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61.
Electrostatic polymer processing of isotactic poly(4-methyl-1-pentene) fibrous membrane 总被引:1,自引:0,他引:1
Isotactic poly(4-methyl-1-pentene) (P4M1P) is a widely used polymer in industrial applications and specifically, in medical products. Producing micro- or nanofibers would expand the usefulness of P4M1P to a broad range of medical applications. The choice and quality of solvent for the solution used for electrospinning can have a dramatic effect on the spinnability of fibers and on their morphological appearance. In this study, four solvent systems: cyclohexane, cyclohexane/acetone mixture, cyclohexane/dimethyl formamide (DMF) mixture and cyclohexane/acetone/DMF mixture have been investigated. As demonstrated by FE-SEM, electrospun fibers with different morphologies including round, twisted with a roughened texture, curled and twisted-ribbon shapes were formed. The fiber shape and morphology depended strongly on the type and amount of non-solvent used. 相似文献
62.
4-(N-异丙氨基)-苯甲酸的合成研究 总被引:1,自引:0,他引:1
对分子中既具有吸电子基,又具有给电子基的化合物4-(N-异丙氨基)-苯甲酸进行了合成,具体的合成步骤和反应条件为:50mL水中加入3g(0.022mol)对氨基苯甲酸,再加入无水碳酸钾1.5g(0.011mol),调整pH约为8,使成羧酸盐,经过滤后加入2-溴丙烷2.5g(0.02mol),加热回流12h,直至下层的2-溴丙烷基本消失,冷却,得灰白色固体,重结晶并用活性炭脱色,得白色晶体4-(N-异丙氨基)-苯甲酸。 相似文献
63.
In order to study the influence of cerium ion implantation on the aqueous corrosion behavior of zircaloy-4, specimens were implanted by cerium ions with a fluence range from 1×1016 to 1×1017 ions/cm2 at maximum 150°C, using MEVVA source at an extracted voltage of 40 kV. The valence and elements penetration distribution of the surface layer were analyzed by X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES) respectively. Glancing angle X-ray diffraction (GAXRD) was employed to examine the phase transformation due to the cerium ion implantation in the oxide films. Three-sweep potentiodynamic polarization measurement was employed to value the aqueous corrosion resistance of zircaloy-4 in a 1 N H2SO4 solution. It was found that a significant improvement in the aqueous corrosion behavior of zircaloy-4 implanted with cerium ions compared with that of the as-received zircaloy-4. The improvement effect will declined with raising the implantation fluence. The bigger is the fluence, the less is the improvement. Finally, the mechanism of the corrosion behavior of the cerium-implanted zircaloy-4 is discussed. 相似文献
64.
M. Nishida T. Hanabusa Y. Ikeuchi N. Minakawa 《Materialwissenschaft und Werkstofftechnik》2003,34(1):49-55
Stress measurement methods using neutron and X‐ray diffraction were examined by comparing the surface stresses with internal stresses in the continuous tungsten‐fiber reinforced copper‐matrix composite. Surface stresses were measured by X‐ray stress measurement with the sin2ψ method. Furthermore, the sin2ψ method and the most common triaxal measurement method using Hooke's equation were employed for internal stress measurement by neutron diffraction. On the other hand, microstress distributions developed by the difference in the thermal expansion coefficients between these two phases were calculated by FEM. The weighted average strains and stresses were compared with the experimental results. The FEM results agreed with the experimental results qualitatively and confirmed the importance of the triaxial stress analysis in the neutron stress measurement. 相似文献
65.
66.
随着苏丹1/2/4区块的深入开发,为了加快开发主力油层,提高原油产量,降低钻井成本,GNPOC在此区块布置水平井开发任务。所开发的区域主要分布于Heglig,Munga,Simbir,Bamboo区块,油层所在是Zaqar和Bentiue地层。此层位具有高渗透,地层温度高,易塌、气窜等复杂问题,尤其是Heglig和Munga地区井壁坍塌严重。为此,根据地质资料、井身结构和对水平井注水泥的技术要求,科学合理设计施工工艺,优选出适合此地区固井施工的冲洗液和隔离液,特别是经过努力实践,开发出了新型膨胀水泥浆体系,此体系具有高强度、低失水、无析水、防气窜之功效。结合使用哈里伯顿CPT—Y4大功率固井车,精确计量和自动密度控制,该体系水泥浆目前已在7口水平井施工中得以应用,均为优质井。现正在被大量使用,此体系的开发,解决了该固井技术难题,创造了中国固井在海外首次水平井作业一次成功的历史记录,具有较高的经济和社会效益。 相似文献
67.
