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991.
Summary The complex forming poly[(ethylene glycol-co-proplene glycol)-g-acrylamide]: polyacrylic acid interpenetrating polymer network hydrogel is able to bend under electric field stimuli. pH, ionic strength gradients and voltage can influence it's bending degree. So we may improve the sample' responsive speed through manipulating those factor in the further study in order to put it into the biomedical application. 相似文献
992.
为了研究抑制剂对银核和硫化银核的不同作用,本工作考察了1-苯基-5-巯基四氮唑(PMT)和苯并三氮唑(BTA)作为抑制剂在银核和硫化银核上物理显影的阳极抑制和解抑制效应。实验结果表明:1)PMT和BTA对Ag核和银离子过量时制得的硫化银核,Ag2S(Ag),的显影催化活性都有不同程度的抑制作用,而对硫离子过量时制得的硫化银核,Ag2S(S),无明显的抑制作用,这可能是由于过量硫离子在硫化银核上的吸附要强于这两种抑制剂;2)S2O3^2-或I^-离子的存在对BTA在Ag核上有解抑制作用,不仅可恢复甚至提高Ag核的显影催化活性,而对Ag2S核的抑制作用无明显影响;3)与BTA不同,S2O3^2-或I^-离子对PMT在Ag核上没有解抑制作用,对Ag2S(Ag)核的抑制作用还稍有增强,而对Ag2S(S)核稍有减弱;4)银溶胶中的表面增强拉曼谱(SERS)测量证实:BTA在Ag核上的吸附导致Ag核显影催化活性的下降,加入S2O3^2-或I^-离子后致使BTA的SERS信号消失则意味着BTA在银核表面的脱附。以上这些结果说明阳极抑制机理在抑制效应中有重要作用。 相似文献
993.
天然肉桂油臭氧化制取苯甲醛 总被引:10,自引:4,他引:10
利用天然肉桂油中富含的肉桂醛,经过臭氧化反应和还原反应制得了苯甲醛。由该法制得的苯甲醛在国际上可作为天然苯甲醛使用。 相似文献
994.
Several Mg–Y binary ribbons with Y content up to 17.9 at.% were fabricated by melt-spinning. X-ray diffraction (XRD) revealed that the phase structure changes with increasing Y content from extended solid solution to partially amorphous, and then fully intermetallic Mg24Y5. Anodic potentiodynamic polarization performed in 0.01 M NaCl electrolyte (pH=12) revealed improved anodic passivity behavior compared to pure Mg for all the Mg–Y alloys. X-ray photoelectron spectroscopy (XPS) revealed that the improved passivity of Mg–Y was more related to the elemental oxidation state rather than the concentration of the surface components. To study the effect of Cl− ion on the passivity behavior, anodic potentiodynamic and potentiostatic polarization were performed on Mg–17.9 at.% Y in alkaline (pH=12) NaCl electrolytes containing Cl− ion in the concentration range from 0.00 to 0.50 M. The passive films formed in 0.01 M NaCl electrolyte were similar to the native film, which were composed of MgO and Y2O3. No CO32− and Cl− ions were incorporated into the passive film. The passivity was significantly degraded in the electrolytes containing higher Cl− concentration (0.1 and 0.5 M). Detailed XPS revealed that the surface films under these conditions were composed of much hydrated species Mg(OH)2 and YOOH and/or Y(OH)3 and CO32− was incorporated into the surface film. The incorporation of Y2O3 in the passive film was given as the reason for the enhanced passivity properties of Mg–Y ribbons. The mechanism of Cl− and CO32− ions to the degradation of the passivity was discussed. 相似文献
995.
Li‐Qiang Shen Zhi‐Kang Xu Qian Yang Hang‐Lin Sun Shu‐Yuan Wang You‐Yi Xu 《应用聚合物科学杂志》2004,92(3):1709-1715
Polyetherimide (PEI) was sulfonated by chlorosulfonic acid (CSA) in 1,2‐dichloroethane for the first time. With the increase of the CSA/PEI repeat unit ratio and/or reaction time, the ion‐exchange capacity (IEC) of the sulfonated polyetherimide (SPEI) increased accordingly. Water‐uptake testing and contact‐angle measurement showed that the hydrophilicity of the SPEI increases with the increase of the IEC. Membranes were fabricated from SPEI/PEI blends with different ratios. The morphologies of the blend membranes were examined by scanning electron microscopy, which showed that the membrane pore size is larger when SPEI with higher IEC was used. With the increase of SPEI ratio in the blend membranes, the membrane pore size also increased. The contact‐angle data of the membranes showed that the hydrophilicity of the blend membrane was elevated because of the sulfonate group on the SPEI molecular backbone. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1709–1715, 2004 相似文献
996.
