Advanced Materials Research Vols. 287-290

Abstract: The effect of non-ferromagnetic Cr interlayer on the high-frequency ferromagnetic properties (HFFMPs) was investigated by use of FeCoTa/Cr/ FeCoTa triple layered films. In conventional thought, the metal interlayer gives rise to a high eddy current loss and therefore a deteriorated HFFMP. However, it is found that HFFMPs depend on the thickness of Cr interlayer. The HFFPMs are improved by Cr-interlayer with a thickness less than 12 nm (sample C1). Comparing with the Cr-interlayer-free FeCoHf single layered film (sample C0), the magnetic anisotropy field of C1 dramatically increases from 185 Oe for C0 to 558 Oe for C1. As a consequence, a high ferromagnetic resonance frequency over than 3 GHz is achieved for sample C1. When the thickness of Cr-interlayer is more than 120 nm (C2), the HFFMPs are reduced due to the increase of eddy current loss and magnetic decoupling between the ferromagnetic layers.

Abstract: Eu³⁺ -doped GdVO₄ powders have been synthesized via a novel hydrothermal method using commercially available Gd₂O₃, NH₄VO₃ and Eu₂O₃ as the reacting precursors. The influences of several important parameters, such as hydrothermal temperature, reaction time and pH value, of the experiment were investigated. The obtained samples were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), and photo-luminescence spectroscopy (PL). The experimental results showed that the optimal reaction condition was processed at 180°C for 12 h and adjusted pH value to 4. The morphology of products was uniform pseudo-octahedron with a little conglomeration. All the phosphors exhibit the characteristic dominant red emission of Eu³⁺ ion (⁵D₀ → ⁷F₂) at 618nm.

Abstract: Aminoalky cellulose is a white, solid cellulose derivative, which could be used adsorbent in order to remove TNT, heavy metal and dyes due to the large of amino. In this paper, the preparation of aminoalky cellulose was reported, and the aminoalky cellulose was characterized by FT-IR, XRD, SEM and TG. The results showed that aminoalky cellulose was successfully prepared, an amorphous phase and a crystalline phase are included in the AmAC, and the decomposition temperature of AmAC was 288.23°C. Some surface properties of AmAC was measured, and the mean pore diameter and total pore volume of the AmAC is about 260.409 Å and 0.363827 cm3 g-1, respectively.

Abstract: The PtRu-SiO₂-TiO₂/C anode electrocatalyst ( loading 10wt% PtRu ) of direct methanol fuel cell is prepared by the surface reductive deposition method, using Vulcan XC-72 carbon black coated with nanometer SiO₂-TiO₂ (SiO₂-TiO₂/C) as the isotopic carrier. The surface characteristics of nanometer SiO₂-TiO₂ is studied through nitrogen adsorption, which shows that it is of porous structure together with large surface area, that is benefit to enhance the activity of SiO₂-TiO₂ and the dispersion of PtRu nanoparticle on the carrier of SiO₂-TiO₂/C. X-ray diffraction( XRD ) and transmission electron microscopy( TEM ) are used to characterize the catalyst. The PtRu nanoparticle homodisperse in SiO₂-TiO₂/C carrier with diameter around 2.4 nm. Cyclic voltammograms and chronoamperograms are conducted to compare the electrochemical methanol oxidation activity of the PtRu-SiO₂-TiO₂/C catalyst with the commercial PuRu/C catalyst ( 20 wt% of PtRu ). The results show that PtRu-SiO₂-TiO₂/C has higher catalytic activity and anti-poisoning ability for methanol oxidation, the addition of porous SiO₂-TiO₂ can replace the PtRu to some extent, comparing with the commercial PuRu/C catalyst, not only the loading of PtRu has been cut down 50%, but also the electro-oxidizing activity of methanol improved. The electro-oxidizing mechanism is basically analyzed.

