Papers by Author: Bo Wen Cheng

Abstract: We have measured the Raman spectra of all samples in the process of preparing polyacrylonitrile (PAN) iron complex nanofibers, and compared their Raman spectral characteristics, and thus gained a preliminary result for the PAN nanofibers structural changes in the different stages. Through its Raman spectral analysis and comparison we can find that the cyano group (C N) of modified PAN nanofibers disappeared while the Raman bands of C = N group appeared. For the pre-oxidized PAN nanofiber, because the D and G bands of the C = C vibration appeared in the Raman spectra, it is concluded that the PAN nanofiber has an apparent structural change. Finally, it is also found that that Fe³⁺ and O^2- ions have formed coordination bonds in the further prepared PAN iron (Fe³⁺) complex nanofibers because the characteristic Raman band of Fe = O bond appears.

Abstract: Polyacrylonitrile (PAN) nanofibers were fabricated via electrospinning technique, and the modified Fe-polyacrylonitrile nanofibers photocatalysts(Fe-AO-n-PAN) were prepared by a reaction between PAN nanofibers (AO-n-PAN) containing amidoxime group and ferric chloride. Then Fe-AO-n-PAN were used as heterogeneous catalysts in the oxidative degradation reaction of C.I. Reactive Red 195(RR195) in water. This paper investigated the influences on the degree of the conversion from nitrile group to amidoxime group (CP%); analyzed the impacts on the Fe (III) ions content (Q_Fe-PAN) in Fe-AO-n-PAN; and studied the effects of Q_Fe-PAN on the decoloration rate of the dye. The results indicated that the CP% value were greatly enhanced not only with concentration of NH₂OH•HCl increasing, but also gradually with the prolongation of reaction time. In addition, the Q_Fe-PAN of Fe-AO-n-PAN increases with the rise of C_Fe and the CP% value. Finally, Fe-AO-n-PAN have remarkable catalytic activity on the degradation of RR 195, and higher Q_Fe-PAN could promote the catalytic performance of Fe-AO-n-PAN.

Abstract: NiFe2O4 nanoparticles was successfully synthesized by hydrothermal decomposition of a gel of Ni-Fe-EG (EG=ethylene glycol) in water solution. The crystal structure and morphologies of the products were characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). All the diffraction peaks in XRD patterns revealed that the as-synthesized nanoparticles were pure NiFe2O4. TEM images disclosed that the particle sizes of the nanoparticles were in the range of 10 − 25nm. The cyclic voltammetry (CV) and galvanostatic charge/discharge results tested in 6M KOH solution revealed a double layer capacitive behavior and a revisable charge/discharge property.

Abstract: PU/CS nanofiber membrane was prepared by means of electrostatic spinning. The morphology of nanofiber membrane was examined by a scanning electron microscope (SEM), and the mechanical property, water absorption, moisture permeability and antibacterial performance were also investigated. The results show that the diameter and mechanical property of PU/CS nanofiber decreased with the increase of the content of CS. However, the water absorption, moisture permeability and antibacterial performance were improved significantly with the addition of CS.

Abstract: A kind of pullulan biopolymer nanofibers with diameter of 100～700nm were obtained using redistilled water as solvent through electrospinning technology in this paper. The effects of the spinning solution concentration, applied voltage, flow rate and capillary–screen distance on morphology and diameter distribution of pullulan nanofiber were studied by SEM. The results show that, different parameters had great influence on nanofibers’ morphology and diameter. The optimal parameters of pullulan nanofibers electrospinning were: 22wt.% spinning solution concentration, 31 kV voltage, 20 cm capillary–screen distance and 0.5ml/h flow rate.

Abstract: Polyurethane-poly (vinyl alcohol)/chitosan (PU-PVA/CS) blend nanofiber nonwovens were successfully prepared by coelectrospinning in this paper. The morphology, diameter and structure of the electrospun nanomaterials were examined by SEM and FITR, and their mechanical properties were tested. The diameter distribution of the nanofibers was measured by Image-Pro Plus. The results show that the ideal nanofibers with the diameter in 50-350 nm can be obtained with the proper technical parameters of PU and PVA/CS nanofibers as follows: the spinning voltage at 30 kV and 40 kV, the extruding speed at 6 mL/h and 0.5 ml/h, the collecting distance at 150 mm and 200 mm, respectively.

Abstract: Alumina fiber, a kind of inorganic fiber, was widely used in many fields owing to its excellent performance. CeCl₃/AlCl₃/PVP was used as spinning solution for producing organic-inorganic hybrid fiber by electrospinning, then, alumina fiber doped cerium can be successfully obtained after high temperature calcination. In the paper, the influence of CeCl₃ to the crystallization and thermal stability was discussed. The results show that alumina nanofiber with average diameters of 200nm-800nm are obtained by calcination of the as-prepared fibers .The addition of CeCl₃ significantly delay the crystallization transformation process of alumina fiber, while the formation of CeO₂ reduce diffusion rate of Al3+, eventually, imped the phase transformation of Al₂O₃ and improve its thermal stability.

Abstract: The PAN/PU nanofiber membrane was prepared by twin-jet electrospinning. By changing the spinning voltage, solidification distance and jet velocity, the effects of each parameter on the fiber morphology could be analyzed. The diameter of the fiber was examined by scanning electron microscopy. The result showed that the excellent product could be got under such experimental conditions, which were 10%PAN and 10%PU solution, 25KV voltage, 15cm solidification distance with the jet velocity of 0.8ml/h and 1.3ml/h.

Abstract: In this paper polyurethane (PU) / polyaniline (PANI) nanofibers were successfully prepared via electrospinning with N, N-dimethylformamide (DMF) and tetrahydrofuran (THF) mixture (1:2 mass ratio). The morphology, diameter and structure of the electrospun nanofibers were examined by scanning electron microscopy (SEM) and the diameter distribution of nanofibers was measured by Image-Pro Plus. Results indicate that the morphology, diameter and uniformity of the fibers were influenced by solution concentration, applied voltage, capillary–screen distance and flow rate greatly, and the finer and uniform nanofibers were electrospun from total solid content of the spinning solutions at 8 wt. %, PU and PANI with ratio of 10/1 (w/w), the spinning voltage at 35 kV, the collecting distance at 15 cm and the extruding speed at 6 ml/h.

Abstract: . In this paper, thin palladium (Pd) membranes, which are supported on alumina nanofiber nonwoven produced by electrospinning method, were prepared by electroless plating method. The influence of different pretreatment methods (iron wire activation) and reducing agent (sodium hypophosphite and hydrazine hydrate) on the structure of Pd membrane were studied. The morphology, surface element and crystal structure of the Pd membrane were investigated by SEM, EDS and XRD. The results showed that the compact Pd membrane was formed on the alumina nanofiber nonwoven when the pretreatment method of iron wire activation was adopted and the reducing agent of sodium hypophosphite was used, which will be applied widely in hydrogen separation area.