Advanced Materials Research Vols. 197-198

Abstract: In order to investigate the possibility of reducing the amount of super-absorbing polymer (SAP) now used in the disposable sanitary products, sodium hydroxide(NaOH) was adopted to treat the cellulosic fibers used in the nonwoven absorbing cores. Firstly, NaOH of three different concentrations were used，fibers treated with the concentration of 10% have the best absorbent capacity and were filtered out for making absorbing core samples. Then, three nonwoven absorbing core samples with different treated fiber contents plus one sample of untreated fibers were developed and their absorbent capacity and absorbency rate tests were made. After analyzing, the results show that when NaOH treated fiber (concentration of 10%，finishing time of 50s) contents are 50%, nonwoven absorbing core sample has the best absorbent capacity. In the end, the possibility of using complex nonwoven structure to increase the absorbent capacity was also discussed. As a result, the absorbent capacity of the spunlacing nonwoven with complex structure is higher than the single layer spunlacing nonwoven by 33.3%.

Abstract: Porous PVA/MMT nanocomposites, which included a great deal of macroporous, mesoporous and a few micorporous were fabricated by directional freezing and freeze-drying. X-ray diffraction (XRD), Scan Electric Microscope (SEM), Fourier Transform Infrared (FT-IR) spectroscopy, and Thermo gravimetric-differential scanning calorimeter analysis (TG-DSC) were used characterize the samples. Results showed that the morphology and the interactions between MMT and PVA of the obtained porous nanocomposites were influenced by nanoparticle size, colloid concentration , aging time etc.O-H bond in PVA and Si-O bond in MMT, "acetate" in PVA and O-H bond in particle flat of MMT which occurred coupling constituted hydrogen bonding which enhanced the driving power to help PVA molecules insert into interlayer spaces of MMT.

Abstract: Cerium doped tantalum oxide (Ce-Ta₂O₅) particles were synthesized with hydrothermal method. The electrochemical behaviour of Ce-Ta₂O₅ film electrode in 0.1 mol dm^-3 KCl containing 10 mmol dm^-3 K₃Fe(CN)₆ was investigated with cyclic voltgrammetry (CV). The CV results indicated that the electrochemical reaction on the Ce-Ta₂O₅ film electrode exhibited stable electrochemical property. In addition, the phase structure of Ce-Ta₂O₅ prepared was performed by X-ray diffraction (XRD). The result revealed that the cerium doped Ta₂O₅ belongs to orthorhombic crystal.

Abstract: A magnetorheological (MR) valve is a device that uses the MR fluid flowing through a cylindrical orifice. In this paper, based on volumetric flow rate equation in the cylindrical MR valve, the necessary active MR fluid volume and the thickness between two cylinders of the valve are carried out. They are the minimum active fluid volume and gap of MR fluid exposed to the magnetic field. The equations for the volume and the gap derived to provide the theoretical foundation for the key geometric design in the valve. The results indicate that the volumetric flow rate can be continuously adjusted by an external magnetic field. The thickness and the volume for the cylindrical MR valve can be calculated based on MR fluid properties, the desired control pressure ratio, and the pressure of the valve.

Abstract: Magnetic materials are one of the promising material for their special magnetic properties and other functionalities. A sol-gel process in reverse microemulsion combined with solvent-thermal technique(ME-SG-ST) was developed for synthesizing nano-sized mesoporous SiO₂/CoFe₂O₄(SCF). Fourier transform infrared spectrometry, TG-DSC, X-ray diffraction, TEM, BET specific surface area measurement, N₂ adsorption-desorption and magnetic analysis were used to characterize the structure and magnetism property. Results showed that spinel CoFe₂O₄ was uniformly dispersed in nanosized SCF particles. The prepared SCF particles possessed mesopore structure and excellent paramagnetism, and will become great promising materials as the supports of catalyst and absorbents for biological and drugs.

