• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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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.

• Macromolecular Research
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• 제14권3호
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• pp.318-323
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• 2006

We investigated the rheological behaviors and orientation of three different types of layered silicate composite systems under external flow: microcomposite, intercalated and exfoliated nanocomposites. Rheological measurements under shear and uniaxial extensional flows, two-dimensional, small-angle X-ray scattering and transmission electron microscopy were conducted to investigate the properties, as well as nano- and micro-structural changes, of polymer/layered silicate nanocomposites. The preferred orientation of the silicate layers to the flow direction was observed under uniaxial extensional flow for both intercalated and exfoliated systems, while the strain hardening behavior was observed only in the exfoliated systems. The degree of compatibility between the polymer matrix and clay determined the microstructure of polymer/clay composites, strain hardening behavior and spatial orientation of the clays under extensional flow.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 봄 학술발표회 논문집
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• pp.195-197
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• 2003

Polymer layered silicate nanocomposite has become an important area of polymer research becaues of its predominant properties in mechanical and thermal properties. Polymer layered silicate nanocomposites show outstanding improvements in tensile strength and modulus, heat distortion temperature, gas and liquid permeability, solvent resistance, and so on. But These improved properties are realized only when silicate particles are well dispersed in polymer matrix. (omitted)

• 한국안전학회지
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• 제21권1호
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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.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.59-62
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• 2003

Nanocomposites are composite materials consisting of polymer matrix and layered silicate that are interacted in nanometer scale. Layered silicate based polymer nanocomposites have attracted considerable attention because of their excellent properties. Nanocomposites usually exhibit improved performance properties compared with conventional composites due to their unique phase morphology and improved interfacial properties. (omitted)

• Macromolecular Research
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• 제17권2호
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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.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.18-18
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• 2003

Natural clays are composed of oxide layers whose thickness is about 1nm and cations existing between the layers. A number of these layers makes primary particles with a height of about 8∼10nm and these primary particles make aggregates with a size of about 0.1∼10$\mu\textrm{m}$. When layered silicate was made to be organophilic, by exchanging the interlayer cations with organic cationic molecules, the matrix polymer can penetrate between the layers to give a nanocomposite, where 1nm-scal clay layers exist separately in a continuous polymer matrix. These nanostructured hybrid organic-inorganic composites have attracted the great interest of researchers over the last 10 years. They exhibit improved performance properties compared with conventional composites, because their unique phase morphology by layer intercalation or exfoliation maximizes interfacial contact between the organic and inorganic phases and enhances interfacial properties. Since the advent of nylon-6/montmorillonite nanocomposite developed by Toyota Motor Co., the studies on layered silicate-polymer nanocomposites have been successfully extended to other polymer systems. They greatly improved the thermal, mechanical, barrier, and even the flame-retardant properties of the polymers.

• 폴리머
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• 제31권4호
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• pp.297-301
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• 2007

본 연구에서는 poly(ethylene oxide) (PEO), 가소제인 ethylene carbonate(EC), 리튬염인 $LiClO_4$ 그리고 $Na^+-MMT/organic$ MMT를 이용하여 고분자/층상 실리카 나노복합재료(polymer/(layered silicate) nanocomposites, PLSN)를 제조하였으며, organic MMT의 첨가에 따른 고분자 매트릭스에 미치는 영향을 이온전도도를 통하여 관찰하였다. 리튬전지의 전해질로서의 응용을 위해, $Na^+$를 양이온으로 갖는 순수한 MMT($Na^+-MMT$)를 유기화한 nanoclay(organic-MMT)를 사용하였다. 그 결과, 층간 거리 및 소수성이 증가하며 이와 같은 특성은 PEO와의 나노복합체를 형성할 때 MMT의 박리 거동에 영향을 미치는 것을 확인할 수 있었다. 또한, 이온전도도에서는 organic MMT가 순수한 $Na^+-MMT$보다 우수함을 나타내었으며, methyl dihydrogenated tallow ammonium으로 개질된 MMT(MMT-2OA)를 첨가하였을 때 가장 높은 이온전도도를 보였다.

• 멤브레인
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• 제15권4호
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• pp.255-271
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• 2005

고분자/층상실리케이트 나노복합체(polymer/layeres silicate nanocomposite, PLSNs) 필름은 보통 내부층을 나트륨과 같은 양이온을 이용한 이온교환을 통해 유기화된 clay로 만든 재료의 새로운 형태이다. 이것은 중합법, 용액법, 그리고 용융법과 같은 다양한 방법으로 제조할 수 있으며, 열경화성, 열가소성이나 탄성고분자와 같은 넓은 범위의 고분자를 기질로 사용할 수 있다. PLSNs 필름은 고분자 사슬이 일정한 간격으로 쌓여있는 실리케이트에 삽입하여 간격을 넓히는 삽입형과 각각의 실리케이트 층이 고분자 기질에 불균일하게 분산되어 형성하는 박리형 두 가지 형태의 구조를 얻을 수 있다. 이러한 새로운 분야의 재료는 보통 5 wt$\%$ 이하의 소량의 clay 함유만으로도 향상된 기계적, 열적 특성을 얻을 수 있다. 그리고 clay의 함유량이 증가할수록 기체 투과경로인 tortuosity가 증가하여 기체 투과도가 감소한다.

• Elastomers and Composites
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• 제46권2호
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• pp.112-117
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• 2011

고기능 포장재료를 포함한 고차단성 소재산업은 국민소득 증가 및 웰빙 문화와 함께 성장성이 높은 산업으로 성장할 것으로 예상된다. 따라서 최근 고차단성 소재로 기존의 소재와 비교하여 우수한 물성을 나타내는 고분자 나노복합재료에 대한 관심이 크게 증가하고 있다. 고분자 나노복합재료는 고분자 수지와 나노 크기의 충전제로 이루어진 소재를 의미하며, 이에 사용되는 무기 충전제는 층상 실리케이트, 탄소나노튜브, 금속 또는 무기물의 나노입자 등 다양한 물질들이 사용되고 있다. 현재 가장 활발히 적용되고 있는 입자는 다른 나노크기의 충전제와 달리 자연에 풍부하게 존재하며 경제적이고 나노 구조적인 특성을 잘 지닌 층상 실리케이트, 즉 점토(Clay)이다. Clay를 이용한 고분자 나노복합재료는 강도 향상, 난연성, 가스 차단성, 내마모성, 저수축화 등의 장점이 있어서 자동차 소재 및 포장재 등에 우선적으로 적용되고 있다. 따라서 본고에서는 가스차단 소재의 필요성과 더불어 관련 소재 및 기술에 대하여 중심으로 살펴보도록 하겠다.