• Advances in nano research
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• 제15권4호
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• pp.315-328
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• 2023

The main goal of the present study was to assess the effects of eggshell powder (ESP) and halloysite nanotubes (HNTs) on the mechanical properties of abaca fiber (AF)-reinforced natural composites. For this purpose, a limited number of indentation tests were first performed on the AF/polypropylene (PP) composites for different HNT and ESP loadings (0 wt.% ~ 6 wt.%), load amplitudes (150, 200, and 250 N), and two types of indenters (Vickers or conical). The Young's modulus, hardness and plasticity index of each specimen were calculated using the indentation test results and Oliver-Pharr method. The accuracy of the experimental results was confirmed by comparing the values of the Young's modulus obtained from the indentation test with the results of the conventional tensile test. Then, a feed-forward shallow artificial neural network (ANN) with high efficiency was trained based on the obtained experimental data. The trained ANN could properly predict the variations of the mentioned mechanical properties of AF/PP composites incorporated with different HNT and ESP loadings. Furthermore, the trained ANN demonstrated that HNTs increase the elastic modulus and hardness of the composite, while the incorporation of ESP reduces these properties. For instance, the Young's modulus of composites incorporated with 3 wt.% of ESP decreased by 30.7% compared with the pure composite, while increasing the weight fraction of ESP up to 6% decreased the Young's modulus by 34.8%. Moreover, the trained ANN indicated that HNTs have a more significant effect on reducing the plasticity index than ESP.

• 대한화학회지
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• 제61권4호
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• pp.179-184
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• 2017

본 논문은 $ZnO/SiO_2$를 나노 복합체(nano-compositions : NCs) 크기로 상온에서 화학적 방법으로 합성하였다. ZnO는 초음파 합성법으로 제조를 하였으며, $SiO_2$는 침전 방법을 이용하여 제조 하였다. $ZnO/SiO_2$의 구조적인 특성을 파악하기 위해 X-선회절 분석기(XRD), 주사전자현미경(FE-SEM), 푸리에 변환 적외선 스펙트럼(FT-IR)를 이용하여 $ZnO/SiO_2$가 형성되는 것을 확인 할 수 있었다. 광촉매적 특성을 판단하기 위해 $SiO_2$의 농도별로 제조된 $ZnO/SiO_2$를 Rhodamine-B 시약을 이용하여 광촉매 특성을 평가하였다. 그 결과 $SiO_2$의 농도가 증가할수록 광촉매 특성이 증가하는 것을 확인하였다. 그리고 $ZnO/SiO_2$를 가지고 항균성 실험을 진행하였다. 실험에 사용된 균(cell)은 대장균(E. coli)과 황색포도상구균(S. aureus)이다. 표면의 $SiO_2$층에 따른 항균 성실험을 진행한 결과 $SiO_2$ 층이 증가 할수록 항균 효과가 증가하는 것을 확인 할 수 있다.

• 한국환경농학회지
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• 제22권3호
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• pp.177-184
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• 2003

Although clay can sorb significant amounts of inorganic contaminants from soils and wastewater, the hydration of exchangeable cations in clay minerals makes it hydrophilic at the clay mineral surfaces and interlayers. Thus, natural clays are often ineffective in complexing and stabilizing toxic organic contaminants in soils and groundwater environment. But, substituting these hydrated cations with cationic surfactant such as QAC(Quaternary ammonium Compound) can change the natural clay from hydrophilic to hydropobic. Furthermore functionalized organoclay can act as a powerful dual function sorbent for both toxic metals and organic compounds. It also can be used as landfill clay liners, slurry walls, nano-composite materials, petroleum tank farms, waste treatment, and filter systems. To use this modified clay minerals effectively, it is required to understand the fundamental chemistry of organoclay, synthetic procedures, its engineering application, bioavailability of sorbed ion-clay complex, and potential risk of organoclay. In this review, we investigate the use, application and historical background of the organoclay in remediation technology. The state-of-the-art of organoclay research is also discussed. Finally, we suggest some future implications of organoclay in environmental research.

• Advances in nano research
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• 제1권2호
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• pp.71-82
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• 2013

A simple chemical precipitation technique is reported for the synthesis of a hybrid nanostructure of single-wall carbon nanotubes (SWCNT) and titania ($TiO_2$) nanocrystals of average size 5 nm, which may be useful as a prominent photocatalytic material with improved functionality. The synthesized hybrid structure has been characterized by transmission electron microscopy (HRTEM), energy-dispersive X-ray analysis (EDAX), powder X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. It is clearly revealed that nearly monodispersed titania nanocrystals (anatase phase) of average size 5 nm decorate the surfaces of SWCNT bundles. The UV-vis absorption study shows a blue shift of 16 nm in the absorbance peak position of the composite material compared to the unmodified SWCNTs. The photoluminescence study shows a violet-blue emission in the range of 325-500 nm with a peak emission at 400 nm. The low temperature electrical transport property of the synthesized nanomaterial has been studied between 77-300 K. The DC conductivity shows semiconductor-like characteristics with conductivity increasing sharply with temperature in the range of 175-300 K. Such nanocomposites may find wide applications as improved photocatalyst due to transfer of photo-ejected electrons from $TiO_2$ to SWCNT, thus reducing recombination, with the SWCNT scaffold providing a firm and better positioning of the catalytic material.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1993-1996
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• 2010

