• Title/Summary/Keyword: nanocomposite materials

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Characterization of Poly(vinyl alcohol) Nanocomposite Films with Various Clays (다양한 점토를 이용한 폴리(비닐 알코올) 나노 복합체 필름의 특성 연구)

  • Ham, Miran;Kim, Jeong-Cheol;Chang, Jin-Hae
    • Polymer(Korea)
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    • v.37 no.2
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    • pp.225-231
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    • 2013
  • Poly(vinyl alcohol) (PVA) hybrid films containing 5 wt% pristine clay mineral were synthesized in the water solution. The various PVA hybrid films were synthesized from structurally different pristine clays: saponite (SPT), montmorillonite (MMT), hectorite (SWN), hydrophilic bentonite (PGV), and mica (Mica). The thermo-optical properties and morphologies of the PVA hybrid films were evaluated with various pristine clays. The nanostructure of the hybrid films was observed using transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. The addition of pristine clay was more effective with regard to improving the thermal properties and gas barrier characteristics, whereas the optical transparency of the PVA hybrid films deteriorated with pristine clay.

TiO2-SiO2 Nanocomposite Fibers Prepared by Electrospinning of Ti-PCS Mixed Solution (Ti-PCS 혼합용액의 전기방사를 통해 제조된 TiO2-SiO2 나노복합 섬유)

  • Shin, Dong-Geun;Jin, Eun-Ju;Lee, Yoon-Joo;Kwon, Woo-Tek;Kim, Younghee;Kim, Soo-Ryong;Riu, Doh-Hyung
    • Korean Chemical Engineering Research
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    • v.53 no.3
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    • pp.276-281
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    • 2015
  • Nanostructured TiO2SiO2 materials have widely been used as anti-reflecting coating, optical-chemical sensors and catalysts because of their superior optical and thermal properties as well as chemical durability. Web type SiO2 microfibers with nano-crystalline TiO2 were prepared by electrospinning of Ti-PCS mixed solution and oxidation controlled heat-treatment, rather simple than sol-gel process. Nano-crystalline anatase phase were formed for the heat-treatment up to 1200C and they were finely dispersed in the amorphous SiO2 matrix.

Preparation of Graphene/Waterborne Polyurethane Nanocomposite through in-situ Polymerization (In-situ 중합을 통한 그래핀/수분산 폴리우레탄 나노 복합체 제조)

  • Cha, Ji-Jung;Yim, Jin-Heong
    • Polymer(Korea)
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    • v.37 no.4
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    • pp.507-512
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    • 2013
  • A graphene/waterborne polyurethane (WPU) nano composite was prepared by in-situ polymerization of PU and graphene having isocyanate (iGO) group in order to improve physicochemical/electrical characteristics. The properties of the graphene/WPU nanocomposite can effectively be enhanced as compared pristine WPU; up to 57% of tensile strength and 102 fold of electrical conductivity with introduction of 2 wt% graphene. In addition, mechanical/electrical properties of the graphene/WPU nanocompsite were higher than those of graphene/WPU composite prepared by a simple physical blend method. It might attribute to homogeneous dispersion of iGO in the WPU matrix via covalent bonds and hydrogen bonds between WPU and iGO from the results of morphological analysis by scanning electron microscopy (SEM).

Study on the Photocatalytic Characteristic and Activity of Cu2O/TiO2 Heterojunction Prepared by Ultrasonification (초음파 합성 적용 Cu2O/TiO2 이종접합 소재의 특성 및 활성도 평가에 관한 연구)

  • Choi, Jeong-Hak;Lee, Joon Yeob
    • Journal of Environmental Science International
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    • v.29 no.12
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    • pp.1213-1222
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    • 2020
  • In the current study, a Cu2O/TiO2 photoinduced nanocomposite materials prepared by ultrasonification method was evaluated the photocatalytic oxidation efficiency of volatile organic compounds (BTEX) under visible-light irradiation. The results of XRD confirmed the successful preparation of photoinduced nanocomposite materials. However, diffraction peaks belonging to TiO2 were not confirmed for the Cu2O/TiO2. The possible reason for the absence of Cu2O peak is their low content and small particle size. The result of uv-vis spectra exhibited that the fabricated Cu2O/TiO2 can be activated under visible light irradiation. The FE-SEM/EDS and TEM showed the formation of synthesized nanocomposites and componential analysis in the undoped TiO2 and Cu2O/TiO2. The photocatalytic oxidation efficiencies of benzene, toluene, ethylbenzene, and o-xylene with Cu2O/TiO2 were higher than undoped TiO2. According to light sources, the average oxidation efficiencies for BTEX by Cu2OT-0.5 were exhibited in the orer of 8 W day light > violet LEDs > white LEDs. However, the photocatalytic oxidation efficiencies normalized to supplied electric power were calculated to be in the following order of violet LEDs > white LEDs > 8 W day light, indicating that the LEDs could be a much more energy efficient light source for the photo-oxidation of gaseous BTEX using Cu2O/TiO2.

