• 한국분말재료학회지
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• 제9권6호
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• pp.381-393
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• 2002

Recent developments in nanocrystalline and nanocomposite rare earth-transition metal magnets are reviewed and emphasis is placed on research work at IFW Dresden. Principal synthesis methods include high energy ball milling, melt spinning, mold casting and hydrogen assisted methods such as reactive milling and hydrogenation-disproportionation-desorption-recombination. These techniques are applied to NdFeB-, PrFeB- and SmCo-type systems with the aim to produce high remanence magnets with high coercivity. Concepts of maximizing the energy density in nanostructured magnets by either inducing a texture via anisotropic HDDR or hot deformation or enhancing the remanence via magnetic exchange coupling are evaluated. With respect to high temperature applications melt spun $Sm(Co_{0.74}Fe_{0.1}Cu_{0.12}Zr_{0.04})_{7.5}$ ribbons were prepared, which showed coercivities of up to 0.53 T at 50$0^{\circ}C$. Partially amorphous $Nd_{60}Fe_xCo_{30-x}Al_{10}(0{\leq}x{\leq}30)$ alloys were prepared by copper mold casting. The effect of transition metal content on the glass-forming ability and the magnetic properties was investigated. The $Nd_{60}Co_{30}Al_{10}$ alloy exhibits an amorphous structure shown by the corresponding diffraction pattern. A small substitution of Co by 2.5 at.% Fe results In the formation of Fe-rich crystallites embedded in the Nd-rich amorphous matrix. The Fe-rich crystallites show hard magnetic behaviour at room temperature with a coercivity value of about 0.4 T, relatively low saturation magnetization and a Curie temperature of 500 K.

• 폴리머
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• 제31권6호
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• pp.461-468
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• 2007

폴리에스터와 trisilanolisobutyl polyhedral oligomeric silsesquioxane(TBPOSS)으로 제조된 나노복합재료에 존재하는 응집체의 구조를 이해하기 위하여 SEM-EDS 분석과 1,1,1,3,3,3-hexafluoro-2-propanol(HFIP) 용매에 녹인 뒤 레이저 광산란법이 실시되었다. SEM에서 평균 직경 120 nm로 나타난 구형 응집체는 가교화된 마이크로겔이 아니라, 320개의 TBPOSS 분자들과 폴리에스터 분절들이 교대로 연결된 선형 중합체 사슬(무게평균 분자량=$2.3{\times}10^6\;g/mol$)이며, 이들은 매트릭스의 폴리에스터와의 화학조성 차이 때문에 상분리된 것으로 여겨진다. 반면에 무게평균 분자량이 $4.0{\times}10^4\;g/mol$인 매트릭스의 폴리에스터는 분자당 2.5개의 TBPOSS 분자를 포함하고 있는 것으로 나타났다. 또한 넣어준 TBPOSS의 약 93%가 매트릭스에 존재하며 나머지 7%는 구형 응집체에 분포하고 있다는 것도 밝혀졌다.

• 한국염색가공학회지
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• 제26권2호
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• pp.88-98
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• 2014

This study is to assess the photocatalytic degradation of PET and Nylon 6 films containing nano-sized $TiO_2$ powders of anatase and rutile types. The PET and Nylon 6 films containing six kinds of the nanoparticles were prepared by melt casting method using a heating press machine. Reflectance in visible region and water contact angles of the irradiated PET and Nylon 6 composite films decreased with increasing UV/$O_3$ irradiation. Also the enhanced hydrophilicity has a close relationship with the increase in the Lewis base parameter, which indicates more oxidized polymer surfaces. The photocatalytic degradation of the nanocomposite films increased with increasing $TiO_2$ content and UV energy, which is more significant with the anatase types rather than the rutile types. The amide linkages in the Nylon 6 seemed to be more susceptible to the UV light compared to the ester groups in the PET, particularly in the presence of the $TiO_2$ photocatalysts. The photoscission and photodegradation of the polymers in the composites produced more degraded structure assisted by the photocatalytic activity of the $TiO_2$ nanoparticles. Also the composite films can bleach the methylene blue dyes more easily under the UV/$O_3$ irradiation, suggesting the photobleaching activity of the $TiO_2$ nanoparticles.

