聚合物电介质材料因质轻、易加工、功率密度高、可靠性高等优点，被广泛应用于高脉冲电子电力系统中，用以实现能源存储与转化。目前使用的电介质薄膜，虽大多数性能都能满足使用要求，但薄膜的力学性能及收缩性、稳定性还有待改善。以抗拉伸高介电电容器薄膜为目标，利用无机纳米填料对增强聚合物的调控实现薄膜材料力学性能的优化，通过调控聚合物内部结构、偶极变化以及热传导系数等方法提升薄膜材料抗拉伸性和收缩稳定性；采用偶联剂和有机小分子对SiC粒子进行接枝改性，提高SiC在聚合物基体中的分散性；用硅烷偶联剂（KH550）将碳化硅表面氨基化后，得到改性填料SiC-KH550；用钛酸酯偶联剂（TBT）进行接枝，得到改性填料SiC-TBT，使改性后的粒子分散性得到改善；以PP为基体、SiC颗粒为无机填料，通过熔融共混法和热压法制备改性聚丙烯基复合薄膜，对其进行一系列的性能测试及微观结构表征。结果表明：与纯PP相比，加入改性SiC粒子后，拉伸强度从30.22 MPa提高到了42.30 MPa；冲击强度从4.76 kJ/m²提高到了6.02 kJ/m²；介电常数从2.5提高到2.9，介电损耗仍维持在较小变化范围内；介电击穿从29.0 MV/m提高到43.6 MV/m；从SEM图的微观形貌来看，改性后的颗粒在聚合物基体中分布更加均匀，无机相与有机界面处相容性较好。
关键词: 高介电 / 抗拉伸 / 表面改性 / 聚丙烯膜 / SiC / 偶联剂
Abstract:
Polymer dielectric materials are widely used in high-pulse electronic power systems for energy storage and conversion due to their advantages of light weight, ease of processing, high power density and high reliability. Although the dielectric films currently in use meet performance requirements in most respects, their mechanical properties and shrinkage stability remain to be improved. With the aim of developing high-dielectric capacitor films with high tensile strength, inorganic nanofillers are used to modulate the reinforced polymer, thereby optimizing the mechanical properties of the film material. The tensile strength and shrinkage stability of the film material are enhanced by regulating the internal structure of the polymer, dipole changes, and thermal conductivity. SiC particles are graft-modified through coupling agents and organic small molecules, to improve the dispersion of SiC within the polymer matrix. The surface of silicon carbide was aminated using a silane coupling agent (KH550) to generate modified filler SiC-KH550. Grafting with a titanate coupling agent (TBT) yields the modified filler SiC-TBT, which improves the dispersion of the modified particles. PP matrix and SiC particles as the inorganic filler are melted and hot-pressed to prepare modified polypropylene-based composite films, followed by a series of performance tests and microstructural characterisation. The results indicate that, compared with pure PP, the incorporation of modified SiC particles leads to improvements in all aspects of performance. Tensile strength increased from 30.22 MPa to 42.30 MPa. Impact strength increased from 4.76 kJ/m² to 6.02 kJ/m². The dielectric constant increased from 2.5 to 2.9, whilst the dielectric loss remained within a narrow range. The dielectric breakdown voltage increased from 29.0 MV/m to 43.6 MV/m. Judging from the microstructure observed in the SEM images, the modified particles are distributed more uniformly within the polymer matrix, and compatibility at the interface between the inorganic and organic phases is better.
Keywords: high dielectric strength / tensile strength / surface modification / polypropylene film / SiC / coupling agent