Fig. 1. Compression curves of (a) ρ300,and (b) ρ600 before and after γ radiation,compression,and γ radiation-compression aging

Fig. 2. Elastic modulus of (a) ρ300,and (b) ρ600 as a function of absorbed dose before and after γ radiation and γ radiation-compression aging

Fig. 3. [in Chinese]

Fig. 4. Morphology of (a) surface,and (b) cross section before and after sealing the tube

Fig. 5. Surface morphology of (a) ρ300,and (b) ρ600 after γ radiation and γ radiation-compression aging

Fig. 6. EPR spectra of (a) ρ300,and (b) ρ600 before and after γ radiation and γ radiation-compression aging

Fig. 7. Radical concentration of samples before and after γ radiation and γ radiation-compression aging of PPO foams (color online)

Fig. 8. ATR-FTIR spectra of (a) ρ300 before and after γ radiation,(b) ρ600 before and after γ radiation,(c) ρ300 after γ radiation-compression,and (d) ρ300 after γ radiation-compression aging

Fig. 9. Infrared spectra of the gases released from (a) ρ300,and (b) ρ600 before and after γ radiation and γ radiation-compression aging (color online)

Fig. 10. Evolved gas yields of CO₂ from (a) ρ300,and (b) ρ600 after γ radiation and γ radiation-compression aging