硅橡胶复合材料的电绝缘性能、耐电老化性能优异，广泛应用于复合绝缘子、防污闪涂料和电缆应力锥等高电压绝缘领域。但随着国家“三纵三横一环”特高压能源安全输电战略的实施，大容量、长距离输电线路的安全问题再次突显。其中，硅橡胶绝缘防护性能提升的要求日益迫切。利用纳米材料提高聚合物基复合材料性能的研究由来已久。研究表明，传统微米颗粒添加量大、功能单一，而少量纳米颗粒便可以显著提高电介质的电气性能，如降低复合材料的介电常数、提高体积电阻率、提高击穿强度。但纳米颗粒的均匀分散和有机/无机界面，始终是影响硅橡胶性能提升的难点。本论文针对上述问题，使用两种方法进行改进：首先，对纳米颗粒进行表面改性设计，以提高其分散性；使用亚微米或者微米级的纳米结构颗粒，结合大尺寸颗粒容易分散的特点，并保留纳米颗粒的优点。探索了颗粒的纳米尺度、纳米形貌和多级结构对硅橡胶电气性能的影响，主要研究内容和结果如下：（1）纳米氧化镁对硅橡胶电气性能的影响通过溶胶-凝胶法及高温煅烧过程（800 °C和1000 °C），制备了两种表面活性的纳米氧化镁（分别标记为MgO800和MgO1000），并用十二烷基三乙氧基硅烷（标记为C12）对其进行改性，得到改性纳米氧化镁（标记为MgOC12）。研究结果表明：随着煅烧温度的升高，颗粒粒径和结晶度增大，表面活性降低，吸附氧和吸附水含量减少；颗粒经过有机改性后，表面疏水化。MgO与硅橡胶基体相容性差，界面结合弱，即使通过表面改性，MgOC12在基体中均匀分散，复合材料的拉伸性能和击穿强度的提高也有限，且颗粒含量较高时，击穿强度稍有下降。由于纳米MgO可以有效束缚载流子的迁移，并捕获自由基，复合材料的热稳定性和体积电阻率显著提升。当MgOC12含量为3 phr (parts per hundred rubber)时，硅橡胶的起始热分解温度提高69.8 °C，体积电阻率达到最大，为7.7×1016 Ω·cm。（2）空心二氧化硅微球对硅橡胶电气性能的影响利用聚苯乙烯微球作为模板，通过溶胶-凝胶法及模板煅烧过程，制备了壁厚分别为15 nm和35 nm的空心二氧化硅微球（Hollow Silica Spheres, 分别标记为HSS15和HSS35），采用stober法制备了实心二氧化硅微球（Solid Silica, 标记为SS）。研究结果表明：亚微米级的HSS和SS颗粒在基体中分散均匀，而纳米二氧化硅虽然经过强力剪切分散，仍然存在团聚体。相比于HSS35和SS，HSS15颗粒的比表面积大，表面粗糙、有破孔，这种特殊的纳米形貌，有利于增强颗粒和基体之间的界面相互作用，使硅橡胶的拉伸性能、热稳定性和击穿强度显著提高。当HSS15含量为5 phr时，复合材料的击穿强度最大提高37.7 %，这主要归因于HSS15与基体之间的强界面相互作用、颗粒对电子破坏通道的阻挡作用以及对基体的保护作用；硅橡胶的起始热分解温度提高75.6 °C。由于界面区域对载流子的束缚作用，降低了载流子的浓度和迁移速率，HSS15使硅橡胶的体积电阻率明显上升。纳米二氧化硅因分散不均匀，颗粒和基体的界面结合较弱，对硅橡胶电气性能的增强作用并不明显。（3）多孔玻璃微珠对硅橡胶电气性能的影响以玻璃微珠（Hollow Glass Microsphere, 标记为HGM）为原料，在水热条件下，通过碱刻蚀的方法，制备了表面多孔的玻璃微珠（标记为HGM-1）和通孔结构的玻璃微珠（标记为HGM-2）。研究结果表明：HGM-2由于丰富的孔结构和高比表面积，与硅橡胶基体的界面结合强度高，明显提高了硅橡胶的拉伸强度和断裂伸长率；由于微球对基体的保护作用及强的界面结合，硅橡胶的热稳定性提高；由于界面层对载流子迁移的限制，低含量（<5 phr）的HGM-2提高了硅橡胶的体积电阻率；由于HGM-2对基体的保护作用、对电子破坏通道的阻挡作用以及强界面相互作用，硅橡胶的击穿强度最大提高22.3%，这对于微米尺寸的颗粒来说是很少见的。但碱刻蚀反应导致HGM-2颗粒表面氢氧根离子和羟基增多，加上颗粒尺寸大、孔结构复杂，复合材料的偶极子极化和界面极化增大，介电常数和介电损耗上升。HGM-1表面多孔，对硅橡胶拉伸性能的增强不如HGM-2，而且由于杂质离子的存在，复合材料的体积电阻率和击穿强度略有下降。;Silicone rubber (SR), with excellent dielectric properties, thermal stability and hydrophobicity, has been widely used in high-voltage insulation fields such as composite insulator, anti-pollution flashover coating and cable stress cone. With the continuous improvement of the voltage level of the power transmission in our country, high-capacity and long-distance transmission lines put forward higher requirements on the mechanical properties and electrical insulating properties of SR.A few percent nanoparticles can significantly improve the electrical properties of the composites, such as reducing the dielectric constant of the composites, increasing the volume resistivity, and improving the breakdown strength, due to their large specific surface area. However, in the study of nanodielectrics, nanofillers are easy to agglomerate and disperse unevenly in the matrix. How to get better dispersion of nanoparticles has always been the difficulty and emphasis in the research of nanodielectrics. In our study, two methods were utilized to enhance the dispersion of particles: 1) For nanoparticles, organic surface modification was carried out to improve the dispersion of nanoparticles; 2) Using submicron or micron nanostructured particles, which retain the advantages of nanoparticles, and easy to disperse. The main research contents and results are as follows:(1) Effects of surface activity and surface modification of nano MgO on the electrical properties of SRBy the sol-gel method and sintering process under high temperature (800 °C or 1000 °C), nano MgO (marked as MgO800 and MgO1000) with different surface activity were prepared. Modified surface of nano MgO (marked as MgOC12) was prepared using dodecyltriethoxysilane (C12). The results demonstrated that by boosting the calcination temperature, the particle size and crystallinity of MgO increased, and the surface activity of particles decreased as well, accordingly the adsorption of oxygen and water became low. After surface modification, the surface of MgOC12 turned hydrophobic, hence the moisture resistant of the particles improved. Due to the poor compatibility between particles and the matrix, MgO800 and MgO1000 almost had no reinforcing effects on the mechanical properties of SR. Even if MgOC12 particles were evenly dispersed into the matrix after surface modification, the tensile properties of SR/MgOC12 composites remainded weak. When the filler loading kept less than 1 phr (parts per hundred rubber), nano MgO increased the volume resistivity of SR by the order of MgO800 > MgO1000 > MgOC12. This phenomenon occured because the particles with high surface activity could effectively