Advanced Materials Research Vols. 306-307

Abstract: Thermoplastic starch composites modified by enzymatic hydrolysis lignin (EHL) were prepared via a simple and environmentally-friendly process. Starch and EHL were plasticized with urea and methanamide as plasticizers in the preparation. The effects of the amount of plasticizers and EHL on the mechanical and water-absorption properties were investigated. The fractured surfaces of the composites were studied by using scanning electron microscopy (SEM). Properties of the composites were improved with adding plasticized EHL into pure thermoplastic starch. It was attributed to the good compatibility of modified EHL with plasticized starch.

Abstract: The calcium terbium aluminate (CaTbAlO4) single crystal was grown by Czochralski method successfully for the first time.The structure of the crystal was determined by X-ray diffraction analysis.The transmission spectrum of the crystal was measured at room temperature at the wavelength of 400-1500nm.The specific Faraday rotation of the single crystal was surveyed at room temperature at the wavelength 532nm, 633nm, and 1064nm respectively.The Verdet constants of the CaTbAlO4 crystal are calculated and the results show that the Verdet constants of CaTbAlO4 are around 110% higher than that of TGG in the visible and near-infrared spectral region.Therefore,crystal CaTbAlO4 can be promising material for the fabrication of magneto-optical devices in the visible region.

Abstract: The possibility of synthesizing nanocrystalline (W, Ti)C is investigated by spark plasma sintering of mechanically alloyed elemental mixed powders of W, Ti and C. The results show that wet-milling generates WxTi1-x instead of directly forming (W, Ti)C, and makes the graphite C transform into amorphous phase surrounding the formed WxTi1-x. Meanwhile, the grain size of the 70 h milled elemental mixed powders reaches about 50 nm under the wet-milling condition. Subsequently, nanocrystalline (W, Ti)C is successfully synthesized by spark plasma sintering of the 70 h milled elemental mixed powders. The formation of (W, Ti)C phase by SPS from the WxTi1-x and amorphous C generated by MA is simply explained based on our proposed model.

Abstract: Rare earth yttria (Y2O3) reinforced polystyrene composites were prepared by melt blending process. Mechanical properties, wear resistance of the PS/Y2O3 composites were characterized in contrast to neat PS. The improvement of the mechanical properties and wear resistance was attributed to the reinforcing effect of Y2O3 powder. Well distribution of Y2O3 powder in the PS matrix and good interfacial bonding were achieved by pretreated of Y2O3 using titanate coupling and dispersant followed by calcinations process. Results indicated that both of the Y2O3 powder pretreatment process and melt blending process have significant effects on the composite properties. When the Y2O3 content were 2.8wt%, the modify effect to PS was optimal. When the Y2O3 calcined at 900°C was used, the impact of the composites were best, other performance improvements have also been good. When the Y2O3 content of 1.4wt%, the wear resistance of the composites were best.

Abstract: In this paper, mesoporous MCM-41 and Al-MCM-41(Si/Al =100, 70, 40, 10, 5) molecular sieves were synthesized by direct hydrothermal process and characterized by various analytical techniques. Their catalytic performance in the synthesis of dioctyl phthalate (DOP) was also studied. The results show that while keeping the mesostructure of Al-MCM-41(Si/Al=100, 70, 40), increasing Al content can increase the acidity and so forth effectively improve the catalytic activity. But too much aluminum incorporation can destroy the structure of Al-MCM-41(Si/Al=10). The Al-MCM-41 molecular sieves with proper Si/Al ratios have good catalytic activity and stability in DOP synthesis. When Al-MCM-41(40) was used as the catalyst, A high PA conversion of 98.45% can be reached in 4 h. After being reused for five times, Al-MCM-41(40) still remains good catalytic activity.

Abstract: To obtain graphite/copper composites with excellent microstructures, preparation process including mechanical milling, compact compressing, vacuum hot pressed sintering and hot extrusion had been put forward. Effect of milling time and hot extrusion on microstructures of composites had been analyzed and investigated by optical microscope. The results show that after mechanical milling, refined and uniform distributed graphite phase could optimize microstructures of composites. While increasing extrusion ratio, graphite particles and graphite fibers in longitudinal cross-section of composites could be refined effectively. Under of the same conditions, grain size of copper in graphite/copper composites is larger when raising extrusion temperature.

Abstract: Diamond single crystals are synthesized using artificial graphite as carbon source and iron-based alloy as catalyst in a cubic anvil apparatus at high temperature and high pressure (HPHT). Four kinds of catalysts at different synthetic times are adopted in synthetic process. After synthesizing the microstructure of the solvent metal samples are characterized by means of scanning electron microscopy (SEM). The results show that when the synthetic quality is relatively superior, the more primary lathy cementites are well distributed and shows parallel growth of the stripe beams. Besides, the edge of the cementite is more even. So the synthesis time and catalyst composition commonly influence the solvent metal microstructure, especially the quantity and shape of cementite.

Abstract: Coal gangue and limestone were used as raw materials with fluorite and gypsum as the mineralizer. The activation mechanism of calcined coal gangue with calcium and the pore structure of its hydrating slurry are discussed. The experimental results show that during calcinations F- and [SO4]2- come into the framework and react deeper with CaO at 850-950°C to create hydraulic-activity C12A7 and C2S. Pore structure analysis of the hydrating slurry indicates that adding gypsum and fluorite into coal gangue is more propitious to strengthen the slurry and optimize the pore distribution than only of gypsum.

Abstract: Porous carbon monolith was used as substrate for microwave plasma chemical vapor deposition. The depositing time was set as 1 hour, 3hours, and 5 hours respectively. The deposited samples were characterized with Raman spectroscope and scanning electron microscope. It was proved that diamond was formed on the surface of all the samples. However, the surface morphology and phase composition of the chemical vapor deposition layer changed with depositing time. It was deduced that the porous carbon monolith was a carbon resource, and it gave out small molecules containing carbon element during the deposition. This changed the ratio of carbon to hydrogen in the growing atmosphere, and correspondingly influenced the growth of carbon on the substrate. With a low ratio of carbon to hydrogen, mainly diamond grew. Or else, other types of carbon would grow on the surface of the porous carbon monolith substrate.

Abstract: WO3 films were deposited on glass substrates by magnetron sputtering at room temperature. Single factor method was employed to investigate the effect of sputtering parameters (sputtering power, oxygen flow and depositing time) on the photocatalytic properties of WO3 films. The crystalline structure and surface microtopography of WO3 film were characterized by X-ray diffraction and Scanning Tunneling Microscope respectively. The results show that the WO3 films are amorphous, and the photo-degradation rate of WO3 films for methylene blue reaches the peak value of 83.3% when the film was deposited under the conditions that the sputtering power was 80W, the oxygen flow was 15SCCM and the depositing time was 60min. The thickness threshold value for WO3 photocatalytic films is 632nm. When the thickness of the WO3 films is less than the threshold value, the photocatalytic degradation activity aggrandizes with the increase of film thickness, and then becomes steady when the thickness exceeds 632nm.