高岭土纳米插层电流变液材料制备及性能研究

【作者】 王宝祥；

【导师】 赵晓鹏；

【作者基本信息】 西北工业大学 ， 凝聚态物理， 2003， 硕士

【摘要】 电流变液（Electrorheological fluids）通常是高介电常数的微小颗粒分散在低介电常数的绝缘液体中形成的悬浮体系。当对它施加电场时，其粘度、剪切强度瞬间变化几个数量级，表现出固体的性质，具有快速可逆的特点。 高岭土有机插层复合物是一种新型纳米复合材料，具有粘土矿物和有机化合物的综合性能，本项研究综合了几种廉价原料的特点，提出一种利用插层的方法，改进电流变性能的思路。在介电极化理论的基础上，考虑了与极化相关的介电参数和电流变效应之间的关系，制备了二甲基亚砜／高岭土复合微粒和羧甲基淀粉插层高岭土的纳米复合材料，分别研究了二甲基亚砜和羧甲基淀粉插层高岭土对电流变行为的影响，取得了如下研究结果： 1 采用直接插层法制备了二甲基亚砜／高岭土复合微粒，用XRD、FTIR对复合颗粒进行了表征。结果表明，二甲基亚砜进入了高岭土的层间，层间距由0.715nm增加到1.110nm，形成高岭土有机插层材料。对复合颗粒所配制的电流变液测试了介电和流变学性能，随着二甲基亚砜插层率的提高，介电常数，电导率，损耗角正切都有不同程度的增长。实验表明，插层复合物电流变液剪切强度为600 Pa(E=3kV／mm，γ=5s^-1)，是插层前的6倍，漏电流密度小于20μA／mm²。同时这种电流变液具有较好的温度稳定性和抗沉降性，插层复合物介电性能的改善是造成流变学性能提高的内在原因。 2 通过羧甲基淀粉的二次插层，结合XRD图谱，红外图谱及SEM图分析可知，CMS的插层引起了高岭土片层之间的剥离，其单一片层分散于羧甲基淀粉中，形成剥离型纳米复合材料。对介电和电导性能的测量显示羧甲基淀粉插层引起复合材料电流变液的介电常数和电导率升高，其介电常数是纯土电流变液介电常数的2.07倍，是羧甲基淀粉电流变液的1.78倍；电导率是纯土的2.73倍。复合材料电流变液的电流变活性获得大幅提高，表现出明显的协同效应，复合材料电流变液的静态剪切应力值是纯高岭土电西北工业大学硕士学位论文摘要流变液的3.6倍。并发现梭甲基淀粉的加入量与电流变性能有密切关系，组分质量比接近1:1时，出现了较强的协同效应，电流变效应最强。这些因梭甲基淀粉插层而导致的高岭土介电和电导性能的变化可解释CMS插层所导致的高岭土电流变行为的变化。 此外，由于高岭土层间被剥离并分散于梭甲基淀粉基体中，复合材料电流变液的温度效应得到明显改善，其工作温区大幅扩展（10⁹0℃）。不仅如此插层还提高了复合材料电流变液的抗沉降性（30天80%未沉降）o更多还原

【Abstract】 Electrorheological(ER) fluids, composed of nonconducting or weakly conducting particles dispersed in an insulating liquid, undergo dramatic, reversible changes when exposed to an external electric field. Apparent suspension viscosities and shear stress can increase several orders of magnitude.The kaolinite-organic matter intercalation compound is a new material with properties both of kaolinite and organic matter. In this paper, we integrate properties of kaolinite, dimethylsulfoxide, and carboxylmethyl starch, proposing a novel way to improve electrorheological effect by intercalating. The experimental result are given as follows:1 Dimethyl sulfoxide/ kaolinite hybrids were synthesized using an direct intercalation method and characterized by XRD and FTIR. The result shows that DMSO were intercalated into the interlayer of kaolinite and basal spacing was swelled from 0.715nm to 1.110nm, so the kaolinite-organic matter intercalation compound was formed. The dielectric and rheological characteristics of ER fluid were measured. The experiment shows that in the electric fields of 3kV/mm when shear rate of 5s-1 was applied to the ERF the shear stress of DMSO/kaolinite hybrids ERF can be 600pa, which is 6 times than that of pure kaolinite ERF. In the meanwhile, the antisedimentation and stability of ERF is excellent. The intrinsic reason for enhancing the rheological property is the improvement of dielectric property of the intercalation hybrids.2 According to the analysis of SEM, FTIR and XRD, we can draw such conclusion: Intercalation of CMS into kaolinite has collapsed the layer construction of kaolinite, which makes the single layers dispersed in the bodies of CMS. Theexperimental results show that intercalation of CMS into kaolinite improves the electrorheological effect. For example, the static shear stress of kaolinite/CMS nanocomposites ERF is 3.6 times as large as that of the pure kaolinite ERF. Furthermore, we also found that the electrorheological effect has the close relationship with the amount of CMS. With the component rate of 1 :1, the synergetic effect is appeared greatly and the kaolinite/CMS ER fluid displays a notable ER effect under DC current field. The test for dielectric and conduction properties shows that intercalatiion has improved the dielectric constant and electric conductivity of nanocomposites ERF. Dielectric constant is 2.07 times as large as that of pure kaolinite ERF, 1.78 times as large as that of CMS ERF; electric conductivity is 2.73 times as large as that of pure kaolinite ERF. These results can well explain the change of ER behaviors of kaolinite. On the basis of these analysis, we found a suitable explanation which can well reveal the increasing of dielectric properties and ER effect.Because the single layers which are collapsed by intercalating dispersed in the bodies of CMS, the nanocomposites ERF’s operational temperature range has been broadened greatly(10-90c). Furthermore, the nanocomposites has a better sedimentation ratio because of the intercalation(sedimentation ratio=20% for 30 days).更多还原