• Fibers and Polymers
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• 제6권4호
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• pp.289-296
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• 2005

Biodegradable nanocomposites were prepared by mixing a polymer resin and layered silicates by the melt intercalation method. Internal structure of the nanocomposite was characterized by using the small angle X-ray scattering (SAXS) and transmission electron microscope (TEM). Nanocomposites having exfoliated and intercalated structures were obtained by employing two different organically modified nanoclays. Rheological properties in shear and extensional flows and biodegradability of nanocomposites were measured. In shear flow, shear thinning behavior and increased storage modulus were observed as the clay loading increased. In extensional flow, strain hardening behavior was observed in well dispersed system. Nanocomposites with the exfoliated structure had better biodegradability than nanocomposites with the intercalated structure or pure polymer.

• 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.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2001년도 가을 학술발표회 논문집
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• pp.440-443
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• 2001

Polymer/layered silicate nanocomposites have recently received considerable attention from both academia and industry as an effective way to overcome the shortcomings of conventional polymer. When the silicate layers are exfoliated and randomly distributed in polymer matrix, the nanocomposites exhibit improved mechanical, thermal and barrier properties. (omitted)

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3411-3420
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• 2014

Deficiencies in wear and frost resistance as well as mechanical strength constitute the main causes of equipment failure under the harsh climatic conditions of the Earth's polar regions. To improve the properties of the materials used in this equipment, nanoparticle composites have been prepared from clays such as kaolinite, hectorite, and montmorillonite in combination with polytetrafluoroethylene (PTFE) or ultrahigh molecular weight polyethylene (UHMWPE). A number of techniques have been proposed to disperse silicate particles in PTFE or UHMWPE polymer matrices, and several successful processes have even been widely applied. Polymer nanocomposites that exhibit enhanced mechanical and thermal properties are promising materials for replacing metals and glass in the equipment intended for Arctic use. In this article, we will review PTFE- and UHMWPE-based layered silicate nanocomposites.

• 한국결정성장학회지
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• 제29권1호
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• pp.19-23
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• 2019

The PMMA (polymethyl methacrylate)/clay nanocomposites were synthesized by in situ radical polymerizations with different clay contents (3 and 7 wt%) using microwave heating. The nanostructure, optical, and thermal properties of the synthesized PMMA/clay nanocomposites were measured by XRD, TEM, AFM, UV-vis, and TGA. It was found that the intercalated- or exfoliated structure of PMMA/clay nanocomposites was strongly dependent on the content of clay. Thus, the imposition of microwave-assisted polymerization facilitated a delamination process of layered silicates to achieve exfoliation state of interlayer distance. The PMMA/3 wt% C10A nanocomposite with well-dispersed and exfoliated clay nano-layers showed the good optical transparency similar to pure PMMA in this study. The thermal decomposition rates of the PMMA/clay nanocomposites become to be lower compared to that of the pure PMMA, indicating the intercalated- or exfoliated inorganic silicate has high thermal stability. A possible reason is that the thermally segmental motion of PMMA polymer into inorganic silicate interlayer spacing has increased the thermal stability of the PMMA/clay nanocomposites.

• 폴리머
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• 제27권4호
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• pp.377-384
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• 2003

직접 중합법으로 내충격성 폴리스티렌과 유기화 층상 실리케이트의 나노복합체를 합성하여 점토 첨가에 의한 고무 입자 크기 및 물성의 영향을 조사하였다. 사용한 유기화 점토 중에서는 벤젠기를 지닌 몬모릴로나이트가 폴리스티렌에 우수한 분산 효과를 나타내었다 유기화 점토를 첨가한 경우 X선 회절 분석에서 층간삽입된 피이크를 관찰할 수 있었으나, 고무의 농도가 증가할수록 낮은 각도쪽으로 이동하는 것으로 보아 유기화 점토는 고무에 더 좋은 분산성을 보이는 것으로 파악된다. 분산상인 고무 입자는 점토를 첨가할수록 평균 입자경이 커지며 넓은 입도 분포를 나타내었는데, 이는 점토 첨가에 의해 폴리스티렌 상에 대한 고무 상의 점도비가 더욱 증가하여 평균 입자가 커졌으며 분산계가 불안정해져 넓은 입도 분포를 갖는 것으로 추정된다. 열중량 분석의 결과 나노복합체는 향상된 열적 물성을 보여주었고, 유변 물성을 측정한 결과 점토가 첨가됨에 따라 재료의 복소 점도 및 저장 탄성률은 향상되었다.