capture carriers and improve the volume resistivity of composites. For untreated nano MgO, as the filler content maintained more than 1 phr, the volume resistivity of composites commenced to decrease owing to the aggregation of the particles. Since MgOC12 was uniformly dispersed in the matrix and held the filler loading at 3 phr as well, the volume resistivity of composites reached the maximum (7.7×1016 Ω·cm). The interface interaction between nano MgO and SR matrix was weak, so the breakdown strength of SR/MgO composites had no obvious change even after surface modification of the particles. When the loading of MgO800 and MgO1000 kept high, the breakdown strength of the composites decreased slightly.(2) Effect of nano-scale morphology of hollow silica spheres (HSS) on the electrical properties of SRUsing polystyrene microspheres as templates, HSS with wall thickness of 15 nm and 35 nm (marked as HSS15 and HSS35) were prepared by sol-gel method and sintering process. Also, monodisperse solid silica (marked as SS) was prepared by stober method. The results revealed that the HSS and SS particles with sub-micron size were uniformly dispersed in the matrix without agglomeration. Fumed silica was easy to form agglomerates in the matrix despite the strong shear of the three-roll extruder. Due to its high specific surface area, the rough surface and the holes on the shell, HSS15 can introduce a strong interface interaction into the composite. Therefore, the tensile properties and thermal stability of SR/HSS15 composites were remarkably improved. Since the molecular chains and dipoles were restrained by the interface zone, and the dielectric constant of air inside the microspheres was low, dielectric constant of the composites was reduced. Because of the binding effect of the interface zone on the carriers, the concentration and migration rate of carriers were diminished, so the volume resistivity of SR/HSS15 composites greatly increased. Compared to pure SR, the breakdown strength of SR/HSS15 composites increased by 37.7 % at most, which was attributed to the strong interface interaction between HSS15 and the matrix, the blocking effect of particles on the development of electron destruction channel and the protection of HSS15 on the matrix. Owing to the introduction of Maxwell-Wagner interfacial polarization in SR/SS composites, the dielectric constant and dielectric loss of the composite increased; the volume resistivity and breakdown strength also decreased with increasing the filler loading and defects.(3) Effect of porous glass microspheres with nanostructure on the electrical properties of SRPorous glass microspheres, namely porous surface HGM (marked as HGM-1) and the through-hole structure HGM (marked as HGM-2) were prepared by alkali etching under hydrothermal conditions using hollow glass microspheres (HGM) as a raw material. Due to the abundant pore structure and high specific surface area of HGM-2, the interface bonding strength among HGM-2 and the matrix was strengthened, so the tensile strength and elongation at break of SR were significantly improved. Moreover, the thermal stability of the composites was improved because of the strong interfacial bonding and the protection of the microspheres on the matrix. Volume resistivity of SR with a few HGM-2 loading (<5 phr) was increased because of the limitation of carrier migration in the interface zone. Furthermore, on account of the protective effect of HGM-2 on the matrix, the blocking of the electron destruction channel by the microspheres and the strong interface interaction, the breakdown strength of SR/HGM-2 composites was notably improved, which is rare for polymer composites doping with micron particles. However, the dipole and interfacial polarization were accelerated owing to the large particle size, pore structure complexity and increasing of hydroxyl ions and hydroxyl groups on the surface of HGM-2, which increased the dielectric constant and dielectric loss of the composite. The HGM-1 porous structure existed on the surface，so the tensile properties of SR/HGM-1 was not as good as that of SR/HGM-2. The volume resistivity and breakdown strength of SR/HGM-1 composites decreased slightly because of the presence of impurity ions. For HGM, the impurity ions on the surface of the particles and the weak interface interaction led to the rapid decrease of the volume resistivity and breakdown strength of the composites.