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羧甲基羟丙基纤维素溶液流变性质的研究 总被引:1,自引:0,他引:1
用旋转粘度计研究了羧甲基羟丙基纤维素(CMHPC)复合醚水溶液在25-80℃温度范围内的热稳定性,以及水溶液和盐溶液的流变性质.借助阿氏方程得到的CMHPC粘流活化能介于离子型羧甲基纤维素醚(PAC)和非离子型羟乙基纤维素醚(HEC)之间.研究发现,CMHPC体系中羧甲基含量较高时流动曲线类似PAC符合Ostwad-Der Waele幂律模型,而羟丙基含量较高时,流动曲线类似HEC,偏离幂律模型.在CMHPC水溶液中加入小分子电解质时,羧甲基受屏蔽,流变行为主要受羟丙基影响,曲线将发生偏离.本文还考察了CMHPC溶液的抗盐能力. 相似文献
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研究了不同羧甲基取代度和不同羟丙基取代度的羧甲基羟丙基纤维素(CMHPC)的某些性质。与某些离子型及非离子型纤维素醚比较表明,CMHPC兼备有离子型和非离子型纤维素醚的性。在稀的无机酸或有机酸中,CMHPC较离子型羧甲基纤维素有较好的溶解性和更高的溶液粘度,更缓慢的降解速度。CMHPC的水汽吸值以及溶液的表面张力值介于离子型与非离子型纤维素醚之间。它具有能溶于一价和二价盐的良好综合耐盐性,离子型纤维素醚能耐一价盐但不能耐二价盐;某些非离子型纤维素醚能耐二价盐但不能耐一阶盐。CMHPC红外吸收光谱图表明具有羧甲基特征峰1610cm~(-1)以及羟丙基(上的甲基)的特征峰1380cm~(-1)。高烃丙基取代度的CMHPC具有非离子型羟丙基纤维素醚溶于某些极性有机溶剂的性质。CMHPC在聚醋酸乙烯乳液中表现出良好的增稠性,配伍性和稳定性。添加有CMHPC增稠剂的乳液粘度长期保持稳定。CMHPC的差热曲线,热重曲线,微商热重曲线表明,它具有较高的热分解温度和较缓慢的热分解速度。是一种用于增稠领域和钻井泥浆处理剂的良好热稳定性材料。 相似文献
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使用新型有机钛络合物交联羧甲基羟丙基纤维素(CMHPC),仍得凝胶具备较高的耐温性,热分析结果亦表明交联产物有良好的热稳定性。对有机钛及其它一些金属离子交联CMHPC反应的行为和红外谱图分析显示,CMHPC与金属离子作用时,不仅由羧甲基提供活性络合部位,而且羟丙基也参予反应,交联机制受取代度和反应条件的影响。 相似文献
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使用新型有机钛络合物交联羧甲基羟丙基纤维素(CMHPC),仍得凝胶具备较高的耐温性,热分析结果亦表明交联产物有良好的热稳定性。对有机钛及其它一些金属离子交联CMHPC反应的行为和红外谱图分析显示,CMHPC与金属离子作用时,不仅由羧甲基提供活性络合部位,而且羟丙基也参予反应,交联机制受取代度和反应条件的影响。 相似文献
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对离子型纤维素醚静电纺丝研究依旧是当前研究的难点. 研究表明, 成功合成新的离子型纤维素醚CMC-Li, 并对比羧甲基纤维钠(CMC-Na)进行流变测试, 两者都表现出非牛顿流体的特性, 且取代度和黏度相近的CMC-Li比CMC-Na具有更低的非牛顿指数, 对于同类物质低取代度、高浓度的溶液表现出更低的非牛顿指数. 并针对聚合物的结构特点, 易与水溶性端羟基高分子量的聚环氧乙烷(PEO)配成静电纺丝优良共纺溶液, 当速率为4 mL/h, 电压为25 kV, 纺丝距离为12 cm时能得到外观形貌较好的平均直径为70 nm左右的纳米纤维. CMC-Li具有更好的纺丝性能, 对CMC-Li包覆碳化功能化复合材料研究进行初步的探讨. 通过使用红外(IR)、流变仪、扫描电镜(SEM)分析取得较好的效果. 相似文献
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R Bauer M J Bjerrum E Danielsen P Kofod 《Acta chemica Scandinavica (Copenhagen, Denmark : 1989)》1991,45(6):593-603
111Cd time-differential perturbed gamma-gamma angular correlation (PAC) has been used to investigate the Zn site in yeast and bovine copper and zinc-containing superoxide dismutases by substitution of the zinc ions with excited 111Cd(2+) ions. The PAC spectra obtained from the enzymes in aqueous solution reveal a single coordination geometry of 111Cd(2+) showing that the coordination of 111Cd(2+) to the Zn site in the two subunits is identical. Furthermore, the PAC spectra of the yeast and bovine enzymes show that the Zn sites are very similar in the two enzymes. The PAC experiments show a clear difference depending on whether the copper ion is in the oxidized or the reduced state. In the latter case the results resemble those obtained for derivatives with no metal ion at the Cu site. Hence the coordination geometry of the Zn site in these two situations must be similar, and it is very unlikely that the imidazole ring of His61 bridges the two metal ions in the reduced enzyme. The PAC spectrum of 111Cd(2+) ions at the Zn site with copper(II) ions at the Cu site is in agreement with that predicted by applying the angular overlap model (AOM) to the known crystal structure of the bovine enzyme, with known nuclear quadrupole interactions for the ligands involved. Furthermore results from experiments with copper in the reduced state show that reduction of the copper ion causes a significant change at the Zn site. An explanation for this conformational change has been proposed by computer modelling. The PAC experiments also show that it is possible to incorporate cadmium ions into the Cu site in the absence of copper ions, and the result has also been interpreted in terms of the AOM. 相似文献
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The ultrasonic degradation of hydroxyethylcellulose (HEC) and poly (ethylene oxide) (PEO) in aqueous solution, and the copolymerization of HEC with PEO were studied. The structure of the copolymer was identified by DTA, IR, MS, x-ray diffraction, and polarizing microscopy. The copolymer prepared is mainly block. The copolymer formed amounts to 55.07% by irradiating 0.5% HEC/PEO aqueous solution for a period of 10 min at 25°C and 18.2 kHz with 2.5 A input current on a reversed main circuit. 相似文献
