共查询到20条相似文献，搜索用时 31 毫秒
1.
The rheological behavior of polyvinyl acetate (PVAc) in N,N′=dimethylformamide (DMF), methyl ethyl ketone (MEK), 1,2-dichloroethane
(DCE), tetrahydrofuran (THF) and toluene (TOL), polystyrene (PS) in DMF, MEK, DCE, THF and cyclohexane (CYH), and random ethylene-vinyl
acetate (EVA) copolymer in DCE, TOL, CYH with and without surfactant of Span80 and in the DCE/CYH solvent mixtures with surfactant
of Span80 was examined at high dilution. It was shown that the extent and type of the upsweep or downsweep (anomalous rheological
behavior) of the reduced viscosity-concentration curves of these different polymers at high dilution are markedly dependent
on the dielectric constant of the solvent and the polarity of the polymer used. The experimental results indicated that the
anomalous rheological behavior of EVA copolymer, widely used as a flow improver, is related to its efficiency in reducing
viscosity and depressing pour point of crude oil and waxy solvents.
Project (No.29774020) suppored by the Natural Science Foundation of China(NSFC). 相似文献
2.
王玉环 《石家庄职业技术学院学报》2008,20(6):27-28
以去甲氨噻肟酸乙酯为原料,在碱性条件下与α-澳代异丁酸叔丁酯合成了头孢他啶侧链酸乙酯,分析了不同溶剂、碱的用量对反应收率的影响．较佳的反应条件为：溶剂DMF350mL,摩尔比为去甲氨噻肟酸乙酯：α-澳代异丁酸叔丁酯：无水碳酸钾=1：1．2：2,反应温度45℃,反应时间24h．在此条件下,反应收率达89．6％． 相似文献
3.
反相乳液聚合制备丙烯酰胺-二甲基二烯丙基氯化铵阳离子共聚物 总被引：1，自引：0，他引：1
采用反相乳液聚合法,以液体石蜡为连续相、丙烯酰胺和二甲基二烯丙基氯化铵水溶液为分散相、N,N′-亚甲基双丙烯酰胺为交联剂、过硫酸铵为引发剂、Span-80和OP-10为复合乳化剂,制备了丙烯酰胺(AM)-二甲基二烯丙基氯化铵(DMDAAC)阳离子共聚物;考察了引发剂含量、单体AM与DMDAAC的摩尔配比、复合乳化剂Span-80与OP-10的质量配比及含量、聚合温度、聚合体系pH等对AM-DMDAAC阳离子共聚物性能的影响.较佳的聚合条件为:过硫酸铵占单体总质量的1.0%,n(AM):n(DMDAAC)=1.6,m(Span-80):m(OP-10)=96:4(Span-80和OP-10复合乳化剂的亲水亲油平衡值约为4.7),Span-80和OP-10占油相质量的6%,聚合温度40℃,聚合体系pH约为5.0.在此聚合条件下,制得的AM-DMDAAC阳离子共聚物的粘度较大,稳定性较好. 相似文献
4.
采用反相乳液聚合法,以液体石蜡为连续相、丙烯酰胺水溶液为分散相、N,N′-亚甲基双丙烯酰胺为交联剂、过硫酸铵为引发剂、Span-80和OP-10为复合乳化剂,制备了丙烯酰胺均聚物(PAM);考察了溶剂、交联剂及其用量、氮气、单体浓度、乳化剂种类、油水比、引发剂用量对PAM均聚物性能的影响.较佳的聚合条件为:交联剂的用量为单体质量的2.5%,单体AM的含量为40%,油/水质量比接近1.0,引发剂过硫酸铵为单体含量的0.9%,使用复合乳化剂Span-80/OP-10,HLB=5.35.在此聚合条件下,制得的PAM均聚物的粘度较大,稳定性较好. 相似文献
5.
Nano-Ag particles/polyacrylamide （PAM） composites were synthesized by γ irradiation method and then blended with ethylene vinyl acetate （EVA）. Dielectric behaviors of the Ag/PAM/EVA composites are investigated as a function of both the concentration and size of Ag particles. When concentration of the Ag fillers is rarely low, dielectric anomalies were first observed in contrast to the traditional percolation theory. As concentration of Ag increases, volume resistivity and breakdown field strength are enhanced, loss tangent （tan δ） reduced and dielectric constant kept invariable. In addition, the above variation became larger when the diameter of the Ag nano-particles is smaller. Such dielectric anomalies may be understood by considering the unique ＂Coulomb Blockade Effect＂ of the nano-sized Ag particles. 相似文献
6.
