Advanced Materials Research Vols. 335-336

Abstract: The nanocomposites of poly(vinyl acetate)/montmorillonite (PVAc/MMT) were prepared using vinyl acetate and organically modified alkaline calcium base montmorillonite (MMT) by in situ emulsion copolymerization. The organic modification was acrylic acid including terminal reactive vinylic group. The samples were characterized using fourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD). Thermal properties of the PVAc/MMT films were studied by thermogravimetric (TG) and differential scanning calorimetric (DSC). The FT-IR results indicated that the vinyl group on the surface of the vinyl MMT nanoparticles had been successfully copolymerized with vinyl acetate. The XRD results demonstrated that the MMT was exfoliated during polymerization. The exfoliated PVAc/MMT nanocomposites showed a lower glass transition temperature (Tg) and a worse thermal stability compared with the pure PVAc. However, bonding power of the nanocomposite latex of PVAc/MMT was improved due to the strong interaction between silica nanoparticles and polymer matrix via covalent bonds.

Abstract: Based on industrial silicon and carbon black as starting materials,β-SiC bonded SiC materials were prepared. The microstructure of such material and the silicon/carbon reaction were analyzed and investigated by XRD, SEM and other tools. The results indicate that the synthesis of β-SiC at 1400°C can be achieved through gas-phase mass transfer, liquid dissolution as well as in-situ reaction. While gas-phase mass transfer is the dominant reaction during the sintering of the material, in which β-SiC exists mainly as nanowhisker. The formation of β-SiC nanowires is believed to be the mechanism of reaction sintering.

Abstract: By means of structure analysis, mechanical properties test and microstructure observation，structure of Ni and Ni/TiO₂ group particles have been obtained, the relationship among partic_{Subscript textSubscript text}le diameter，electric field strength and shear ratio of the properties of Ni/TiO₂ group core-shell particles ER fluid have been researched. It has been found that with increasing particle diameter，the shear stress of ER fluid decreased, and with increasing shear ratio，the shear stress of ER fluid increased for same diameter particle and composition ER fluid. At same time, the smaller of particle diameter, the higher of ER properties such as shear stress, but there is a critical value for shear ratio, when shear ratio is larger than critical value, the properties of ER is nearly a value for same composition ER fluid. Particles chain of ER fluid under certain electric field is different with diversity Ni group Particles.

Abstract: A static magnetic field is applied during the hot press molding of high-density polyethylene (HDPE)/carbon black (CB)/ferrous powder composites and HDPE/CB/carbon nanotube (CNT) composites. The effect of magnetic field treatment on the temperature-sensing property of polyethylene-based positive temperature coefficient (PTC) composites is investigated. Experimental results indicate that the magnetic field treatment can lead to the alignment of ferrous powders and CNT in HDPE along the direction of the applied external magnetic field, thus guaranteeing the composites have low room-temperature resistivity and high PTC intensity as the concentration of CB is cut down. This also can significantly improve mechanical property and processability of the composites. When the mass concentrations of ferrous powders and CNT are equal, HDPE/CB/ferrous powder composites present better PTC property than HDPE/CB/CNT composites after the magnetic field treatment.

Abstract: Nano-compounds of ZrO₂/CNTs were prepared by hydrothermal method. The ZrO₂/CNTs nano-compounds were characterizated by XRD, TEM, BET and Zeta potentials. The results showed that perfect hydrothermal temperature was 180°C, hydrothermal time was 11h, pH was 9.5. It is showed by the analysis of TEM and Zeta potential, adding surfacant CTBA, the surface of nano-tube and Zr(OH)₄ colloids take different charge, and they adsorpt each other. And ZrO₂ particles were successfully coated on the CNTs in surface-active agent of CTBA.

Abstract: In-doped ZnO thin film has been found as one of the most promising materials in the optoelectronics, but its optical properties are rarely reported. We calculated optical band gaps and optical properties of Zn_1-xIn_xO with different In doping by using first-principle. The results reveal that the lattice constants of Zn_1-xIn_xO increase linearly with the doping increasing and Zn_1-xIn_xO (x=0.125, x=0.25) crystal comes to be degenerate semiconductor with band gap reduced. The imaginary part of dielectric function has an increasing trend and the absorption capacity significantly increases in ultraviolet (UV) range after doping. Also there is an obvious red-shift in the absorption spectrum. The reflectivity and energy loss spectrum were investigated, too. The results can provide a theoretical reference for finding appropriate UV protective material.

Abstract: The core-nanoshell composite materials doped with Nd were prepared by a solid-state reaction method. The core is magnetic fly-ash hollow cenosphere, and the shell is the nanosized ferrite doped with Nd. The thermal decomposition process of the sample was carried out by the thermogravimetry and differential thermal analysis ( TG-DTA ). The morphology and components of the composite materials were investigated by the X-ray diffraction analysis ( XRD ), scanning electron microscope ( SEM ) and energy disperse spectroscopy ( EDS ). The microwave absorption property was investigated by vector network analyzer ( VNA ). The results indicated that the exchange-coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating. The exchange-coupling interaction enhances magnetic loss of composite materials. So, in the frequency between 1 MHz and 1 GHz, the absorbing effectiveness of the core-nanoshell composite absorbers can achieve –31 dB, it is better than single material and is consistent with requirements of the microwave absorbing material at the low-frequency absorption.

Abstract: In view of the LED lights' high efficiency property, compared to the common driving circuit of large power LED, ARM microprocessor and Buck-Boost power converter are used to design the high efficiency LED lights' driving circuit. At the same time, PID adjustment mode is applied to realize Illumination control of the high efficiency LED lights, which improves the adjustable speed of the system and reduces the power loss. According the principle of design, experiment platform is rebuilt. Tests to the different kinds of lamps indicate that the driving is stable and realizes the Illumination setting and automatic Illumination adjustment.

Abstract: Semantics is the study of the meaning of language learning. Semantics is the study of product form of the product symbol in the use of context features, and how to apply the knowledge in product creation. Ceramic products for both modern and beautiful because of their two properties and highly favored people. Ceramic product designer of consciousness, form, ideas, often through the collation and creation of mud, glaze, texture, firing and other semantic features to express and aspirations. And this eventually led to the demands of the continuous distillation of contemporary ceramic products in China re-opened to the door of modern ceramic art for daily use, a sharp self-semantic features.