Nanofilled dielectrics for high voltage electrical insulation

由于粘性组合物的混合已经达到当前材料加工技术的限制，使用微米级填料的高压应用中使用的复合材料不太可能进一步改进。然而，纳米颗粒(纳米颗粒)填充介电材料的初步发现显示，在大大减少了填充剂的添加后，材料的性能得到了类似的改善；因此，现有的加工技术很可能会进一步改进介电材料。大多数研究人员一致认为，有机材料(纳米复合材料)中纳米颗粒的问题是颗粒的分散，而均匀混合是开发纳米复合材料的关键。其中一个问题是，由于颗粒的高表面能，纳米颗粒容易团聚，而传统的混合技术不能使纳米颗粒团聚。另一个问题是疏水聚合物与亲水纳米颗粒不相容，导致界面相互作用不佳。因此，迫切需要寻找替代方法来获得更好的纳米颗粒分散性。本研究主要是利用表面活性剂对纳米粒子进行物理和化学修饰。虽然表面活性剂通常应用于液体，但其在形成固体介电材料的组合物中分散纳米颗粒的应用尚未见报道。使用表面活性剂的主要优点是它降低了纳米颗粒的表面和界面张力，从而减少了团聚，使颗粒更容易分散。初步研究结果表明，Triton是一种常见的表面活性剂，有助于纳米二氧化硅和纳米氧化铝在硅橡胶中的分散。这项研究将集中于了解表面活性剂如何改善纳米介电材料的性能，以及哪些复合体系适合于优化高压电绝缘复合材料的介电性能。

Further improvements to composite materials for use in high voltage applications using micron size fillers are not likely, as mixing of the viscous compositions has reached the limitation of current material processing technology. However, initial findings of nano-size particle (nanoparticle) filled dielectrics show similar improvements to materials at considerably reduced filler additions; thereby, the promise of further improvements to dielectric materials are likely with the existing processing technology. Most researchers agree that the problem with nanoparticles in organic materials (nanocomposites) is the dispersion of particles and uniform mixing is critical in the development of nanocomposites. One of the problems is that the nanoparticles agglomerate easily because of the high surface energy of the particles and conventional mixing techniques do not break apart the nanoparticle agglomerates. Another problem is the incompatibility of the hydrophobic polymer with hydrophilic nanoparticles, resulting in poor interfacial interactions. Thus, there is a great need to discover alternative ways to obtain a better dispersion of the nanoparticles. The reseach focuses on the surface modification of the nanoparticles by physical and chemical methods using surfactants. Although surfactants are commonly applied to liquids, their application to disperse nanoparticles in compositions forming solid dielectric materials has not yet been reported. The main advantage of using a surfactant is that it lowers the surface and interfacial tensions of the nanoparticles resulting in reduced agglomeration and makes it easier to disperse the particles. Preliminary findings have shown that triton, a common surfactant, aids in the dispersion of nanosilica and nanoalumina in silicone rubber. The research will concentrate on the understanding of how surfactants can improve the properties of nanodielectrics and which composite systems are appropriate to optimize the dielectric properties of these composites for high voltage electrical insulation.