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排序方式: 共有8837条查询结果,搜索用时 828 毫秒
121.
Yu-Han Teng 《Polymer》2006,47(11):4004-4011
Relatively high molecular weight polyamines with aromatic nitro groups in the repeat units were prepared by the reactions of aliphatic diamines, and 1,5-difluoro-2,4-dinitrobenzene, at elevated temperatures in diphenyl sulfone. The physical characteristics, including solubility, thermal stability, and viscosity of the resulting polyamines were found to be strongly dependent on the aliphatic chain length of the diamines used. All polymers exhibited exceptional solvent resistance. Except for strong acids with bulky counter-ions, including sulfuric, perchloric, and nitric acids, the polymers were found to be insoluble in all common organic solvents at room temperature. 相似文献
122.
123.
介绍了以甲基异丁基酮(MIBK)和甲乙酮(MEK)为溶剂进行脱蜡脱油生产微晶蜡的试验研究,对溶剂脱蜡脱油过程的各种工艺条件进行了考察。结果表明,与采用常规溶剂的过程相比,其过滤速度和微晶蜡产品的收率都得到提高,而且微晶蜡的含油量达到小于1%的食品级标准要求。MIBK—MEK拥有的良好的选择性使其在溶剂脱蜡脱油生产微晶蜡工艺中有较好的应用前景。 相似文献
124.
耐水性木材用脲醛粘合剂的研究 总被引:6,自引:1,他引:6
研究了改进胶合板用脲醛粘合剂的耐水性的方法。针对脲醛粘合剂耐水性低的原因,提出在胶液中添加碱性物质——耐水添加剂,可显著改善胶合板的耐水性,几种添加剂并用,胶合板可达一级耐水板的水平。 相似文献
125.
A theoretical DFT study was employed to confirm the Kolbe-Schmitt reaction mechanism and investigate solvent effects on this reaction. The use of a solvent in the Kolbe-Schmitt reaction is desirable to facilitate a homogeneous reaction mixture and potentially improve the reaction rate. The candidate solvents were designed using computer aided molecular design (CAMD) and tested using DFT solvation calculations. The results from the quantum mechanical calculations were then used to determine the rate constants for each elementary step, the overall reaction yields and the corresponding residence time. The methodology was tested on the reaction without solvent, with solvents reported in the literature, and with the designed solvents. The study revealed that in the presence of solvents with high dielectric constant the reaction becomes reversible, leading to low product yields. 相似文献
126.
分析了镀暗锡和光亮镀锡引线的可焊性,讨论了添加剂对镀锡引线可焊性的影响,适量的添加剂能提高引线的平整性和可焊性,获得了具有良好可焊性所需的最佳添加剂的加入量。 相似文献
127.
128.
甲烷磺酸电镀Sn-Pb合金添加剂研究 总被引:4,自引:1,他引:4
介绍了国内外磺酸型Sn-Pb合金电镀添加剂近十年的研究历程现况并根据各组分的化学结构及其在电镀中所体现出的性质将添加剂分为Sn^2 离子稳定剂、光亮剂及分散剂三类。最后列出了新研制的甲烷磺酸Sn-Pb合金电镀添加剂的主要性能及具体工艺配方。 相似文献
129.
Previously, it was reported that the direct partial oxidation (DPO) of CH4 with O2 over HZSM-5 catalysts produces C5+ hydrocarbon liquids when the feed contains a propane or propene additive. This work studies additive effects on C5+ production in this system by processing a CH4/C3H8 feed with subsequent removal of the C3 additive and by processing natural gas feed. Results show C5+ production is maintained at constant yields for HZSM-5 catalysts having different zeolitic Al contents after removal of the C3 additive. Mechanistic implications are discussed. Natural gas DPO consistently produced C5+ liquids due to the presence of C2+ components in the feed. While C5+ yields from natural gas DPO are higher than those observed for CH4/C3 feeds, increasing feed O2 concentration, and thus conversion, deleteriously affected C5+ selectivity. 相似文献
130.
Jeffrey A Galloway 《Polymer》2004,45(2):423-428
The effect of sample size on the results of solvent extraction measurements for detecting cocontinuity in polymer blends was investigated. Poly(ethylene oxide)/polystyrene (PEO/PS) blend samples of several thicknesses were analyzed by removing the PEO phase using water extraction. The experimental degree of continuity was shown to have a linear dependence on the reciprocal of sample thickness. A model is proposed to explain this dependence and to allow the bulk or true degree of continuity to be determined. Measurement of the bulk degree of continuity is useful for understanding properties of cocontinuous polymer blends such as electrical conductivity, impact strength, or tensile strength. 相似文献