Abstract: Rare earth modified SO^2-₄/ZrO2 solid acid catalysts were prepared by coprecipitation and impregnation methods respectively. The properties of the samples were characterized by XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy). And their catalytic performances were evaluated and investigated by transesterification of waste oil with methanol. The results showed that the catalyst containing 4% Ce and calcined at 550°C displayed the highest production rate and the better reuse ability than the others. 63.5% yield of fatty acid methyl ester was achieved. An analysis of XRD patterns reveal that the incorporation of rare earth into tetragonal zirconia stabilizes the compound, and the calcination at 550°C increases the reactivity of the catalyst by producing a greater fraction of active tetragonal zirconia. It can be seen from the FT-IR spectra that superacids structures are formed in the catalysts and the acidity is strengthened remarkably and the activated centre of the catalyst were increasesed.

Abstract: Carbon-coated lithium iron phosphate (LiFePO₄/C) powders were synthesized by a simple hydrothermal method and incipient wetness impregnation. The structural and morphological properties were investigated by XRD and SEM. The results show that the LiFePO₄ powders are composed of small plate particles with diameter size of 1-3μm and thickness of 0.2μm. Through incipient wetness impregnation, monodisperse LiFePO₄/C particles were obtained and carbon was uniformly distributed over LiFePO₄ particles to avoid the direct contact of them, which reduces the trend of agglomeration of the particles during the calcinations process.

Abstract: Water-based ink in low-energy surface wetting more difficult and hinder its application. In order to solve water ink in low-energy on the surface wettability problem, change the kind of cosolvent, kind and content of surfactants prepared ink. They were tested in low-energy CD the surface contact Angle to examine wettability of ink, test the surface tension, ink affecting wettability factors were analyzed. Results show that: in water-based ink add isopropyl alcohol, flow ping agent 432 and substrate wetting agent 245, can better improve its surface wettability in low-energy, and base material wetting agent 245 content about 1.25% wet effect is good.

Abstract: Colorless alicyclic polyimides (ALPIs) were synthesized from an alicyclic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA) and an aromatic diamine, 3,4'-oxydianiline (3,4'-ODA). For comparison, a series of crosslinkable ALPI membranes with different content of crosslinkable reagents were prepared. The crosslinkable PI reacts with the crosslinkers and forms covalent bond to create the crosslink structure between PI backbones by free radical reaction. Almost of the crosslinkable PIs exhibit excellent dimensional stability and higher transparency because of the crosslink structure and non-conjugate alicyclic chain. All of the crosslink ALPIs could be coated into flexible and tough films. They had a UV-Vis cut-off at 297 nm and a transmittance of higher than 80% in near ultraviolet region. These PIs show low coefficient of thermal expansion ranging from 57.36 to 47.53 ppm/°C, the glass transition temperature in the range of 336.2-333.0 °C, the decomposition temperature in the range of 433.7-440.0 °C. The crosslinkable ALPIs show excellent optical properties with the excited wavelength ranging from 340 to 328 nm and stronger emission intensity than linear PI, the haze lower than 0.7, the refractive index about 1.6 and the abbe numbers over 165.

Abstract: The modification process of recycled melamine-formaldehyde(MF) plastic on polypropylene(PP) has been studied, and the optimal compounding parameters were obtained by twin extruding system in this paper. The results showed that with increasing of recycled MF plastic in PP, the tensile strength, elongation at break, molding shrinkage and impact strength decreased, the modulus, heat distortion temperature(HDT) and melt flow rate(MFR) increased, which indicates that the addition of recycled MF plastic can improve rigidity, heat resistance, size stability and flowability of PP. More importantly, the oxygen index(OI) of PP was increased with the addition of recycled MF plastic, which indicates that recycled MF plastic can improve the flame-retardant property of PP.

Abstract: Ultra-high molecular weight polyethylene (UHMWPE) was prepared by thermal compression molding method and was irradiated by gamma rays at dose of 100 kGy in air. The wettability and water absorption of non-irradiated and irradiation crosslinked UHMWPE were investigated. It was shown that irradiation crosslinking increased the wettability of UHMWPE. The water absorption rate of UHMWPE was extremely low (<0.02%). After irradiation crosslinking, the water absorption rate of UHMWPE increased.