• 공업화학
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• 제18권1호
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• pp.48-53
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• 2007

진동 밀을 이용한 kenyaite의 분쇄특성과 에폭시에 대한 분산특성을 SEM, XRD, TEM, 입도분석을 통하여 조사하였다. 분쇄는 0.5~5 h 동안 진행되었으며, SEM 분석 결과 1 h 분쇄할 경우 다발을 이루던 판상입자가 거의 깨어져 흩어짐을 알 수 있었으며, 그 이상 분쇄하게 되면 판상형태가 거의 사라졌다. 또한, XRD 분석결과, 1 h 이하로 분쇄한 입자의 경우 H-kenyaite 고유의 피크가 유지되었고, 3 h 이상 분쇄된 입자의 경우 H-kenyaite 고유의 피크가 사라지면서 결정구조가 파괴되어 거의 무정형으로 변환되었다. 에폭시 수지와 나노복합체를 만들 경우, 분쇄를 하지 않은 시료는 단지 3~5 nm의 층간거리 확장을 나타내지만, 1 h 분쇄한 경우엔 5~10 nm로 층간거리가 크게 확장됨을 TEM 분석을 통하여 확인할 수 있었다. 상기의 결과는 넓은 판들이 다발을 이루는 kenayite 입자의 적절한 분쇄가 박리형 kenyaite-polymer 나노복합체 제조에 큰 영향을 줄 수 있음을 확인할 수 있다.

• 한국표면공학회지
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• 제45권6호
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• pp.232-241
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• 2012

Cr-Ti-B-N coatings were synthesized by a hybrid coating system combining high power impulse magnetron sputtering (HIPIMS) and DC pulse magnetron sputtering from a $TiB_2$ and a Cr target in argon-nitrogen environment, respectively. By changing the power applied on the Cr and $TiB_2$ cathodes, the Cr-Ti-B-N coatings with various Ti/Cr ratio and B content were deposited. The phase structure, microstructure and chemical compositions of the Cr-Ti-B-N coatings were studied by X-ray diffraction (XRD), transmission scanning electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). With increase of Cr element in the coatings, the nanocomposite microstructure consisting of nano-sized (Cr, Ti) N crystallites and amorphous BN phase were obtained in the coatings. The microhardness of the Cr-Ti-B-N coatings exhibited a peak value of ~41 GPa for the $CrTi_{0.1}B_{0.4}N_{1.3}$, and then decreased with further increase of Cr content in the coatings, and all the coatings exhibited low friction coefficient. The oxidation and corrosion behavior of the Cr-Ti-B-N coatings revealed better properties due to the formation of a nanocomposite microstructure.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.348-354
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• 2009

Copper(II) complexes with tetraoxo dithia tetraaza macrocyclic ligands; [18]ane$N_4S_2$: 1,4,10,13-tetraaza-5,9,14,18-tetraoxo-7,16-dithia-cyclooctadecane, [20]ane$N_4S_2$: 1,5,11,15-tetraaza-6,10,16,20-tetraoxo-8,18-dithia-cyclocosane,Bzo2[18]ane$N_4S_2$: dibenzo-1,4,10,13-tetraaza-5,9,14,18-tetraoxo-7,16-dithia-cyclooctadecane, Bzo2[20]ane$N_4S_2$: dibenzo-1,5,11,15-tetraaza-6,10,16,20-tetraoxo-8,18-dithia-cyclocosane; were entrapped in the nanopores of zeolite-Y by a two-step process in the liquid phase: (i) adsorption of [bis(diamine)copper(II)] (diamine = 1,2-diaminoethane, 1,3-diaminopropane, 1,2-diaminobenzene, 1,3-diaminobenzene); $[Cu(N-N)_2]^{2+}$-NaY; in the nanopores of the zeolite, and (ii) in situ template condensation of the copper(II) precursor complex with thiodiglycolic acid. The obtained complexes and new host-guest nanocomposite materials; $[Cu([18]aneN_4S_2)]^{2+}-NaY,\;[Cu([20]aneN_4S_2)]^{2+}-NaY,\;[Cu(Bzo_2[18]aneN_4S_2)]^{2+}-NaY,\;[Cu(Bzo_2[20]aneN_4S_2)]^{2+}$-NaY; have been characterized by elemental analysis FT-IR, DRS and UV-Vis spectroscopic techniques, molar conductance and magnetic moment data, XRD and, as well as nitrogen adsorption. Analysis of data indicates all of the complexes have been encapsulated within nanopore of zeolite Y without affecting the zeolite framework structure.

• 멤브레인
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• 제15권4호
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• pp.255-271
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• 2005

고분자/층상실리케이트 나노복합체(polymer/layeres silicate nanocomposite, PLSNs) 필름은 보통 내부층을 나트륨과 같은 양이온을 이용한 이온교환을 통해 유기화된 clay로 만든 재료의 새로운 형태이다. 이것은 중합법, 용액법, 그리고 용융법과 같은 다양한 방법으로 제조할 수 있으며, 열경화성, 열가소성이나 탄성고분자와 같은 넓은 범위의 고분자를 기질로 사용할 수 있다. PLSNs 필름은 고분자 사슬이 일정한 간격으로 쌓여있는 실리케이트에 삽입하여 간격을 넓히는 삽입형과 각각의 실리케이트 층이 고분자 기질에 불균일하게 분산되어 형성하는 박리형 두 가지 형태의 구조를 얻을 수 있다. 이러한 새로운 분야의 재료는 보통 5 wt$\%$ 이하의 소량의 clay 함유만으로도 향상된 기계적, 열적 특성을 얻을 수 있다. 그리고 clay의 함유량이 증가할수록 기체 투과경로인 tortuosity가 증가하여 기체 투과도가 감소한다.

