稀土掺杂硅铝氧烷凝胶的制备及电流变效应

采用乳液聚合的方法以α－甲基丙烯酸甲酯为单体对硅铝氧烷溶胶进行表面覆合，将所制得包裹了PMMA的高介电硅铝氧烷凝胶粉末，与硅油相充分混合是到了电流变效应非常显著的ER流体。同时，通过掺杂稀土化合物得到了一系列掺杂了稀土离子的PMMA包裹的硅铝氧烷凝胶粉末样品，测量 了在外加电场作用下该ER流体粘度随不同的样品浓度，不同的掺杂离子，温度的改变等影响，同时测量了漏电流密度，介电常等相关的物理量。讨论了乳液聚合原理，电流变效应机制。     

择优取向生长的Gd2O3高K栅介质薄膜

使用射频磁控溅射法在n型Si(001)基片上生长了Gd2O3薄膜。X射线衍射扫描研究和高分辨透射电子显微镜观察表明,薄膜由立方相和单斜相混合构成,且表现出立方(111)晶面和单斜(401)晶面的择优取向生长。XPS分析表明薄膜的元素组成接近化学计量比。电性能测试发现,薄膜拥有合适的介电常数,较小的漏电流密度和较大的击穿场强,厚度为15 nm的薄膜介电常数为23,漏电流密度为3.6×10-5A.cm-2(偏压为 1 V时),击穿场强为3.5 MV.cm-1。     

合成皂石及其交联物在偏三甲苯歧化反应中的催化行为

以羟基铝低聚物与其交联制得柱撑皂石,并在偏三甲苯歧化反应中考察了它们的催化性能.结果表明,催化活性随柱撑皂石表面酸量增加而增加;四甲苯中均四甲苯和二甲苯中邻二甲苯的百分含量皆高于热力学平衡值.催化特性与柱撑皂石的柱密度相关.     

ICP-AES法测定酒中金属元素时用内标法补偿乙醇的影响

酒类饮料中含有一定量乙醇,与水溶液相比,当其引入ICP时会产生许多差异。Gree-nfield等曾报道了将甲醇及其他有机酸引入ICP时,发射强度与溶液粘度、表面张力、密度等物理特性的相关关系;伊藤等研究了将0～5％乙醇引入ICP时,某些谱线强度的变化;王小如等研究了不同浓度乙醇对某些元素的离子线和原子线强度、溶液粘度、提取率、雾化效率、ICP电学参数、激发温度等的影响;孙雅如等据此提出了一种分析酒样中微量元素的方法,就是根据酒样喷入ICP时,自激式R.F.发生器阳流、栅流变化情况,     

质子型离子液体N,N-二甲基乙醇胺丙酸盐的密度、粘度及电导率

在283.15-333.15 K温度范围内, 测量了质子型离子液体N,N-二甲基乙醇胺丙酸盐(DMEOAP)的密度、粘度及电导率. 讨论了温度对密度、粘度和电导率等物理化学参数的影响. 通过经验和半经验方程得到了该离子液体的热膨胀系数、分子体积、标准摩尔熵及晶格能等热力学性质参数. 由电导率和密度计算出了该离子液体的摩尔电导率. 利用Vogel-Fulcher-Tamman (VFT)方程, 将测量的动力粘度和电导率对温度拟合, 得到了动力粘度和电导率随温度变化方程式.并通过Walden规则, 建立了粘度与摩尔电导率之间的联系.     

一种含碘氢碘酸浓度的分析方法

正公布号:CN105675809A公布日:2016.06.15申请人:清华大学摘要:本发明首先建立含碘氢碘酸标准样品的浓度与物料密度,以及浓度与粘度三者之间的数学关系式,构成联立方程组;对未知浓度的待测含碘氢碘酸,采用密度测定装置和粘度仪分别测出其密度和粘度,利用上述方程组即可求解出待测样品的具体浓度。当采用在线式密度计和粘度计时,可实     

阳离子高分子絮凝剂的合成与其表面电性的测定

以三乙烯四胺对聚氯乙烯(PVC)进行改性,合成一系列胺化产物,并经硫酸二甲酯季铵化,得到阳离子高分子絮凝剂.采用元素分析、红外光谱对产物进行结构表征,并通过电荷密度、特性粘度和Zeta电位等测定,研究了该高分子絮凝剂的结构与相关性质间的关系.结果表明:通过控制合成条件,可以改变阳离子高分子絮凝剂的分子量和电荷密度,以适应各种应用条件的需求.     

