In this paper,the surface of Al2 O3 was modified with the different content ofγ-aminopropyltriethoxyl silane.The obtained modified Al2 O3 particles were characterized by spectroscopy(FT-IR)and X-ray diffraction (XRD).Results showed that KH550 was attached on the surface of Al2 O3 particles successfully.And the Al2 O3 particles and KH550-modified Al2 O3 particles were added to the PI matrix,respectively,PI composite films with 16wt% of Al2 O3 content were prepared with in-situ polymerization.The cross-section microstructure of the obtained composite films was characterized with scanning electron microscope (SEM).Results indicated that different contents of KH550 have a great influence on the dispersion of inorganic particles.In addition,the me-chanical properties and breakdown field strength of the composite films were tested.Test results showed that when the content of KH550 was 2wt%,the tensile strength and elongation at break of PI/KH550-Al2 O3 com-posite films were optimal and were 130 MPa,12% respectively.Compared with the PI/Al2 O3 films,the tensile strength and elongation at break of PI/KH550-Al2 O3 composite films were increased by 22.8% and 44.5%,re-spectively.And the breakdown field strength of that was similar to PI/Al2 O3 films.%通过调整KH550的含量对Al2 O3粉体表面进行改性,并用红外光谱(FT-IR )和 X 射线衍射(XRD)对改性后的粉体进行表征,表征结果显示KH550成功的键合到 Al2 O3粉体表面.然后分别使用Al2 O3以及改性Al2 O3制备了一系列无机粉体含量为16％(质量分数)的PI复合薄膜,通过扫描电子显微镜(SEM)对复合薄膜的断面微观形貌进行表征,并对复合薄膜的力学性能和击穿场强进行测试.测试结果显示KH550的含量对无机粉体分散情况有较大影响.当 KH550含量为2％(质量分数)时,PI/KH550-Al2 O3复合薄膜的拉伸强度和断裂伸长率最优,分别为130 MPa,12％,与PI/Al2 O3薄膜相比,拉伸强度和断裂伸长率分别提高了22．8％,44．5％,击穿场强与其相近.
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