• 폴리머
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• 제34권4호
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• pp.326-332
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• 2010

Poly(amic acid)(PAA), poly(o-hydroxyamide)(PHA) 및 층상형인 유기화 점토를 블렌딩하여 나노복합재료 필름을 제조하였다. PAA/PHA 나노복합재료들의 모폴로지를 연구하기 위해 XRD, SEM 그리고 TEM을 사용하였으 며 DMA, TGA, UTM, LOI 및 PCFC를 이용하여 나노복합재료들의 기계적, 열적 성질 및 난연성을 조사하였다. 유기화 점토는 PAA/PHA 매트릭스에 잘 분산되어 박리 및 삽입형 모폴로지를 보였다. PAA/PHA 블렌드에 3 wt% 유기 화 점토를 첨가함으로써 PAA/PHA 블렌드의 초기 모듈러스가 약 48% 향상된 3.68 GPa까지 증가하였다. 유기화 점토 함량이 4 wt% 이상에서는 초기 모듈러스와 인장강도가 모두 감소하였는데 이는 PAA/PHA 매트릭스에 대한 유기화 점토의 뭉침 현상 때문인 것으로 유추된다. 유기화 점토의 함량이 3 wt% 이하일 때 PAA/PHA 나노복합재료들의 열 안정성 및 난연 특성들은 유기화 점토의 함량이 증가함에 따라 증가하였다.

• 폴리머
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• 제38권1호
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• pp.16-23
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• 2014

A novel poly(AM-DMDAAC)/MMT superabsorbent nanocomposites are prepared by radical polymerization using ammonium persulfate (APS) and anhydrous sodium sulfite as a free radical initiator and N,N-methylene bisacrylamide (MBA) as a crosslinker. In this paper, an optimization study on the synthesis of superabsorbent nanocomposites is carried out. Orthogonal array experiment indicates that the optimized conditions is acrylamide (AM) content 23 wt%, diallyl dimethyl ammonium chloride (DMDAAAC) content 6 wt%, montmorillonite (MMT) content 4 wt%, initiator content 0.2 wt% and crosslinker content 0.02 wt%. Under the optimization syntheses conditions concluded, the maximum water absorbency in distilled water is $659.53g{\cdot}g^{-1}$ and in 2 wt% sodium chloride solution is $116.25g{\cdot}g^{-1}$. Compared with the range values of different factors ($R_j$), the order of significance factors in distilled water is C (MMT) > B (DMDAAC) > A (AM) > D (crosslinker) > E (initiator). MMT is intercalated during polymerization reaction and a nanocomposite structure is formed as shown by TEM analysis and XRD analysis.

• Computers and Concrete
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• 제27권2호
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• pp.111-130
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• 2021

In the present work, an extensive study for predicting efficiency parameters (��i) of various simulated nanocomposites including Polymethyl methacrylate (PMMA) as matrix and different structures including various sizes of graphene platelets (GPLs), single, double, and multi-walled carbon nanotubes (SWCNTs-DWCNTs-MWCNTs), and single and double-walled boron nitride nanotubes (SWBNNTs-DWBNNTs) are investigated. It should be stated that GPLs, carbon and boron nitride nanotubes (CNTs, BNNT) with different chiralities (5, 0), (5, 5), (10, 0), and (10, 10) as reinforcements are considered. In this research, molecular dynamics (MDs) method with Materials studio software is applied to examine the mechanical properties (Young's modulus) of simulated nanocomposite boxes and calculate η1 of each nanocomposite boxes. Then, it is noteworthy that by changing length (6.252, 10.584, and 21.173 nm) and width (7.137, 10.515, and 19.936) of GPLs, ��1, ��2, and ��3 approximately becomes (0.101, 0.114, and 0.124), (1.15, 1.22, and 1.26), (1.04, 1.05, and 1.07) respectively. After that efficiency parameters of SWCNTs, DWCNTs, and MWCNTs are calculated and discussed separately. Finally efficiency parameters of SWBNNTs and DWBNNTs with different chiralities by PMMA as matrix are determined by MD and discussed separately. It is known that the accurate efficiency parameters helps a lot to calculate the properties of nanocomposite analytically. In particular, the obtained results from this research can be used for analytical work based on the extended rule of mixture (ERM) in bending, buckling and vibration analysis of structure in future study.