复合材料的超微粒子在电流变液体中的应用

目的得到一种能够满足工程应用要求的高性能电流变液体,方法用微乳液法得到一种复合材料的超微粒子并作为分散相与硅油混合,得到3种不同体积分数的电流变液体,分别测试其在不同温度、电场强度、剪切率下电致应力和表观粘度的变化规律,结果大量的系统测试表明,用超微粒子制成的体积分数为30％的这种新型电流变液体具有明显的电流变效应,结论双电层极化对液体的电流变效应具有重要影响。     

乙二醇基铁/氧化钛纳米复合粒子的制备及其电流变性能

采用两步法制备出乙二醇基铁/氧化钛纳米复合粒子,并将制备的纳米复合粒子分散在硅油中得到一系列的电流变液。首先采用高温回流法制备出乙二醇基铁模板,然后分别用水解法和溶剂热制备出氧化钛纳米颗粒包覆在乙二醇基铁模板表面。使用X射线衍射仪(XRD),扫描电子显微镜(SEM),电流变仪等对纳米复合粒子进行结构的表征和性能的测试。研究了不同种类的表面活性剂复配体系对纳米复合粒子电流变性能的影响。通过对比,水解法得到纳米复合粒子相比于溶剂热在形貌和电流变性能方面都有所提高,水解法制备得到的纳米颗粒基的电流变液电流变效率可以达到200。     

SrTiO3/PMMA复合型ER材料的制备及性能研究

以NDZ-311为偶联剂,十二烷基硫酸钠(SDS)为表面活性剂和乳化剂,采用原位聚合的方法制备了SrTiO3／PMMA核壳结构复合型电流变材料,用FT-IR,SEM等手段对材料进行表征．利用改装后的旋转粘度计分别对未掺杂蒙脱土和掺杂一定量蒙脱土的SrTiO3／PMMA微囊复合颗粒电流变液的电流变性能进行研究,并利用高压电桥测量其介电性能．结果表明：PMMA已经包覆在SrTiO3表面;未掺杂蒙脱土的SrTiO3／PMMA电流变液其剪切应力随电场增大上升幅度较小,而掺杂适量蒙脱土的SrTiO3／PMMA电流变液其剪切应力上升幅度很大,增量约是前者的14倍．     

纳米二氧化钛的制备及其电流变性能

利用水热法和水解法制备TiO_2纳米颗粒,通过改变表面活性剂的复配,研究了不同表面活性剂组合条件对纳米TiO_2形貌、结构和电流变性能的影响,将得到的二氧化钛纳米颗粒分别分散在硅油中得到了一系列的电流变液。采用X射线衍射仪,扫描电镜对纳米颗粒的表面形貌和结构进行了分析表征,采用流变仪对电流变液的电流变性能进行了测试。X射线图谱分析得知不同的制备方法得到的TiO_2纳米颗粒的晶型不同,在水热法和水解法两种制备方法中分别得到锐钛矿型结构和无定型结构的TiO_2纳米颗粒,并且,由水热法制备的纳米TiO_2电流变性能相比水解法总体上要好一些。     

γ—Fe2O3／聚丙烯酸盐复合微粒电流变效应的研究

用反乳液聚合法制得了γ－Ｆｅ２Ｏ３／聚丙烯酸盐复合微粒，将其悬浮分散于硅油中形成电流变流体，考察了外加电场强度，粒子化学组成，分散剂等因素对电流变流体的剪切应力及电流这密度的影响。结果表明，在其他条件相同的情况下。γ－Ｆｅ２Ｏ３／聚丙烯酸锂盐形成的电流变流体具有较好的电流变效应。     

