Advanced Materials Research Vols. 512-515

Abstract: Spinel Li4Ti5O12 was prepared by a solution method. The structure and morphology of the samples were characterized by X-ray diffraction, scanning electron microscopy. The electrochemical performance was investigated by initial charge-discharge at different rate. The results revealed that the crystallinity of Li₄Ti₅O₁₂ was well, the Li₄Ti₅O₁₂ prepared by solution method had a relatively smaller particle size and homogeneous morphology. It delivered a discharge capacity 178.59 mAh•g⁻¹ for the Li₄Ti₅O₁₂ at the 0.2C discharge to 1V. The reversible capacity 141.98mAh•g⁻¹ could be achieved at the 5C . Li₄Ti₅O₁₂ prepared by a solution method showed good rate performance.

Abstract: SiO₂ aerogel is prepared under normal conditions by taking tetraethyl orthosilicate (TEOS) as the silica source, N-hexane as the displacer, trimethylchlorosilane hexane as the modifier and hydrolysis environment provided by hydrochloric acid and ammonia water. The effect of pH value, time, temperature, initial concentration on the adsorption of nitrobenzene by aerogel has been studied. The results show that the best range of the pH value for adsorption is 10.72. When adsorption time is 100 min, adsorption equilibrium can be reached. The best temperature for adsorption is 40 °C. The adsorption capacity becomes larger with the concentration increasing of the nitrobenzene solution. When the concentration reaches 500 mg/L, the adsorption reaches 32.402 mg/g. The adsorption equation matches Langmuir model. Scanning Electron Microscopes (SEM), infrared absorption spectrum and specific surface area measurements have shown that the adsorption property of SiO₂ aerogel for the nitrobenzene is related to cellular structure of the aerogel and large specific surface area.

Abstract: This paper describes general situation and hot spots of development of aviation fuel from two aspects of high density, thermal stability, and studies direction of research and development of jet fuel in the future.

Abstract: A new stud—double-nut stud was present. The goals of the study were two fold, firstly to compare with traditional stud and secondly to search the affect factors of capacity, get calculation equations .We present an analysis of double-nut stud, include different concrete strength and different stud size. This study showed double-nut stud is better than traditional stud, for it has higher shearing stiffness and bearing capacity, makes steel beam and the concrete slab to work together. These results suggest that all equations of stud are not applicable computation double -nut stud, it should make 1.35-1.5 adjustment coefficient.

Abstract: Based on Maxwell’s electromagnetic theory of the relationship between particle mass fraction and conductivity in suspension, this paper presents a method to determine the stability of nanofluid, and validates it by experiment. In the experiment, nanofluid consisting of deionized water and CuO nanoparticles is made by ultrasonic vibration. Relationship is obtained between mass fraction and conductivity by measuring conductivity. It studies the effects of temperature on the conductivity in the experiment. The result shows that: conductivity increases with the increasing of mass fraction, temperature almostly has no effect on conductivity.

Abstract: A proton exchange membrane, poly (vinylidene fluoride) blended polystyrene sulfonated acid (PVDF-PSSA) was prepared. Fourier transform infrared spectroscopy is used to characterize changes of the membrane's microstructures after grafting and sulfonation. The morphology of the membrane's microstructures and distribution of sulfur on the cross section after grafting and sulfonation is studied by scanning electrolytic microscope. The results showed that polystyrene is easily blended into PVDF. The sulfonation reaction occurred not only on the surface of the membrane, but also in the membrane.

Abstract: A proton exchange membrane, poly (vinylidene fluoride)(PVDF) blended polystyrene sulfonated acid(PSSA) was prepared by Blend polymerization method. Mechanical properties of membranes were investigated by the multi-functional material experiment machine.The influences of the content of the styrene on the proton conductivity and methanol permeability of the membranes were studied by the impedance analyzer and gas chromatography instrument. The results showed that Polystyrene is easily blended into PVDF and mechanical properties were improved, with increasing of the content of styrene, the proton conductivity of PVDF-PSSA membranes was increased, and arrived at maximum as the styrene content was 20%, correspondingly, methanol permeability became large gradually.

Abstract: In situ namometer silicon bioxide modification of Poly-2-acrylamido-methyl propane sulfonic acid (PAMPS)-composite-polyvinyl alcohol (PVA) membranes were prepared by sol-gel for DMFC. The mechanical properties and thermal stability of the membranes were measured, at the same time, the influences of the content of the AMPS on the proton conductivity and methanol permeability of the membranes were studied by the impedance analyzer and gas chromatography instrument. The results showed that AMPS is easily blended into PVA modified by SiCl₄ and mechanical properties and thermal stability were improved, with increasing of the content of AMPS, the proton conductivity of SiO2/PVA-PAMPS membranes was increased, correspondingly, methanol permeability became large gradually.

Abstract: Fatigue life can be divided into crack initiation life and crack propagation life in fatigue damage process. Fatigue crack comes of the initial discontinuity states （IDS） of material, and goes through short crack , long crack and rupture failure. A estimation model based on fracture theory is built, in which includes of IDS, short crack, long crack and rupture failure. A fatigue holistic life (including fatigue life, the residual life and the calendar life ) estimation model was built on the basis of IDS in which the aircraft structures had not been corrosion damage. A lot of fatigue tests with different stress level and different stress ratio are carried out to validate the model. The results demonstrate that the approach is reasonable and feasible.

Abstract: Magnetic polyurethane was synthesized by a prepolymerization body method using poly(1,4-butylene adipate glycol), 4,4'-diphenylmethane diisocyanate, 1,4-butyl glycol, and a magnetic chain extender. The magnetic chain extender is synthesized by a method involving the use of dimethylolpropionic acid (DMPA) and ferrous powder in dimethyl formamide as solvent conditions. Fourier-transform infrared spectroscopy is used to characterize the magnetic chain extender, and the rheological properties of magnetic Polyurethane are measured by a torque rheometer.