Papers by Keyword: Nanocomposite

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Authors: Amir Reza Shirani-Bidabadi, Ali Shokuhfar, Mohammad Hossein Enayati, Mazda Biglari
Abstract: In this research, the formation mechanisms of a (NiCr)Al-Al2O3 nanocomposite were investigated. The structural changes of powder particles during mechanical alloying were studied by X-ray difractometry (XRD) and the morphology and cross sectional microstructure of powder particles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The methodology involved mechanical alloying of NiO, Cr, and Al with molar ratios of 3:3:8. During mechanical alloying, NiO was first quickly reduced by aluminum atoms to produce NiAl nanocrystalline and Al2O3. Subsequently, and when a longer milling time was applied, chromium atoms diffused into the NiAl lattice. The heat treatment of this structure led to the formation of the (NiCr)Al intermetallic compound as well as Al2O3 with crystalline sizes of 23 nm and 58 nm, respectively.
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Authors: Xiao Ying Lu, Hao Wang, Sheng Yi Xia, Jian Xin Wang, Jie Weng
Abstract: Carbon nanotubes (CNTs)/hydroxyapatite (HA) nanocomposites have been successfully fabricated by a novel method for the biomedical applications, which is in situ growing CNTs in HA matrix in a chemical vapor deposition (CVD) system. The results show that it is feasible to in situ grow CNTs in HA matrix by CVD for the fabrication of CNTs/HA nanocomposites. Multi-walled CNTs with 50-80 nm in diameter have been grown in situ from HA matrix with the pretreatment of sintering at 1473K in air. The nanocomposites are composed with carbon crystals in CNTs form, HA crystallites and calcium phosphate crystallites, one of most important CaP bioceramics. And the CNTs content is about 1% proportion by weight among the composites in our experiments, which can enhance the HA mechanical properties and the CNTs content does not affect the HA performances. These CNTs/HA nanocomposites have the potential application in the biomedical fields.
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Authors: Dan Feng Qiu, Yong Jun Xia, He Qing Ma, Gang Bu
Abstract: Graphene-NiO nanocomposites were prepared via a solvothermal method. The nanostructure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). SEM and TEM results indicated that NiO nanoplates distributed homogeneously on graphene sheets. The electrochemical properties of the samples as active anode materials for lithium-ion batteries were examined by constant current charge-discharge cycling. With graphene as conductive matrix, homogeneous distribution of NiO nanoplates can be ensured and volume changes of thenanocomposite during the charge and discharge processes can be accomodated effectively, which results in good electrochemical performance of the composites.
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Authors: Frank Kern, Rainer Gadow
Abstract: Zirconia-alumina composites are structural ceramics which due to their high strength and toughness are interesting in biomedical and engineering applications. Reinforcement of such materials with in situ formed platelets can improve fracture toughness and reliability, the mechanisms are however not yet fully understood. In this study alumina and zirconia based composites (ZTA and ATZ) reinforced with various hexaaluminates were investigated. In ZTA materials the main effect of platelets is the improvement of toughness as the the grain size distribution of the microstructure is broadened and transformability of the zirconia dispersion is improved. Crack deflection by platelets is unimportant, toughening is commonly achieved at the expense of strength and hardness. In case of zirconia based composites results are strongly depending on the type of stabilizer (Y-TZP or Ce-TZP) used and the type of hexaaluminates formed in situ. Here platelets can cause crack deflection and crack bridging. By variation of the composite recipes a multitude of compositions can be produced which have mechanical properties tailored for individual applications.
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Authors: Lian Liu, Teng Yu, Pei Wang, Guang Shuo Wang
Abstract: Nanocomposites of poly(ε-caprolactone) (PCL) and layered double hydroxide (LDH) were prepared by in situ polymerization at low LDHs loadings in this work. The resultants were characterized by FTIR spectroscopy, X-ray diffraction (XRD), differential scanning calorimeter (DSC) and UV-visible spectroscopy (UV-vis). FTIR showed that the PCL/LDHs nanocomposites were prepared successfully by in situ polymerization and XRD spectra showed that the crystal structure did not change greatly in the presence of LDHS. DSC results confirmed that LDHs could act as nucleating agents. UV-vis spectra showed that LDHs had stronger absorbance peak than LDH. Moreover, the PCL/LDHs nanocomposites had strong anti-ultraviolet effect by introduction of LDHs into polymer matrix.
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Authors: Hu Wang, Ji Ping Liu
Abstract: Poly (p-phenylene benzobisoxazole)/Nano-sized titanium dioxide (PBO/TiO2) composites with different TiO2 compositions were prepared through in situ polymerization and the fibers had been successfully spun via dry-jet wet spinning technique. PBO/TiO2 composite fibers were characterized by FTIR spectroscopy, Ubbelohde capillary viscometer, TG analyses and so on. Mechanical property of the fibers was investigated before and after UV accelerated aging which being exposed under ultraviolet radiation for up to 100 hours. Results showed that the molecular weight of PBO in the Nano composites was less declined with low content of TiO2; the thermal degradation temperature of PBO/TiO2 fibers were at less 10°C higher than that of pure PBO fiber in the atmosphere of N2; The pure PBO had a large deterioration in mechanical properties, and in the initial exposure time tensile strength of fibers dropped slowly after TiO2 adding in. From these results, the nano-TiO2 had good UV-aging shielding efficiency for PBO fiber.
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Authors: Hong Lin Li, Gui Sheng Yang, Yu Cheng Wu
Abstract: Nylon 6/MgAl-LDH nanocomposites had been successfully prepared by In situ hydrolyzed ring opening polymerization in this work. The structures and properties of Nylon 6/MgAl-LDH nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The nanodispersion of exfoliated MgAl-LDH layers in nylon 6 matrix has been verified by the observation of TEM image in Nylon 6/MgAl-LDH nanocomposites with 0.3 wt% MgAl-LDH (MANM-0.3). The XRD results showed that the exfoliated MgAl-LDH favored the formation of the γ-crystalline of nylon 6 form. DSC data showed that the exfoliated MgAl-LDH layers play the role of nucleating agents with strong heterogeneous nucleation effect on the crystallization of nylon 6. But TAG results showed the thermal stability of nylon 6/MgAl-LDH nanocomposites were worse than that of neat nylon 6.
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Authors: Masanori Kikuchi, Atsushi Irie
Abstract: Osteoclast differentiation of bone marrow cells on hydroxyapatite/collagen self-organized bone-like nanocomposite (HAp/Col) disk in vitro was evaluated by coculture of mouse bone marrow cells with mouse osteoblasts with or without addition of osteoclastic inducers, 1,25-Dihydroxyvitamin D3 and 1 µM prostaglandin E2. Dentine slice and tissue culture polystyrene were used as controls. Good osteoclastic differentiation at day 7 were observed among the bone marrow cells cultured on the HAp /Col disk and controls with osteoclastic inducers. On the contrary, osteoclastic differentiation was observed only for marrow cells cultured on the HAp/Col disk. Nano- and micro- structures as well as chemical and mechanical properties have a potential to control cell differentiation.
449
Authors: Kazuki Tajima, Hae Jin Hwang, Mutsuo Sando, Koichi Niihara
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Authors: Kazuki Tajima, Hae Jin Hwang, Mutsuo Sando, Koichi Niihara
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