Advanced Materials Research Vol. 664

Abstract: In this present paper, the two square cross-section pultruded composite tubes E-glass reinforced polyester unfilled and polyurethane hybrid foam-filled subjected to oblique load are investigated and examined experimentally. The oblique angles were varied from 5 to 20 with an increment of every 5 degree. The bottom base platen of clamped specimen was adjusted inclination angle of loading direction with respect to the tube axis. During the experimental observation, three characteristic crushing stages were identified as initial peak load stage, progressive crushing stage and compaction zone stage. The pultruded composite tube wall-thicknesses of at 3 mm were examined, and the effects of crushing behaviors and failure modes were analyzed and discussed. Results showed that the tube’s energy absorption capability was affected significantly by varying of oblique loading. It is also found that as the filling polyurethane foam into pultruded E-glass reinforced polyester composite square tube increases the amount of specific absorbed energy than the empty tubes.

Abstract: Aqueous suspensions of zinc oxide (ZnO) nanoparticles are prepared at 0.5 wt% solid content using polyacrylic acid (PAA) as a dispersant. Average particle sizes of the ZnO powder are 65, 175 and 225 nm and the dispersant molecular weights (MW) are 1.8k, 450k and 3000k g/mol. Particle dispersion and stability of the ZnO nanoparticles in aqueous suspensions are investigated to determine the efficiency of each PAA as a dispersant. It is found that the efficiency of PAAs depends significantly on their MW and size of the ZnO nanoparticles. At relatively low dispersant concentration, the PAA(1.8k) is the most efficient one for all ZnO nanoparticles. When the dispersant concentration and size of the ZnO nanoparticles increase, the PAA(450k) becomes the most efficient one. The PAA(3000k) is the worst dispersant in all conditions. This research provides a fundamental knowledge on relationship between particle size and dispersant MW, which is essential for producing a well-dispersed and highly stable aqueous suspension.

Abstract: Photocatalyst is an environmental clean-up material when exposed to light. It can decompose organic compounds, bacteria and fungi as well as foul odors. Titanium dioxide (TiO₂) has long been well known for its powerful photocatalytic activity. However, its properties depend on several factors and synthesis method is one of them. In this work, TiO₂ powders were prepared by three methods, namely microwave-assisted hydrolysis of titanium oxysulfate (TiOSO₄), hydrolysis of TiOSO₄, and also by calcining of TiOSO₄. Photocatalytic activity of the obtained TiO₂ powders were evaluated through the decomposition of methylene blue in comparison with P25 (Degussa). Results showed that the TiO₂ prepared at conditions of microwave 100 watts, irradiation time of 10 min was most effective when compared with the others in this work.

Abstract: The work deals with joining active metals as Ti, Zr and Hf with Al₂O₃ ceramics. The solubility of these active metals in selected Sn and In based solders was studied at a selected soldering temperature. Capability of active metals to wet Al₂O₃ ceramics and to form a diffusion bind was ascertained. Soldering was performed with Sn, Sn5Ag, In and In30Sn solders, which were enriched by an active element from metallic substrate of the joint in soldering process. Soldering temperature in vacuum varied from 770 to 870 °C and soldering time was selected from 8 to 20 min. It was found out that the most suitable metal for active solders is Ti, because it is dissolved in Sn solder already at temperature 780 °C. Wetting of ceramic Al₂O₃ substrate and formation of a diffusion bond was achieved already at temperature 830 °C/8 min. Diffusion bond with Zr was formed just at temperature 870 °C/20 min. and it was impossible to form a diffusion bond with Hf.

Abstract: We present first-principles investigations on the elastic properties of XBi (X=Ho, Er) compounds. Basic physical properties, such as lattice constant, elastic constants (C_ij), isotropic shear modulus (G), bulk modulus (B), Young’s modulus (Y), Poisson’s ratio (υ), and Anisotropy factor (A) are calculated. The calculated energy band structures show that the two compounds possess semi-metallic character. We hope that these results would be useful for future work on two compounds.

