OPTICAL DEGRADATION OF HEAT RESISTANT POLYMER FILM UNDER ULTRAVIOLET AND CHARGED PARTICLE RADIATION

摘要

For exploration of inferior planets, long term heat resistance is required in thermal control materials based on polyimide film. Since UPILEX-S (developed by UBE Industries, Ltd.) is polyimide film with glass transition temperature of exceeding 500°C, thermal control materials based on UPILEX-S film are presently designed by evaluation of flight test, ground test, and degradation mechanism. In this paper describes incident angle dependence of solar absorptance and temperature dependence of total hemispherical emittance of UPILEX-S, results of flight test and ground test, and causes of degradation in polyimide films. The degradation of polymer films is evaluated with optical characteristics. From experimental results, the peak of difference in absorption coefficient was confirmed at 0.44μm in wavelength. The wavelength region conformed to absorption band of radicals including benzene nucleus in the chemical structure. Duration time of recovery and lifetime of these radicals also accord with each other. It was deduced that degradation in polyimide films is occurred by generation of the radicals.