P molar ratio and pH of the water-phase.