玻纤增强PA66／PP合金的特性及应用

介绍玻纤增强ＰＡ６６／ＰＰ合金的制备工艺及特性，与纯尼龙６６树脂相比，加工性能好，综合性能优异。该材料适用于中小型油浸式变压器的分接开关及其它绝缘部件。     

Electrooxidation of formic acid on carbon supported PtxPd1−x (x = 0-1) nanocatalysts

In this work, carbon supported Pt_xPd_1−x (x = 0-1) nanocatalysts were investigated for formic acid oxidation. These catalysts were synthesized by a surfactant-stabilized method with 3-(N,N-dimethyldodecylammonio) propanesulfonate (SB12) as the stabilizer. They show better Pt/Pd dispersion and higher catalytic performance than the corresponding commercial catalysts. Furthermore, the electrocatalytic properties of Pt_xPd_1−x/C were found to depend strongly on the Pt/Pd deposition sequence and on the Pt/Pd atomic ratio. At a lower potential, formic acid oxidation current on co-deposited Pt_xPd_1−x/C catalysts increase with increasing Pd surface concentration. Nanoscale Pd/C is a promising formic acid oxidation catalyst candidate for the direct formic acid fuel cell.     

SO_4~(2-)/TiO_2-MoO_3催化合成己二酸二丁酯

以固体超强酸SO2 -4/TiO2 MoO3 为催化剂 ,通过己二酸和正丁醇反应合成了己二酸二丁酯 ,并探讨了诸因素对产率的影响。正交实验结果表明 :SO2 -4/TiO2 MoO3 具有良好的催化活性 ,醇酸物质的量比为 6∶1,催化剂用量为反应物料总质量的 3.3% ,反应时间 1.5h ,反应温度 10 6～ 10 9℃ ,酯收率可达 77.6 %。     

Band Gap Modification of Diamond Photonic Crystals by Changing the Volume Fraction of the Dielectric Lattice

Photonic crystals with a diamond structure of epoxy lattices in which TiO₂-based ceramic particles are dispersed were fabricated by stereolithography. The periodicity of the lattice was designed to reflect electromagnetic waves in the gigahertz range. The volume fraction (β) of the dielectric lattice medium was modified from 14% to 33% by changing the rod diameter of the lattice. The photonic band gap was observed along Γ-L 〈111〉, Γ-X 〈100〉, and Γ-K 〈110〉 directions and the complete photonic band gap was formed at over β= 20%. The width of the forbidden gap increased gradually when the β increased over 14%, and reached 2.4 GHz at β= 33%. These results agreed with the band calculation using the plane wave expansion method.     

Determination of the vapor pressures of select polychlorinated dibenzo-p-dioxins and dibenzofurans at 75-275 °C

Vapor pressures were determined for several polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at 75-275 °C, extending the available literature data to more relevant temperature regions and providing the first experimental data for 2,3,7-trichlorodibenzo-p-dioxin (2,3,7-TriCD). A modification of the effusion technique, based upon controlling the diffusion of the target compound and subsequent high resolution gas chromatography/low resolution mass spectrometry (HRGC/LRMS) analysis, was proven comparable to other accepted methods for determining the vapor pressures of semi-volatile organic compounds (SVOCs). Vapor pressures for octachlorodibenzo-p-dioxin (OCDD) and octachlorodibenzofuran (OCDF) were in excellent agreement with those reported in literature. The application of the current method for the vapor pressure determinations of eight polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/PCDFs) in the extended temperature range (up to 275 °C) is reported. The extension of the vapor pressures to such temperatures, unprecedented for the PCDDs/Fs, is important for vapor-particle partitioning modeling in regions relevant to PCDD/F formation and control. Estimates for the melting temperatures and enthalpies of sublimation and vaporization are also reported, the latter for which no experimentally determined values have been found in the literature. The use of the method to deliver reproducible, trace concentrations (ppt-ppb) of targets was applied to the calibration of the jet-REMPI/TOFMS as an online detector for low chlorinated PCDDs/Fs.     

