Research On Surface Modification Technique Of Polyimide For Resisting To Atomic Oxygen And Static Electricity

The material of polyimide film has excellent mechanical property as well as itschemical stability, thermal property and optical performance. It is widely used in thearea of aerospace, aviation, chemical, microelectronics and precion optical which can’tbe replaced by other material.Due to the atomic oxygen that exists in the low earth orbitspace which poses a serious threat to the spacecraft and the charging or dischargingeffect on the spacecraft surface caused by the complex plasma environment,it is verynecessary for us to take measures to protect the body of polyimide out of the attackingfrom atomic oxygen and static electricity.This paper studies the technology of making protective coating against theatomic oxygen for polyimide film through silane modification method and ion-exchange method with the reagent such as HMDS, bis, MTS, SiCl4, SnCl4, AlCl3,Zn(NO3)26H2O. Then we studied the change of their optical properties, elements, surface morphology, chemical structure, and the affect of AO. After that a layer of antistatic ITO coating was prepared on the atomic oxygen resistance protective layer by magnetron sputtering process.Then the optical properties, surfacemorphology, electrical performance, and the combination ability between ITO coating and the modified polyimide was researched.The results show that: PI modified by MTS and PI modified by SiCl4have theleast quality loss per unit area and optical transmittance decline compared with PImodified by HMDS、PI modified by bis1with photoactivation、PI modified by bis1withwet chemical method、PI modified by bis2with photoactivation、Al2O3/PI、SnO2/PI、ZnO/PI. Their surface topography is not obvious corroded also. The quality loss per unitarea of original polyimide is as large as26.7times and24.9times of themrespectively.There is a large number of crack on the surface of PI modified by SiCl4.Nocrack is found on the surface of PI modified by MTS.PI modified by MTS has the bestcomprehensive performance for anti-AO.The optical stability, electrical conductivity, and the atomic oxygen erosionresistance increased significantly after ITO was made on the anti-AO modifiedPI.Compared with ITO/PI, binding force between ITO and anti-AO modified PI wassignificantly enhanced. So, ITO can play a great advantage combined with anti-AOmodified PI.