以4,4'-二氨基二苯醚(ODA)、3,3'4,4'-二苯甲酮四羧酸二酐(BTDA)为单体,1,6己二胺(HD)为交联剂,采用先交联后环化方法制备了具有交联结构的新型聚酰亚胺电介质材料。利用傅里叶变换红外光谱仪、X射线衍射仪、原子力显微镜、扫描电子显微镜等对交联聚酰亚胺的化学结构和形貌进行了表征,通过电子试验机、宽频介电阻抗谱仪、击穿强度测试仪测试了交联聚酰亚胺的力学性能、介电性能和击穿强度。结果表明,交联结构在减小聚酰亚胺分子链间距的同时,引入了深电子陷阱能级,不但阻碍了分子链的运动,降低了内部自由体积和微观缺陷,同时抑制了内部偶极子的取向极化以及载流子的迁移;随着HD含量的增加,交联聚酰亚胺的拉伸强度、杨氏模量和击穿强度逐渐升高,介电常数和介电损耗降低。当HD质量分数为2%时,交联聚酰亚胺的击穿强度为550.1MV/m,比非交联聚酰亚胺击穿强度提高了44.1%。
Novel polyimide dielectric materials with cross-linked structure were prepared by the cross-linking followed by cyclization method using 4,4'-diaminodiphenyl ether (ODA),3,3'4,4'-benzophenone tetracarboxylic dianhydride (BTDA) as the monomers,and 1,6 hexanediamine (HD) as the cross-linking agent.The chemical structure and the morphology of the cross-linked polyimide were characterized by FT-IR,XRD,AFM and SEM,and the mechanical properties,dielectric properties and breakdown strength of the cross-linked polyimide were tested by material testing machine,broadband dielectric impedance spectrometer and breakdown strength tester.The results showed that the cross-linked structure introduced a deep electron trap energy level while reducing the spacing of the polyimide molecular chains,which not only hindered the movement of the molecular chains and reduced the internal free volume and microscopic defects,but also inhibited the orientation polarization of the internal dipole as well as the carrier migration.With the increase of HD content,the tensile strength,Young's modulus,and breakdown strength of the crosslinked polyimide gradually increased,and the dielectric constant and dielectric loss decreased.When the HD content was 2 wt%,the breakdown strength of the cross-linked polyimide was 550.1MV/m,which was 44.1% higher than that of the non-crosslinked polyimide.
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