• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.219-219
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• 2006

This study focuses on the effects of dispersion method of a nanoparticle in a polymer matrix such as melt mixing, solution blending, and in-situ polymerization on the physical properties of the nanocomposites. Introduction of a nanoparticle to a polymer resulted in some unusual physical properties. In some cases the nanoparticle played a role of a nucleating agent, leading to decreasing induction time to crystallization. In addition, the dispersion state of the nanoparticle in the polymer matrix also had a significant influence on the physical properties of the nanocomposites. Hence the method of introducing the nanoparticle to the polymer made contribution to the rheological properties of the nanocomposite systems.

• 대한전기학회논문지
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• 제37권1호
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• pp.55-62
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• 1988

The variation of electrical resistivity of silver particle-filled polymers with the volume percent of silver particles was investigated. Also, the relationships between the surface tension of polymer and dispersion effect of silver particles were studied to find the steep drop of electrical resisivity, in view of agglomerate morphology. The critical volume precent of silver particles varied depending on the polymer species and increased with the increasing surface tension of polymer. The steep variation of resistivity with the increasing temperature was explained with the expansion of polymer at the melting temperature of polymer. The conductive break down current increased with the increasing volume percent of silver particles in the Ag/LDPE system and that was attributed to heat of Joule taken througn the contact area between the silver particle.

• 폴리머
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• 제36권3호
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• pp.364-371
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• 2012

폴리스티렌(PS)/단일벽 탄소나노튜브(SWCNT) 나노복합재료를 라텍스 기술로 제조하여 계면활성제(SDS) 첨가에 따른 SWCNT의 분산 정도와 나노복합재료의 유변학적, 전기적 물성을 고찰하였다. 나노복합재료는 단분산 PS 입자에 SDS를 첨가한 SWCNT 분산액을 혼합한 후 동결건조하여 제조하였다. SDS 함량이 증가함에 따라 나노튜브의 분산성이 향상되어 나노복합재료의 저장 탄성률과 복소 점도는 증가하지만, 지나치게 증가시킨 경우에는 저분자량의 SDS로 인해 감소하는 결과를 보여주었다. 전기 전도도는 SDS를 첨가함에 따라 급격히 향상된 후 큰 변화를 보이지 않았다. 이는 나노튜브의 분산성 향상에 의한 전기 전도도 증가와 SDS 도포에 의한 SWCNT의 전기 전도도 저하의 경쟁에 의한 것으로 추론된다. SDS를 SWCNT 함량의 2배로 첨가한 경우가 나노복합재료의 전기 전도도 및 사용 물성 향상에 최적 조건이었다. 이 경우 전도성을 부여하는 SWCNT의 임계 함량은 1 wt% 이하에서 나타났다.

• 폴리머
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• 제32권6호
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• pp.549-554
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• 2008

분산중합법에 의해 고분자 미립자를 합성하기 위해 스티렌과 n-butylmethacrylate가 알루미나와 함께 중합되었다. 스티렌과 n-butylmethacrylate의 비는 3 : 1이었고, 입자안정제는 poly (N-vinyl pyrrolidon), 중합 개시제로는 2,2'-azobis(isobutyronitrile)를 커플링제는 3-methacryloxypropyl trimethoxysilane을, 분산매로 이소프로판올과 이온교환수를 70 : 30의 비로 사용하였다. TEM 사진을 통해 알루미나가 고분자 미립자에 분산되어 있음을 확인하였고 알루미나의 농도가 증가함에 따라 평균 입자경이 증가하였으며 입자경 분포는 감소되는 경향을 보였다. XRD 측정에 의해 알루미나의 농도 증가는 피크 강도와 2$\theta$값의 증가를 보였으며 TGA 측정으로 알루미나의 농도의 증가는 고분자 미립자의 내열성을 증가시킴을 알 수 있었다. 사용한 개시제의 반감기가 길수록 입자경은 감소하였고 입자인정제의 농도가 증가할수록 반응초기의 핵생성이 증가하여 입자경이 또한 감소함을 알 수 있었다.