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Hydroxyethylcellulose (HEC) was synthesized by a fully homogenous method from cellulose in 7.5 wt.-% NaOH/11 wt.-% urea aqueous solutions under mild conditions. HEC samples were characterized with NMR, SEC-LLS, solubility, and viscosity measurements. The MS and DS values of the obtained HEC samples are in the range from 0.54 to 1.44 and 0.45 to 1.14, respectively, and the relative DS values at C-2 and C-6 hydroxyl groups are slightly higher than those at C-3 hydroxyl groups. HEC samples are soluble in water starting from a MS of 0.57 and DS of 0.49, which display high viscosity in aqueous solutions. Moreover, a NaOH/urea aqueous solution is a stable system for cellulose etherification. In this way, we could provide a simple, pollution-free, and homogeneous aqueous solution system for synthesizing cellulose ethers. 相似文献
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This work presents experimental results on simple shear and porous media flow of aqueous solutions of two hydroxyethyl celluloses (HEC) and two hydrophobically modified hydroxyethyl celluloses (HMHEC) with different molecular weights. Mixtures of these polymers with a cationic surfactant, cetyltrimethylammonium p-toluenesulfonate (CTAT) were also studied. Emphasis was given to the range of surfactant concentrations in which wormlike micelles are formed. The presence of hydrophobic groups, the effect of the molecular weight of the polymers, the surfactant and polymer concentrations, and the effect of the flow field type (simple shear versus porous media flow) were the most important variables studied. The results show that the shear viscosity of HEC/CTAT solutions is higher than the viscosities of surfactant and polymer solutions at the same concentrations, but surface tension measurements indicate that no complex formation occurs between CTAT and HEC. On the other hand, a complex driven by hydrophobic interactions was detected by surface tension measurements between CTAT and HMHEC. In this case, the viscosity of the mixture increases significantly more (up to four orders of magnitude at high CTAT concentrations) in comparison with HEC/CTAT aqueous solutions. Increments in the molecular weight of the polymers increase the interaction with CTAT and the shear viscosity of the solution, but make phase separation more feasible. In porous media flow, the polymer/CTAT mixtures exhibited higher apparent viscosities than in simple shear flows. This result suggests that the extensional component of the flow field in porous media flows leads to a stronger interaction between the polymer and the wormlike micelles, probably as a consequence of change of conformation and growth of the micelles. 相似文献
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The adsorption kinetics of hydroxyethylcellulose (HEC) on silica and relaxations in adsorbed HEC layers were probed using total internal reflectance fluorescence and near-Brewster reflectivity. Like many random-coil polymers, HEC was found to adsorb at the transport-limited rate. Relaxations occurred at nearly constant interfacial mass when HEC layers were exposed to aqueous solvent, causing the subsequent exchange of chains between the layer and the free solution to become increasingly hindered. Eventually, on the time scale of a day, layers became immobilized and unable to accommodate chains from free solution. A continued fluorescence decay, beyond time scales that could be probed with self exchange, suggested further relaxations of the adsorbed HEC. The polydisperse HEC system (with an average molecular weight near 450,000) behaved qualitatively similar to molecular weight standard polyethylene oxide (PEO) layers on silica. For instance, relaxations in PEO layers occurred on a time scale of 10-20 h, like the HEC layers. Young layers of the latter, however, exhibited self-exchange kinetics that were an order of magnitude slower than PEO layers of similar age. This difference in adsorbed layer dynamics was attributed to HEC's stiffer backbone, compared with flexible PEO. Copyright 2000 Academic Press. 相似文献
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Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weight-average molecular weights Mw, number-average molecular weights Mn and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration. 相似文献