• Journal of Pharmaceutical Investigation
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• 제41권3호
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• pp.179-184
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• 2011

This study aimed to confirm the effect of molecular weight (MW) in solid dispersion of carvedilol with poly-vinylpyrrolidone (PVP) of various MW. Solid dispersion of carvedilol with PVP was prepared by spray-drying method. Scanning electron microscopy (SEM) was used to analyze the surface of solid dispersion samples. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to analyze the crystalline of solid dispersion. Fourier transform infrared spectroscopy (FT-IR) was used to analyze the change of chemical structure characteristic of solid dispersion. DSC and XRD show that drug crystalline was changed. FT-IR revealed that chemical structure of solid dispersion comparing the chemical structure of drug was changed. The dissolution studies of solid dispersion presented at simulated gastric juice (pH 1.2). The dissolution rate of solid dispersion was dramatically enhanced than pure drug and the MW of PVP has an effect on the release property of carvedilol in solid dispersion. In conclusion, the present study has confirmed the effect of MW of PVP on release property of solid dispersion formulation of carvedilol with PVP.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.55-58
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• 2003

This paper presents a study on the permittivities of the carbon nano fiber/epoxy composite at microwave frequency. The permittivities of composite materials depend on the concentrations and the dispersion methods of the carbon nano fibers. The experimental values of complex permittivities were obtained for the specimen made by dispersion method using ethyl alcohol as dispersion media and compared with the results by simple mechanical mixing method.

• 한국세라믹학회지
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• 제49권5호
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• pp.417-422
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• 2012

Copper nano particles have been considered as the materials for conductive ink due to its good thermal, electrical conductivity and low cost. However, copper nanoparticles oxidize easily, decreasing dispersion stability and electrical conductivity. Therefore, it is important to develop a method to minimize oxidation of copper nano particles to improve its dispersion stability property in copper nano ink. In this study, copper nano particles were coated with 1-Octanethiol VSAM(Vaporized Self Assembled Multilayers) to prevent oxidation and coated copper powders were dispersed in conductive ink successfully by studying its relationship of different chain length of solvents to 1-Octanethiol coating layer to fabricate nano ink. Various alcohol solvents, such as 1-Hexanol, 1-Octanol, and 1-Decanol were used. The coating layer was observed using FESEM and TEM. Furthermore, dispersion of copper nano particles in nano inks, was characterized using Turbiscan analyzer, viscometer, and contact angle measurement tool.

• 한국세라믹학회지
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• 제48권6호
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• pp.510-515
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• 2011

In this study, as a material used to replace silica fumes for high strength concrete, nano-silica compound with organic functional group for dispersion and with inorganic silica group that can cause a pozzolan reaction is synthesized, These nano silica compound is divided into IC, which is nano size $SiO_2$ with irregularly combined hydroxyl group and carboxyl group, and RC, which is nano size $SiO_2$ with regularly combined hydroxyl group and carboxyl group. The effects of these nano silica compound on the hydration of cement are reviewed. As a result, all of synthesized nano-silica compounds have excellent dispersion on the cement flow, we think that dispersion property is the effect of air entraining by synthesized nano-silica compounds. The result of the microstructure observation showed that the particle size of the synthesized nano-silica is smaller than silica fume and spread evenly among the cement particles. In initial The phenomenon of strength decreasing occurred due to delayed hydration reaction by the synthesized nano-silica with carboxyl(-COOH) and hydroxyl(-OH) functional group.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.413-414
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• 2006

The effects of several experimental parameters on the formation of stable Ni nanoparticles dispersion were investigated. The suspensions of Ni nanoparticles were produced in organic solvents using Hypermer KD-2 as a dispersant. The transmission profiles, particle size distribution, zeta potential, and visual inspection results were used to discuss the stability of the dispersion. The optimal conditions for the formation of stable dispersion are evaluated.

• Composites Research
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• 제26권6호
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• pp.337-342
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• 2013

나노입자를 이용하여 강화 효과를 높이기 위해서는 고분자 기지 내부의 균일한 분산 상태를 확보하여야 한다. 또한 균일분산 조건 확보 후 균일 분산상태를 증명할 평가자료가 필요하다. 본 연구는 에폭시 수지와 SiC 나노입자를 혼합한 SiC/에폭시 복합 수지를 제조할 경우 커패시턴스 측정법을 이용한 강화재 분산도 예측 연구를 진행하였다. 커패시턴스는 전기용량을 의미하며 측정 재료의 내부 전하량과 비례한다. 기존 에폭시 수지에 비해 나노 SiC 입자를 함유할 경우 전하량이 증가되는 이론을 바탕으로 구간별 커패시턴스 측정에 따른 분산도 평가를 진행하고, 커패시턴스 분산도 예측방법에 대한 타당성을 FE-SEM과 물리적 강도 증가 방법으로 평가하였다. 소니케이션 분산 방법과 교반기 분산 방법을 이용하여 분산 방법에 따른 SiC 나노입자 분산도 상태를 비교하였다. 인장강도와 커패시턴스 간의 상관관계가 있었으며, 파단면에 대한 비교를 할 때 분산성 향상에 대한 차이를 확인할 수 있었다.

