In this study, polyimide (PI)/carbon fiber (CF) aerogel was fabricated via a freeze-drying method. The introduction of CF endows PI aerogels with good dimensional stability in the thermal imidization process. The resulting aerogel possesses excellent mechanical property (as high as 58.45 MPa) and good hydrophobic property (contact angle above 120°). The PI/CF aerogel also has very good radiation resistance, with a compressive modulus of 50.45 MPa even after 10 MGy irradiation, which is 86.53% of the initial modulus. These characteristics make the PI/CF aerogel very suitable for applications in radiation environment. Subsequently, a carbon aerogel with high temperature resistance and good mechanical properties was obtained by carbonization of the PI/CF aerogel. Its comprehensive property is comparable to traditional porous carbon-bonded carbon fiber composites.

Gamma radiolysis behaviors and mechanisms of silica-filled o-cresol formaldehyde epoxy are studied at 2.20 × 10 −5 to 1.95 × 10 −1 Gy/s. The radiolysis-induced changes in chemical structures do not severely affect its thermostability. The slightly deteriorated mechanical strength at temperature exceeding 100 °C is accompanied by the declining glass transition temperature (from 185.9 to 172.2 °C) and enhanced damping ability. The gas yields of hydrogen, methane, and carbon dioxide manifest a remarkable dose rate effect. Based on the Schwarzschild law, their yields at an extremely low dose rate are accurately predicted by the established master curves. Besides, the latent radiolysis of gas products and postradiation effect are found with caution. The radiation-caused residual spin species are proved to be composed of silica defects and a phenoxy-type free radical with a tert-butyl group, according to the experimental results, theoretical calculations, and spectra simulations. The lower vertical ionization potential (7.6 eV) and adiabatic ionization potential (7.1 eV) are primarily due to the ionization of the benzene ring moiety with the tert-butyl group, which is likely to suffer from radiolysis. The calculated bond dissociation energy (260.8−563.5 kJ/mol) of the typical chemical bonds of epoxy is consistent with its radiolytic vulnerability and degradation mechanisms.

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