Yingxin Chen

A new route for preparing corundum-type In2O3 nanorods used as gas-sensing materials

Corundum-type In2O3 nanorods were synthesized under ambient pressure by annealing, at 600 ◦ C, orthorhombic InOOH nanorods obtained by solvothermal reaction. The samples were characterized by x-ray diffraction (XRD) and transmission electronic microscopy (TEM), and their gas sensitivities were obtained. The results of XRD and TEM experiments show that solvent and surfactants have significant effects on the formation and morphology of the metastable phase during the synthesis of the precursor. The gas-sensitivity results show that hexagonal In2O3 nanorods are very sensitive to dilute ethanol and H2S. (Some figures in this article are in colour only in the electronic version)

High-yield production of quasi-aligned carbon nanotubes by catalytic decomposition of benzene

High-yield production of quasi-aligned carbon nanotube (CNT) bundles is presented. Benzene was used as the precursor for this catalytic process at a moderate temperature of 650°C over γ-Al2O3-supported Fe–Ni alloy catalysts with different mole ratios. The maximum yield of high-quality CNTs per hour is even greater than 350% for the optimized catalyst. The products were characterized by thermal gravimetry/differential scanning calorimetry and high-resolution transmission electron microscopy. The results indicated that the products are well graphitized with tube diameters of about 20 nm. Three typical morphologies of the end parts of the CNTs were identified as the open end capped with an Fe–Ni catalyst, the open end without catalyst and the closed end, respectively. A hexagonal carbon-cluster-based growth for this synthesis is suggested.

Sound insulation of glass fiber felt composite structure via the flame blowing process

Glass fiber felt has emerged as a popular material for noise reduction. In this paper, glass fiber felt is produced by flame blowing process. Fiber distribution, microstructure, permeation rate and sound transmission loss (STL) are explored. The results show that, the internal and cross-sectional structures of glass fiber felt are disordered and micro-layer, respectively. There is a directly proportional relationship between fiber diameter and permeation rate. For composite structure, if the face sheet of glass fiber felt with high reflection coefficient, STL of composite structure can be improved. It is also found that STL can be improved by increasing the number of air-layers. However, the influence of the position changing of air-layer can be ignored for STL.

Effect of physical and subsequent processing parameters of glass fiber felts on sound insulation

Abstract The aim of this study is to explore the effect of physical parameters (fiber diameter, thickness, and resin content) and subsequent processing parameters (heat treatment and rolling compaction) on sound insulation of glass fiber felts. The results show an inversely proportional relationship between fiber diameter and sound insulation. The decrease of fiber diameter results in improvement of sound transmission loss (STL). Alternatively, the thickness of glass fiber felts increase leading to the increase of corresponding sound insulation. With the increase of resin content, STLs of glass fiber felts do not increase monotonically. The STLs of glass fiber felt are also improved with the increase of heat treatment temperature. Compressing can reduce the STL due to the reduction of thickness.

Regulation of energy storage capacitance and efficiency in semi-crystalline vinylidene fluoride copolymers through cross-linking method

The increasing demands for compact and low-cost electrical power systems lead to developing high-energy-density dielectric materials. We carry out systematic investigation on the regulation of the semi-crystalline structure in the polymers and their related energy storage/release behavior through the cross-linking method. With respect to poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)], the cross-linked system exhibits a higher energy density and charged-discharged efficiency, as well as lower dielectric loss. In contrast, cross-linked poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] has a lower energy density/charged-discharged efficiency and higher dielectric loss than the pristine polymer. The somewhat contradicted results for these two polymers are closely related to the semi-crystalline structure controlled by cross-linking. The cross-linking mainly take place in the crystalline phase for P(VDF-HFP), while in both the crystalline phase and amorphous matrix for P(VDF-TrFE-CFE). Besides, crystal structures keep intact when setting up cross-linking networks in the polymers. Our approach provides a facile and straightforward way to tailoring PVDF-based polymers for high-energy-density capacitors.