含氰基离子液体的合成、表征及流变性质研究

摘要合成、 表征了一系列新的含氰基咪唑类离子液体. 测定了该离子液体的密度、 熔点及溶解性等物理性质, 研究了其在稳态、 瞬态和动态条件下的流变行为. 结果表明, 当剪切速率在0.1～50 s^-1范围内时, 其粘度不随剪切速率的变化而变化, 但随温度升高而降低, 粘流活化能随取代基长度变化呈现规律性变化. 对于1-丁基-3-氰乙基咪唑六氟磷酸盐离子液体, 维持剪切速率不变时, 其剪切应力和粘度均不随时间变化, 且随着温度的升高而降低; 在动态条件下, 在线性粘弹区, 复合粘度和损耗模量G″ 随温度升高而降低. 关键词     

非共价键自组装制备聚对苯撑乙炔/聚丙烯酸水溶性荧光纳米粒子及其光物理行为研究

通过功能化聚对苯撑乙炔(含羟基与氨基)和聚丙烯酸之间的非共价键自组装制备了一系列含共轭聚合物的水溶性荧光纳米粒子, 并进行了相关结构和光学性质表征. 研究表明, 纳米粒子的大小和聚丙烯酸/聚对苯撑乙炔质量比直接相关. 光物理性质研究表明, 形成水溶性纳米粒子后, 疏水的聚苯撑乙炔链在纳米粒子中易于形成π-链间聚集, 其光物理性质与其在薄膜态时相似.     

天然橡胶的粘弹性质Ⅲ——本体粘度与粘均分子量之间的关系

关于非晶态高分子化合物的本体粘度依赖于分子量的关系,过去曾有不少工作,但对天然橡胶的数据尚付缺如。 本工作的目的,卽在阐明了天然橡胶本体的非牛顿粘流特性贝及粘流与塑流的互相转变之后,对天然橡胶的本体粘度与粘均分子量之间的关系进行了研究,借所订定的关系式卽可应用机械方法来测定天然橡胶本体的粘均分子量。     

二氧化硅负载胺丙基硅烷电流变流体

研究用二氧化硅负载胺丙基三乙氧基硅烷［ＮＨ２（ＣＨ２）３Ｓｉ（ＯＥｔ）３］作为分散颗粒，制备无水型的电流变（ＥＲ）流体．考察电场强度（Ｅ）、剪切速率（γ·）、分散颗粒含量、分散介质种类以及极性小分子等因素对ＥＲ流体流变性能的影响．结果发现，以硅油为分散介质，含分散颗粒为１５％（ｇ／ｍｌ）的流体，不添加任何活化剂，在γ·为８０６６ｓ－１时，Ｅ从０升至１６６６ｋＶ／ｍｍ，流体的表现粘度（ηａ）从０３９６Ｐａ．ｓ增大到１６６６８Ｐａ．ｓ．γ·提高，ηａ降低．分散颗粒含量增加，ηａ增大．用硅油作分散介质，ＥＲ效应比用矿物油或石蜡油显著．加入极性小分子苯胺，可以增强流体的ＥＲ效应，但随着苯胺含量增多，漏电流密度也增大．     

聚苯胺类电流变体的稳态剪切流动分析

对聚苯胺、及聚苯胺/聚丙烯酸盐复合粒子的稳态剪切流动行为进行了综合考察.结果表明, 在交流电场下,电流变体的剪切应力和剪切速率的关系符合Bingham流体形为.并对此现象进行了分析,提出用非理想塑性体的新模型来描述交流电场下聚苯胺类电流变体的稳态剪切流动.     

Frequency dependence of the electrorheological effect in the nematic phase of pentyl cyanobiphenyl

The effect of an electric field on the viscosity, the electrorheological (ER) effect, is studied as a function of the frequency of the electric field for the nematic phase of 4-n-pentyl-4'- cyanobiphenyl (5CB). In the frequency region between 10Hz and 1kHz, a gradual change of the ER effect is observed, with its behaviour depending on the shear rate and the amplitude of the electric field. On the basis of a calculation of the orientational motion of the director and its effect on the viscosity, the observed frequency dependence is suggested to occur as a result of an orientational relaxation of the director.     

沸石电流变液材料的研究

系统地研究了沸石的由离子类型、数目、骨架的孔道大小和结构特性对沸石电流变液性能的影响. 证实了阳离子在电场中的迁移所引起的晶粒极化是Y，A和M等沸石电流变特性的基础，指出了较大的孔径和具有足够多易迁移的阳离子是该类沸石具有较好电流变性的的前提．根据NaZSM－5沸石在高电场中与其它沸石表现不同，具有屈服应力大而漏电流小的特点，提出了沸石晶粒极化还可能存在的另一种新的晶格变形机理．     

稀土掺杂PMMA包裹硅铝氧烷凝胶的ER效应

以二氧化硅微粒制备电流变液是研究者使用较多的一种方法[1] ,但由于二氧化硅的密度相对于分散相硅油来说太大 ,所以制成的电流变液稳定性较差。而用导电高分子微粒制成的电流变液则有在高电场时漏电流密度较大的问题[2 ] 。有研究者用直接聚合法在二氧化硅纳米微粒外包裹一层有机共聚物 ,生成一种微囊复合颗粒 ,可以使其相对密度减小 ,提高了电流变液的稳定性[3] 。我们以廉价水玻璃为原料制取硅铝氧烷溶胶 ,在其表面包裹聚甲基丙烯酸甲酯 (ＰＭＭＡ)后 ,得到ＰＭＭＡ包裹的硅铝氧烷凝胶具有相当的稳定性和易极化性 ,易形成较稳定的悬浮液 …     

Effects of medium oil on electroresponsive characteristics of chitosan suspensions

Biocompatible chitosan particle suspensions in host oils of corn, soybean, and silicone were prepared and their electrorheological (ER) characteristics were examined under the imposition of electric fields. The effects of the weight concentration of particulate chitosan and the strength of the applied electric field on ER response in the various chitosan particle suspensions were investigated via measurements of rheological properties including flow curve, shear viscosity, and yield stress. The yield stresses of the three different chitosan–oil systems showed different values of slope in the electric field, but all data were found to fit well with our previously proposed universal scaling function.     

