Advanced Materials Research Vols. 1033-1034

Abstract: Poly (vinyl alcohol)-silver nanoparticles (PVA:AgNPs), and poly (vinyl alcohol)-silver nanoparticles-poly (3, 4-ethylene dioxythiophene)/poly (styrene sulfonate) (PVA:AgNPs: PEDOT/ PSS) were generated as ultra-fine electrospun fibers using the aligned fiber mat and aligned single fiber techniques. SEM and TEM were used to confirm the morphology, diameter size, and fiber alignment of the ultra-fine fibers. A two-probe technique was utilized to assess the electrical conductivity of the ultrafine fibers. The highest conductivity of PVA:AgNPs, (10 %w/v:0.75 %w/v) with a fiber diameter of 0.152 μm, with voltage applied at 17.5 kV within a 20 min collection period in the electrospinning process, was 43.20 S/cm; whereas the highest conductivity of PVA:AgNPs: PEDOT/PSS, (10 %w/v:0.25 %w/v:0.084 %w/v), with a fiber diameter of 0.158 μm and voltage applied at 17.5 kV within a 45 min collection period in the electrospinning process, was 92.18 S/cm.

Abstract: A kind of novel biodegradable Chlorinated Polyvinyl Chloride (CPVC) nanofibers using a mixture of Dimethyl Formamide (DMF) and Tetrahydrofuran (THF) as solvent were prepared by electrospinning process in this paper. The morphology of electrospun CPVC nanofiber nonwovens were investigated by scanning electron microscopy (SEM). Results indicated that the morphology and diameter of the electrospun fibers were influenced by CPVC solution concentration and the THF amount in the mixed solvents, and the finer and uniform nanofibers were electrospun from a mixed solvent of DMF and THF with ratio of 3/1(w/w).

Abstract: This research project produced two fabricated ultrafine conductive polymeric fibers. The first fiber was fabricated from a polymer and conductive polymer solution, and the second was fabricated from a polymer and metal nanoparticle/ nanocomposite. The resulting fibers were characterized and analyzed. For all fiber samples, the ultrafine polymeric fibers were fabricated using polyvinyl alcohol (PVA). The conductive polymer used in the first fiber sample was poly (3,4-ethylenedioxythiophene)/ polystyrene sulfonate (PEDOT/PSS). The conductive nanoparticles used in the second fiber sample were silver nanoparticles (AgNPs). The ultrafine conductive polymer fibers and the ultrafine conductive nanoparticle fibers were fabricated using an electrospining process. During the fabrication process of each fiber sample, different concentrations of either PEDOT/PSS, for fiber sample one, or AgNPs, for fiber sample two, were combined in PVA solution. Using optimal conditions, ultrafine fibers were fabricated at intervals of 5 min for the creation of random fibers, and intervals of 20 min for the creation of aligned fiber mats. The resulting fibers ranged from 0.1 μm to 0.2 μm in diameter. After characterization and analysis of the conductive ultrafine polymeric fibers, using either the PVA:PEDOT/PSS compound or the PVA:AgNPs compound, both samples produced greater conductive capacities with greater concentrations of solution. For the random fiber samples, the conductive capacity was sporadic. However, the ultrafine fiber mats (PVA:AgNPs) supported a capacity from 3.64 S/cm to 10.64 S/cm, and the PVA:PEDOT/PSS ultrafine fiber mats supported a capacity from 4.49 S/cm to 7.08 S/cm.

Abstract: The nanofibers of EVOH which was dissolved in DMAC/IPA solution system were successfully prepared by eletrospinning. Through designed the electrospinning parameter of EVOH and observed the fiber morphology by the Field Emission Scanning Electronic Microscope(FESEM), we analyzed the influence of different spinning parameters to the fibers. And finally the optimum spinning process of EVOH nanofibers was obtained, which has the spinning concentration of 18wt%, spinning voltage of 29kV and receiving distance of 18cm. The average diameters of the well spun fibers using the solution system were concentrated between 65nm-105nm.

