共查询到19条相似文献,搜索用时 62 毫秒
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N-乙烯基吡咯烷酮(NVP)是一种重要的精细化工产品。简要叙述NVP的国内外市场情况,分析了乙炔法、催化脱水法及吡咯烷酮法等NVP合成技术,对比分析反应历程、催化剂种类、产品的选择性及原料的转化率,提出了国内研究发展的建议。 相似文献
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对于应用于食品和医药等领域的N-乙烯基吡咯烷酮聚合物,要求N-乙烯基吡咯烷酮单体的纯度高于99.9%,但精馏法往往达不到要求。为了解决这个问题,本文采用结晶法对纯度为99.5%的工业级N-乙烯基吡咯烷酮进行提纯以制备纯度高于99.9%的医药级产品。考察了晶种添加量、晶种添加温度、降温速率、结晶终温、养晶时间、升温速率、发汗终温和发汗时间对最终产品的收率和纯度的影响,并确定了较为适宜的工艺条件:晶种添加量为原料质量的0.1%,晶种添加温度为11℃,降温速率为6℃/h,结晶终温为6℃,养晶时间为20min,升温速率为6~8℃/h,发汗终温为12℃,发汗时间为30min。在这些条件下通过单级结晶就可以将纯度为99.5%的N-乙烯基吡咯烷酮原料提纯至99.95%以上,收率大于74.5%。该方法相对其他分离方法具有较为明显的优势。 相似文献
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通过对单体活度、引发剂以及温度等因素的研究,确定了一套可行的N-乙烯基吡咯烷酮-1-乙烯基咪唑(VP/VI)共聚物的聚合方法。采用该方法制备的VP/VI共聚物分子量比较稳定,残留单体较低,且VP/VI共聚物具有良好的防沾色性能,应用前景和市场价值良好。 相似文献
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引 言黏度是碳纤维前驱体聚丙烯腈原丝纺丝工艺过程中重要的控制指标之一 .为得到高性能的原丝 ,一般采用提高共聚物的分子量、增加纺丝原液中共聚物的浓度或改变共聚单体等方法 ,结果使得纺丝原液黏度急剧上升 ,纺丝压力过大 ,不便于输送 ,易出现危险 .增加共聚单体的含量可降低原液黏度 ,但共聚单体的含量也有极限值[1,2 ] .少量文献曾提到过无机盐对聚丙烯腈溶液黏度是有影响的[3 ,4] ,指出某些无机盐的加入可使得丙烯腈共聚物溶液黏度下降[5] ,这对于原丝生产具有重要意义 ,但对于原液中常出现的离子Na 、Zn2 、Fe3 、Cu2 、K 、… 相似文献
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以γ-丁内酯和甲胺水溶液为原料合成了N-甲基吡咯烷酮(NMP),利用气相色谱仪和全自动电位滴定仪对原料和产物进行了分析,考察了间歇反应的反应温度、反应时间、不同原料的配比等因素对NMP收率的影响,并搭建了连续化装置,在间歇反应条件的基础上进行了连续化实验,进一步优化了反应条件,为中试研究过程提供了基础数据。 相似文献
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叙述了N-乙烯基己内酰胺的国内外研究现状和进展,介绍了它的合成工艺及应用.论述了制取乙烯基己内酰胺的液相法:在氢氧化钾存在下,通过乙炔和己内酰胺发生反应生成.该方法操作简单,易于控制,且为常压反应. 相似文献
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Radiation graft copolymerization of comonomer mixtures of acrylic acid (AAc) and styrene (S) onto polypropylene (PP) films by the mutual method has been investigated. The effect of different factors that may affect the grafting yield, such as inhibitor concentration (Mohr’s salt), solvent composition (MeOH and H2O), radiation dose and dose rate, was studied. It was found that Mohr’s salt was very effective when the content of AAc in the comonomer mixtures was low. However, the addition of 1·25wt% of Mohr’s salt reduced homopolymer formation and enhanced the grafting process. Graft copolymerization in the presence of a solvent mixture composed of methanol and water was found to afford a higher grafting yield than in pure methanol, regardless of the composition of the comonomer mixture used. However, the highest degree of grafting was obtained at a solvent composition of 20% H2O: 80% MeOH and a comonomer mixture of 20% AAc: 80% S. An attempt was made to determine each PAAc and PS fraction by different methods in the graft copolymer obtained. Elemental analysis indicated that the PAAc fraction with respect to PS in the graft copolymer decreased with increasing AAc ratio in the comonomer feed solution. The rough assessment of these fractions by IR spectroscopy showed similar trends. The reactivity ratios of AAc and S monomers determined in the present graft copolymerization system were found to be 0·45 and 1·3, respectively. © of SCI. 相似文献
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交联型聚氨酯乳液的研究 总被引:10,自引:1,他引:10
以聚醚,TDI,1,4-丁二醇及含羧基和羟基的交联剂等为主要原料合成聚氨酯乳液。讨论了nNCO/nOH,交联剂加入量及-COOH的质量分数对乳液性能的影响,得到原料的合适用量。 相似文献
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双组分聚氨酯胶黏剂的研究 总被引:1,自引:0,他引:1
合成了四种相对分子质量和官能度各不相同的聚酯多元醇,并与MDI反应合成了端羟基及端异氰酸基预聚体,通过红外光谱对其结构进行了表征。用聚醚多元醇与TDI及HDI反应合成了端异氰酸基预聚体。研究了不同体系的粘接性能及热失重情况,结果表明-OH/-NCO固化体系室温剪切强度为35~40MPa、90度剥离强度为5~7kN/m,-NCO/-NH2固化体系室温剪切强度为20~30MPa、90度剥离强度为6~15kN/m。研制的聚氨酯胶黏剂具有优异的耐磨、耐空蚀性能,可用于水轮机过流部件的修补及材料的结构粘接。 相似文献
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形状记忆聚氨酯的研究现状 总被引:4,自引:0,他引:4
从形状记忆聚氨酯的记忆机理、数学模型、形状记忆影响因素、以及近期实验和理论研究进展等方面介绍了形状记忆聚氨酯的研究现状。并对当前形状记忆聚氨酯的应用领域和发展趋势作了阐述。 相似文献
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The synthesis of N-vinyl caprolactam (NVCL), with acetylene as alkylene agent, was studied in a stirred reactor system. With potassium hydroxide (KOH) being used as catalyst and 18-crown-6 ether as cocatalyst, NVCL was synthesized by the reaction of acetylene with caprolactam (CL). Crude products were purified by vacuum distillation. The addition of 18-crown-6 ether accelerates the reaction rate of the nucleophilic addition much greatly. The initial explanation suggests that the hole radius of 18-crown-6 ether is close to the one of K+. A complex is formed between 18-crown-6 ether and K+ ion on the formed intermediate of potassium caprolactam, so the addition reaction between acetylene and caprolactam was accelerated greatly. In the stirred tank reactor (500 mL four flask bottle), the CL conversion is 30.5% and the product selectivity is up to 73.4%. The experimental data indicate that the product mixture is a non-ideal liquid mixture. A single process of distillation is difficult to obtain a high purity NVCL product. The combination of extraction and distillation is an ideal separation process for producing high purity NVCL. 相似文献