Advanced Materials Research Vol. 662

Abstract: The 0.5 wt.% Pd/C catalysts used for purification of terephthalic acid(TA) were prepared, and the effects of dodecyltrimethylammonium bromide(DTAB) concentration on activity and microstructure of catalysts were investigated by means of SEM, TEM, XRD,HPLC,specific surface area(BET) and porosity test. The results show that DTAB can increase the activity of Pd/C catalysts, and the catalytic activity increases with the increase in DTAB concentration and nearly remains constant with further increase after it exceeds 0.5 wt.%.. DTAB can clean the surface of activated carbon and diminish the palladium size of Pd/C catalysts. The addition of DTAB has effects in crystal structure of nano Pd/C catalysts, and the Pd crystal planes of (111) and (200) was replaced by a broad reflections after DTAB added. DTAB tends to form various meta-stable structures(spherical or cylindrical)at the solid-liquid interface that helps finer grain for mation and hinders subsequent coarsening of the palladium particles.

Abstract: Carbon nano fibers reinforced polymers have good mechanical properties but are difficult to process. In order to find out the influences of carbon nano fibers (CNF) on processing performance of epoxy resin, a series of tests on viscosity were carried out, including the influence of CNF weight fraction, CNF oxidation and temperature change. Infrared spectrum was used to detect the functional groups in CNF. The mechanism of CNF influence on viscosity of CNF reinforced epoxy resin has been discussed. The experimental results indicate that the weight fraction and oxidation of CNF enhanced viscosity of epoxy and the temperature have an inverse relationship with viscosity.

Abstract: In this study, the researcher’s interest is focused on establishing a model with La Sota live vaccine immobilized into chitosan, which was prepared using a ionic gelation method. The formulation, preparation procedure, influence factors, physicochemical characteristics were evaluated. The results of study demonstrate that the NDV-CS-NPs have been produced with suitable size, morphous regulation, extremely spherical shape, regular and well-distributed. The NDV-CS-NPs produced by the optimal formulation were average size (371.1nm) and proper zata potential (+2.84 mV). The entrapment efficiency was (74±3.7) %. It can provide a new useful information for the development and evaluation of synthetic vaccines.

Abstract: The traditional method of preparing 0.5 wt.% nano Pd/C catalysts used for pure terephthalic acid(PTA) refining is the precipitate-reduction method, and this paper proposed the sol-gel method, in which the palladium colloid was firstly prepared, and followed by the load process onto the activated carbon. The activity and microstructure of catalysts were investigated by means of SEM, TEM, EDS，XRD and HPLC. It was found that the activity of catalyst with the sol-gel method was much higher than that with precipitate-reduction method. The preparation technology has less effects on the micostructure of Pd/C catalysts, while the palladium particles of catalyst obtained with sol-gel method are much finer and the relatively palladium content is much higher.These two factors contribute to the higher activity of Pd/C catalyst.

Abstract: The nanostructured SrTiO3 film was prepared by sol-gel method and spin-coating process. The X ray diffraction (XRD) analysis shows that the SrTiO3 film is perovskite structure and has the average particle size 25.39nm. The photocatalytic degradation experiments were carried out in methylene blue solutions with the SrTiO3 film. The experimental results show that: the critical concentration of methylene blue solution is slightly higher than 3.289×10-5mol/L at which concentration the degradability of film can be most effectively exploited; when the molar concentration is less than the critical concentration, the photocatalytic degradation reaction can be expressed as the first-order reaction kinetics model and the reaction rate decreases with increasing initial concentration; when the concentration is higher than the critical concentration, the degradation reaction is more consistent with the zero-order reaction kinetics model, and the reaction rate remains almost constant with the varied concentration

Abstract: Abstract. The surface plasmon resonance photocatalysts of Ag-AgBr/RGO were synthesized by chemical precipitation and photochemical reduction method. The samples were characterized by X-ray diffraction and UV-Vis absorption spectroscopy. The photocatalytic activities of catalysts were studied using the photocatalytic degradation of helianthine as a probe reaction. The results showed that the degradation rate of 10 mg/L helianthine reached 95% after 60 min of visible light irradiation.