• Macromolecular Research
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• 제17권10호
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• pp.776-784
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• 2009

N,N-dimethyldodecylamine (tertiary amine)-modified MMT (DDA-MMT) was prepared as an organically modified layered silicate (OLS), after which styrene-butadiene rubber (SBR) nanocomposites reinforced with the OLS were manufactured via the latex method. The layer distance of the OLS and the morphology of the nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). By increasing the amount of N,N-dimethyldodecylamine (DDA) up to 2.5 g, the maximum values of torque, tensile strength and wear resistance of the SBR nanocomposites were increased due to the increased dispersion of the silicate layers in the rubber matrix and the increased crosslinking of the SBR nanocomposites by DDA itself. When SBR nanocomposites were manufactured by using the ternary filler system (carbon black/silica/OLS) to improve their dynamic properties as a tire tread compound, the tan $\delta$(at $0^{\circ}C$ and $60^{\circ}C$) property of the compounds was improved by using metal stearates instead of stearic acid. The mechanical properties and wear resistance were increased by direct substitution of calcium stearate for stearic acid because the filler-rubber interaction was increased by the strong ionic effect between the calcium cation and silicates with anionic surface. However, as the amount of calcium stearate was further increased above 0.5 phr, the mechanical properties and wear resistance were degraded due to the lubrication effect of the excessive amount of calcium stearate. Consequently, the SBR/organoclay nanocomposites that used carbon black, silica, and organoclay as their ternary filler system showed excellent dynamic properties, mechanical properties and wear resistance as a tire tread compound for passenger cars when 0.5 phr of calcium stearate was substituted for the conventionally used stearic acid.

• 멤브레인
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• 제16권2호
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• pp.85-105
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• 2006

Poly(lactic acid) (PLA)는 옥수수나 설탕수와 같은 재생자원에서 추출된 환경친화적 재료로서 이에 대한 관심이 증대되고 있다. PLA는 선형 지방족 열가소성 polyester로써, lactide와 lactic acid 모노머의 고리 개환 중합법에 의해 제조된다. PLA는 높은 기계적 능력과 열가소성, 직물능력과 생체적합성을 가지고 있어서, 다양한 end-use application에 유망한 고분자이다. 그러나 열점도, 충격인자, 열변형온도(HDT), gas barrier 특성 등과 같은 다른 몇몇 특성들은 충분히 만족시키지 못한다. 최근에, clay의 실리케이트 층에 용액이나 용융법을 이용한 고분자의 삽입은 순수 고분자나 전형적인 복합체에 비해 기계적, 열적, 광학적, 그리고 물리화학적 특성에서 훌륭한 증진을 꾀할 수 있는 나노복합재료를 제조하기 위한 가장 좋은 기술이다. 층상실리케이트는 자연적으로 풍부하고, 경제적이며, 환경친화적 물질이다. 본 논문에서는 생분해성 고분자를 기초로 한 재생자원 poly(lactic acid)의 여러 합성과 특징, 그리고 그것의 층상실리케이트 나노복합체 분리막으로의 응용과 특징을 알아보고자 하였다.

• 폴리머
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• 제29권5호
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• pp.451-456
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• 2005

폴리이미드 나노복합재의 나노충전제를 설계함에 있어 가장 중요한 요소는 나노충전제의 내열성 및 매트릭스 고분자인 폴리이미드와의 상용성이다. 본 연구에서는 두 가지의 요소를 만족시키기 위하여, 알킬사슬을 가지며 말단기가 아민인 올리고 아믹산을 설계하였고 이를 이용하여 층상 실리케이트의 표면을 개질하는 연구를 수행하였다. 분자량이 2000g/mol로 조절되고 말단기가 아민인 올리고 아믹산을 제조하였고 이후 이온 교환반응을 통하여 고내열 친유기 층상 무기소재를 제조하였다. 본 연구에서 제조된 고내열 친유기 층상 무기물은 TGA로 분석한 결과 초기분해 온도가 $280^{\circ}C$ 이상이었으며, XRD로 분석한 결과, 개질하지 않은 층상 무기물에 비해 최소 $4{\AA}$ 이상의 층간거리 증가를 나타내었다. 또한 이들의 나노복합필름의 경우 X선 실험을 통해 친유기성 층상 무기물이 고르게 분산되어 있음을 알았으며, 친유기성 층상 무기물의 함량이 증가함에 따라 CTE 역시 최대 $26\%$ 감소함을 TMA실험 결과를 통해 확인하였다.

• Elastomers and Composites
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• 제44권1호
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• pp.22-33
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• 2009

최근에 나노충전제를 낮은 부피 분율로 보강한 엘라스토머-나노복합체는 흥미 있는 물성 때문에 관심을 크게 불러 일으켰다. 특히 층화 규산염 클레이(clay), 카본 나노튜브(carbon nanotube), 나노섬유, 탄산칼슘, 금속 산화물 또는 실리카 나노입자 등과 같은 나노충전제를 탄성체에 혼입하면 기계적 물성, 내열성, 동적 기계적 물성, 화염지연성, 차단성 등이 크게 향상된다. 나노복합체의 물성은 크게 고분자 기질, 나노충전제의 성질과 이들의 혼입 방법에 좌우한다. 탄성체 기질 내에 나노충전제들의 균일한 분산은 원하는 물리적 특성과 기계적 특성을 얻기 위한 일반적 필수조건이다. 본 논문은 층화 규산염, 실리카(silica), 카본 나노튜브(carbon nanotube), 나노섬유와 여러 가지 다른 나노입자로 보강된 탄성체 나노복합체의 현재 개발 현황을 소개하였다.