Ajaya K. Pradhan
材料科学技术（英文）
Multiwalled carbon nanotubes (MWCNTs)/poly(methyl methacrylate) (PMMA) nanocomposites were prepared by ultrasonic assisted emulsifier free emulsion polymerization technique with variable concentration of functionalized carbon nanotubes. MWCNTs were functionalized with H2SO4 and HNO3 with continuing sonication and polished by H2O2. The appearance of Fourier transform infrared absorption bands in the PMMA/MWCNT nanocomposites showed that the functionalized MWCNT interacted chemically with PMMA macromolecules. The surface morphology of functionalized MWCNT and PMMA/MWCNT nanocomposites were studied by scanning electron microscopy. The dispersion of MWCNT in PMMA matrix was evidenced by high resolution transmission electron microscopy. The oxygen permeability of PMMA/MWCNT nanocomposites gradually decreased with increasing MWCNT concentrations.
关键词:
Nanocomposites
Fedir Ivashchyshyn
材料科学技术（英文）
In this work, for the first time, photosensitive nanostructures with alternate semiconductor and magnetic oriented nematic molecular nanolayers were obtained. The established dependency on the ordering type of kinetic and optical properties is deserving attention. For the first time, the notion of `rotary' polaron in such structures is introduced and microscopic model is created, which explains band structure transformation. The model is well coordinated with experimental optical data, which, at the same time, indicate the prospects of application of materials obtained due to the intercalation engineering for photoenergetics.
关键词:
Nanocomposites
Dongyan TANG
,
Liangsheng QIANG
,
Zheng JIN
,
Liancheng ZHAO
材料科学技术（英文）
Interpenetrating polymer networks (IPNs) composed of acrylate-modified polyurethane (PU)/unsaturated polyester (UP) resin $via$ simultaneous polymerization with various component ratios of PU/UP were prepared. The polymerization processes of IPNs were traced through infrared spectrum (IR) techniques, by which the phase separation in systems could be controlled effectively. Results for the morphology and miscibility among multiple phases of IPNs, obtained by transmission electron microscope (TEM) indicated that the domains between two phases were constricted in nanometer scales. The dynamic mechanical thermal analyzer (DMTA) detection results revealed that the loss factor (tanδ) and loss modulus (E'') increased with the polyurethane amounts in system, and the peak value in curves of tanδ and E'' appeared toward low temperature ranges. Maximum tanδ values of all samples were above 0.3 in the nearly 50℃ ranges. Also, the mechanical properties of PU/UP IPNs were studied in detail.
关键词:
Interpenetrating polymer networks (IPNs)
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null
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null
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null
X.Yao
,
C.Z.Wu
,
H.Wang
,
H.M.Cheng
,
G.Q.Max Lu
材料科学技术（英文）
Hydrogen storage in traditional metallic hydrides can deliver about 1.5 to 2.0 wt pct hydrogen but magnesium hydrides can achieve more than 7 wt pct. However, these systems suffer from high temperature release drawback and chemical instability problems. Recently, big improvements of reducing temperature and increasing kinetics of hydrogenation have been made in nanostructured Mg-based composites. This paper aims to provide an overview of the science and engineering of Mg materials and their nanosized composites with nanostructured carbon for hydrogen storage. The needs in research including preparation of the materials, processing and characterisation and basic mechanisms will be explored. The preliminary experimental results indicated a promising future for chemically stable hydrogen storage using carbon nanotubes modified metal hydrides under lower temperatures.
关键词:
Hydrogen storage
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null
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null
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null
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null
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null
Juxian ZHANG
,
Jinjun FENG
,
Longqiao GAO
材料科学技术（英文）
Properties of Al2O3-coated nano-SiC have been compared with those of as-received SiC. The isoelectric point (IEP) of SiC changed from pH3.4 to pH7.3 after coating with the alumina precursor, which is close to that of alumina. Because both surfaces of coated SiC and Al2O3 possess higher positive charge at pH=4.5~5.0, they are uniformly dispersed in the two-phase aqueous suspensions, Then a mixed powder containing nano-SiC dispersed homogeneously into the Al2O3 matrix was achieved from flocculating the two-phase suspension. Finally, Al2O3/SiC nanocomposites were obtained by coating nano-SiC with Al2O3, in which the majority of SiC particles were located within the Al2O3 grains. The observation by transmission electron microscopy (TEM) and the analysis by the X-ray photoelectron spectroscopy (XPS) showed that cracks propagated towards the intragranular SiC rather than along grain boundaries.
关键词:
Coated nano-SiC
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null
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null
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null
Zhifeng XU
材料科学技术（英文）
Selective laser sintering (SLS) is a new process to prepare the polystyrene (PS)/ Al2O3 nanocomposites. In this paper, with different laser power and other processing parameters unchanged, the morphology, density and mechanical properties of the sintered specimens were investigated. It was found that nano-sized inorganic particles are uniformly located in the PS matrix and the maximum density of the sintered specimens with pure PS powder reaches 1.07 g/cm3, higher than 1.04 g/cm3 that of the sintered specimens with mixture powder. Due to strengthening and toughness of the nano-sized Al2O3 inorganic particles, the maximum notched impact strength and tensile strength of the sintered part mixed with nano-sized inorganic particles are improved greatly from 7.5 to 12.1 kJ/m2 and from 6.5 to 31.2 MPa, respectively, under the same sintering condition.
关键词:
Selective laser sintering (SLS)
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null
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null
范秀娟
,
李欣
新型炭材料
doi:10.1016/S1872-5805(12)60007-9
通过FeCl2·4H2O和FeCl3·6H2O混合共沉淀,合成平均粒径为6nm和10 nm的Fe3O4纳米粒子.然后将两种Fe3O4纳米粒子分别与经HNO3氧化处理的多壁碳纳米管(MWCNTs)置于乙醇水溶液(水和乙醇的体积比为1∶1)中,在超声波作用下制备Fe3O4/MWCNT复合材料.用高分辨透射电子显微镜、X-射线光电子能谱、振动样品磁强计、X射线衍射仪、热重分析仪对所制备的Fe3O4/MWCNT复合材料进行表征.结果表明:由6nm和10 nm Fe3O纳米粒子所制备的Fe3O4/MWCNT复合材料中,Fe3O4的质量分数分别为26.65％和29.3％,相应的磁饱和强度分别为16.5 emug-1和7.5emug-1.
关键词:
碳纳米管
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修饰
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Fe3O4
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磁性纳米材料
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纳米复合材料
