Advanced Materials Research Vols. 233-235

Abstract: Shotcrete lining has been increasingly used in tunnel and underground structure since 1960. Cement in shotcrete is the most vulnerable to aggressive sulphate ions from the environment in the presence of moisture. Sulfate attack can change the chemical composition of the cement matrix.The sulfate attack can be caused by alkali sulfates or due to thaumasite form of sulfate attack (TSA). Based on the mechanism of sulfate attack in conrete, the features of the interaction of the sulfate bearing ground water with shotcrete linings are presented in this paper. Under sulfate attack environment, shotcrete durability and the specification of materials should be highlighted in design. The basic requirements to the shotcrete are high strength, low permeability and good homogeneity, which can be produced by well controlled wet process.

Abstract: The chemical and electrochemical equilibrium of oxygen-chlorine-titanium system in the presence of gaseous phase were investigated. Many species, which consisted of oxygen, chlorine and titanium, were considered. Various thermodynamic equilibriums were calculated in the different pressures and temperatures. Calculation results were shown as E-T diagram. This diagram will be used as important tools for corrosion study and titanium production, and it is also used to thermodynamically determine the existence areas of various species and so on.

Abstract: Composites, as a type of new material with typical characteristics, has been applied in aerospace, space, buildings, bridges and many other areas. Rapid repair from damaged composites has become a hot research project. This paper proposed a technique of light repair on composites, which is often used as specimen in aerospace composites. The research has taken advantage of modern optical measurement to study the influence of light remediation on the structural bending of composites, put forth a law of deflection variation, and proven that light remediation is feasible. The result of this research has laid the foundation that light remediation can be further studied and applied in many fields.

Abstract: UV-curable bi-component coating of glycidyl methacrylate (GMA)/polyurethane –acrylate (PUA) modified with the methylacryloylpropyl polyhedral oligomeric silsesquioxanes (MAP-POSS) were prepared. The dynamic mechanical properties and thermal behavior of nano-hybrid coating (GMA/PUA/MAP-POSS) were characterized with dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and the Fourier transform infrared spectrometer (FTIR). The results indicate the three components have very good compatibility and can co-cure in UV-radialization by a free radical polymerization. The addition of MAP-POSS enhanced the thermal properties, the mechanical loss peak temperature T_p is 85.5°C when the amount of MAP-POSS is 10wt%, which is increased by 12.6 °C than the pure system. When the content of MAP-POSS is 20wt%, thermal decomposition temperature in the initial stages was increased by 7 °C than that of the pure GMA/ PUA.

Abstract: Ultraviolet(UV) irradiated polymerization is a new way to synthesis of the polymeric nanoparticles due to its security, environmental protection, and low investment, as compared to the thermal-initiated polymerization. In this paper, polystyrene-g- poly(N-isopropylacrylamide) (P(St-g-NIPAAM)) nanospheres were prepared by photo-initiated dispersion copolymerization of St and macromonomers, PNIPAAM with a vinyl end group, in a mixture of ethanol and water using 2,2-dimethoxy-2-phenylacetophenone (BDK) as the photo-initiator. The obtained nanospheres were characterized by scanning electron microscopy (SEM) and laser light scattering (LLS). The results showed that the P(St-g-NIPAAM) particles were highly spherical and monodisperse. The size of the nanospheres could be controlled by changing the concentration of the macromonomers, polymerization temperature, and irradiation time and energy.

Abstract: Property right is the core issue of emission trading. Because of the immature market mechanism, emission trading in China is restrained by these problems as follow: the definition of property right is not clear, the transaction cost of emission trading is high, the lack of the corresponding institutions for the reorganization of the pollution right. This paper expounds these problems mentioned above according to the theory of property right, and holds out the measures for the improvement of the emission trading in China, which is that the definition of pollution right and emissions trading and restructuring of pollution right are different and interactive aspects of pollution right, and that we should make an overall planning and coordinate the implementation of them three.

Abstract: The γ-Bi₂MoO₆ nanoplates with uniform length and width about 100-200nm have been successfully fabricated by SDS assistant hydrothermal process. The γ-Bi₂MoO₆ nanoplates were characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy and transmission electron microscopy. The results show that the SDS plays an important role in controlling the crystallization and morphologies of Bi₂MoO₆. The γ-Bi₂MoO₆ nanoplates show high efficient photocatalytic activities in decomposition of methyl orange.

Abstract: Silicon nanowires (SiNWs) are new one-dimensional material with unique properties, which have been widely used in field-effect devices, nano-sensors and other nano-electronic devices. In this paper, the new progress in research on the synthesis methods of SiNWs is summarized. The influencing factors and characteristics of each synthesis method are discussed. Finally, a new method is put forward which based on the advantages both on thermal evaporation and template method, and this method can synthesize SiNWs arrays with uniform diameter, high-order, high-purity and with high-yield. This method will be a new research orientation in the future.

Abstract: This paper describes the heat exchanger (condenser) of underground cooling is likely to be technically feasible for geothermal power cycles, i.e. burying the condenser below the ground, instead fan and cooling tower. Through mathematical and ANSYS analyses, the same result T_surface＞T_amb was obtained; otherwise more heat is entering the soil (650w/m) than leaving it to atmosphere (250w/m) has been achieved, which validated heat in the working fluid may then be rejected to the soil and in turn dissipated to the atmosphere.

Abstract: Different Pd precursors were used to prepare Pd catalysts supported by using organic group modified silica. The catalysts were characterized by TEM and FTIR analysis. The results indicated that the small Pd nanoparticles (1-2nm) were achieved using Pd precursors with negative charge, while the size of Pd particle increased to 2-4 nm using Pd precursors with positive charge. For semihydrogenation of phenylacetylene, large-sized Pd partcles (2-4nm) exhibited high styrene selectivity compared with small-sized ones (1-2nm).