• Carbon letters
• /
• 제12권4호
• /
• pp.194-206
• /
• 2011

Carbon nanomaterials in organic photovoltaic (OPV) cells have attracted a great deal of interest for the development of high-efficiency, flexible, and low-cost solar cells. Due to the complicated structure of OPV devices, the electrical properties and dispersion behavior of the carbon nanomaterials should be controlled carefully in order for them to be used as materials in OPV devices. In this paper, a fundamental theory of the electrical properties and dispersion behavior of carbon nanomaterials is reviewed. Based on this review, a state-of-the-art OPV device composed of carbon nanomaterials, along with issues related to such devices, are discussed.

• 한국분말재료학회지
• /
• 제14권2호
• /
• pp.123-126
• /
• 2007

In this work, the dispersion behavior of $Y_2O_3$ particles in binary aluminum (Al)-copper (Cu) cast alloy was investigated with respect to Cu contents of 20 (hypoeutertic), 33 (eutectic) and 40 (hypereutectic) wt.%. In cases of hypo and hypereutectic compositions, SEM images revealed that the primary Al and ${\theta}$ phases were grown up at the beginning, respectively, and thereafter the eutectic phase was solidified. In addition, it was found that some of $Y_2O_3$ particles can be dispersed into the primary Al phase, but none of them are is observed inside the primary 6 phase. This different dispersion behavior of $Y_2O_3$ particles is probably due to the difference in the val- ues of specific gravity between $Y_2O_3$ particles and primary phases. At eutectic composition, $Y_2O_3$ particles were well dispersed in the matrix since there is few primary phases acting as an impediment site for particle dispersion during solidification. Based on the experimental results, it is concluded that $Y_2O_3$ particles are mostly dispersed into the eutectic phase in binary Al-Cu alloy system.

• Advances in nano research
• /
• 제12권1호
• /
• pp.1-23
• /
• 2022

To date, nondestructive tests (NDT) applications and advances in detecting the dispersion and defections of the nano concrete (NC) materials fields are very limited. The current paper provides a review of the dispersion efficiency of nanomaterials in cement-based materials and how NDT can be efficiently used in detecting and visualizing the defections and dispersions of NC. The review identifies the characteristics of different types of nanoparticles used in NC. Nanomaterials influences on concrete characteristics and their dispersion degree are presented and discussed. The main aim of this article is to present and compare the common NDT that can be used for detecting and visualizing the defections and dispersions of different kinds of nanomaterials utilized in NC. The different microscopy and X-ray methods are explicitly reviewed and compared. Based on the collected data, it can be concluded that the fully detecting and visualizing of NC defections and dispersions have not been fully discovered and that needs further investigations. So, the distinction of this paper lies in defining NDT that can be employed for detecting and/or visualizing NC defections and dispersions.

• 한국건설순환자원학회논문집
• /
• 제7권2호
• /
• pp.174-186
• /
• 2019

This paper reviews the development condition of nanomaterials used in concrete over years. The definitions of nanomaterial, nanotechnology, and nano-concrete are reviewed. The impacts of nanomaterials on cementitious material in the point of advantages and disadvantages are analyzed. Moreover, this paper analyzes and classifies the nanomaterials into the extra quality enhancement and modification to plain cementitious composite. Indeed, the outstanding properties of the embedded nanomaterials can be introduced to concrete such as the mechanical improvement, pore structure refinement, hydrate acceleration, and smartness modifying of self-cleaning, and/or self-sensing. Before the full potential of nanotechnology can be realized in concrete applications, various techniques have to be solved including proper dispersion, compatibility of the nanomaterials in cement, processing, manufacturing, safety, handling issues, scale-up, cost, the impact on the environment and human health.

• 한국광물학회지
• /
• 제28권2호
• /
• pp.95-108
• /
• 2015

광산배수가 지표에 노출되거나 주변 수계로 유입됨에 따라 나노크기의 철 교질물질이 형성되며, 이러한 철 교질물질은 심미적 오염을 발생시킬 뿐만 아니라 수생태계에도 악영향을 미친다. 이를 제어하기 위해 철 나노물질의 거동특성을 파악하는 것이 매우 중요한데, 아직까지 이에 대한 연구가 미흡하다. 본 연구는 영가철과 자철석을 이용하여 배경용액의 pH와 조성, 그리고 자연유기물에 따른 철 나노물질의 거동특성을 고찰하기 위해 수행되었다. 이를 위해 동적광산란분석기를 이용하여 철 나노물질의 입자크기와 표면 제타전위를 측정하였으며, DLVO (Derjaguin, Landau, Verwey, and Overbeek) 이론에 적용하여 응집 및 분산 등의 거동특성을 비교하였다. 철 나노물질은 영전하점 pH 근처에서는 입자간의 전기적 인력으로 인한 응집이 발생되며, 그보다 pH가 낮거나 높으면 전기적 반발력에 의해 분산이 잘되는 것을 확인하였다. 배경용액 내 양이온이 음이온보다 거동특성에 더 큰 영향을 끼치는 것을 확인하였으며, 특히 1가 양이온보다 2가 양이온이 입자표면간의 전기적인 인력 및 반발력에 더 큰 영향을 주는 것을 알 수 있었다. 수용상의 자연유기물은 철 나노물질을 코팅함으로써 표면을 음전하로 띠게 하여 분산이 잘 되게 하는 것을 확인하였다. 동일한 환경조건에서 자철석보다 영가철이 응집이 더 잘 되는 것으로 나타났는데, 이는 영가철의 낮은 안정성과 빠른 반응성으로 인해 철 산화물로 변질되기 때문인 것으로 판단된다.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.280-280
• /
• 2006

