Fig. 1. FTIR spectra of the P（AN-co-IA）samples (a) and partial enlarged image (b) (color online)

Fig. 2. Content of IA as a function of ratio of intensities of－COOH to－C≡N

Fig. 3. Different samples were heat treated at 220 ℃ for 30 min: (a) FTIR spectra of P0~P5 samples; (b) FTIR spectra of P0~P5 samples after pretreatment with an absorbed dose of 75 kGy; (c) FTIR spectra of P3 samples after irradiation with different absorbed doses; (d) EOR result chart of all samples

Fig. 4. DSC curves of P（AN-co-IA）powder irradiated at various doses in nitrogen atmosphere(a) 0 kGy; (b) 25 kGy; (c) 50 kGy; (d) 75 kGy; (e) 100 kGy; (f) 200 kGy

Fig. 5. DSC results of samples with different absorbed doses and IA contents: (a) released heat; (b) difference between initiation temperature and termination temperature; (c) velocity of releasing heat

Fig. 6. Influence coefficient of two modification methods on the cyclization reaction of P(AN-co-IA)

Fig. 7. TG curves of a part of powder samples heated at 10 ℃/min: (a) not irradiated by electron beam; (b) irradiated by 100 kGy electron beam; (c) irradiated by 150 kGy electron beam; (d) P3 samples irradiated by electron beam with different absorbed doses(color online)

Fig. 8. DTG curves of a part of powder samples heated at 10 ℃/min: (a) not irradiated by electron beam; (b) irradiated by 75 kGy electron beam; (c) irradiated by 150 kGy electron beam; (d) P3 samples irradiated by electron beam with different absorbed doses(color online)