• Transactions on Electrical and Electronic Materials
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• 제14권1호
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• pp.43-46
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• 2013

In order to develop electrical insulation material, organically modified layered silicate was incorporated into an epoxy matrix to prepare nanocomposite. Transmission electron microscopy (TEM) observation showed that organophillic clay was in an exfoliated state, while hydrophilic clay was not dispersed into nanolayers within the epoxy matrix. Epoxy/organophilic clay (2.8 wt%) nanocomposite was mixed and cured at $150^{\circ}C$ for 4.5 hr. I-V characteristics, volume resistance and dielectric properties for the cured nanocomposite were estimated. Current density increased with increasing temperature, and volume resistance decreased with increasing temperature, in neat epoxy and epoxy/organophilic clay (2.8 wt%) nanocomposite. As frequency increased, the dielectric loss value decreased in the two systems.

• Environmental Engineering Research
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• 제25권1호
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• pp.96-103
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• 2020

The aim of this study is to investigate the effect of five different combinations including: sand 70%, bentonite 30% (S₇₀B₃₀)- sand 80%, bentonite 20% (S₈₀B₂₀)- sand 80%, organophilic 20% (S₈₀M₂₀)- sand 60%, bentonite 20%, organophilic 20% (S₆₀B₃₀M₂₀) and sand 75% - bentonite 15% - organophilic 10% (S₇₅B₁₅M₁₀) on landfill linear structure in order to decrease phenol leaching. Hydraulic conductivity and adsorption behavior of the samples were investigated. The results demonstrated that the lowest hydraulic conductivity coefficient ($1.16{\times}10^{-11}{\frac{m}{s}}$) was obtained for S₇₀B₃₀. Furthermore, adding more than 20% of bentonite had no significant effect on reducing permeability. Moreover, Freundlich isotherm was introduced as the best model explaining adsorption behaviour due to its highest determination coefficient (0.945). The best samples for adsorption capacity of phenol and for both permeability and adsorption are S₈₀M₂₀ and S₆₀B₃₀M₂₀, respectively. Although the presence of bentonite was effective in reducing hydraulic conductivity, organic clay had no considerable impact on reducing permeability. Though, it's an exceptional role in adsorbing organic contaminants including phenol cannot be ignored. To meet all regulatory constraints, the optimal compound is made up of 10.2% of bentonite and 2.8% of organophilic clays with a minimized cost of 13.64 ($/ton).

• Macromolecular Research
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• 제8권2호
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• pp.95-101
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• 2000

Clay/poly(styrene-co-acrylonitrile) copolymer (SAN) hybrids have been prepared by simple meltmixing of two components, SAN and organophilic clays with a twin screw extruder. Effects of intercalant on the dispersibility of silicate layers in clay-dispersed nanocomposite were studied by using five different organophilic clays modified with the intercalants of different chemical structures and different fractions of intercalant. The dispersibility of 10-$\AA$-thick silicate layers of clay in the hybrid was investigated by using an X-ray diffractometer and a transmission electron microscope. It was found that if the fraction of intercalant in the organophilic clay becomes too high, SAN is difficult to intercalate into the inter-gallery of silicate layers in the hybrid prepared at 180$\^{C}$, and thus the hybrid shows poor dispersibility of silicate layers. The flexural modulus of the hybrid increases as the dispersibility of silicate layers in the hybrid increases.

• Fibers and Polymers
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• 제7권3호
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• pp.229-234
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• 2006

Poly(vinyl acetate) (PVAc)/poly(vinyl alcohol) (PVA)/montmorillonite (MMT) clay nanocomposite microspheres with a core/shell structure have been developed via a suspension polymerization approach. In order to prepare the PVAc/ MMT and PVAc/PVA/MMT nanocomposite microspheres, which are promising precursor of PVA/MMT nanocomposite microspheres, suspension polymerization of vinyl acetate with organophilic MMT and heterogeneous saponification were conducted. A quaternary ammonium salt, cetyltrimethylammonium bromide, was mixed with the MMT in the monomer phase prior to the suspension polymerization. The rate of conversion decreased with an increase in MMT concentration. The incorporation of MMT into the PVAc was verified by FT-IR spectroscopy. Organic vinyl acetate monomers were intercalated into the interlayer regions of organophilic clay hosts and followed by suspension polymerization. Partially saponified PVA/MMT nanocomposite microspheres with a core/shell structure were successfully prepared by heterogeneous saponification.

• 폴리머
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• 제24권2호
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• pp.228-236
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• 2000

알킬암모늄 브로마이드로부터 몬모릴로나이트 ($Na^{+}$-MMT)를 개질하여 2종류의 polyamic acid (BPDA-PPD, BTDA-ODA/MPD)를 삽입 후, 열이미드화 반응으로부터 폴리이미드/clay 나노복합재료를 제조하였다. 제조된 나노복합재료를 XRD로 관찰한 결과, 층간에 유기물질로 치환 되어 있는 MMT에 polyamic acid를 삽입하였을 경우 치환되어 있는 알킬 암모늄 양이온의 사슬 길이에 따라 MMT의 실리케이트의 층간거리가 증가하였다. 그리고 polyamic acid (PAA)가 삽입된 MMT를 승온하여 폴리이미드 복합재료를 제조한 결과 알킬 암모늄 양이온의 사슬길이와 PAA 종류에 상관없이 실리케이트의 층간 간격이 약 13.2 $\AA$이었으며, XRD와 TEM을 통하여 폴리이미드 매트릭스 내에 몬모릴로나이트의 실리케이트층이 규칙적으로 분산되어 있는 삽입형 (intercalated ) 나노복합재료임을 확인하였다. 그리고 복합재료의 열안정성을 TGA로 관찰 결과 폴리이미드 복합재료는 순수한 폴리이미드보다 열안정성이 약간 향상됨을 확인하였다. 그리고 동적 기계적 특성을 조사한 결과 나노복합재료가 폴리이미드보다 1.2~l.8배 저장탄성율이 증가됨을 확인하였다.