• Journal of Pharmaceutical Investigation
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• 제34권3호
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• pp.169-176
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• 2004

Acyclovir(ACV) is an important antiviral drug used extensively against infections caused by herpes viruses, especially herpes simplex and varicella zoster. Because of high crystallinity and large particle size, solubility of intact ACV is very low in water(1.3 mg/ml). The goal of this work is to enhance the solubility of ACV. To make solid dispersion, Polyethyleneglycol, Hydroxyprophylmethylcelluose and Polyvinylpyrrolidone were used as polymer carriers in this work. Polymer carriers and drug were dissolved in acetic acid. And then spray drying method and freeze drying method were used as solvent extraction. Morphology, crystallization and functional group were characterized using SEM, XRD and FT-IR. The result of in vitro test showed the sample using PVP as polymer carrier had higher dissolution rate(up to 466%) than intact ACV.

• Carbon letters
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• 제26권
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• pp.25-30
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• 2018

The dielectric medium used in electrophoretic displays (EPDs) is required to be an environmentally friendly solvent with high density, low viscosity, and a large electric constant. Hydrofluoroether, a highly fluorinated solvent with eco-friendly characteristics, is regarded as a viable alternative medium for EPDs, owing to the similarity of its physical properties to those of the conventional EPD medium. Surface modification of particles is required, however, in order for it to disperse in the charged solvent. Also, positive/negative charges should be present on the particle surface to enable electrophoretic behavior. In this study, carbon black particles wrapped with positively charged nitrogen (N-CBs) were fabricated by a simple hydrothermal process using a poly(diallyldimethylammonium chloride) solution as a black coloring agent for the EPD. The dispersion behavior of N-CBs was investigated in various solvents.

• Macromolecular Research
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• 제16권4호
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• pp.293-302
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• 2008

In our previous publication, the problem of particle deformation and coagulation at the nucleation stage in the presence of cross-linker was intensely studied by seeded batch dispersion polymerization of methyl methacrylate (MMA). In the present work, highly cross-linked, monodisperse PMMA particles were prepared under various reaction conditions by seeded semi-continuous process. Monodisperse, $6.5{\mu}m$-diameter PMMA particles containing up to 8 wt% of DVB or EGDMA were successfully made by seeded semi-continuous process and multi-semi-continuous addition process, respectively. Therefore, this study shows that seeded semi-continuous process is more effective and efficient to prepare highly cross-linked, monodisperse particles than non-seeded and seeded batch processes.

• 펄프종이기술
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• 제38권5호
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• pp.24-30
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• 2006

This study was performed to characterize inverse emulsion type cationic polyacrylamide (PAM) and to compare with powder and salt dispersion type PAMs as a retention and drainage aid. Salt dispersion type PAM has defects of high amount of salt which increases conductivity of white water, low active polymer contents and relatively worse retention and drainage properties than others because of its low molecular weight. Powder type PAM has benefit of high active polymer contents and good retention and drainage properties, but defects of low dissolution speed and insoluble particle generation were observed. However, inverse emulsion type showed the best retention and drainage aids among them by controlling molecular weight and morphology easily and it had relatively higher active polymer contents and better solubility.

• 한국고분자학회지:고분자과학과기술
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• 제9권6호
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• pp.492-499
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• 1998

• Journal of Pharmaceutical Investigation
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• 제38권2호
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• pp.119-126
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• 2008

Solid dispersions of poorly water-soluble drug, sibutramine, were prepared with hydrophilic polymer, poly-N-vinylpyrrolidone (PVP), hydroxypropylmethylcellulose (HPMC) and organic acid, citric acid, to improve the solubility of drug. Physicochemical variation and shape of microsphere were characterized by scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and Fourier-transform infrared spectroscopy (FT-IR). Microspheres containing additives showed more spherical shape than non additive microspheres. In vitro release behavior of microspheres presented at simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 6.8). The solid dispersion form transformed the drug into an amorphous state and dramatically improved its dissolution rate. These data suggest that the solid dispersion technique is an effective approach for developing the appetite depressant drug products and various pharmaceutical excipients are able to control the release behaviors.