【作者】 魏建红；

【导师】 袁润章； 官建国；

【作者基本信息】 武汉理工大学 ， 材料学， 2002， 博士

【摘要】 电流变(Electrorhological,ER)材料是一种在外加电场作用下，其流变性能可以发生快速、可逆和明显改变的材料，这种材料可广泛的应用在汽车和工业机械制造等领域。有许多种材料都可以用作电流变材料，例如，聚合物半导体材料，无机非金属材料等，聚合物半导体ER材料的优点在于有较高的力学值、较小的密度、优良的疏水性，可以通过控制掺杂量和后处理程度有效控制电导的大小。它的缺点在于材料基体的热稳定性较差；无机化合物如氧化物、盐类，其特点是具有较高的介电常数；其主要缺点是密度大，颗粒的悬浮稳定性差；屈服应力低等。 有机物与无机物在纳米尺度上的复合是纳米复合材料的研究热点。有机物与无机物在纳米尺度上的复合，不仅可以充分利用它们的优点，而且有可能开发出新的性能。根据目前电流变液中出现的问题(如屈服应力不够高，漏电流密度不够低，稳定性不够好等问题)，基于聚苯胺有较高的热稳定性，且密度又小，特别是聚苯胺的介电常数和电导率均可按需调整，此外，钛酸钡无机纳米粒子作为一种无机铁电体，在电场作用下具有自发极化的能力，一方面可以为体系提供高的介电常数，另一方面又可保证体系的绝缘性能。本研究工作将导电聚苯胺与钛酸钡纳米粒子进行复合，这样，既可充分利用聚苯胺的热稳定性，密度可调及介电可调等优点，又可充分利用具有高介电常数钛酸钡纳米粒子的绝缘性能，这种性能可以阻止粒子与粒子间的跃迁，降低电损耗，同时发挥其高介电性能，这样可增强悬浮粒子与基油的介电不匹配性，从而有望制备出高性能的电流变液。 本学位论文利用有机-无机纳米复合技术，制备了不同结构的聚苯胺／钛酸钡纳米复合粒子，对它们的结构，性能进行了一系列的探讨工作，同时对它们在电流变液方面的应用进行了系统的研究。 本学位论文在以下几个方面进行了重点和系统的研究。第一，用原位复合法及改性的溶胶—凝胶法制备了不同结构的聚苯胺-钛酸钡纳米复合粒子，研究了复合粒子的粒径，形貌以及聚苯胺与钛酸钡纳米粒子的相互作用关系；第二，研究了聚苯胺与钛酸钡纳米复合粒子的复合机理，研究并提出了 武汉理工大学博士学位论文聚苯胺与钛酸钡纳米复合粒子的结构模型；第三，研究了聚苯胺与钛酸钡纳米复合粒子的介电性，导电性，热稳定性及长期稳定性；第四，制备了由聚苯胺与钛酸钡纳米复合粒子与氯化石腊油组成的电流变液，研究了电流变性能，探讨了复合粒子的导电性，介电性与其电流变性能的关系；第五，比较了不同结构的复合粒子的电流变性能的优缺点，为进一步设计和制备高性能电流变液打下基础。 为了制备原位复合型的聚苯胺－钛酸钡纳米复合粒子，我们首先用溶胶一凝胶法制备了不同粒径的钛酸钡纳米粒子，系统研究了所制备的无机纳米粒于的形貌，结构以及其介电性与导电性与温度及频率的关系。研究结果表明：钛酸钡纳米粉末在900℃处理时为最佳，随热处理温度的升高，粒径长大，而其介电常数随着粒径长大，逐渐降低，在相同条件下，随温度的升高，钛酸钡纳米粉末的介电常数在120℃出现最大值。其次，本文采用原位复合技术制备了聚苯胺／钛酸钡纳米复合粒子。研究结果表明：复合粒子为不很规则的球形，在室温下其平均粒径在1－Zpm之间，BaTIOs和PAn之间存在化学键的连接，一个复合粒子中包含有许多个BaTIOa纳米粒子，在此基础上我们提出了“蛋糕一花生米”模型。研究结果还表明：在P汕和 ＊。乃O3纳米粒子的原位复合过程中，首先是An单体与BaTIO3纳米粒子相互作用，由于钛酸钡权于的存在，苯胺单体首先吸附在钛酸钡粒子表面，当过硫酸铰加入溶液中时，聚合过程首先在这些氧化物的表面进行，这导致了聚合物对钛酸钡粒子的吸附及围绕钛酸钡粒子的受限生长。对于复合粒子的介电性能而言，其介电常数随温度的升高出现最大值。 将所制备的原位复合型PAn－BaTIO。纳米复合粒子与氯化石腊油混合组成电流变液，研究了它们的电流变性能，研究结果表明：对于原位复合型的PA38’纳米复合粒子组成的电流变液，其电流变性能与复合粒子中钛酸钡的百分含量有关，当复合粒子中的钛酸钡的百分含量为 48．ZI％时，复合 体系具有最佳的电流变性能；其电流变性能与复合粒子中钛酸钡的粒径大小 也有关，复合粒子中钛酸钡的粒径越小，其电流变性能越强。同时，我们发现复合粒子组成的ER液具有较好的温度稳定性和抗沉降稳定性，可长期使 用。 一 二互 一 武汉理工大学博士学位论文 此外，在用化学氧化法制备聚苯胺的基础上，本文用改性的溶胶一凝 胶法制备了以聚苯胺为核，以钛酸钡为壳的具有核壳结构的聚苯胺／钛酸钡纳 米复合粒子，对这种材料的结构及合成机理作了一系列的探讨工作，包括钛 酸钡膜的溶胶一凝胶工艺制备，复合粒子表面微结构的控制及表征，表?更多还原