不同引发剂下醋酸乙烯酯共聚乳液的合成及性能研究 总被引：1，自引：0，他引：1
采用双氧水(H2O2)、亚硫酸氢钠(NaHSO3)和双氧水-亚硫酸氢钠(H2O2-NaHSO3)三种不同引发剂引发醋酸乙烯酯和丙烯酸单体乳液共聚,制得了一种改性聚醋酸乙烯酯乳液,研究了引发剂用量对乳液的固含量、粘度和耐水性等性能的影响,并且对三种引发剂的引发性能进行了对比.结果表明,改性后的聚醋酸乙烯酯乳液的外观光滑细腻并且其耐水性,稳定性都有所提高,且使用质量比为1:3的双氧水-亚硫酸氢钠复合引发剂时,聚合物乳液的综合性能最佳. 相似文献
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8.
研究了氯乙烯-醋酸乙烯（简称VCM—VAc）共聚树脂（氯醋树脂）合成技术在30m,聚合釜中的工业化生产情况。该工艺采用复合引发剂体系、复合分散剂体系、VCM滴加工艺、微正压汽提技术和3#塔冷风干燥技术。应用结果表明,该工艺运行平稳、安全,装置利用率高,产品中醋酸乙烯酯分布均匀。 相似文献
9.
Acrylonitrile(AN)/1-vinyl-3-ethylimidazolium bromide(VIMB) copolymer was prepared via solution polymerization using dimethyl sulfoxide(DMSO) as a solvent and azodiisobutyronitrile as an initiator. The effects of comonomer VIMB on the polymerization, rheological properties of the polymer solution and thermal properties of the copolymer were investigated. The ionic liquid VIMB resulted in higher polymerization conversion ratio and higher average molecular weight when copolymerized with AN than itaconic acid(ITA). Rheological measurements indicated that the transition shear rate increased linearly with increasing temperature for P(AN/ITA)/DMSO solution, while an exponential growth with temperature was observed for P(AN/VIMB)/DMSO solution. The exothermic peaks of DSC curves in N_2 appeared at 276.67 and 257.34 °C for P(AN/VIMB) and P(AN/ITA), respectively. As a potential comonomer of AN for PAN carbon fibers, the VIMB resulted in about 7% higher char yield in N_2, and 23.7% less weight loss at 600 °C in air than ITA copolymer. 相似文献
10.
Azeotropic liquid mixture cannot be separated by conventional distillation. But extractive distillation or combination of the two can be valid for them. An experiment to separate benzene and cyclohexane by batch extractive distillation was carried out with N,N-dimethylformide (DMF), dimethyl sulfoxide (DMSO) and their mixture as extractive solvent. The effect of the operation parameters such as solvent flow rate and reflux ratio on the separation was studied under the same operating conditions. The results show that the separation effect was improved with the increase of solvent flow rate and the reflux ratio; all the three extractive solvents can separate benzene and cyclohexane, with DMF being the most efficient one, the mixture the second, and DMSO the least. In the experiment the best operation conditions are with DMF as extractive solvent, the solvent flow rate being 12.33 mL/min, and the reflux ratio being 6. As a result, we can get cyclohexane from the top of tower with the average product content being 86.98%, and its recovering ratio being 83.10%. 相似文献
11.
A new model was developed to describe the diffusion limitation on free radical polyme-rization. In this model the termination
rate coefficient (k
t) and propagation rate coefficient (k
p) were expressed as a function of bulk viscosity (η). This model was used to simulate the batch thermal polymerization of
styrene (St) and the continuous thermal bulk copolymerization of St (monomer 1) and maleic anhydride (MAH, monomer 2) in a
CSTR with on-line monitor of the rheological behavior. The simulated results on polymerization conversion, copolymer composition,
molecular weight and its distributions were compared with the experimental data, and the results calculated by two previous
gel-effect models i.e. Martin-Hamielec and Tulig-Tirrell models. It was found that the present model produces better prediction
than that of the Tulig-Tirrell model and has the same accuracy as that of the Martin-Hamielec model, but is much simpler.
Project (29734130) supported by Natural Science Foundation of China. 相似文献
12.
ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｓｅｃｔｐｏｓｔｅｍｂｒｙｏｎｉｃｄｅｖｅｌｏｐｍｅｎｔｃｏｎｓｉｓｔｓｏｆｇｒｏｗｔｈｐｕｎｃｔｕａｔｅｄｂｙａｓｅｒｉｅｓｏｆｍｏｌｔｓｆｏｌｌｏｗｅｄｂｙｍｅｔａｍｏｒｐｈｏｓｉｓ.Ｔｈｅｓｅｍｏｌｔｓａｎｄｍｅｔａｍｏｒ ｐｈｏｓｉｓａｒｅｉｎｉｔｉａｔｅｄａｎｄｃｏｏｒｄｉｎａｔｅｄｂｙｈｏｒｍｏｎｅｓ(Ｒｉｄｄｉｆｏｒｄ ,1 994 ) .Ｉｔｉｓｇｅｎｅｒａｌｌｙａｃｃｅｐｔｅｄｔｈａｔｔｈｅｉｎｔｅｒｐｌａｙｏｆｅｃｄｙｓｔｅｒｉｏｄｓ,ａｇｒｏｕｐｏｆｓｔｅｒｏ… 相似文献
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14.
