【作者】 张建华；

【导师】 张直明；

【作者基本信息】 上海大学 ， 机械设计及理论， 1999， 博士

【摘要】 电流变(ER)液，作为近年来发展较快的一类智能材料，由于其在电场作用下能在毫秒级时间内发生快速、可逆、可控的流变响应，因此在机电控制方面有重要的潜在应用。ER液一旦实现应用突破，将有可能引起机械、交通、液压等领域的重大变革，具有重要的国防价值与商业价值。 80年代以来，由于无水ER液的出现，ER液的研究进入了繁荣时期。但因人们对ER效应的机理仍缺乏清楚的认识，ER液还存在着剪切应力低、漏电流大等问题，不能很好地满足工程实际应用的要求而受到限制。另外，对ER液及其悬浮介质的应用性能特别是与机械传动密切相关的摩擦学问题缺乏系统而深入的分析，也是减缓ER液实现应用突破的重要原因之一，很遗憾的是，直到目前人们对此仍未引起足够的重视。本学位论文在建立ER测试系统和方法的基础上，围绕ER液固体粒子材料设计、悬浮介质的应用性能及氯化石蜡油的改性，ER液的性能考察和ER效应的机理研究以及添加剂对ER液性能的影响、ER液的悬浮稳定性状况等内容进行了系统而深入的研究。 甲壳胺(chitosan,CTS)是一类结构与纤维素相似的阳离子型聚电解质，具有较强的ER效应。对甲壳胺／蓖麻油(CTS／CTO)悬浮体系的ER性能进行了基础研究，结果表明甲壳胺ER液的剪切应力(τ)与漏电流密度(J)随电场强度(E)、固体颗粒浓度(C)的增大而增大，随剪切速率((?))的升高而减小，并存在临界固体1999年上海大学博士学位论文颗粒浓度及临界剪切速率，对以上实验事实，用极化机理和逾渗理论进行了解释.提出了甲壳胺类化合物ER液的r与J随脱乙酞度(D .D)的升高而增大，并指出其原因可能在于ER体系中可移动离子的数目增多. 系统研究了活化剂(水、甘油)、表面分散剂及悬浮介质对甲壳胺ER液性能的影响及其作用机理.结果表明:l)甲壳胺在少量水(固体粒子含量的10.owt%)的活化下即产生明显的ER效应，并且ER液的公、J与含水量(Q)密切相关，随Q的增加而一直增加，未出现降低或饱和的现象.针对此现象，提出了适合CTS/C To ER体系的可移动离子、“氢键桥”机理.2)表面分散剂单聚异丁烯丁二酞亚胺(Tl 51)和二壬基蔡磺酸钡(T 705)的加人，大多使CTs/Cro ER液的公与J减小.表面分散剂的憎水基(R一)端越长、空间位阻越大，减小ER液T与J的效果越显著，其中，二壬基蔡磺酸钡(T705)由于具有较长的憎水基和较大的空间结构，可明显降低体系的漏电流密度.在以上实验结果基础上，提出了表面分散剂影响ER液性能的“绝缘层”，与分散剂憎水基扭一)端的分子链长和空间结构有关，发现绝缘层的厚度随表面分散剂R一端链长及空间结构的增大而变大.3) CTS在不同悬浮介质中的ER效应有差异，按丁氯化石蜡汕>公保护的氛化石蜡油>T蓖麻沪公硅耐项序降低，并用极化机理进行了解释. 利用甲壳胺分子中的游离氨基(一HZ)易与金属及非金属碘(Iz)络合的特点，本文采用分子设计的观点对甲壳胺进行了分子设计和改性，通过在甲壳胺分子中引人金属离子或非金属碘(lz)化合物，研制了cTs一Mn+和cTs一l:络合物，并利用现代分析仪器对它们的结构与特性进行了表征.对其ER性能的研究结果表明随金属离子含量的增加，甲壳胺一金属络合物组成的ER液性 电流变材料的设计、研制及其流变和应用性能研究能亦加强.发现由甲壳胺一非金属碘(Iz)组成的ER液不需水分子的活化作用，并且具有较强的ER效应，是一类较优良的无水ER材料.针对CTS一Mn+和CTS一12络合物的ER效应提出了不同的ER作用机理，前者在于增加了ER体系中的可移动离子数目，后者是由于n一cT型电荷转移络合物的形成.鉴于CTS一I:络合物是具有较高活性的新型无水ER材料，本文已就此申请了专利. 空心微珠具有较低的密度，对改善ER液的悬浮稳定性非常有吸引力.本文较详细地研究了悬浮介质及预热处理温度对由空心微珠组成的ER液性能的影响作用.结果表明空心微珠在蓖麻油中不产生ER效应，在硅油中有ER效应产生，并且ER液的丁随预热处理温度的升高而增加，即随结合水含量的减小而增大.就此发现了空心微珠是一类无水ER材料. 空心微珠密度很小，在ER悬浮介质(如氯化石蜡油、硅油等)中易漂浮起来.为充分利用好它的低密度优势，本文对其进行了分子设计，通过共混法制备了以空心微珠为“核”，以高分子化合物(甲壳胺或聚乙烯醇)为“外壳”的“核壳”型复合物.离心强化及静止沉降实验结果表明空心微珠复合物ER液的稳定性很好;另外，研究结果同时表明空心微珠形成“核壳”复合物后，其ER液的剪切应力明显升高.鉴于空心微珠及以空心微珠为核制备的系列新的“核壳”型ER材料的特性和优点，本文已就此申请了专利. 采用长脂肪链环氧保护法，对ER悬浮介质一氯化石蜡油中的游离氯(Cl一)进行了保护，对比研究了氯化石蜡油被保护前后的ER性能.结果表明由其组成的ER体系的漏电流显著减小，剪切应力也减小，并用极化机理进行了解释.应用性能研究亦表明保护的氯化石蜡油不产生铜腐蚀、钢锈蚀的问题，悬!999年上海大学博士学位论文浮介质的热稳定性也得到显著改善. 针对?更多还原