Na-bentonite (local clay mineral) and Na-montmorillonite were treated with quaternary alkylammonium cations. The effect of the molecular structure and functional groups of the surfactants on the organoclays was investigated by X-ray diffraction (XRD). For the preparation of nanocomposites, organoclays were melt-blended with polypropylene in a twin screw extruder and $Surlyn^{(R)$. ionomer was used as a reactive compatibilizer. The clay dispersions in the composites were investigated by X-ray diffraction (XRD). XRD spectra showed no peak at low angle indicated that the silicate clay layer has a nearly exfoliated dispersion in the polymer matrix. Thermal and mechanical properties of nanocomposites were higher than those of PP.

• Applied Microscopy
• /
• 제45권4호
• /
• pp.203-207
• /
• 2015

Sample preparation is very important for crystal structure analysis of novel nanostructured materials in electron microscopy. Generally, a grid dispersion method has been used as transmission electron microscope (TEM) sampling method of nano-powder samples. However, it is difficult to obtain the cross-sectional information for the tabular-structured materials. In order to solve this problem, we have attempted a new sample preparation method using focused ion beam. Base on this approach, it was possible to successfully obtain the electron diffraction patterns and high-resolution TEM images of the cross-section of tabular structure. Finally, we were able to obtain three-dimensional crystallographic information of novel zeolite nano-crystal of the tabular morphology by applying the new sample preparation technique.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2017년도 추계 학술논문 발표대회
• /
• pp.149-150
• /
• 2017

It is known that physical and chemical changes of cement hydrates cause problems in the volume stability of concrete. In order to overcome these problems, there is a growing interest in research on mixing technology of cement-based materials and nanomaterials. Among the nanomaterials, carbon nanotubes (CNTs) are attracting attention due to their excellent mechanical properties. The CNTs are made of cylindrically shaped graphene sheets. According to the number of sheets, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) are classified. Although the SWCNT has superior mechanical properties, the research using MWCNT is vigorous due to the difficulty of marketability and manufacturing, but the research using SWCNT is insufficient. In this study, we investigate the effect of SWCNT on the formation of hydrate of cement paste by observing the microstructure of broken cement paste after measuring the flexural strength of cement paste with SWCNT dispersion.

• 폴리머
• /
• 제29권3호
• /
• pp.271-276
• /
• 2005

폴리프로릴렌(Polypropylene, PP)과 몬모릴로나이트(Montmorillonite, MMT)의 나노복합체를 용융 혼합 방법으로 제조하였다. MMT는 dimethyl hydrogenated tallow 2-eaylhexyl ammonium으로 개질된 MMT(Cloisite 15A)를 사용하였다. 상용 화제로는 telechelic OH 그룹을 갖는 폴리올레핀 올리고머를 사용하였다. X선 회절 패턴의 분석과 TEM 사진을 통해 MMT의 박리 정도를 조사하였다. 상용화제의 함량이 25 phr일 경우 MMT의 박리가 잘 일어나는 것을 알 수 있었다. 열중량분석법(TGA)으로 측정한 열안정성은 MMT의 함량이 5 phr까지 증가할수록 우수해짐을 확인하였다. 복합전단 점도와 저장 탄성률은 상용화제의 함량이 감소할수록, MMT의 함량이 증가할수록 우수해지는 것으로 나타났다.

• Toxicological Research
• /
• 제26권4호
• /
• pp.253-259
• /
• 2010

We are consistently being exposed to nanomaterials in direct and/or indirect route as they are used in almost all the sectors in our life. Nations across the worlds are now trying to put global regulation policy on nanomaterials. Sometimes, they are reported to be more toxic than the corresponding ion and micromaterials. Therefore, safety research of nanoparticles has huge implications on a national economics. In this study, we evaluated and analyzed the research trend of ecotoxicity of nanoparticles in soil environment. Test species include terrestrial plants, earthworms, and soil nematode. Soil enzyme activities were also discussed. We found that the results of nanotoxicity studies were affected by many factors such as physicochemical properties, size, dispersion method and test medium of nanoparticle, which should be considered when conducting toxicity researches. In particular, more researches on the effect of physicochemical properties and fate of nanoparticles on toxicity effect should be conducted consistently.