新型可控结构聚酰亚胺纳米复合纤维膜的制备、介电性能及其耐电晕机理研究

In recent years, use of variable frequency technology in industries has continuously increased because of the demand for energy-saving. However, the remarkable difficulty face to us is that pre-breakdown of the invertors. To extend the lifetime of inverter-fed motors insulation，the researchers have taken lots of studies on the preparation of polyimide films by employing blend or in-situ polymerization. However, the corona resistance with dispersivity was not good enough in practice use. The reason is that the method of preparation is not good for nanoparticles dispersived in the polymer matrix. There was no accordance with the mechanism of corona resistance among the researches. Electrospinning is an efficiency and convenient method of preparing nanofibers which has been reported in Science published in January 20, 2006. In this proposal, we present that the novel high performance polyimide/inorganic nanofiber films with controllable structures were prepared by electrospinning. We focus the design of the structure of the fibers on insulating properties, considering with the diameter and distribution of nanofiber, beads-in-wire structures. The dielectric properties, surface potential, space charge and corona aging of the nanofiber films were also studied. The relationship between the consistence of the films and dielectric properties and aging will be revealed. And the mechanism of corona resistance also would be built.

应对世界"节能"需求，变频技术受到越来越广泛的应用。因各种原因引起的大批电机绝缘过早破坏，是电机使用变频技术后面临的一大难题。国内外学者通过普通共混或原位聚合的方法研制了聚酰亚胺耐电晕薄膜，但由于其制备方法在纳米粒子分散问题上的局限性，使得材料的耐电晕性能不稳定且分散性较大，对机理的研究至今也没有统一的认识。静电纺丝是一种高效便捷的制备纳米纤维的纺丝技术。2006年1月20日出版的《Science》杂志对此有专题报道。申请人提出通过静电纺丝工艺获得新型可控结构的高性能聚酰亚胺/无机纳米复合纤维膜，重点研究纳米纤维结构的设计(材料选取、纳米纤维直径、串珠结构、空间排布等)对绝缘特性的影响规律，同时研究纳米复合纤维膜的介电性能(介电常数、电导率等)、 空间电荷和表面带电与电晕老化特性，揭示材料组成、制备工艺、多层次结构与介电性能和绝缘老化特性之间的相互关系，提出纳米复合纤维膜的耐电晕机制。

本项目根据研究计划认真执行，成功的在聚酰亚胺基体中引入了零维的TiO2粒子和一维的TiO2纳米线，这种零维与一维的纳米材料相结合，有效的提高了复合材料的介电性能、击穿场强、耐电晕性等综合性能。同时研究了通过静电纺丝技术制备的钛酸钡（BT）纳米纤维与PI基体复合，得到的复合薄膜具有优异的介电性能。为了实现电纺技术在其他电介质材料方面的普适性，还制备了聚酰亚胺/碳纳米管、聚偏氟乙烯/碳纳米管以及环氧树脂/氧化铝纳米纤维等复合电介质材料，在电导特性、力学性能、热性能等方面都得到大大提升。在项目执行期间，共发表各类论文共31篇，其中SCI收录论文24篇，标注本基金项目资助的共21篇，重要论文包括Applied Physics Letters 2篇, Journal of Applied Physics 3篇，Journal of Physical Chemistry C 1篇，Journal of Materials Chemistry A 1篇，IEEE DEI 2篇。培养毕业硕士生8名。