Electrokinetic and electrorheological properties of poly(vinyl chloride)/polyindole conducting composites

In this study, poly(vinyl chloride) (PVC), polyindole (PIN), and PVC/PIN conducting composites having five different compositions were used. Particle sizes, densities, dielectric constants, and sedimentation ratios of the materials were determined. The zeta‐potentials of the samples were measured in aqueous and nonaqueous (silicone oil [SO]) media. The dispersions prepared in SO were subjected to external electric field strength, and their electrorheological properties were investigated. Then the effects of dispersed particle volume fraction, shear rate, external electric field strength, frequency, and temperature onto electrorheological activities of the dispersions were examined. Further, creep and creep‐recovery tests were applied to the PIN/SO and PVC/PIN/SO dispersions, and reversible viscoelastic deformations were observed. Finally, the vibration damping capacity of PVC (66%)/PIN (34%)/SO dispersion system was tested by using an automobile shock absorber. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation and electrorheological property of rare earth modified amorphous BaxSr1-xTiO3 gel electrorheological fluid

In this paper, we present a newly developed rare earth modified amorphous barium strontium titanate (Ba(x)Sr(1-x)TiO3) gel/silicone oil electrorheological (ER) fluid. The ER behaviors of suspensions of pure and rare earth modified amorphous Ba(x)Sr(1-x)TiO3 particles in silicone oil have been investigated under a dc electric field. The shear yield stress of the rare earth modified amorphous BaTiO3 gel/silicone oil ER fluid could reach 14.9 kPa at E=3.5 kV/mm while the leaking current density was very low, about 7.64 microA/cm2. The ER fluids with a higher volume fraction had a higher current density and a higher shear yield stress under the same electric field. The ER fluid has a long-term stability against sedimentation. The problem of caking was not serious and the agglomerated particles could be easily broken up by strongly stirring.     

An Electrorheological Study on the Behavior of Water‐in‐Crude Oil Emulsions Under Influence of a DC Electric Field and Different Flow Conditions

The influence of an applied DC electric field on viscosity and droplet size distribution of different water‐in‐crude oil emulsions was monitored in order to investigate the induction of coalescence of the water droplets. The effects caused by the voltage imposition were studied by rheological analysis and the validity of the obtained results was discussed, comparing with the features of real electrocoalcscer systems. A low field NMR technique (CPMG NMR) and digital video microscopy (DVM) were used to elucidate the behavior of the emulsions. Experiments performed at low shear rate with increasing electric field magnitude showed an increase in viscosity until a critical value. E_CRIT was reached. Thereafter coalescence occurred and viscosity decreased irreversibly below its initial value. The electrorheological behavior of the emulsions can be attributed to the organization (flocculation) of water droplets induced by the electric field, accompanied by an increase in viscosity. The structure breaks down as the shear rate is increased, leading to a decrease in viscosity. Experiments performed at high shear showed only a small decline in the viscosity. Although it was evident that coalescence took place, it did not involve the whole sample, because the electrodes were uncoated. As a direct consequence, the mean value of the droplet size within the emulsion did not change noticeably. Nonetheless this mean value was less recurrent and the formation of droplets of very large diameter occurred.     

Electrorheological properties of polyaniline suspensions: field-induced liquid to solid transition and residual gel structure

Polyaniline (PANI) was synthesized via oxidative coupling polymerization in acid conditions and de-doped in solution of ammonia. The electrorheological (ER) properties of the PANI/silicone oil suspensions were investigated in oscillatory shear as functions of electric field strength, particle concentration, and host fluid viscosity. Consistent with literature, the PANI ER fluid exhibits viscoelastic behavior under the applied electric field and the ER response is strongly enhanced with increasing electric field strength and particle concentration. The dynamic moduli, G' and G' increase dramatically, by 5 orders of magnitude, as the electric field strength is increased to 2 kV/mm. A viscoelastic liquid to solid transition occurs at a critical electric field strength, in the range Ec = 50-200 V/mm, whose value depends on particle concentration and host fluid viscosity. The fibrillar structure formed in the presence of the applied field has a static yield strength tau(y), whose value scales with electric field strength as tau(y) approximately E(1.88). When the field is switched off a residual structure remains, whose yield stress increases with the strength of the applied field and particle concentration. When the applied stress exceeds the yield stress of the residual structure, fast, fully reversible switching of the ER response is obtained.