电流变流体及其应用前景

介绍电流变效应,以电流变液体和电流变效应的工作机理,着重探讨电流变效应和电流变流体在机电一体化工程中的应用前景。     

电流变效应初探

介绍电流变效应实验、归纳电流变实验现象、探讨电流变效应的物理机制、阐述寻求电流变液体的途径、展望电流变液体的应用前景。     

电流变效应的机理进展

电流变液体是一种由固体小颗粒和绝缘液体组成的智能材料,在电场作用下黏度和软硬度连续可调。在移走电场后,流变性能具有可逆转性,其响应速度极快,可达毫秒级。电流变材料潜在的巨大经济和社会效益使其从20世纪40年代至今一直是一个研究热点。随着材料的研究,相继提出了双电层理论和＂水桥＂机理、极化模型、导电模型以及解释巨ER效应的表面极化饱和模型。综述了电流变效应的传统机理和最新的机理进展模型,介绍了一种适用于颗粒类型电流变液体的剪切应力方程。     

一种新型半导体ER流体材料的设计及实验分析

寻求一种新型的电敏粒子材料,旨在提高电流变流体的电流变效应.制备一种含有氮、氧、硫类杂原子与大π共轭体系的高聚物--聚萘醌作为电敏粒子材料.含这种材料的电流变流体在交、直流电场下有明显的电流变效应,特别是在交变电场作用下,与其它材料相比,其剪切应力与电压成良好的二次关系.实验结果表明,含有大π共轭体系的有机半导体高聚物是一种新型的具有开发价值的电敏粒子材料.     

沉积法掺金改善碳纳米管电接触特性

研究了沉积法在碳纳米管中掺杂金属金对碳纳米管与金属电极间的电接触特性的影响。首先,采用酸回流方式在碳纳米管表面构造缺陷及亲水官能团并配制碳纳米管分散液;然后,采用柠檬酸钠和氯金酸配制金溶胶溶液,再将配制好的碳纳米管分散液滴入金溶胶溶液中,经震荡沉积得到掺杂金纳米粒子的碳纳米管样品。扫描电子显微图片及红外吸收光谱表明,酸回流成功地在碳纳米管管壁及端部构造了一些缺陷及亲水官能团。形貌表征及X射线光电子谱表明,在碳纳米管表面及端部成功地掺杂了金纳米粒子。掺金后碳纳米管拉曼光谱的G带波数增大,表明该掺杂类型为p型。最后,采用介电电泳法将原样与掺金碳纳米管分别组装到金电极之间,并实时测量接触电阻。结果表明,沉积法掺金可降低碳纳米管与金电极间的接触电阻,其阻值平均降幅高达71.49%。     

电流变液在灵巧窗中的应用

电流变液是介电颗粒分散于非导电性液体中而成的典型非水悬浮体,在外加电场作用下,具有粘度增大的可逆特性。由于电流变液在外加电场下具有透射率的明显变化,文中提出了电流变液应用于灵巧窗的设想。结果表明,在波长500nm下,外加强度为500·V.mm-1的电场前后,电流变液灵巧窗可逆透射率变化可达42.0%。     

分散介质的粘度对γ-Fe2O3聚丙烯酸锂复合微粒电流变效应的影响

采用反相乳液聚合的方法制备了γ-Fe2O3/聚丙烯酸锂复合微粒,将其分别悬浮分散于不同粘度的硅油、甲苯、邻苯二甲酸二辛酯、溴苯中形成电流变体,以考察分散介质的粘度对电流变效应的影响．研究结果表明,对于介电常数相同或相近的分散介质,粘度的影响不容忽视,如其粘度过低（甲苯和溴苯的情况)将不利于微粒的稳定分散和使用,从而导致电流变效应变差;在某一适中的粘度范围内,粘度对电流变效应的影响很小（粘度50~500 cS硅油的情况);介质的粘度越小,电流变体的电流密度越大．     

Effect of carrier liquid on electrorheological performance and stability of oxalate group-modified TiO<Subscript>2</Subscript> suspensions