Silver nanoparticles has been prepared by the $\gamma$-irradiation and in situ reduction methods. Based on the Raman spectra, TEM images, X-ray Diffraction (XRD) patterns and UV-vis spectra, the in situ reduction method is more stable and the average size of the silver nanoparticles is also smaller than by the $\gamma$-irradiation reduction method. It is identified that the silver ions interacting with nonbonding electrons of oxygen atom in the carbonyl group of polyvinylpyrrolidone (PVP) by the in situ reduction method. It is also found advantages of the in situ reduction method including no additional reducing agents, without $\gamma$-irradiations treatment and the room temperature treatment suitability.

• 한국전기전자재료학회논문지
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• 제30권6호
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• pp.381-386
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• 2017

A railway track generates severe levels of vibrations. In order to reduce these vibrations and to provide structural stability, various rail pads, mats, etc., are used for vibration protection. In this study, a specially designed rail pad was developed to reduce vibration and to generate electric power simultaneously, that is, by using the vibrations generated by railway cars on the track. The newly developed rail pads were tested to evaluate the characteristics of electric power by investigating the generated voltage and the current levels and patterns. In addition, we proposed an optimal laminated structure and adhesive by comparing the voltage generated by each type of adhesive required for optimal adhesion of the rail pad and the piezoelectric device.

• 동력기계공학회지
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• 제21권1호
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• pp.11-17
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• 2017

This study is about the mechanical properties of epoxy composite reinforced with nano $TiO_2$ particle. Tensile strength, fracture toughness, vicker's hardness and Izod Impact test were carried out to investigate the effect of particle size and content of $TiO_2$ on the mechanical properties of $TiO_2$/epoxy composites. The results showed that the strength of the $TiO_2$/epoxy composites were higher than that of the pure epoxy. The best improvement of tensile strength was achieved in case of the particle size was 21 nanometer and the content was 3 weight percent. However, the Izod Impact value and the Vicker's hardness of $TiO_2$/epoxy composites showed no clear tendency.

• 한국해양공학회지
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• 제23권3호
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• pp.35-39
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• 2009

The main objective of this study was to investigate fiber reinforced composite materials (FRCM) with electromagnetic shielding characteristics using aluminum (Al) film and copper (Cu) meshes. This study investigated the electromagnetic interference (EMI) shielding effectiveness (SE) of fiber reinforced composites filled with Al film, Cu meshes, and nano carbon black as hybrid conductive fillers to provide the electromagnetic shielding property of the fiber reinforced composites. The coaxial transmission line method of ASTM D 4935-89 was used to measure the EMI shielding effectiveness of composites in the frequency range of 300 MHz to 1.5 GHz. The variations of SE of FRCM with Al film, fine Cu, and general Cu meshes are described. The results indicate that the FRCM having Al film exhibited up to 75 dB of SE at 1.5 GHz.

• 전기화학회지
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• 제8권4호
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• pp.177-180
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• 2005

유 무기 혼성 막의 계열은 티타니움 디옥사이드 나노파티클 함량의 체계적인 변화에 의해 조제된다. 유 무기 혼성 막의 수분함량, 메탄올 투과도와 전자 전도 특성은 무기 산화물의 함량의 기능에 따라 연구된다. 그 결과 망상구조의 무기 산화물은 전자 전도 특성과 수분함량의 감소를 보였다. 또한 무기 산화물의 함량이 증가할수록 메탄올 투과도도 감소함을 나타내었다. 형태학적인 관점에서 막은 폴리머 기반과 무기영역 사이에 균일하고 잘 점착됨을 보여준다. 혼성막의 특성은 나피온막과 비교 실험되었다.

• 한국재료학회지
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• 제11권11호
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• pp.986-990
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• 2001

An optimum route to fabricate the $A1_2O_3/Fe-Ni$ alloy nanocomposites with sound microstructure and enhanced mechanical properties as well as magnetism was investigated. To prepare homogeneous nanocomposite powders of Fe-Ni alloy and $Al_2O_3$, the solution-chemistry routes using $Al_2O_3 \; Ni(NO_3)_2{\cdot}6H_2O$ and $Fe(NO_3)_3{\cdot}9H_2O$ powders were applied. Microstructural observation of the powder mixture revealed that the Fe-Ni alloy particles of about 20 nm in size were homogeneously surrounded $A1_2O_3$, forming nanocomposite powder. The hot-pressed composite showed improved fracture toughness and magnetic response. These results suggest that the synergy materials with an improved mechanical properties and excellent functionality can be fabricated by controlled powder preparation and consolidation processing.