• Macromolecular Research
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• v.17 no.11
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• pp.842-849
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• 2009

Polycarbonate (PC)/sulfonated polystyrene (SPS) ionomer/organoclay nanocomposites were prepared by a solution intercalation process using the SPS ionomer as a compatibilizer. The effect of an organoclay on the melt crystallization behavior of the ionomer compatibilized PC were examined by differential scanning calorimetry (DSC). The melt crystallization behavior of PC was dependent on the extent of organoclay dispersion. The effect of the ionomer loading and cation size on intercalation/exfoliation efficiency of the organoclay in PC/SPS ionomer matrix was also studied using wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). Dispersion of the organically modified clay in the polymer matrix improved with increasing ionomer compatibilizer loadings and cation size. The SPS ionomer compatibilized PC/organoclay nanocomposite showed enhanced melt crystallization compared to the SPS ionomer/PC blend. Well dispersed organoclay nanocomposites showed better crystallization than the poorly dispersed clay nanocomposites. These nanocomposites also showed better thermal stability than the SPS ionomer/PC blend.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1340-1341
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• 2008

에폭시-Organoclay 나노콤포지트를 두가지 분산기법으로 적용하여 제조하였다. 하나는 Centrifugal 기법과 또다른 하는 강력초음파를 이용하여 제조하였다. 초음파를 적용하지 않고 Centrifugal만으로 제조된 나노콤포지트를 충진함량별 교류/직류정극성 전압을 인가한 절연파괴 특성과 Organoclay 종류별 교류절연파괴 특성을 연구하였다. 충진함량 특성으로 원형에비하여 나노콤포지트의 절연파괴 특성을 향상되었고, 함량이 5wt%까지는 거의 같은 파괴강도를 나타내었고, 이후 함량이 증가될수록 오히려 감소되는 경향을 나타내었다. 종류별 Organoclay의 경우 10A특성이 가장 높은 교류절연파괴 강도를 나타내었다. 초음파를 적용한 경우 함량별 교류절연파괴 강도 역시 초음파를 적용하지 않은 경우와 유사한 함량별 절연파괴 경향을 나타내었다. 파괴강도는 초음파를 적용한 경우가 월등히 높은 47.3%가 향상된 결과를 나타내었다. 이는 향후 몰딩용 및 함침용 절연재료로서 응용될 고압절연물에 크게 이용될 것으로 본다.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.966-972
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• 2007

A novel organoclay has been developed with aluminium-pillared clay modified with an amphoteric surfactant, N-Dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (DDAPS). This novel organoclay is expected to have phosphorus removal capacity as well as organic and inorganic contaminant removal capacity, due to aluminum inside the clay structure. It also exhibited less surfactant desorption than conventional cation surfactant-based organoclays. Phosphorus in water can be decreased from 0.2 mg/L to 0.0012 mg/L in 27 hours with this organoclay. Also, cadmium could removed from water using this proposed organo-clay. Experiments were performed under various pHs and amphoteric surfactants sorption capability was the highest at pH 5 when more of the amphoteric surfactant head group took on positive charges.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.226-227
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• 2007

Nanostructured materials are attracting increased interest and application. Exciting perspectives may be offered by electrical insulation. Epoxy/Organoclay nanocomposites may find new and upgraded applications in the electrical industry, replacing conventional insulation to provide improved performances in electric power apparatus, e.g, high voltage motor/generator stator winding insulation, dry mold transformer, etc. This paper shows that electrical and thermal properties of epoxy/organoclay nanocomposites insulating materials for dsc, dielectric constant, I-V characteristics, breakdown volatge, can improve significantly with respect to the basic, virgin materials.

• Macromolecular Research
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• v.16 no.6
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• pp.503-509
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• 2008

A series of colorless polyimide (PI) nanocomposite films were synthesized from 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) with various organoclay contents by solution intercalation polymerization to poly(amic acid)s, followed by thermal imidization. The variation with the organoclay content of the thermomechanical properties, morphology, and optical transparency of the hybrids was examined at organoclay loadings ranging from 0 to 1.0 wt%. The hybrid films showed high optical transparency and almost no color, with cut-off wavelengths ranging from 352 and 356 nm and very low $b^*$ values of 1.19-1.77. The hybrid PI films showed good thermal properties with a glass transition temperature of $280-287^{\circ}C$. Most films did not show any significant thermal decomposition below $490^{\circ}C$. The addition of only a small amount of organoclay was sufficient to improve the tensile properties of the PI films with maximum enhancement being observed at 0.25 wt% organoclay. Moreover, these PI hybrids also had low coefficients of thermal expansion (CTE).

