制备了BPDA/ODA、BP DA/PDA和PMDA/ODA体系的聚酰亚胺(PI)薄膜,探究不同化学结构的PI薄膜在热氧和紫外辐照等外界环境条件下的结构与性能演变。力学性能测试表明,热氧和紫外辐照会导致PI薄膜力学性能下降,但不同化学结构的PI薄膜下降趋势不同,其中PMDA/ODA下降最快,BPDA/PDA下降最慢。红外测试结果表明,热氧和紫外辐照老化过程中酰亚胺环中的C—N键最先发生断裂,导致PI薄膜亚胺化程度降低,力学性能下降。此外,电子自旋共振光谱仪相对其他表征方法在PI薄膜老化初期可以较为直观地检测到自由基浓度随老化时间的变化,可作为PI材料早期老化诊断的手段。
In order to explore the structure and performance evolution of polyimide (PI) films with different chemical structures under external environmental conditions such as thermal oxygen and UV irradiation,BPDA/ODA,BPDA/PDA and PMDA/ODA films were prepared.The results of mechanical properties tests showed that thermal oxygen and UV irradiation could lead to the decline of mechanical properties of PI films,but the decline trend of PI films with different chemical structures was different,with PMDA/ODA declining the fastest and BPDA/PDA declining the slowest.Infrared test results indicated that the C—N bond in the imide ring was the first to be broken during the aging process caused by thermal oxygen and UV irradiation,resulting in a decrease in the degree of imidization and mechanical properties of the PI film.In addition,compared with other characterization methods,electron spin resonance spectrometer could more intuitively detect the change of free radical concentration with aging time in the early stage of PI film aging,which could be used as a means of early aging diagnosis of PI materials.
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基金资助
国家自然科学基金项目(51790501、51673017、21404005);国家重点基础研究发展计划(973计划)(2014CB643604、2014CB643606)
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