997.
Donggang Yao Pratapkumar Nagarajan Lei Li Allen Y. Yi 《Polymer Engineering and Science》2007,47(4):530-539
An embossing strategy involving a hot station and a cold station for sequentially heating and cooling the embossing tool was investigated to reduce cycle times in hot embossing polymer microstructures. Experimental studies showed that aluminum stamps with a thickness of 1.4 mm can be rapidly heated from room temperature to 200°C in 3 s using contact heating against a hot station at 250°C. Microchannels and microlenses were successfully embossed onto high‐density polyethylene and acrylonitrile–butadiene–styrene substrates using a heating time less than 3 s and a total cycle time around 10 s. The two‐station embossing process for the microlens was also numerically studied. The simulated filling behavior agreed with the experimental observation and the predicted thermal and deformation history of the polymer offered a good explanation on the experimentally observed process characteristics. POLYM. ENG. SCI., 47:530–539, 2007. © 2007 Society of Plastics Engineers. 相似文献
998.
产业及装饰用聚酰胺纤维产品的应用状况与开发前景 总被引:2,自引:1,他引:2
聚酰胺纤维以其强度、耐磨性、弹性恢复率、韧性等优良性能在产业用纺织品和装饰用纺织品方面的应用日趋扩大,如在轮胎帘子布、汽车用纺织品、过滤材料、BCF地毯膨体纱、特种和军用纺织品上都开发了新产品,受到了市场的欢迎。面对化纤品种结构和市场需求的不断变化,聚酰胺纤维产品应着眼于其性能特点,发展优势产品,拓宽应用面,在化纤市场中占据一定的位置。 相似文献
999.
A nanosized silica particle was used as the support to prepare an Et[Ind]2ZrCl2/MAO catalyst for propylene polymerization of polypropylene. The catalyst and the polymer produced were characterized with nitrogen adsorption, ICP, DSC, SEM, TEM, XRD, solution viscometer, 13C NMR and optical microscopy. The effects of polymerization temperature and [Al]/[Zr] ratio on catalyst activity and polymer melting point were investigated. Under identical reaction conditions, nanosized catalyst exhibited better polymerization activity than the microsized catalyst (e.g., the former had 64% higher activity than the latter at the optimum polymerization temperature (50°C) and [Al]/[Zr] = 570). DSC results indicated that polymer melting point increased with the increase of [Al]/[Zr] ratio and with the decrease of polymerization temperature. XRD results showed that the percentage of γ crystals increased with decreasing [Al]/[Zr] ratio. Electron microscopic results showed that the polymer particle size increased with increasing polymerization temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2573–2580, 2006 相似文献
1000.
Mesoporous Ni–alumina catalysts (Ni–alumina-pre and Ni–alumina-post) were synthesized by one-step sol–gel method using micelle
complex comprising lauric acid and nickel ion as a template with metal source and using aluminum sec-butoxide as an aluminum source. The Ni–alumina catalysts showed relatively high surface areas (303 m2/g for Ni–alumina-pre and 331 m2/g for Ni–alumina-post) and narrow pore size distributions centered at ca. 4 nm. Highly dispersed Ni particles were observed
in the Ni–alumina catalysts (ca. 5.2 nm for Ni–alumina-pre and ca. 6.8 nm for Ni–alumina-post) after reduction at 550 °C,
while a catalyst prepared without a template (NiAl-comp) exhibited inferior porosity with large metal particles (ca. 12.3 nm).
Mesoporous Ni–alumina catalysts with different porosity were obtained by employing different hydrolysis step of aluminum source.
When aluminum source was hydrolyzed under the presence of micelle complex, a supported Ni catalyst with highly developed framework
mesoporosity was obtained (Ni–alumina-post). On the other hand, when aluminum source was pre-hydrolyzed followed by mixing
with micelle solution, the resulting catalyst (Ni–alumina-pre) retained high portion of textural porosity. It was revealed
that the hydrolysis method employed in this research affected not only textural properties but also metal-support interaction
in the Ni–alumina catalysts. It was also found that the Ni–alumina-pre catalyst exhibited weaker interaction between nickel
and alumina than the Ni–alumina-post, leading to higher degree of reduction in the Ni–alumina-pre catalyst. In the hydrodechlorination
of o-dichlorobenzene, the Ni–alumina catalysts exhibited better catalytic performance than the NiAl-comp catalyst, which was attributed
to higher metal dispersion in the Ni–alumina catalysts. In particular, the Ni–alumina-pre catalyst showing 1.5 times higher
degree of reduction and larger amounts of o-dichlorobenzene adsorption exhibited better catalytic performance than the Ni–alumina-post catalyst. 相似文献