【Abstract】 Electrorheological (ER) fluids are materials that undergo fast, reversible and obvious changes in their rheological properties upon the application of electric field. Such kind of materials can be used in auto and machine building industries. There are many things can be used as electrorheological (ER) materials, such as polymer semiconductor ER materials, inorganic nonmetal materials et al. The advantage of polymer semiconductor ER materials attributes to theirs high mechanical mass, lower density and fine hydrophobic properties, at the same time, theirs conductivity can be adjusted by doping and after-treatment, but theirs poor thermo-stability confines theirs extensive use. The main characteristic of inorganic compound such as BaTiO3, TiO2 lies in theirs high permittivity, the main disadvantages for inorganic compound used as electrorheological materials are theirs high density and low shear stress et al.Organic-inorganic nanocomposite, which are the complex of inorganic nanopraticles with organic compound, is a popular study subject in nanoscale composite. The nanocomposite can not only take advantage of several advantage, but also produce new properties. In this thesis, taking account of the problems in electrorheological fluids such as high leakage current, low yield stress and stability, the PAn-BaTiO3 nanocomposite with different structure are prepared by in-situ complex technology and modified sol-gel method. The structure, properties and their application in ER fluids are studied by the numbers.In this thesis, several subjects have been studied in detail. First, PAn-BaTiO3 nanocomposite have been prepared by in situ complex technology and modified sol-gel method. Second, the size and shape of the nanoparicles complex and the complex mechanism of PAn with BaTiO3 nanoparticles and have been studied, at the same time, the structure model of PAn-BaTi03 nanocomposite have been studied and put forward. Third, several properties of PAn-BaTiO3 nanocomposite such as dielectric properties, conduct electric properties ,heatstability, and long period stability have been studied. Fourth, the electrorheoldgical fluids composed of PAn/BaTiO3 nanocomposite and chlorated paraffin oil are prepared and the relationship between dielectric performance and electrorheological effect are discussed. Fifth, The advantage and disadvantage of electrorheological fluids composed of different structure PAn-BaTiO3 nanocomposite are compared, which put a favorable basis for farther design and prepare electrorheological fluid with high performance.In order to prepare insitu-composite PAn-BaTiO3, the BaTiO3 nanoparticles with the different size has been prepared by sol-gel processing primarily, the shape, structure and the relationship between dielectric properties and conducting properties with temperature and frequency are studied. The result shows: 900℃ is the optimum heat-treated temperature for the preparing BaTiO3 nanoparticles. With the heat-treated temperature increasing, the size of BaTiO3 increase and the dielectric constant decrease. At the same condition, the maximal dielectric constant value appears at 120℃. At the existence of BaTiO3, the PAn/BaTiO3 nanocomposite are prepared by in situ complex technology. The shape of complex is not regular and their mean size is in the range of 1~2 u m There are chemical bond between PAn and BaTiO3 in PAn/BaTiO3 nanocomposites, For the complex mechanism of PAn with BaTiO3 nanoparticles, first, there are complex between PAn and BaTiO3 nanoparticles. PAn have the function of cohering BaTiO3 nanoparticles. A considerable number of PAn combine with BaTiO3 nanoparticles on the surface of the BaTiO3 to form PAn-BaTiO3 nanocomposite . All the processes above take place spontaneously. BaTiO3 nanoparticles scatter inside the PAn-BaTiO3 nanocomposite without order, on the surface of complex has only the existence of PAn. Such kind structure can be described with the model "cake-peanut", the cake refers to polymer and the peanut refers to BaTiO3 nanoparticles. As far as the dielect更多还原