环境因素对聚酰亚胺薄膜及涂层侵蚀效应分析

目的采用不同表面改性方法处理聚酰亚胺,研究温度、湿度、紫外辐照和原子氧等环境因素对聚酰亚胺基体及涂层的侵蚀效应。方法用碱性溶液(NaOH)、硅烷偶联剂(KH-550)分别在水热及溶剂热条件下处理聚酰亚胺薄膜。用溶胶凝胶法制备二氧化硅溶胶,并在改性后的聚酰亚胺薄膜表面制备二氧化硅涂层。处理后样品的亲水性变化由接触角测量仪测定,透光率用紫外可见分光光度计表征,表面形貌用扫描电镜观察,表面结构变化由傅里叶变换红外光谱仪测定。环境效应试验用紫外老化箱和原子氧模拟试验装置进行评价,并用扫描电镜和材料显微镜表征环境因素对涂层产生的影响和破坏作用。结果实验得出的最佳表面处理条件为:(1)NaOH浓度0.1 mol/L,水热温度120℃,时间60 min;(2)20vol%KH-550+80vol%Et OH,溶剂热温度180℃,时间60 min。在此条件下处理后的聚酰亚胺基体与二氧化硅涂层界面结合较牢固。结论使用碱液水热处理与硅烷偶联剂溶剂热相结合的处理方法,可有效改善Si O2涂层与聚酰亚胺基体的界面粘附性。所制备的涂层均匀致密,具有很好的抗原子氧侵蚀能力,但在储运过程中必须注意环境湿度对涂层产生的破坏作用。

Analysis of Erosion Effect of Environmental Factors on Polyimide Films and Coatings

The work aims to study erosion effect of environmental factors including temperature, humidity, ultraviolet and atomic oxygen radiation on polyimide films and coatings by treating polyimide in different surface modification methods. The polyimide films were treated by alkaline solution (NaOH) under hydrothermal condition and silane coupling agent (KH-550) under solvothermal condition respectively. Silica sol was prepared in sol-gel method, and silica coatings were prepared on the modified polyimide films. Hydrophilicity, transmittance, surface morphology and surface structure change of the modified po-lyimide films was characterized by contact angle meter, ultraviolet visible spectrophotometer, scanning electronmicroscopy (SEM) and Fourier transform infrared spectrometer, respectively. Environmental effect test was evaluated with ultraviolet acce-lerated weatherometer and atomic oxygen simulator. The effect and destructive effect of environmental factors on the coatings were characterized with SEM and material microscope. The optimum surface treatment conditions were obtained: (1) 0.1 mol/L NaOH solution under hydrothermal condition at 120 , 60 min; (2) 20vol% KH℃ -550 + 80vol% EtOH under solvothermal con-dition at 180 , 60 min. Interface between the polyimide substrate treated under the above conditions and silica coatings was℃bonded securely. The interface adhesion between polyimide substrate and SiO2coatings can be effectively improved in surface modification methods of alkali hydrothermal treatment combined with silane coupling agent solvothermal process. The prepared silica coatings are homogeneous and dense, and resistant to atomic oxygen attack. However, destructive effect of environmental humidity on the coatings during the process of storage and transportation must be noted.