Abstract: The effect of different carbonizing agents; ethylene glycol, glycerol, and pentaerythritol to the char formation were studied in this research. After burning process, formulation with ethylene glycol, glycerol, and pentaerythritol showed chars thickness of 10 mm, 32 mm, and 45 mm. The chars’ strength at peak force was recorded at 3.20 N, 7.75 N, and 9.48 N while the burning rate of each sample were 5.23 x 10^-4 mm/s, 4.20 x10^-4 mm/s, and 6.24 x10^-4 mm/s respectively. Formulation with glycerol as carbonizing agent showed the lowest burning rate as compared to the other formulations. Additional formulation with glycidyl silane as coupling agent in glycerol formulation was also studied. The formation of chemical bonding between silane, glycerol, and epoxy glycerol was confirmed by Fourier Transform Infrared (FTIR) absorption peak at 767.25 cm^-1. The burning rate was 1.44 x 10^-5 mm/s after silane treatment. Thermal degradation of the silane-treated resin started at 220°C as measured by thermogravimetric analysis (TGA).

Abstract: Heavy metals, including Pb, Cr, Cd, Zn, Cu and Ni, were solidified/stabilized by magnesium potassium phosphate cement (MKPC). The unconfined compressive strength test shows that the strengths of the solidified bodies containing 10%-40% MKPC all exceeded 0.5 MPa, which have met the requirements of storage and landfilling. The toxicity characteristic leaching procedure (TCLP) test shows that no detectable Pb, Cr and Cd were leached from the solidified body containing 40% MKPC after being cured standardly for 28 days, and the concentrations of heavy metals leached from the solidified body containing 10% MKPC after being cured for only 7 days were still significantly lower than the limits in related Chinese National Standards. The leaching concentrations of heavy metals followed a descending order of Cu＞Zn＞Ni＞Pb＞Cd＞Cr. In the simulated acid rain eluviation test, heavy metals were eluviated in different patterns, and the sequence of releasing amounts was similar to that of leaching concentrations. The experimental results indicate that heavy metals can be satisfactorily solidified by MKPC.

Abstract: Co-doped mesoporous TiO₂ photocatalyst was successfully prepared by an ionic liquid modified sol-gel method from TBOT and Co(NO₃)₂·6H₂O. The Co-doped mesoporous TiO₂ samples were characterized by TG-DSC, XRD, XPS, BET, UV-Vis and TEM, respectively. TG-DSC and XRD results showed that the mesoporous TiO₂ samples exhibited high thermal stability, and the samples calcined at 650 oC indicated well-crystallized anatase structure. XPS spectra proved the Co₃O₄ structure of Co in Co-doped mesoporous samples. Large specific surface area was shown from the BET analysis, and the largest specific surface area was obtained when the Co-doping amount was 0.3%. UV-Vis DRS spectra showed that all of the samples exhibited obvious absorption in the visible light range. Photocatalytic activity of the samples was evaluated by photodegradation of MB under visible light (λ>420 nm). Co-doped mesoporous TiO₂ exhibited high photocatalytic activity for MB oxidation, and the 0.3% Co/TiO₂ sample showed the highest visible light activity.

Abstract: Based on the research and design activities conducted at Brno University of Technology, Czech Republic this paper deals with the basic information on problems of the design and actual behaviour of selected FRP structural components for civil engineering. In particular, the recorded experimental studies are focused mainly on the design assessment of glass-fibre grid flooring components. The design criteria for structural FRP parts of load-carrying systems should verify especially the final displacements. Thus, in general, the ultimate limit state of structural system is not only the problem of ultimate strength but namely the problem of accordant final displacements. The analysis of test results gives data for verification of numerical modelling and of conventional design criteria. Considering the specific character of structural all-FRP systems, for the structural design the recognition of the deflection advancement can be decisive.

Abstract: Nowadays, bio-plastic is the most popular in packaging field. Green chemistry and environmental responsibility has led it to develop the bio-plastic for use as packaging. Polylactic acid (PLA) is the well known staring material in this area. However, some properties of PLA films have to develop. Polymer blend is the interesting technique, in this work, PLA/Cellulose acetate (CA) blend films were prepare by casting solution at various compositions. Mixing solvent of Chloroform and acetone in acid condition were used, it was found that the mixing solvent can improved the compatibility and mechanical properties of the blend films. From this work CA can significantly increase PLA properties both the usefulness and the possible applications for bio-plastic material.