• 한국분말재료학회지
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• 제17권5호
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• pp.390-398
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• 2010

Aqueous gold nanoparticle dispersion was synthesized by chemical reduction method using diethanolamine as reducing agent and polyethyleneimine as dispersion stabilizer. The synthesis conditions for the stable dispersion of the gold nanoparticle suspension were determined by changing the amount of the reducing agent and dispersant during the wet chemical synthesis procedures. The face centered cubic lattice structure of the gold nanoparticles was confirmed by using X-ray diffraction and the morphologies of the nanoparticles were observed by transmission electron microscope. The synthesized gold nanoparticle dispersion was concentrated by evaporating the dispersion medium at room temperature followed by the addition of ethyleneglycol as humectant for the increase of the elastic properties to obtain gold nanoparticle inks for direct ink writing process. The line patterns were obtained with the gold nanoparticle inks during the writing procedures and the morphologies of the fine patterns were observed by scanning electron microscope.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.251-251
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• 2009

The generation of energy and the cooling of system using thermoelectric semiconductor material have been in spotlight. Thermoelectric effect increases with the decrease of the thermal conductivity. In the thermoelectric devices, thermal conductivity is related to phonon scattering. Therefore, few studies have been conducted in the thermoelectric materials dispersed nano oxide particle for increasing the phonon scattering. However, core-shell structure which nano particle disperses in solvents and then which thermoelectric materials coated on the nano oxide particles has not been reported. In this study, we selected commercial nano powder such as $Al_2O_3$. This nano particle was about 20nm and was crushed aggregate by mechanical treatment. We have developed the effect of the dispersant and the solvent. The properties of particles were evaluated by SEM, TEM, particle size analysis, and BET. Dispersion and dispersion stability were evaluated by electronic microscope and turbidity.

• 폴리머
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• 제35권1호
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• pp.60-65
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• 2011

고분자 나노복합재의 성능을 극대화 하기 위해서는 나노업자 분산도의 향상과 더불어 분산상태가 물성 변화에 미치는 영향을 정확히 이해하는 것이 매우 중요하다. 본 연구에서는 탄소나노튜브 첨가 고분자 복합재의 분산상태를 정량적으로 평가할 수 있는 방법을 제시하고자 하였다. 자외선-가시광선 분광광도법을 이용하여 탄소나노튜브의 분산상태에 따른 투과도를 측정하였으며, 동일 농도에서 분산상태가 향상됨에 띠라 투과도가 감소하는 것을 확인하였다. 이러한 결과를 바탕으로 기존의 Beer-Lambert 투과도 법칙에 분산상태의 변화를 포함할 수 있는 새로운 분산도 평가인자인 유효 농도 인자를 제시하였다. 이를 통해 탄소나노튜브의 분산상태의 변화와 함께 다양한 탄소나노튜브의 농도 및 시편 두께에 따른 투과도 결과를 분석함으로써 제시한 분산도 평가방법과 유효 농도 인자의 유효성을 확인하였다.

• 폴리머
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• 제39권1호
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• pp.33-39
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• 2015

올메사탄은 BCS 2단계에 해당하는 약물로 물에 잘 녹지 않는 난용성 약물이다. 이런 약물이 낮은 생체이용률과 제형을 설계하는 과정에서 어려움을 주는 원인이 된다. 본 연구에서는 올메사탄을 분무건조법 및 회전용매증 발법을 이용해 고체분산체를 제조하여 제법에 따른 난용성약물의 용출률을 확인하였다. 수용성 고분자로 PVP를 사용하여 약물과 고분자의 비율별로 고체분산체를 제조하였다. SEM을 이용하여 고체분산체의 형태학적인 특성을 분석하였고, 고체분산체의 결정학적 성질은 XRD와 DSC를 통하여 확인하였다. 또한 FTIR을 통해 화학적인 변화를 확인하고, 생체 외 용출거동 실험을 통하여 변화된 용출률을 확인하였다. 제조된 고체분산체는 pH 1.2에서 용출을 확인하였으며, 올메텍과 용출률을 비교하였으며, 분무건조를 통해 약물의 용출률을 향상시킬 수 있다는 것을 확인할 수 있다.