面对激烈的市场竞争,国有商业银行在实行减员增效的同时,也都在努力构建科学合理高效的绩效管理体系。本文从经济增加值(EVA)的基本概念和特点出发,针对商业银行绩效管理的现状,探讨通过建立以EVA绩效评价为核心的商业银行绩效管理体系,提高银行内部治理成效。 相似文献
15.
无水三氯化铝催化合成乙酸乙酯的研究 总被引：10，自引：1，他引：9
以无水乙醇和冰乙酸为原料 ,采用无水三氯化铝作催化剂合成乙酸乙酯 .考察了催化剂用量、原料配比和反应时间等因素对反应的影响 .找到了一种无污染、催化活性较高的催化剂无水三氯化铝 ,确定了无水三氯化铝作为催化剂的最佳反应条件∶无水乙醇∶冰乙酸 =2 ∶1 (摩尔比 ) ,无水三氯化铝用量占整个反应体系总质量的 7 2 % ,反应时间为 30min ,转化率 (以冰乙酸计 )达 80 6 % . 相似文献
16.
新型咪唑啉两性表面活性剂的合成 总被引：1，自引：0，他引：1
李明 《楚雄师范学院学报》2002,17(3):71-72
以十二醇双氧乙烯基乙酸为原料，与二乙三胺反应合成了咪唑啉环，进而合成了乙酸盐型咪唑啉两性表面活性剂，测定了其水溶液的表面张力，起泡性能，临界胶束浓度，讨论了反应条件对表面活性剂性能的影响。 相似文献
17.
张延琪 《安徽科技学院学报》2006,20(1):30-32
进一步研究了高纯氧化钕(99．5 %)催化合成乙酸异丁酯的性能。采用文献[1]的反应条件,经多次实验证明:实际酯收率只有58％,远达不到文献[1]中数据(酯收率80％)。此外又进一步采用了纳米级氧化钕催化合成酯,酯收率也只有66％左右。因此文献[1]中80％的酯收率有待于进一步商榷和考证。 相似文献
18.
将抽象因子分析法用于解析配合物体系的吸光度数据以确定体系中的吸光物种数，为研究表面活性剂对金属离子与显色剂反应体系增敏作用机理提供一种新方法。用该法对Fe（Ⅲ）-SCN和Fe（Ⅲ）-SCN-Tween-80两显色体系的吸光度数据进行处理，结果表明，新的多元配合物的生成是表面活性剂对Fe（Ⅲ）-SCN显色反应增敏的主要原因。 相似文献
19.
研究了双峰中密度聚乙烯(BMDPE)与纳米碳酸钙不同配比复合物的流变行为与力学性能.讨论了复合物的组成、剪切应力和剪切速率以及温度对熔体粘度和膨胀比的影响,测定了不同配比熔体的非牛顿指数(n)、熔体流动速率(MFR)、粘流活化能以及习用屈服应力,断裂应力和断裂伸长率,用扫描电镜观察了纳米碳酸钙在复合材料中的分散情况.结果发现:纳米碳酸钙可以均匀地分散在BMDPE中,少量的纳米碳酸钙就可以明显提高材料的力学性能,在较高的剪切速率下还可以改善材料的加工性能. 相似文献
20.
ＩＮＴＲＯＤＵＣＴＩＯＮＳｈｏｒｔｂｏｗｅｌｓｙｎｄｒｏｍｅｌｅａｄｓｔｏｓｉｇｎｉｆｉｃａｎｔｍｏｒｂｉｄｉｔｙａｎｄｉｓｐｏｔｅｎｔｉａｌｌｙｌｅｔｈａｌ,ｅｓｐｅｃｉａｌｌｙｗｈｅｎｉｎｔｅｓｔｉｎａｌｌｏｓｓｉｓｅｘｔｅｎｓｉｖｅａｎｄｗｈｅｎｔｈｅｐａｔｉｅｎｔｉｓｖｅｒｙｙｏｕｎｇ (Ｋｕｒｋｃｈｕｂａｓｃｈｅｅｔａｌ.,1 993;Ｗｅｂｅｒｅｔａｌ.,1 991 ;Ｖａｎｄｅｒｈｏｏｆｅｔａｌ.,1 997) .Ｄｅｓｐｉｔｅｔｈｅａｄｖａｎｃｅｓｉｎｍｅｄｉｃａｌａｎｄｓｕｒｇｉｃａｌｔｅｃｈｎｉｑｕｅａｎ… 相似文献