Advanced Materials Research Vols. 557-559

Abstract: In this paper, the graphene oxide reducing by photochemical-thermal reduction and high-temperature thermal reduction was studied to get qualified graphene and avoid the re-aggregation. The results show that graphene obtained by both of the two reduction methods all maintained the original well-layered morphology of the graphene oxide. The graphene had smooth surface and high quality as completely reduced by high-temperature thermal method. However, the reduction the photochemical-thermal reaction was not sufficient and caused many vesicles on the graphene surface due to the low temperature and the lack of reaction time.

Abstract: The Pd-based oxidation catalysts on stainless steel wire mesh(SSWM) monolith were prepared by electroless plating method. The effect of two different acid bath (including HNO3-HF and concentrated HCl) on the surface morphology of SSWM substrate and the adhesion of palladium particles with substrate were firstly studied. Then the etched SSWM monoliths were used as support to prepare Pd/SSWM monolith catalysts by electroless plating method and their application in toluene catalytic oxidation was also studied. The results indicated that the optimal palladium loading was 0.3wt% and the calcination temperature was 600°C. And the catalyst etched by HNO3-HF showed better activity in toluene catalytic oxidation and worse adhesion of palladium particles with substrate than that etched by concentrated HCl.

Abstract: LaF₃ and LaF₃: Re (Re= Ce³⁺, Eu³⁺ and Tb³⁺) nanocrystals have been successfully synthesized by a facile and rapid microwave heating method. The structure, morphology and fluorescent properties of the as-prepared products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and photoluminescence spectroscopy (PL). XRD patterns showed that the undoped and doped LaF₃ nanocrystals had hexagonal structure with good crystallinity and high purity. TEM and HRTEM images showed that the LaF₃ nanocrystals have uniform sizes with mean diameter about 20 nm and are characteristic of inner cavities. The luminescence spectra of the LaF₃: Re (Re= Ce³⁺, Eu³⁺ and Tb³⁺) nanocrystals indicated that different rare-earth ions have been successfully doped in LaF3 matrix via the microwave heating method.

Abstract: A enviromentally friendly solid chemical cleaner is made from citric acid,sulfamic acid,polyasparticacid,sulfourea and accessory ingredient.The performances of corrosion inhibition and biodegradability of cleaner are studied by the static hanging piece and shaking-bottle incubating test.The corrosion inhibition mechanism of cleaner is studied by potent iodynamic polarization and the corrosion testing piece is observed by means of SEM.The results show that the cleaner has good corrosion inhibition performance on carbon steel,stainless steel,copper and aluminum.The biodegradation rate is above 94% after 28 days.

Abstract: A newly developed water-soluble azobenzene-containing monomer, 4-(4-((4- ethoxyphenyl)diazenyl)phenoxy)-N-(2-(methacryloyloxy)ethyl)-N,N-dimethylbutan-1-aminium bromide (assigned to M), was synthesized, and then a thermo-/light-sensitive gel was prepared by copolymerization of M and N-isopropylacrylamide. The properties of the gel were subsequently investigated by DSC, UV-vis, and gravimetry. The results showed that the copolymer hydrogel had a very quickly tran-cis photoisomerization rate upon UV irradiation. The critical solution temperature (CST) of the copolymer hydrogel could be toned by the M content and U, did also of the swelling ability.

Abstract: Wood is being used extensively in timber construction in China. It is important to understand its response when exposed to elevated temperatures. In fire-resistant design for timber construction, the main goal is to ensure that enough structural integrity is maintained during a fire to prevent structure collapse. To study the effect of temperature on bending strength (MOR) and stiffness (MOE) of solid clear wood from Chinese larch, a total of 108 samples with various target temperatures were tested in static bending under same temperatures to ensure the wood temperature to be sustained. The results indicated that exposure to sustained temperatures caused significant degradation of bending strength and stiffness. The degradation of chemical composition of larch wood happened after 170 °C and caused a serious drop in mechanical properties of larch wood after 225 °C. The bending strength and MOE of larch wood behaved negative linear relationship with temperatures before 100 °C.

Abstract: This paper adopts nonlinear vibration method to analyze the fluctuation process of fiber movement. Based on Hamilton Principle, this paper establishes differential equation of fiber axial direction movement. Using variable-separating method, this paper separates time variable from space variable. By using the disperse movement equation of Galerkin method, this paper also discusses the stable region of transition curve and points out those influencing factor and variation trend of fiber vibration.

Abstract: A transient numerical model and experimental study of combustion and heat transfer for methane and oxygen within a two-section porous burner are presented in this paper. It is found that the maximum flame velocity is influenced by the combined effects of extinction coefficient and convection heat transfer coefficient, and that the minimum flame velocities of ceramics with various pore densities have slight differences at different equivalence ratios, while maximum flame velocities have large differences. In addition, the flame velocity depends not only on the interfacial convection heat transfer, but also on the radiation heat transfer of the ceramic foams, which is in accordance with our numerical simulation. Meanwhile, the numerical research in the present paper indicates that radiation extinction coefficient or pores per inch is not the only reason to characterize the heat regeneration effect of ceramic foams.

Abstract: Activated carbon (AC) was pretreated by H₂O₂ or HNO₃ and then loaded with cerium to obtain Ce/AC composites as desulfurization adsorbents. The adsorption isotherms of as-prepared Ce/AC composites for dibenzothiophene were measured in static batch desulfurization of model fuel and compared with the one prepared without AC pretreatment. It was found that both H2O2 and HNO3 pretreatment could enhance the adsorption capacity of Ce/AC composites. The results were discussed in terms of surface chemistry and texture property. The improvement could be related to increased surface acidic groups and better dispersion of loaded metal species bought about by the two pretreatment methods

Abstract: Five groups of polyacrylate dispersion are prepared with emulsion polymerization technique. Methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA) and styrene (St) are employed as basic polymerizing monomers; acrylic acid (AA) and glycidyl methacrylate (GMA) as reactive monomers; sodium dodecylsulfate (SDS), composite fatty alcohol ether polyethylene oxide (composite AEO) as emulsifier and ammonium persulfate (APS) as initiator. The polymerizing monomers and their charge ratio, pH of pre-emulsions and product emulsions as well as the dosage of ecological cross linker GMA are changed for their effects on the reaction conversion rate, gelatinization rate and staining resistance, yellowing resistance and water tolerance of samples. The studies show that the pH value of pre-emulsion and product emulsion as well as GMA content act on remarkable effects on the application properties of the ecological polyacrylate pigment binder.