Abstract: With the widely research of nano-TiO₂, researchers have found another way of managing air quality. As an excellent photocatalyst material, nanometer titanium dioxide has begun to be used in road engineering in recent years. In this paper, substantial gas decomposition tests are performed utilizing the self-designed sealed container and UV aging box. At first, the catalytic efficiencies of nanometer titanium dioxide dispersed in silane solvent and in asphalt mixture were compared. The results show that nanometer titanium dioxide is able to decompose CO, HC and NO after being dispersed in silane solvent and asphalt mixture. To achieve the same catalytic efficiency, the amount of the nanometer titanium dioxide dispersed in silane solvent is much less than that in asphalt mixture. For asphalt mixture, high void fraction may mean high catalytic efficiency. Then the long-term decomposition of asphalt mixture was discussed. The asphalt mixture still has good catalytic decomposition effect after six months. The catalytic effect of asphalt mixture does not diminish over time and the effect of decomposing HC has improved after six months. At last, for cement paint, the catalytic effect of decomposing NO and HC does not diminish over time, but the effect of decomposing CO reduces.

Abstract: Radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) technique is widely used in preparing uniform and large area a-Si:H films for various photoelectric devices. However, in the deposition processes of PECVD, the plasma bombardment to the deposited films will result in hindering the processes of crystallization. In the processes of hot-wire chemical vapor deposition (HWCVD), high-crystallinity films with a quickly growth rate can be obtained. In this article, hydrogenated microcrystalline silicon (μc-Si:H) films on glass substrate were prepared by a combination technique of HWCVD and RF inductively coupled plasma (ICP) at a low pressure (7Pa). The deposition parameters including the distance between the glass substrate with the hot wire and the flow ratio of SiH4/H2 in order to optimize the properties of μc-Si:H films. The crystallinity, microstructure, electrical and optical properties of the μc-Si:H films were investigated by Raman Spectroscopy, X-ray diffraction analysis (XRD), and UV-visible spectrometer, respectively. The results indicate that the crystallinity of the μc-Si:H films can be controlled at a very wide range and the deposition rate is up to 3nm/s. The deposited films show excellence electrical and optical properties.

Abstract: Photoelectrodes of mixed polymethylmethacrylate (PMMA) and TiO₂ paste with different ratios were fabricated and studied for improved photovoltaic conversion efficiency in quasi-solid state dye-sensitized solar cells(QS-DSCs). The large pore nanocrystalline TiO₂ films were prepared by the doctor blade method and charicterized by SEM and UV-Vis spectroscopy. SEM images show that large pores have been formed in the TiO₂ films. The transmittance of the films increased with an increase amount of PMMA, while the light-absorption decreased when the films covered by dyes. I-V curves show that a relatively high photovoltaic conversion efficiency of 2.1%~2.26% was achieved when the PMMA/ TiO₂ paste weight ratio was in the range of 1:25~1:35 under AM 1.5 illumination at 100mW/cm².

Abstract: With the development of national economy in Mainland China, the heavier vehicles and traffic flow have arisen in highway transportation. Concrete pavement has high strength and good durability, and thus is widely used in high-grade highway. Due to the small dimension, nano- materials have many unique physical and chemical properties, and become the focus of material science field. In this thesis, based on the unique characteristics of nano-materials, the ordinary concrete with nano-SiO2 or nano-TiO2 is prepared to research the drying shrinkage of pavement concrete. The test results indicate that the concrete with nano-SiO2 and nano-TiO2 in the amount of 2.0% and 1.0% by weight of binder have the respectively biggest drying shrinkage rate of the same concrete type, which are significantly increased than the ordinary concrete. After 28 days, the dying shrinkage rate of the concrete with nano-TiO2 is 1.6 times to the ordinary concrete.