Proton and electron irradiation effects on outgassing behaviors of polymers in vacuum and its mechanism

The effects of 160keV electron and 100keV proton on outgassing feature of DGEBA/DICY and dimethyl silicone rubber were investigated using a simulating facility of space radiation environment. Under radiation of electrons and protons, the mass loss of DGEBA/DICY exhibits an exponential increase with increasing irradiation fluence. The dimethyl silicone rubber shows higher irradiation stability than DGEBA/DICY. The mass loss of dimethyl silicone rubber has little change under electron irradiation, and increase under proton irradiation. The maximum mass loss of rubber is lower than that of DGEBA/DICY under the same irradiation condition. The in-situ analyses of mass spectrum and fourier infrared spectrum show that, the charged particles cause the breaking of C-C, C-H, C-N, and C-O, of which have lower binding energy in DGEBA/DICY, leading to degradation reaction and formation of small-molecular substance. The volatilization of the formed small-molecular substance enhances the outgassing process. The net structure produced by reaction of pendant group plays an obstacle role for outgassing. Cross-link reaction was found in the proton irradiated rubber. The partial degradation of molecular chain resulted from the irradiation induced bond breaking of Si-O facilitates the outgassing process.