• Journal of Adhesion and Interface
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• v.4 no.4
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• pp.15-21
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• 2003

Polysulfone/organophilic layered silicate nanocomposites were prepared in the range of 0.25 to 9 wt% of organophilic-layered silicate by solution blend. Nano-hybridized films were cast from the blend solution. Exfoliation and intercalation of the polysulfone/organophiliclayered silicate nanocomposite films were confirmed by an X-ray diffractometer and a transmission electron microscope. Surface morphologies of polysulfone/organophilic layered silicate nanocomposite films were determined by a scanning electronic microscope and an atomic force microscope. When the organophilic layered silicate was added more than 1.5 wt%, the surface roughness (RMS) was rapidly increased because clusters of intercalated organophilic layered silicate particles existed on the polysulfone/organophilic-layered silicate film surface. Surface tension revealed an upward tendency over the contents of 1.5 wt% organophilic layered silicate in polysulfone/organophilic layered silicate nanocomposite. The change of surface morphology in polysulfone/organophilic layered silicate nanocomposite were affected by nano scale dispersed and intercalated organophilic layered silicate particles.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1694-1699
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• 2013

Frequency accelerated partial discharge resistance (PDR) aging of epoxy/layered silicate nanocomposite with 1.5wt % additions of layered silicate was investigated in comparison with that of epoxy without layered silicate in terms of PD(partial discharge) erosion depth. It was found that the change in the erosion depth is far smaller in specimens with layered silicate than those without layered silicate nano particles. Frequency acceleration can be done from 60Hz to 1000Hz. But the depth of erosion is less proportional to frequency. Acceleration factor is almost 2 times between 500Hz and 1000Hz, but it is much less than about 8.3 times between 60Hz and 500Hz. This superior PD resistance is caused by the presence of nanofillers, anano-effect due to closely packed nanofillers, and strong chemical bonds at layered silicate nanofillers /resin interfaces.

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.85-88
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• 2012

Studies on the effects of layered silicate content on the AC electrical treeing and breakdown behaviors of epoxy/layered silicate nanocomposites were carried out in needle-plate electrode geometry. Wide-angle X-ray diffraction (WAXD) analysis and transmission electron microscopy (TEM) observation showed that 1 wt% of the multilayered silicate was fully exfoliated into nano-sized monolayers in the epoxy matrix however, over 3 wt% of the silicate was in an intercalated state. When 1 wt% layered silicates were incorporated, an electrical tree was initiated in 439 min and propagated at a speed of 2.3 ${\mu}m$/min after applying 781.4 kV/mm, representing a decreased in starting initiation time by a factor of 11.0 and increase in propagation speed by a factor 8.2 in comparison with neat epoxy resin. These values were in great decline after the layered silicate content was increased to 3wt% which implies that the exfoliated silicate blocked the tree initiation and propagation processes effectively. However the effect was largely decreased in the intercalated state.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.137-140
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• 2005

Exfoliated nanocomposites of polypropylene/layered silicate were prepared by a melt compounding process using maleic anhydride modified polypropylene (PP-g-MAH) and organoclay. It was found that polypropylene/layered silicate nanocomposites exhibited remarkable reinforcement compared with the pure polypropylene or conventional composite filled with agglomerated organoclay. The polypropylene /layered silicate nanocomposites showed stronger and earlier shear thinning behaviors and outstanding strain hardening behavior than pure polypropylene or other conventional composites in shear and uniaxial elongational flows, respectively. We simulated rheological modeling for the pure polymer matrix and polypropylene/layered silicate nanocomposite in shear and elongational flows using K-BKZ integral constitutive equation. The two types of K-BKZequations have been examined to describe experimental results of shear and uniaxial elongational viscosities of pure polypropylene and polypropylene/layered silicate nanocomposite.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.79-85
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• 2006

Olefinic compatibilized blend(R-PP/R-PE)/layered silicate composites have been prepared by melt intercalation technique directed from $Na^{+}$ montmorillonite(MMT) or organophilic montmorillonites while using magnesium hydroxide as flame retardant. Morphology and flammability properties were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), thermogravimetry analysis(TGA), limiting oxygen index(LOI), UL94 test. It is found that the compatibilized blend/layered silicate(Cloisite 20A) nanocomposites have a mixed immiscible-intercalated structure and there is better intercalation when a compatibilizer is combined with the polymer and layered silicate to be melt blended. A very large increase in the LOI value was observed with hybrid filler addition and further enhancement in thermal stability and compatibility of blend was obtained for the compatibilized blend containing small amount of layered silicate.

• Transactions on Electrical and Electronic Materials
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• v.13 no.3
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• pp.149-152
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• 2012

The effects of amino silane coupling agent on the AC electrical treeing and breakdown behaviors in an epoxy/layered silicate (1 wt%) were examined in needle-plate electrode geometry. A layered silicate was exfoliated in an epoxy base resin by using our AC electric field apparatus. To measure the tree initiation and propagation and the breakdown rate, an alternating current (AC) of 10 kV (60 Hz) was applied to the specimen in needle-plate electrode arrangement with a $30^{\circ}C$ insulating oil bath. In the epoxy/amino silane system, the tree initiation time was 11.5 times higher and the breakdown time was 17.9 times higher than those of the neat epoxy resin. The tree initiation time in the epoxy/layered silicate (1 wt%) system with the amino silane was 2.0 times higher, and the breakdown time was 1.5 times higher than those of the epoxy/layered silicate (1 wt%) system.

• Macromolecular Research
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• v.17 no.2
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• pp.121-127
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• 2009

The cure kinetics of the epoxy-layered, silicate nanocomposites were studied by differential scanning calorimetry under isothermal and dynamic conditions. The materials used in this study were o-cresol novolac epoxy resin and phenol novolac hardener, with organically modified layered silicates. Various kinetic parameters, including the reaction order, activation energy, and kinetic rate constants, were investigated, and the storage stability of the epoxy-layered silicate nanocomposites was measured. To synthesize the epoxy-layered silicate nanocomposites, the phenolic hardener underwent pre-intercalation by layered silicate. From the cure kinetics analyses, the organically modified layered silicate decreased the activation energy during cure reaction in the epoxy/phenolic hardener system. In addition, the storage stability of the nanocomposite with the pre-intercalated phenolic hardener was significantly increased compared to that of the nanocomposite with direct mixing of epoxy, phenolic hardener, and layered silicate. This was due to the protective effect of the reaction between onium ions and epoxide groups.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1539-1542
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• 2007

We have synthesized novel organic passivation materials to protect organic thin film transistors (OTFTs) from $H_2O$ and $O_2$ using polyvinyl alcohol (PVA)/layered silicate (SWN) nano composite system. Up to 3 wt% of layered silicate to PVA, very homogeneous nanocomposite solution was prepared.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.188-193
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• 2008

Epoxy/Organically Modified Layered Silicate Nanocomposites were prepared by dispersing synthetic layered silicate modified with alkyl ammonium ions. In the dispersing process, the organically modified layered silicate were mixed in epoxy resin with shearing, and aggregation of the silicate were removed by centrifugal separation after mixing epoxy resin and silicates. Micrographs taken by transmission electron microscopy(TEM) indicate that the nanocomposites have a mixed morphology including both parallel silicate layers and exfoliated silicate layers area, As the thermal properties, the glass transition temperature of the nanocomposites was shifted to a higher temperature($+6^{\circ}C$)than pure epoxy. Furthermore, dispersion of OMLS will prevented relative permittivity from increasing at a high temperature above the glass transition temperature.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1561-1562
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• 2003