A study on the free-radical evolution and its correlation with the optical degradation of 170 keV proton-irradiated polyimide |
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Authors: | Yiyong Wu Jingdong Xiao Ruifeng Li Dezhuang Yang Shiyu He |
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Affiliation: | Laboratory of Space Materials and Environment Engineering, Harbin Institute of Technology, Harbin 150001, China |
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Abstract: | In this paper, the damage process was investigated on the 170 keV proton-irradiated polyimide, based on the evolution of free radical and its correlation with degradation of the optical transmittance using electron paramagnetic resonance (EPR) and optical-transmittance measurements. The results indicate that the g value of irradiated free radicals keeps at a constant of 2.0025 but the spectral intensity of the free radicals increased with the increasing proton fluence. It is found that during the post-storage after irradiation, the concentration of free radical decreased in an exponential rule with the post-storage time and the free-radical stability can be defined by the corresponding time constant at around 2.3 h. It is interested that the recovery of optical-transmittance follows the same mode as that of free radicals. The mechanisms on the free-radical evolution and the correlation between free radical and optical property are discussed in the paper. |
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Keywords: | Polyimide Free radical Optical transmittance Degradation evolution |
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