• Macromolecular Research
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• v.14 no.6
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• pp.610-616
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• 2006

An azoinitiator linked to an epoxy oligomer, which could easily diffuse into the organoclay gallery and swell it, was used as an initiator to enhance the delamination of an organoclay, Cloisite 25A, in a matrix of styrenic polymers, poly(styrene-co-acrylonitrile) and polystyrene, during the preparation of a nanocomposite via an in-situ polymerization method. X-ray diffraction results and transmission electron microscopic observation of the morphology showed that the epoxy segment enhanced not only the delamination but also the extrication of ammonium cations from the organoclay gallery into the polymer matrix. The latter phenomenon induced the structural change of the alkyl group of ammonium cations in the gallery from a bilayer to monolayer structure, and also decreased the glass-rubber transition temperature as measured by a differential scanning calorimeter and dynamic mechanical analyzer.

• Polymer(Korea)
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• v.32 no.4
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• pp.347-352
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• 2008

High impact polystyrene (HIPS) nanocomposites with organically modified montmorillonite (organoclay) via in situ polymerization were synthesized, and the effects of organoclay incorporation on material properties were investigated. Organoclays having a reactive group, vinylbenzyltrimethyl clay (VBC) and octadecylvinylbenzyldimethyl clay (ODVC), were prepared by the ion-exchange reactions of sodium montmorillonite with vinylbenzyltrimethyl ammonium chloride (VBTMAC) and octadecylvinylbenzyldimethyl ammonium bromide (ODVBDAB), respectively, and a commercial organoclay, $Cloisite^{(R)}$ 10A(C10A), was used for comparison. It was confirmed that the X-ray diffraction (XRD) peak of the nanocomposites prepared by ODVC disappeared, which indicates the exfoliation of silicate layers. On the contrary, the XRD peak of the nanocomposites prepared by C10A shifted to lower angle, indicative of the intercalation of polymer chains into silicate layers. Rheological properties such as storage modulus and complex viscosity increased with increasing organoclay.

• Elastomers and Composites
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• v.42 no.3
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• pp.177-185
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• 2007

Polyamic acid(PAA)/organoclay nanocomposites containing phosphorous were prepared by solution blending of phosphorylated PAA(PPAA) and organically modified montmorillonite(O-MMT) as a type of layered clays. The nanocomposites were characterized by FT-IR, DSC, TGA, PCFC, SEM, and XRD. The preparation of nanocomposites was confirmed by FT-IR and XRD. SEM pictures showed that the organoclay was dispersed well in the PAA matrix relatively. XRD results indicated that the O-MMT layers were intercalated. The thermal stability and flame retardancy of O-MMT/PPAA nanocomposites were higher than those of pure PAA. PCFC results also showed that the heat release capacity and total heat release values of O-MMT 4 wt%/PPAA-0.2, 0.4, 0.6 composites were decreased with increasing the mole ratio of phosphorous. It was found that the nanocomposite films had the potential to be used as a fire safe material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.39-40
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• 2008

유기용매를 사용한 나노분산체의 경우, 유기용매를 완전하게 제거 것은 극히 어렵다. 이는 유기용매와 유기고분자와의 일부 반응되는 경우가 발생되어 전기적 물성에 영향을 줄 수 있다. 본 연구는 친환경적인 분산기법으로 물리적 분산기법을 제안하는 바이다. 양호한 분산체를 얻기위해 균질한 상태인 마이크로적 분산기법과 층상실리케이트인 층간사이에 고분자인 에폭시분자가 삽입되어 박리가 양호하게 일어나게 하는 나노적인 분산기법을 통시에 적용하여 분산이 훌륭하게 일어나는 경우를 개발하였다. 마이크로적인 분산을 위해 사용된 Homogenizer의 적용속도와 적용시간에서 원형인 Organoclay_10A Powder의 d-spacing이 262%, 263%로 증가되는 결과를 얻었다. 또한 DSC의 유리천이온도 분석에서도 적용시간의 증가에 따라 유리천이온도가 되어 원형에폭시수지에 비하여 $9^{\circ}C$상승된 결과를 얻을 수 있었다.

• Elastomers and Composites
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• v.39 no.1
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• pp.51-60
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• 2004

The cure, viscoelastic and mechanical characteristics of organoclay filled NR/BR blends were studied and compared with the properties of carbon black and silica filled NR/BR blends. The nanocomposites with extensive exfoliation state can be fabricated by a solution mixing method. In the composites, the amount of filler content was fixed to 10 phr. Degree of intercalation and exfoliation was characterized by X-ray diffraction (XRD). XRD results indicated exfoliation of the silicate layers into the rubber matrix. While the degree or intercalation and exfoliation is lowered by the conventional mixing method, extensive exfoliation can be obtained by the solution mixing method. It was found that the clay filled NR/BR compound showed better viscoelastic (tan ${\delta}$) and mechanical properties than the carbon black or silica filled NR/BR compounds.