【Abstract】 Electrorheological (ER) fluids, or suspensions, as a kind of smart materials, have very important and potential applications in electromechanical control due to their attractive features of rapid (with ms order), reversible, and controllable changes in rheological properties upon application of an external electric field with kv/mm order. Once ER fluids have met the engineering targets, they will bring revolution in several areas of industry and technology such as mechanics, transportation, hydraulics and so on.Upon the emergence of anhydrous ER fluids, the research of ER suspensions has been in wide progress. But the development of ER technology in industry is currently hindered by ER fluids for want of excellent properties such as high activity and low density. On the other hand, a lack of systematical analysis of ER fluids’or dispersing media’s application properties, especially the want of tribological studies, has also slowed down the progress of application of ER fluids. Based on the establishment of ER measuring instrument in this dissertation, the design, properties and mechanism of ER fluids based on chitosan(CTS) or hollow cenosphere, the influence of the dispersing media and protection of chlorinated paraffin, the influence of additives(including water, surfactant) on ER fluids and the stability of ER fluids, were investigated.The ER suspensions containing CTS as dispersed particulatematerial, exhibited good ER effect. Factors influencing the ER effect and leak current density (J) were studied. The results showed that the shear stress( ) and J increased with the increasing field strength (E) and weight fraction of particles(C) respectively, and decreased with the increasing shear rate ( ). The phenomena were studied with the polarization mechanism and percolation model. It was found that with the increasing deacetylation degree, the ER effect and J of CTS-based ER fluids also increased. The viewpoint of moving ions was used to elucidate this phenomenon.The factors influencing properties of CTS-based ER fluids such as water, glycerol, some surfactants and dispersing media were studied in detail. The results showed that and J of CTS-based ER fluids increased with the increasing water content (Q). It was discussed upon the principles of moving ions and "hydrogen-bond bridges". The ER effect of the suspensions decreased with the increasing surfactant, such as T151 and T705. It was found that the longer the non-polar molecules and the bigger the space volume of the surfactants, the lower will be and J. Based on these experimental results, the viewpoint of "insulation film" was proposed. ER effect was typically affected with the dispersing media. For CTS-based ER fluids, the value of r decreased in the order of chlorinated paraffin oil, protected paraffin oil, castor oil or silicone. Polarization mechanism was used to explain this phenomenon.With the molecular design method, a series of CTS-Mn+ and iodine doped chitosan (CTS-I2 complex) have been prepared and characterized by IR, X-Ray and TGA or DSC. Their characteristicsas ER dispersed particles and influence factors have been investigated. The and J of CTS-Mn+ based ER fluids increased with the increasing of Mn+ content due to the increasing number of moving ions. It was found that CTS-I2 complex was an excellent anhydrous ER dispersed particulate material. The value of of CTS-I2 complex was about twice of that of CTS-based ER fluids (Q=10.0wt%, of particles).In investigating hollow cenosphere ER effect, it was shown that the hollow cenosphere particles had ER effect in silicone oil, but no effect in castor oil. It was also found that hollow cenosphere is an anhydrous ER dispersed particulate material because that r increased with the increasing pre-heated temperature. After heat treatment at 400 C for 2 hours, the hollow cenosphere particles show stronger ER effect than those pre-heated at 100 C.Hollow cenosphere composite particles with core-shell structure were prepared by surface modification of hollow cenosphere particles by ble更多还原