Advanced Materials Research Vols. 750-752

Abstract: The structures of nonwovens are so nonlinear and out-of-order that traditional methods can hardly measure it. There exist several basic parameters to characterize it, such as thickness, grammage, average density and pore characteristics etc.. It is necessary to find one integrated parameter to characterize nonwovens, and fractal approach seems to be a useful tool. In this paper, the fractal dimension is implemented to describe the structure of nonwovens. And then the relationship between the fractal dimension and several basic structural parameters are built up.

Abstract: This paper introduces briefly the application of thermal analysis in energetic materials and its importance. Thermal analysis has many advantages: operation is simple and quick, wide fields fit to, the characteristic of the high precision and so on. It plays an important role in the thermal decomposition kinetics of energetic materials, stability and compatibility, and the determination of thermal physical constants.

Abstract: In this experiment, preparation of samples were based on original ratio of bauxite matrix Al₂O₃-SiC-C castable for iron runner, and partial bauxites of size 8-5 mm, 5-3 mm, 3-0 mm and <0.074 mm were replaced by the same size granular recycling Al₂O₃-MgO-C materials from spent ladle bricks, respectively. Si₃N₄ and B₄C were introduced as appropriate additives. Effects of their amount on the performance of Al₂O₃-SiC-C castable for iron runner were investigated by testing on physical properties and erosion resistance of the samples after sintering. The results showed that the introduction of Si₃N₄ and B₄C led to high temperature flexural strength of the recycled castable samples decline, while the right amount could improve the room temperature flexural and pressure strength along with the erosion resistance to blast furnace slag. When introduced 3% of Si₃N₄and 0.3% of B₄C respectively, the comprehensive performance of the samples were the best.

Abstract: The spongy dressing was widely used in the pharmacy and medicine field. In this paper the classification, preparation and defects of the spongy composite wound dressings based on the literature at domestic and overseas were introduced. The freeze-drying method was commonly used to prepare spongy composites.

Abstract: Mixtures of an ionic liquid (IL) with organic solvents and a lithium salt have been studied in order to develop new electrolytes for lithium-ion cells with enhanced safety profiles. In this work, N-allyl-N-methylpiperidinium bis (trifluoromethanesulfonyl) imide (PP_1ATFSI) was synthesized and characterized to exhibit high decomposition temperature and wide electrochemical stability window. The evaluation of the coin cell LiFePO₄/Li with the mixed electrolyte based on PP_1ATFSI with 0.35mol/kg LiTFSI, and 30 wt% VC/DMC (1:1) shows a nice reversibility and cycle performances. All above prove that PP_1ATFSI is one of the most promising safety electrolytes of Li-ion battery.

Abstract: The electronic structure, band structure, density of states (DOS) and electronic density difference of paraelectric SrTiO₃ in the cubic phase were performed by the first-principles calculation based on the density functional theory (DFT). The energy levels of high symmetry points in the Brillouin zone were listed and Mulliken population analysis was performed for valence bond structures. The top valence band of SrTiO₃ is at the R point, and the minimum of the conduction bands is at the Γ point. The calculated value for indirect band gap is 1.84eV in the Brillouin zone. As in other perovskite ABO₃ ferroelectrics, the population analysis, DOS and electron density difference show that there is a very strong hybridization between the Ti3d and O2p states in the valence bands, which is responsible for the ferroelectricity tendency.

Abstract: A new series of two-arm (MB1, MB2), four-arm (MB3), six-arm (MB4) chiral liquid crystalline compound containing isosorbide as chiral core were first synthesized. Four precursors of branched-arm B1~B4 were obtained at first and then were esterized separately with isosorbide and got four chiral branched-arm liquid crystals (MB1~MB4). The chemical structures and LC properties of the liquid crystalline molecule were measured by spectrum and thermal analysis techniques. XRD curves of MB1~MB4 samples only showed broad peaks at wide-angle, but no sharp peak was seen for all the samples. The results showed that MB1~MB4 appeared cholesteric phase with oily streak texture or lined texture and finger print texture. Isosorbide successfully induced cholesteric phase. The values of melting point and clearing point for MB1~MB4 decreased. The quantity of branched-arm and chiral core had effects on their liquid crystalline properties.

Abstract: We have studied the dispersion curves of the thickness-modulated one-dimensional (1D) periodic phononic crystal. The dispersion curves of acoustic wave propagating perpendicular to the surfaces of the models are calculated based on the plane wave expansion (PWE) method. By compared the band gaps in thickness-modulated structure with the simple periodic structure, we have found that the band gaps in simple periodic model split into many sub-band gaps when the thickness of media layer is modulated periodically. This can be explained that the thickness-modulated structure can be considered to be made up of many periodic structures with different lattice spacing. It provides flexible choices for real engineering requirement.

Abstract: Phase change material has been widely used in the fields of solar energy, aerospace, aviation, and buildings. In this paper, paraffin is applied in the thermal design of electronic equipment, in order to maintain a constant working circumstance. Finite-element analysis is implemented to analyze the feasibility of this thermal design.

Abstract: The definition and structure of high temperature proton conductors is reviewed. Discusses the high temperature proton conductors of commonly used several preparation methods.