Advanced Materials Research Vols. 391-392

Abstract: In this work pyromellitic dianhydride (PMDA) was used as the chain extender to increase the molecular weight of the recycled poly(ethylene terephthalate) (R-PET) and improve the rheological properties of the R-PET. The reaction was performed in a Brabender torque rheometer. The rheological and thermal characterization were performed by means of a fusion index instrument and a differential scanning calorimeter (DSC ) to compare the effectiveness of the chain extending reaction of different percentages of PMDA. The experimental results showed that compared with the unmodified R-PET, the addition of PMDA decreased the melt flow index and increased the viscosity of the R-PET. In addition, increased crystallization temperatures ( ) were observed with the modified R-PET. It was also found that the modified R-PET with the concentration of 1.0wt% PMDA exhibited the lowest MFI.

Abstract: The influences of endo-cellulase pretreatment of bleached softwood pulp before refining was investigated in this paper. Refining energy consumption, paper properties, wetting properties, electric charge and aggregation structure of fiber were investigated. The results showed that pretreated with endo-cellulase at the dosage of 0.4ECG/g before refining could increase the refining degree by 53.09%, and it would reduce refining energy consumption significantly. At this dosage, the tensile index of the paper sheet increased while the tear index of paper sheet decreased slightly. Additionally, enzymatic pretreatment could raise fiber surface wettability, lower the absolute value of Zeta potential and decrease the crystallinity of fiber, which was help to improve refining performance.

Abstract: Studied on electrorefining metallurgical grade silicon to prepare solar grade silicon(SOG-Si) with electrochemical method in molten KCl and NaF mixture salt. Molten KCl and NaF mixture salt as electrolyte, the metallurgical grade silicon as anode and little metal nickel crucible for collecting silicon powder as cathode, electrorefining experiments were performed at 800 and 2.0V for 14h under dry argon atmosphere. The results showed that the metallurgical grade silicon could be dissolved and deposited on the cathode through molten potassium chloride (KCl) and sodium fluoride (NaF) mixture salt electrolyte. The nickel crucible was full of deposit, which was pure silicon by XRD and EDS. Purity of refined silicon was close to 99.99%, most of impurities like B and P were reduced significantly. Impurity level of silicon was reduced to the desired range for SOG-Si by advancement of the materials for the cell components.

Abstract: According to practical situation of Mg-based desulphurization, this paper has defined the formula of bubble effectiveness with low ratio of height to diameter, and derived the theoretical formula of the bubble utilization rate relating to gas flow rate, bubble diameter and mass transfer coefficient. When the absorption rate is treated as first order reaction, the theoretical formula is presented which includes physical conditions, equipment conditions and operating conditions. It indirectly reflects the three conditions on the effective of bubble utilization rate. The calculation formula of bubble utilization rate at different sizes and different residence time distribution is derived.

Abstract: Well-dispersed nanosized Tb3+ doped hydroxyapatite (Tb-HA) powder was synthesized by hydrothermal method using poly(diallyl dimethylammonium) chloride as template. The influence the doped amount of Tb³⁺ on the fluorescence performance of the samples were discussed. The results show that the hydroxyapatite become luminescent by the appropriate reaction conditions. The Tb3+ ions prefer to occupy the sites Ca(II) in hydroxyapatite crystal. With the increase of Tb³⁺ concentration, the luminescence intensity of Tb-HA reached a maximum at the content of 4 mol%.

Abstract: Microstructure and mechanical properties of W9Mo3Cr4V high speed steel fabricated by spray deposition have been studied. Spray deposited W9Mo3Cr4V high speed steel has a typical equiaxed structure which is finer and more homogeneous with a grain size of 20-30 micrometer compared with conventional casted counterparts. There are pores in the matrix of the deposited steel, which involve gas porosity, filling porosity and solidification shrinkage. As-deposited high speed steel is mainly composed of martensite, austenite and carbides which comprise MC carbide and M₆C carbide. Mechanical properties show that the hardness and bending strength of the as-deposited steel are higher than that of the conventionally casted ones. However, impact toughness of the high speed steel is lower than that of the conventionally casted steel, which can be attributed to the existence of porosities and M₆C carbides which reduce the impact toughness of high speed steels.

Abstract: The morphologies and microstructures of cornstarches with different amylose/amylopectin ratios (waxy: 0/100; maize: 23/77; Gelose 50: 50/50; Gelose 80: 80/20) were studied by a combined SEM and confocal laser scanning microscope (CLSM). CLSM allowed the visualization of cross-sections of starch granules without the need for sectioning techniques that lead to destruction of the microstructure of sample. The influence of the amylose/amylopectin ratio on the internal structures and morphologies was able to be revealed by this choice of techniques. It was found that the granules of the high-amylopectin starches were more regular in shape than those of the high-amylose starches, but the surfaces of the high-amylose starches were smoother than those of the high-amylopectin starches. The high-amylose starches (G50 and G80) were brighter than that of low-amylopectin starches (waxy and maize) under confocal laser light, and the average fluorescence intensity sequence of the granules was G80>G50>maize>waxy. Waxy and maize starches show clearly cavities and channels while G50 and G80 present bright core.

Abstract: Through analyzing inclined asphalt concrete wall rockfill dam structure’s mechanical characteristics in construction process and operational process, this paper adopts finite element method to carry out simulation analysis for inclined asphalt concrete wall rockfill dam of Mobankeng reservoir. Deducing distribution law of the dam’s stress and displacement in construction process and operational process. Analysis results show that, inclined asphalt concrete wall rockfill dam of Mobankeng reservoir construction is reasonable, it meets the requirements for design.

Abstract: Different concentration of copper (II) doped TiO₂ photocatalyst powders were synthesized through the sol-gel method and characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET)-specific surface area, transmission electron microscopy (TEM), and Ultraviolet–Visible (UV-Vis) spectroscopy. Cu²⁺-doping in the TiO₂ promotes the particle growth, decreases the specific surface areas of powders, extends the absorption to visible light regions, and exhibits the vis-photocatalytic activity for methylene blue (MB) degradation. Appropriate content of Cu²⁺-doping is an effective means to improve the photocatalytic activity of TiO₂ for MB degradation under visible light irradiation.

Abstract: We give the analytic solution of Ono-Kondo equation based on lattice theory to describe the supercritical high-pressure hydrogen adsorption inside slit pores of adsorbents, and predict adsorption isotherms for hydrogen on microporous ZSM-5 zeolite at 77K,195K and 293K. The results from prediction are compared with the experimental data. It shows that the model can elucidate the peculiar features in adsorption isotherms of supercritical hydrogen which are fundamentally different from those of standard (IUPAC) classification, and the results from the equation also qualitatively reflect the experimental results.