Abstract: In this Letter, we reported the facile synthesis of manganese (III) oxide (Mn₂O₃) nanowires via the facile hydrothermal treatment in the presence of ammonia, which were prepared simply by hydrothermal treatment of commercial bulky Mn₂O₃ crystals at 160 ^oC for 24 h. The obtained Mn₂O₃ products consist a large quantity of nanwires with the diameters of 30-90 nm, and lengths ranging from 1 to 10 μm. Such high quality nanowires with high aspect ratio have a variety of promising applications. The simplicity of hydrothermal process, cheapness, and availability of raw materials, without the need of catalyst or template, are advantages favoring industrial manufacturing in scaled-up process by the novel method. X-ray and transmission electron microscopy, electron diffraction, and scanning electron microscopy have been employed to characterize these materials. In addition, the possible growth mechanism of the Mn₂O₃ nanowires was also proposed. The growth of Mn₂O₃ nanowires occurred via a dissolution-recrystallization process.

Abstract: ZnNb₂O₆ powder was successfully synthesized via coprecipitation method with Nb₂O₅、Zn(NO₃)₂·6H₂O as raw materials and ammonia as precipitant agent. This precursor on heating at750°C, produced ZN powders. Phase composition, morphology and chemical composition were studied via a combination of XRD, TEM and EDS technique. The effects of synthesis temperature on phase composition and particle morphology were investigated in this paper. The results showed that with the increase of the synthesis temperature, the particle size decreases. We could get the ZnNb₂O₆ powder with high purity, fine crystalline when the synthesis temperature is at 50°C.

Abstract: In order to improve the water resistance of silicate wood adhesive, a kind of silicate adhesive was prepared from water glass with silica as curing agent, and ammonium stearate as modifier. The chemical structure, surface morphology and thermal properties of the silicate adhesive were characterized by Fourier transform infrared spectrometer, scanning electron microscope, and thermo-gravimetric analyzer. As the two main measures of adhesion properties, the bonding strength and water resistance were also determined. The results showed that ammonium stearate was successfully introduced into the molecule structure of silicate, the silicate adhesive have good thermal stability in the range of 30~800 °C and the modified silicate adhesive had more smooth cured morphology. The bonding strength and 24h water absorption rate of poplar plywood glued by the silicate adhesive was 0.71 MPa and 22.81%, respectively, reaching the grade II of plywood performance's national standard.

Abstract: ZnS: Cu/Fe nanocrystals were synthesized by hydrothermal method with thioglycolic acid as a stabilizer. The phases, grain size and luminescent properties of the nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fluorescence photometer respectively. The results showed that ZnS: Cu/Fe nanoparticles have a particle size about 7nm and possess a cubic zinc blende crystal structure. The luminous intensity of ZnS: Cu/Fe nanocrystals was strongly when they were reacted at 140°C for 12 hours.

Abstract: Co/Cu/Fe mixed oxides (Co/Cu/Fe-MOs) were prepared by calcination of Cu/Co/Fe hydrotalcites (Co/Cu/Fe-HTs) precursors. Their structure and morphology were characterized by XRD, TGA, IR and SEM. Co/Cu/Fe-MOs were used for selective catalytic reduction of NO by hydrocarbon. Their catalytic activities were studied by NOx analyzer. The results show that Co/Cu/Fe-MOs have homogeneous distribution of hexagon with particles size around 30~50nm and the specific surface areas are around 70~110 m²∙g^–1. Cu₂Co₈Fe₅-MOs sample exhibits the highest NOx conversion of 32%. Co/Cu/Fe-MOs with lower calcination temperature have higher catalytic activities.

Abstract: With the H₂C₂O₄·2H₂O and Mg(NO₃)₂·6H₂O as the raw materials, nanometer-MgO powder was synthesized at different temperature by the low temperature solid phase method. After the characterization of the structure and property of this kind of nanometer-MgO powder with TG, XRD, SEM and FT-IR, etc, the antibacterial property of nanometer-MgO powder to Escherichia Coli and Staphylococcus Aureus was examined through the bacteriostatic circle method. The results indicated that the powder was single crystal, complete crystallization and uniform distribution with the 10 nm of particle size. It had better resistance and capacity of killing bacteria and the diameter of the bacteriostatic circle was greater than 19 mm.