Abstract: The polyhedral crystals, octahedral crystals and cube crystals of Zinc hydroxystannate (ZHS) were prepared by the homogeneous precipitation synthesis method. The organic compounds, PEG-400, β-cyclodextrin (β-CD) and L-alanine were added in the reaction systems to control the crystal structure. The crystal structure and morphology of products were characterized by SEM and XRD. The crystal structure of all products could be attributed to the cubic ZnSn(OH)₆ by the XRD analysis. The SEM pictures of the products were different with the change of organic compounds. The FTIR spectrum indicated the ZHS without organic residual and the possible formation mechanism was discussed.

Abstract: Calcium carbonate and zinc hydroxystannate-coated calcium carbonate (ZHSCC) was prepared by biominetic synthesis in template of sodium dodecyl benzene sulfonate (SDBS), and was characterized by XRD, SEM and TG/DSC, moreover, the flame retardant property of ZHSCC in PVC was studed by LOI. The XRD analysis clearly showed the diffraction peaks of zinc hydroxystannate (ZHS) in ZHSCC and calcite crystal structure of calcium carbonate. The TG/DSC and SEM results showed that ZHSCC product was roughly spherical with the size of was about 4 μ. The LOI of PVC/ZHSCC blend increased 5.5 units which showed that ZHSCC had a good flame retardant efficiency for PVC.

Abstract: Tungsten doped tantalum oxide (W-Ta₂O₅) particles were synthesized by a low temperature hydrothermal method. The phase structure of W-Ta₂O₅ particles was characterized by X-ray diffraction (XRD). The XRD results indicated that the samples belonged to orthorhombic crystal. The photocatalytic activity of samples was investigated with degradation methylene blue (MB) under ultraviolet light. The degradation efficiency of MB under the catalysis of W-Ta₂O₅ particles attained 91% when the reaction time was 7 h. The kinetics of MB degradation was respect to the first-order in the presence of the photocatalysts.

Abstract: Microwave dielectric ceramics Y(Nb_0.5Ti_0.5)₂O₆, SmTiNbO₆, LaTiNbO₆ have been prepared by conventional solid state method. The single phase of these three kind of samples are obtained at 1350°C, 1340°C and 1280°C, respectively. SmTiNbO₆ has positive τf (50.05ppm/°C) and Y(Nb_0.5Ti_0.5)₂O₆ (-64.27ppm/°C), LaTiNbO₆ have negative τf (-67.39ppm/°C). Dielectric constant, quality factor and temperature coefficient of resonant frequency increase with the increased sintering temperature firstly and then decrease which is due to the lower density. Dense Y(Nb_0.5Ti_0.5)₂O₆, SmTiNbO₆ ceramics are obtained at the proper sintering temperature but for LaTiNbO₆ ceramics there are many pores on the grain surface.

Abstract: Red fluorescence was widely applied in full color organic light-emitting display and anti- counterfeit technology. Due to concentration quenching red fluorescence was weak and even no luminescence in a solution or solid state. Therefore, novel red fluorescent pigment bis(4-(N-(9, 9- diethyl-2-fluorenyl)phenylamino)phenyl)fumaronitrile (EFPAFN) with non-planar fluorenylamino group and fumaronitrile core was prepared. The compound existed a pair of antiparallel dipole limiting molecular interaction, showed strong red photoluminescence which centralized at 657 nm in solid film. The decomposition temperature of EFPAFN was observed at around 422 °C. In different polarity of solvents the absorption and emission peaks of EFPAFN showed positive and then negative solvatochromic shifts. EFPAFN in water/tetrahydrofuran (v/v, 9:1) mixture was adjusted and aggregated into small size particles in the range of 141-531 nm or big size particles of 255-825 nm as fluorescent organic nanoparticles (FONs). FONs of EFPAFN with donor-acceptor group showed strong emission at 653 nm and had potential applications in nano-sized fluorescence and optoelectronic device.