Co^3+—modified Surface of LiMn2O4 Spinel for its Improvementof Electrochemical Properties 总被引:3,自引:0,他引:3
ZishanZHENG ZilongTANG ZhongtaiZHANG JunbiaoLU WanciSHEN 《材料科学技术学报》2003,19(4):359-362
Cobalt was used to modify the surface of spinel LiMn2O4 by a solution technique to produce Co^3 -modified surface material (COMSM). Cobalt was only doped into the surface of LiMn2O4 spinel. XPS(X-ray photoelectron spectroscopy) analysis confirms the valence state of Co^3 . COMSM has stable spinel structure and can prevent active materials from the corrosion of electrolyte. The ICP(inductively coupled plasma) determination of the spinel dissolution in electrolyte showed the content of Mn dissolved from COMSM was smaller than that from the pure spinel. AC impedance patterns show that the charge-transfer resistance (Rct) for COMSM is smaller than that for pure spinel. The particles of COMSM are bigger in size than those of pure spinel according to the micrographs of SEM(scanning electron microscopy). The determinations of the electrochemical characterization show that COMSM has both good cycling performance and high initial capacity of 124.1 mA/h at an average capacity loss of 0.19 mAh/g per cycle. 相似文献
68.
The influence of NaCl and CO2 on the atmospheric corrosion of magnesium alloy AZ91 is studied in the laboratory. Samples were exposed under carefully controlled air and flow conditions; the relative humidity was 95%, the temperature was 22.0°C and the concentration of CO2 was < 1 ppm or 350 ppm. Different amounts of sodium chloride (0–70 μg/cm2) were added before exposure. The corrosion products were analyzed by gravimetry, ion chromatography, X‐ray diffraction and scanning electron microscopy. Mass gain and metal loss results are reported. The combination of high humidity and NaCl is very corrosive towards AZ91. However, the NaCl‐induced corrosion is inhibited by ambient concentrations of CO2. Exposure in the absence of CO2 gives rise to heavy pitting, with brucite, Mg(OH)2, being the dominant corrosion product. In the presence of CO2 a layer of hydrated magnesium hydroxy carbonate, Mg5(CO3)4(OH)2 · 5 H2O forms. A tentative corrosion mechanism is presented that explains the behavior in the two environments. 相似文献
69.
We report a study of a series of heavy rare earth tris‐8‐hydroxyquinolines (REQ3s), using UV‐visible absorption spectroscopy, infrared absorption spectroscopy, and photoluminescence (PL) measurements. We show that the heavy REQ3s are all chemically similar to each other and to aluminium tris‐8‐hydroxyquinoline, at least in terms of the ligand behavior. Characteristic rare earth 4f–4f luminescence is only observed for ErQ3 and YbQ3 due to the relatively low energy of the ligand triplet state. We show that a triplet transfer mechanism cannot be responsible for the observed Yb 4f–4f luminescence observed in YbQ3. Instead, an internal chemiluminescent process is shown to be energetically favorable. The thin film PL spectra of all the heavy REQ3s are dominated by triplet emission, except for that of ErQ3, for which transfer to the Er3+ ion represents an efficient alternative. The PL spectra of powder samples, which would be expected to consist of approximately equal amounts of both isomers, are dominated by singlet emission. This is in contrast to the results from the thin films, and suggests that the isomer which predominates in the thin films has a much higher intersystem crossing rate than the other isomer. 相似文献
70.
环境友好包装材料是一类具有环境意识特征的概念.环境友好包装材料依据“4R 1D“原则,注重包装材料与环境的协调性,指导包装材料的研发,一是有利于保护自然资源;二是对生态环境损害最少化.运用环境友好包装材料的概念,实现包装的可持续发展. 相似文献