聚酰亚胺/TiO_2纳米杂化薄膜耐电晕性能的研究

Study on Corona-resistance of the Polyimide/Nano-TiO_2Hybrid Films

通过原位聚合法制备聚酰亚胺/二氧化钛(PI/TiO2)纳米杂化薄膜并研究其耐电晕性能。利用光激发放电方法(photon-stimulated discharge,PSD)与光度计测试杂化薄膜的陷阱状态与紫外吸收光谱,通过扫描电镜与小角X射线散射技术(small angle X-ray scattering,SAXS)表征薄膜表面的形貌与分形特征。实验结果表明:引入TiO2增加了薄膜中的陷阱密度,提高了薄膜的质量分形维数,在5%组分时出现表面分形,薄膜结构变得致密;随着TiO2组分的增加,薄膜的耐电晕寿命由3.9 h(0%)增加到49 h(7%),薄膜的紫外吸收能力提高;随着电晕时间增加,杂化薄膜表面的聚酰亚胺分解,TiO2颗粒逐渐积累,起到屏蔽电晕侵蚀的作用。因此,有机-无机界面的陷阱状态、TiO2的特性以及薄膜整体分形结构的协同效应提高了杂化薄膜耐电晕性能。

Polyimide/nano-TiO2（PI/TiO2） hybrid films were fabricated via in-situ dispersive polymerization and corona-resistance of films was studied.The trap state and ultraviolet absorption spectra of the films were measured by photon-stimulated discharge（PSD） and ultraviolet spectrophotometer.The surface morphology and fractal characteristics of the films were also analyzed by SEM and small angle X-ray scattering（SAXS）.The results show that the trap density and mass fractal dimensions of hybrid films increase as TiO2 is filled into PI.Meanwhile,surface fractal appears at 5% doping.The variation of fractal characteristics proves hybrid films with more compact and complex structure.With the TiO2 doping concentration increasing,the time-tobreakdown of the hybrid films can be lengthened from 3.9h（0%） to 49h（7%）,and ultraviolet absorptive capacity is improved.With the corona ageing continuing,PI matrix on the surface of films decomposes.Then,a large number of TiO2 particles are gradually accumulated and play a role in shielding further erosion.The corona-resistance of hybrid films is enhanced by synergistic effects which are composed of trap state in the interface,TiO2particles properties and film fractal characteristics.