The influence of nano-silica on the wear and mechanical performance of vinyl-ester/glass fiber nanocomposites

  • Sokhandani, Navid;Setoodeh, AliReza;Zebarjad, Seyed Mojtaba;Nikbin, Kamran;Wheatley, Greg
    • Advances in nano research
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    • v.13 no.1
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    • pp.97-111
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    • 2022
  • In the present article, silica nanoparticles (SNPs) were exploited to improve the tribological and mechanical properties of vinyl ester/glass fiber composites. To the best of our knowledge, there hasn't been any prior study on the wear properties of glass fiber reinforced vinyl ester SiO2 nanocomposites. The wear resistance is a critical concern in many industries which needs to be managed effectively to reduce high costs. To examine the influence of SNPs on the mechanical properties, seven different weight percentages of vinyl ester/nano-silica composites were initially fabricated. Afterward, based on the tensile testing results of the silica nanocomposites, four wt% of SNPs were selected to fabricate a ternary composite composed of vinyl ester/glass fiber/nano-silica using vacuum-assisted resin transfer molding. At the next stage, the tensile, three-point flexural, Charpy impact, and pin-on-disk wear tests were performed on the ternary composites. The fractured surfaces were analyzed by scanning electron microscopy (SEM) images after conducting previous tests. The most important and interesting result of this study was the development of a nanocomposite that exhibited a 52.2% decrease in the mean coefficient of friction (COF) by augmenting the SNPs, which is beneficial for the fabrication/repair of composite/steel energy pipelines as well as hydraulic and pneumatic pipe systems conveying abrasive materials. Moreover, the weight loss due to wearing the ternary composite containing one wt% of SNPs was significantly reduced by 70%. Such enhanced property of the fabricated nanocomposite may also be an important design factor for marine structures, bridges, and transportation of wind turbine blades.

A Review of Epitaxial Metal-Nitride Films by Polymer-Assisted Deposition

  • Luo, Hongmei;Wang, Haiyan;Zou, Guifu;Bauer, Eve;Mccleskey, Thomas M.;Burrell, Anthony K.;Jia, Quanxi
    • Transactions on Electrical and Electronic Materials
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    • v.11 no.2
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    • pp.54-60
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    • 2010
  • Polymer-assisted deposition is a chemical solution route to high quality thin films. In this process, the polymer controls the viscosity and binds metal ions, resulting in a homogeneous distribution of metal precursors in the solution and the formation of crack-free and uniform films after thermal treatment. We review our recent effort to epitaxially grow metal-nitride thin films, such as hexagonal GaN, cubic TiN, AlN, NbN, and VN, mixed-nitride Ti1xAlxN, ternary nitrides tetragonal SrTiN2, BaZrN2, and BaHfN2, hexagonal FeMoN2, and nanocomposite TiN-BaZrN2.

Transparent Polyimide Nanocomposite Films with Various Equi-biaxial Stretching Ratios (다양한 이축연신 비율에 따른 투명 폴리이미드 나노복합체 필름)

  • Kim, Young-Min;Chang, Jin-Hae
    • Polymer(Korea)
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    • v.36 no.4
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    • pp.478-485
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    • 2012
  • A series of transparent polyimide (PI) nanocomposite films was synthesized from bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTDA) and 1,3-bis(3-aminophenoxy)benzene (BAPB) with various organoclay contents via solution intercalation polymerization to poly(amic acid)s, followed by thermal imidization. Varying organoclay loading in a range of 0 to 1.5 wt% produced variations in the optical transparency, morphology, and oxygen barrier property of the hybrids. An optimum oxygen barrier property was observed for the hybrids containing 1.0 wt% Cloisite 30B; these properties were degraded gradually by further increases in the clay content. The PI hybrid films were found to exhibit excellent optical transparency and almost no color. However, the transparency of the hybrid films decreased slightly with increasing organoclay content. Transparent PI hybrid films containing 1.0 wt% Cloisite 30B were stretched equi-biaxially with various stretching ratios in a range of 100-140% to investigate their optical transparency and oxygen permeability in detail; the variations of clay dispersion and morphology were also determined as a function of equi-biaxial stretching ratio. PI hybrid films with 120 stretching were found to contain homogeneously dispersed clay in the polymer matrix and exfoliated nanocomposites. The highest barrier to oxygen permeation was found at an equi-biaxial stretching ratio of 130%.

