基于极性分子掺杂和结构设计的聚丙烯薄膜绝缘性能提升方法

Improvement in Insulating Property of Polypropylene Film Based on Polar Molecule Doping and Structural Design

聚丙烯薄膜具有击穿场强高、介质损耗低等优点,是金属化薄膜电容器中应用最广泛的介质材料。为提高聚丙烯薄膜在高温强场下的绝缘性能,选择对酞醛和八氟对二甲苯二聚体作为添加剂,制备3种复合薄膜试样并开展了不同温度下的电导率、击穿场强、储能密度测试。研究结果表明:掺杂质量分数0.02%对酞醛、0.02%八氟对二甲苯二聚体的复合薄膜电导率降低了95.3%~98.6%,击穿场强提高了26.7%~32.1%,储能密度提升了86.9%~89.4%,相比纯聚丙烯薄膜具备更优异的介电性能。基于密度泛函理论计算了极性分子的静电势分布与禁带宽度,研究表明分布在薄膜两侧的添加剂将引发电荷捕获效应,促进电极薄膜界面处反向电场的形成,进而提升聚丙烯薄膜的绝缘性能。该研究结果将为服役于金属化薄膜电容器中聚丙烯薄膜的界面改性及极性分子选择提供参考。

Polypropylene(PP)film has the advantages of high breakdown field strength and low dielectric loss,which is the most widely used dielectric material in metallized film capacitors.In order to improve the insulation performance of polypropylene film under high temperature and strong field,terephthalaldehyde and parylene were selected as additives to prepare three kinds of composite film samples.The conductivity,breakdown field strength and energy storage density at different temperatures were tested.The results showed that the composite film with 0.02%terephthalaldehyde and 0.02%parylene doping in each functional layer exhibited the best performance.The conductivity decreased by 95.3%~98.6%,the breakdown field strength increased by 26.7%~32.1%and the energy storage density increased by 86.9%~89.4%.Based on the density functional theory,the electrostatic potential distribution and band gap of polar molecules were calculated.The results showed that the additives concentrated on both sides of the film could cause the charge trapping effect,promote the generation of reverse electric field at the interface,thus improving the insulation performance of the polypropylene film.The research results will provide a reference for the interface modification and the selection of polar molecule.