X-ray photoelectron spectroscopic study of the oxidation and reduction of a cerium(III) oxide/cerium foil substrate

X-ray photoelectron spectroscopy has been used to examine the nature of the oxide overlayers on a passivated cerium metal foil as a function of a variety of oxidation and reduction treatments. Oxidation of a clean uncontaminated cerium(III) oxide surface is facile at room temperature and produces non-stoichiometric ceria (CeO_2–x) at oxygen doses as low as 10 L. At higher doses the overlayer thickens, and after a dose of 160 L the layer depth exceeds the Ce 3d photoelectron attenuation distance of about 20 Å. High pressure treatment of the foil in oxygen (0.5 bar at RT and 473 K) produces CeO₂ in a high degree of crystallographic order such that O 1s photoelectron intensities are increased above that expected from a randomly oriented powder. An attempt to reduce the CeO₂ layer formed by controlled oxidation with CO (633 K, 14 h, 0.6 bar) results in the formation of a carbonated surface layer. Results following attempts to reoxidise this layer are discussed.     

Phase transitions and dimensional and morphological changes in an “Aluminum Hydroxide-Alumina” system under a shock-wave action

A method is proposed to study the sequence of phase transitions in powdered materials under a shock-wave action. It is shown that the aluminum hydroxide-alumina system has the following sequence of phase transformations under a shock-wave action: bayerite boehmite -Al₂O₃ -Al₂O₃. It is found that there are no transitional high-temperature modifications of alumina. A method is developed for obtaining a submicron alumina powder, which allows obtaining materials with a controlled phase composition, including a thermodynamically stable -modification of Al₂O₃. The specific features of the morphological structure and the phase and structural characteristics of powders after a shock-wave action are considered.Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 1, pp. 110–119, January–February, 2005.     

Quantitation of volatile compounds in heated triolein by static headspace capillary gas chromatography/infrared spectroscopy-mass spectrometry

Static headspace and capillary gas chromatography/infrared spectroscopy-mass spectrometry were used to collect, separate, identify and quantitate the oxidative and thermal decomposition products in heated triolein. Approximately 4 L of triolein was heated in a deep-fat fryer at 190°C for 12 h each day for a total of 60 h, until it contained>-20% polymeric material. The concentration of heptane and octane increased after 12 h heating, then decreased upon further heating, while the concentration of volatile aldehydes decreased gradually during heating. After 12 h of heating, the concentrations of the major volatiles changed as follows: heptane (16.36 to 30.17 ppm), octane (24.48 to 40.77 ppm), heptanal (21.68 ppm to 9.11 ppm), octanal (35.53 to 36.64 ppm), nonanal (68.95 to 43.16 ppm), (E)-2-decenal (135.00 to 89.00 ppm) and (E)-2-undecenal (88.50 to 61.00 ppm). After 60 h of heating, when the oil contained over 20% polymeric material, the concentrations of heptane, octane, heptanal, octanol, nonanal, (E)-2-decenal and (E)-2-undecenal were 5.16, 4.39, 5.45, 7.02, 18.07, 12.50 and 6.00 ppm, respectively.     

双－（p－N，N－二甲氨基苄叉）酮／二苯基碘鎓盐复合体系的电子转移光显色

不同的双－（ｐ－Ｎ，Ｎ－二甲氨基苄叉）酮ＤＭＢＫ和二苯基碘盐（ＤＰＩＯＦ）复合，组成一种新型的电子转移光显色体系，ＤＭＢＫ／ＤＰＩＯＦ复合体系在暗处有良好的热稳定性。在光作用下很快发生从激发态ＤＭＢＫ至ＤＰＩＯＦ的电子转移，并伴随ＤＭＢＫ染料的褪色，测得ＤＭＢＫ光褪色速度的次序为：ＤＭＢＡ＞ＤＭＢＰ＞ＤＭＢＨ。与此同时，电子转移又引起新的光显色反应，对ＤＭＢＡ化合物，在７００ｎｍ处出现新吸收峰。其光密度随光照时间而增长，然而，ＤＭＢＰ和ＤＭＢＨ体系这种光显色现象并未观察到，这可能由于它们的中间产物不能共平面的缘故，ＤＭＢＡ的光显色速度和最大密度明显取决于浓度和溶剂性质。本文对这种短波区光褪色和长波区光显色的光化学反应过程作了讨论。