研究了不同紫外辐照时间对聚醚酰亚胺(PEI)薄膜介电性能的影响。采用FT-IR和SEM表征了PEI薄膜的分子结构和微观形貌。结果表明, 紫外辐照后PEI薄膜在1742 cm-1处的吸收峰比原薄膜增大, 说明PEI分子链中的C=O基团随辐照时间的增加而增加, 并在薄膜表面产生了微裂纹。对PEI薄膜的介电性能进行的研究结果表明, 随着紫外辐照时间的增加, PEI薄膜的介电常数和介电损耗增大, 而表面电阻率下降, 体积电阻率基本不变。并随紫外辐照时间的增加, 直流击穿强度呈先增加后降低的趋势, 一定辐照剂量可使薄膜发生交联反应, 使击穿场强较原薄膜提高20%以上。

The effect of ultraviolet irradiation on the dielectric properties of polyetherimide (PEI) film samples was investigated. FT-IR and SEM were used to characterize the molecular structure and the surface morphology of the untreated and treated PEI films in different UV irradiation time. The results show that the absorption peak of the irradiated PEI film at 1724 cm-1 was greater than that of the virgin, which indicates the amount of C=O groups increases with increasing irradiation time, and cracks occurred on the PEI surface. The dielectric properties of PEI films were also studied in detail. The results show that, with the increase of irradiation time, the relative dielectric constant and the dielectric dissipation factor increased, surface resistivity decreased, and volume resistivity was almost unchanged. PEI film of DC breakdown strength firstly increased, and then decreased with the increase of radiation time. Moreover, the irradiated film’s breakdown strengh at a certain irradiation dose is 20% greater than that of the original film, which may be attributed to the crosslinking action under the ultraviolet irradiation.