Advanced Materials Research Vols. 287-290

Abstract: Carbon Nanotubes (CNTs) are functionalized with ethylenediamine by chemical cut and grafting process. CNTs/nylon-6 (PA6) composite is prepared by solution-evaporation method. The dispersivity of CNTs and mechanical properties of CNTs/PA6 composites are tested. Reinforced mechanism is also investigated. The results show that the ethylenediamine-functioned CNTs (s-CNTs) are well dispersed in the formic acid and the weight content of grafted ethylenediamine is about 30%. With only 2wt% addition of s-CNTs, the modulus, strength and strain of PA6 are dramatically improved by about 46%, 85%, and 200% respectively. The tensile course of s-CNTs/ PA6 composites shows that the increase of modulus were provided by both the increase of matrix crystallinity induced by s-CNTs and the recruitment of s-CNTs, and the improvements of strength and strain were attributed to the malleable integration between the s-CNTs and matrix, which was formed with s-CNTs, crystal matrix based on the tubes and the partial entanglements of tubes.

Abstract: Magnesia-alumina spinel-corundum composite was prepared with waste slide plate and waste magnesia carbon brick. The magnesia-alumina spinel-corundum composites were investigated with XRD, SEM, DSC/TG. With the increasing amount of the waste slide plate used and increasing of synthesis temperature, the bulk density of the sample increase and the apparent porosity decrease, but the crystallinity of the sample decrease and the magnesia-alumina spinel phase increases. The obtained composite contained 72 wt % spinel, corundum 26 wt %. Primary and secondary phase were bonded by glass phase. The results shows that it is feasible to synthesis magnesia-alumina spinel-corundum material with waste slide plate and waste magnesia carbon brick.

Abstract: Traffic accidents are the worldwide problem. Based on many reports in the word, the front parts of vehicle is the most likely to strike at pedestrians when the accident occurs. And the fatal injuries almost occurred to pedestrians when their head impact to the vehicle hood. So it’s necessary to reduce the pedestrian injuries as much as possible to enhance the safety characteristic, one of the most importance criteria for vehicles manufactures. In this study, the effect of sandwich structure with material of carbon fiber reinforced polycarbonate (CF/PC) will be concerned as vehicle bonnet change. The finite element model of headform impactor and Honda vehicle model was analyzed detail by LS-DYNA as simulation. The impact between headform impactor and original vehicle model or the carbon fiber reinforced polycarbonate material bonnet vehicle model was executed and the comparison result was shown. This study, the European Enhanced Vehicle-safety Committee/ Working Group 17 (EEVC/WG17) and NCAP requirements was adopted.

Abstract: Building a simulation network of road based on VISSIM and road planning of Guangzhou bio-island. According to the field data and statistic method to calculate the confidence interval of the calibration Parameters, at the same time, calibrating and verifying the simulation model, then using the simulation model calibrated to play the simulation and collect the traffic flow data, setting up four traffic organization projects, using improved AHP method to evaluate the effect of whole road network based on the data collected on the simulation network, then getting the sequence of all kinds of traffic organization projects.

Abstract: Bi₂O₃ is an important additive in the composition of ZnO varistors. However, the effect of Bi₂O₃ on novel SnO₂ based varistors is still unclear. This paper reports the nonlinear electrical characteristics of (98.95-x)mol%SnO₂-0.5mol%CoO-0.05mol%Nb₂O₅- xmol% Bi₂O₃ (x = 0, 0.05, 0.1, 0.5 mol%) system, and the influence of sintering temperature is also investigated. The addition of Bi₂O₃ can improve the electrical nonlinearity of SnO₂-CoO-Ta₂O₅ based varistors, this may be due to the higher barrier height and barrier voltage. The optimum Bi₂O₃ doping level is between 0.1-0.5mol% and the optimum sintering temperature is 1350°C.

Abstract: Yb³⁺and Er³⁺ co-doped BaF₂ phosphors were prepared by high temperature solid reaction method. Effects of mol content ratios of Yb³⁺ ion to Er³⁺ion (CYb3+∶CEr3+) and charge compensation agent Na₂SiF6 contents on the up-conversion luminescence of the samples were studied. The XRD and PL were carried out to investigate the phases and the up-conversion luminescence. Three up-conversion emissions were observed with peaks at 460nm, 548nm and 660nm respectively. The up-conversion luminescence intensity increases firstly, and then decreases with increasing CYb3+∶CEr3+ and the optimal ratio was found to be at 12:2 with fixed Er³⁺ contents 2mol%. The up-conversion emission intensity was enhanced by introducing Na₂SiF6 as the charge compensation agents and its optimal content was found to be 2mol%.

Abstract: Magnetic nickel nanoparticles are prepared by NaBH₄ reducing agent in AOT reverse microemulsion, the influence of water content on the morphology and magnetic properties of nickel nanoparticles are investigated by TEM study, size distribution, XRD characterization and magnetization curves. The results show that spherical and polydispered particles are obtained in microemulsion. The dimension and polydispersity of particles increased with the increasing of water content. Magnetization curves clearly indicate a ferromagnetic behavior with high coercivity values. At water content of W₀=41.7, the product has a high saturated magnetization 70.68 emu/g with its residual magnetizations 28.02 emu/g, higher than the sample obtained at water content of W₀=13.9.

Abstract: A technical condition for the reaction of preparing superabsorbent is investigated. The results indicates that reaction temperature is 30 °C, reaction time is 2 h, the ratio of monomer and starch (RMS) is 5.5, pH of solution is 6.1, the ratio of initiator and starch (RIS) is 0.01 and crosslinker concentration is 0.0013 g. The maximum of distilled water absorbency is 387 times, the maximum of 0.9% saline water absorbency is 45 times. Analysis from FTIR and SEM showed that starch grafting with acrylic acid was success, and a three-dimensional network structure was formed in superabsorbent.

Abstract: In this work, effect of low sintering temperature and time on the new lead-free perovskite (Ba_0.7Ca_0.3)TiO₃-Ba(Zr_0.2Ti_0.8)O₃ (BCZT) solid solution ceramics have been investigated. X-ray diffraction (XRD) was used to understand the phase transition of the BCZT during heating. The Curie temperature decreased nonlinearly 43 K in BCZT ceramics. Diffuse phase transitions were observed in BCZT ceramics and the Curie-Weiss exponent (CWE) was nearly 2. The dielectric permittivity versus temperature characteristics and the γ in the modified Curie-Weiss law, as a function of the dc bias field was obtained for BCZT ceramics. The fitting of parameters (T_m vs. f ) have close agreement with the data of Vogel-Fulcher’s relationship.

Abstract: The finite element software was applied to simulate the splitting test of asphalt mixture, and the computational formula of resilient modulus was fitted out. On the basis of the measured resilient deformation from the splitting test, the computation process of splitting resilient modulus of the asphalt mixture was illustrated in detail. The splitting resilient moduli of the asphalt mixtures at three temperatures were analyzed. Finally the resilient moduli of the asphalt mixture measured through three kinds of tests were compared with each other. The results are of significance in the determination of resilient modulus of the asphalt mixture and parameter selection in specifications for asphalt pavement design.