• Macromolecular Research
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• 제16권1호
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• pp.6-14
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• 2008

Polypropylene (PP)-layered silicate nanocomposites were developed using a new processing method involving a supercritical carbon dioxide ($scCO_2$)-assisted co-rotating twin-screw extrusion process. The nanocomposites were prepared through two step extrusion processes. In the first step, the PP/clay mixture was extruded with $CO_2$ injected into the barrel of the extruder and the resulting foamed extrudate was cooled and pelletized. In the second step, the foamed extrudate was extruded with venting to produce the final PP/clay nanocomposites without $CO_2$. In this study, organophilic-clay and polypropylene matrix were used. Maleic anhydride grafted polypropylene (PP-g-MA) was used as a compatibilizer. This study focused on the effect of $scCO_2$ on the dispersion characteristics of the clays into a PP matrix and the rheological properties of the layered silicate based PP nanocomposites. The dispersion properties of clays in the nanocomposites as well as the rheological properties of the nanocomposites were examined as a function of the PP-g-MA concentration. The degree of dispersion of the clays in the nanocomposites was analyzed by X-ray diffraction and transmission electron microscope. Various rheological properties of the nanocomposites were measured using a rotational rheometer. In the experimental results, the $scCO_2$ assisted continuous manufacturing extrusion system was used to successfully produce the organophilic-clay filled PP nanocomposites. It was found that $scCO_2$ had a measurable effect on the clay dispersion in the polymer matrix and the melt intercalation of a polymer into clay layers.

• Macromolecular Research
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• 제8권4호
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• pp.186-191
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• 2000

Clay-dispersed nanocomposites have been prepared by simple melt-mixing of three components, i.e. poly (styrene co-acrylonitrile) copolymer (SAN), poly ($\xi$-caprolactone ) (PCL), and an organophilic clay(Cloisite(R) 30A). In the present study, poly($\xi$-caprolactone) was added in the mixtures in order to facilitate the intercalation of SAN into the gallery of silicate layers, and the molecular weight effects of PCL on the dispersion of silicate layers were compared by changing the amount of added PCL. The degree of dispersion of 10-$\AA$-thick silicate layers of clay in the nanocomposites was investigated by using an X-ray diffractometer and a transmission electron microscope. It was found that PCL added in the mixture facilitate the intercalation of SAN copolymers into the galleries of silicate layers modified with an organic intercalant, resulting in the better dispersion of clay. It was, also, observed that the processing temperature influences the degree of clay dispersion.

• Macromolecular Research
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• 제8권3호
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• pp.120-124
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• 2000

Clay-dispersed nanocomposites have been prepared by simple melt-mixing of two components, styrenic polymers with different content of functional groups and two different organophilic clays (Cloisite(R) 25A and Cloisite(R)30A) with a twin screw extruder. Dispersibility of 10-$\AA$-thick silicate layers of clay in the hybrid was investigated by using an X-ray diffraction method and a transmission electron microscope. It was found that if the interaction force between intercalant and matrix polymer is attractive, the matrix polymer intercalates more rapidly into the gallery of silicate layers. The faster intercalation of matrix polymer leads to the better dispersibility of silicate layers in the matrix polymer.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.359-359
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• 2006

This study deals with development of new bio-based polymeric materials from epoxidized soybean oil (ESO). The curing of ESO in the presence of organophilic montmorillonite produced an oil polymer-clay nanocomposite ("green nanocomposite") showing flexible property. A green nanocomposite (oil polymer-silica nanocomposite) coatings were synthesized by an acidcatalyzed curing of ESO with 3-glycidoxypropyltrimethoxysilane. The curing of ESO in the presence of a biodegradable plastic, poly(caprolactone), produced a composite with semi-IPN structure. The mechanical properties of the composite was much superior to those of polyESO. These new oil-based materials have large potential for applications in various fields.

• 접착 및 계면
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• 제8권4호
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• pp.1-7
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• 2007

친환경적인 수분산 폴리우레탄은 코팅, 접착제 등의 분야에서 급속하게 사용되어지고 있다. 하지만 수분산 폴리우레탄은 용제형 폴리우레탄에 비해 내화학성, 내열성, 기계적 물성 등이 떨어져 이를 개선하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 polyester polyol, 4,4-dicyclohexylmethane diisocyanate ($H_{12}MDI$), dimethylolpropionic acid (DMPA), ethylenediamine (EDA) 및 유기화된 나노클레이를 사용하여 폴리우레탄/클레이 나노복합체의 열적, 기계적 물성을 측정한 결과, 물성이 향상됨을 확인할 수 있었다. 또한, 나노클레이의 함량이 증가할수록 접착강도가 증가하였으며, 특히 3 wt% 함량일 때 최적의 접착력을 나타내었다.