基于辐照交联改性的电容器用聚丙烯薄膜介电性能

Dielectric Properties of Polypropylene Film for Capacitor Based on Irradiation Crosslinking Modification

针对高温强电场环境下传统聚丙烯(polypropylene,PP)薄膜存在击穿场强低、电导损耗高的问题,提出了一种基于γ射线辐照交联的PP薄膜改性方法,研究了辐照剂量和敏化剂等参数对PP薄膜介电性能的影响;制备了含有三羟甲基丙烷三丙烯酸酯(trimethylolpropanetriacrylate,TMPTA)、季戊四醇三丙烯酸酯(pentaerythritol triacrylate,PETA)等敏化剂的PP薄膜,将PP薄膜在60Co-γ射线下进行0、5、10 kGy(1 Gy=1 J/kg)的辐照处理;分析了辐照交联PP薄膜的分子链与聚集态结构表征,研究了高温强场下交联结构对PP薄膜电导率与击穿场强的影响规律。研究表明:高能射线辐照可在PP薄膜内部形成三维网状结构,增强分子链间作用力与热稳定性,有效抑制PP内部载流子输运,显著提升PP薄膜的高温介电性能。115℃下交联度为25.04%的改性PP薄膜电导率降低64.2%,击穿场强提升16.6%,最高理论储能密度达3.78 J/cm3。该方法表明辐照交联改性手段能够有效提升PP薄膜的高温介电性能。

The traditional polypropylene(PP)film has the problems of low breakdown field strength and high conductivity loss under high temperature and strong electric field environment.We proposed a new modified method based onγ-ray irradiation for polypropylene film,and studied the effects of irradiation dose and sensitizer on the dielectric properties of polypropylene films.Polypropylene films containing sensitizers such as trimethylolpropane triacrylate(TMPTA)and pentaerythritol triacrylate(PETA)were prepared.Total irradiation dose of 0,5 and 10 kGy were carried out under 60Co-γ-ray source.The molecular chain and aggregation structure of irradiated cross-linked polypropylene film were analyzed,and the influences of cross-linked structure on the conductivity and breakdown field strength of polypropylene film under high temperature and strong field were studied.The results show that high energy radiation can form a three-dimensional network structure in the polypropylene film,enhance the force between molecular chains and thermal stability,effectively inhibit the carrier transport in polypropylene,and significantly improve the high-temperature dielectric properties of polypropylene film.At 115℃,the conductivity of the modified polypropylene film with the crosslinking degree of 25.04%is decreased by 64.2%,the breakdown field strength is increased by 16.6%,and the maximum theoretical energy storage density reaches 3.78 J/cm3.It is revealed that irradiation crosslinking modification can effectively improve the high temperature dielectric properties of polypropylene films.