By using oxalate group-modified TiO₂ nanoparticles as the dispersing phase, different kinds of silicone oil with various viscosities and terminal groups (hydroxyl, hydrogen, and methyl) were used as the dispersing media to prepare different electrorheological (ER) fluids. Their zero-field viscosity, yield stress under direct current electric fields, ER efficiency, shear stability, leakage current density, and sedimentation stability were tested to study the effect of carrier liquid on the properties of ER fluids. The results indicate that the zero-field viscosity, the yield stress, and the leakage current density increase with increasing viscosity of the silicone oils. The effects of the viscosity on the ER efficiency, the shear stability, and the sedimentation ratio depend on the competition between the viscous resistance and the aggregation of the particles. Among the three ER fluids prepared with silicone oil with different terminal groups, hydroxyl-terminated oil based sample has the highest zero-field viscosity, the highest field-induced yield stress and ER efficiency, the largest current density, and the best sedimentation stability.     

Electro-rheological Effect of Barium Titanate Particles Coated with Urea and Suspended in Methyl Silicone Oil

Barium titanate nano-powders were synthesized under defined conditions.The surface of these particles was successfully modified by coating with urea.The characteristics of these composite particles were studied by X-ray diffraction, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy.The electro-rheological (ER) effects of these particles suspended in methyl-silicone oil were measured.The particle, methyl-silicon oil ratio was 30%-35% weight percent.The experimental results indicate that these ER particles exhibit a remarkable ER effect.The ER fluid shows Bingham characteristics and the static shearing stress increases with an increase of the electric field strength.The highest static shearing stress under a 4 MV/m electric field is 13.2 kPa at room temperature, an increase of about 8.7 kPa compared to untreated BaTiO(C2O4)2 powders.     

Effect of Carrier Liquid on Electrorheological Performance and Stability of Oxalate Group-modified TiO_2 Suspensions

By using oxalate group-modified TiO_2 nanoparticles as the dispersing phase, different kinds of silicone oil with various viscosities and terminal groups(hydroxyl, hydrogen, and methyl) were used as the dispersing media to prepare different electrorheological(ER) fluids. Their zero-field viscosity, yield stress under direct current electric fields, ER efficiency, shear stability, leakage current density, and sedimentation stability were tested to study the effect of carrier liquid on the properties of ER fluids. The results indicate that the zerofield viscosity, the yield stress, and the leakage current density increase with increasing viscosity of the silicone oils. The effects of the viscosity on the ER efficiency, the shear stability, and the sedimentation ratio depend on the competition between the viscous resistance and the aggregation of the particles. Among the three ER fluids prepared with silicone oil with different terminal groups, hydroxyl-terminated oil based sample has the highest zero-field viscosity, the highest field-induced yield stress and ER efficiency, the largest current density, and the best sedimentation stability.     

丙烯酰胺在炭黑表面接枝聚合研究

利用Ｃ_ｅ~（４＋）和羟甲基组成的氧化还原体系，探讨丙烯酰胺在炭黑表面的水溶液接枝聚合机理。经接枝聚合改性的炭黑，在水分散体系中具有优异的分散稳定性。     

Electrorheological Properties of Suspensions of PAn-PEO-PAn Triblock Copolymer Particles

The PAn-PEO-PAn triblock copolymer with the PEG chain length of 400 was synthesized by chemical oxidation copolymerization of aniline and α,ω-bis（p-aminophenyl）poly（ethylene glycol）and characterized by FT-IR and TEM.The experimental results show that the copolymer particles are of μtypical core-shell structure after the self-assembly process in water.Its conductivity is much lower than that of the pure PAn.The suspension containing 20 vol% PAn-PEO-PAn tiblock copolymer in silicone oil exhibits.a typical electrorheological （ER） effect in DC electric field.while it shows a lower leakage current density than that of the pure PAn-based ER fluids.Therefore,the PEO shell hinders the electric hop among PANI chains and decreases the current density of ER fluids in an external electric field.at the same time the interface polarity improves the ER effects.