Fluorescence-Quenched Sensor for Trinitophenol in Aqueous Solution Based on Sulfur Doped Graphitic Carbon Nitride

  • Min, Kyeong Su;Manivannan, Ramalingam;Satheshkumar, Angu;Son, Young-A
    • Textile Coloration and Finishing
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    • v.30 no.2
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    • pp.63-69
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    • 2018
  • In this study, we report on successful attempt towards the synthesis of sulfur self-doped gC3N4 by directly heating thiourea in air. The synthesized materials were characterized using UV-vis spectral technique, FT-IR, XRD and TEM analysis. Further, the obtained material shows an excellent detection of carcinogenic TNP(Tri nitro phenol) in the presence of 10-fold excess of various other common interferences. The strong inner filter effect and molecular interactions(electrostatic, ππ, and hydrogen bonding interactions) between TNP and the SgC3N4 Nano sheets led to the fluorescence quenching of the SgC3N4 Nano sheets with an excellent selectivity and sensitivity towards TNP compared to that of other nitro aromatics under optimal conditions and the detection limit calculated was found to be 6.324 nM for TNP. The synthesized nanocomposite provides a promising platform for the development of sensors with improved reproducibility and stability for ultra-sensitive and selective sensing of TNP.

The Fabrication of PVA Polymer Coated on the Surface of B4C Nanocomposite by High Energy Ball Mill (고에너지볼밀을 이용한 PVA 고분자가 표면 코팅된 B4C 나노복합재 제조)

  • Uhm, Young-Rang;Kim, Jae-Woo;Jung, Jin-Woo;Rhee, Chang-Kyu
    • Journal of Powder Materials
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    • v.16 no.2
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    • pp.110-114
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    • 2009
  • Mechanical coating process was applied to form 89 %-hydrolyzed poly vinyl alcohol (PVA) onto boron carbide (B4C) nanopowder using one step high energy ball mill method. The polymer layer coated on the surface of B4C was changed to glass-like phase. The average particle size of core/shell structured B4C/PVA was about 50 nm. The core/shell structured B4C/PVA was formed by dry milling. However, the hydrolyzed PVA of 9899 with high glass transition temperature (Tg) was rarely coated on the powder. The Tg of polymer materials was one of keys for guest polymer coating on to the host powder by solvent free milling.

Modeling of CNTs and CNT-Matrix Interfaces in Continuum-Based Simulations for Composite Design

  • Lee, Sang-Hun;Shin, Kee-Sam;Lee, Woong
    • Korean Journal of Materials Research
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    • v.20 no.9
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    • pp.478-482
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    • 2010
  • A series of molecular dynamic (MD), finite element (FE) and ab initio simulations are carried out to establish suitable modeling schemes for the continuum-based analysis of aluminum matrix nanocomposites reinforced with carbon nanotubes (CNTs). From a comparison of the MD with FE models and inferences based on bond structures and electron distributions, we propose that the effective thickness of a CNT wall for its continuum representation should be related to the graphitic inter-planar spacing of 3.4\AA. We also show that shell element representation of a CNT structure in the FE models properly simulated the carbon-carbon covalent bonding and long-range interactions in terms of the load-displacement behaviors. Estimation of the effective interfacial elastic properties by ab initio simulations showed that the in-plane interfacial bond strength is negligibly weaker than the normal counterpart due to the nature of the weak secondary bonding at the CNT-Al interface. Therefore, we suggest that a third-phase solid element representation of the CNT-Al interface in nanocomposites is not physically meaningful and that spring or bar element representation of the weak interfacial bonding would be more appropriate as in the cases of polymer matrix counterparts. The possibility of treating the interface as a simply contacted phase boundary is also discussed.