Dose rate effects on shape memory epoxy resin during 1 MeV electron irradiation in air

Experimental and Theoretical Study of Gamma Radiolysis and Dose Rate Effect of o-Cresol Formaldehyde Epoxy Composites

“…More specifically, a lower dose rate gives rise to more gas yield with the equivalent radiation dose, which is supported by their increased radiation chemical yields ( G -values) with the descending dose rates (Table ). The physiochemical nature of the dose rate effect is ascribed to the heterogeneous radiochemical kinetics, complex competition reactions, diffusion-controlled reactions, and coupling environment condition-induced synergistic/antagonistic effects. ,,− The abnormal accumulation of CO (Figure d) will be discussed later. These results help to comprehend and cautiously cope with the possible dose rate effects of epoxy materials used in the radiation environments.…”

“…The samples irradiated by γ ray have residual spin species in the matrix, similar phenomena have been hypothetically reported by other authors ,,, without theoretical support and in-depth analysis. According to the chemical structure and radiation condition, phenoxy-type free radicals, nitrogenous free radicals, and alkoxy or peroxy radicals were proposed to be formed. , Their formation may benefit from the low gaseous permeability, stability of free radicals, and low mobility of chains . In our study, the EPR spectra of the investigated samples are all singlets without a perceptible hyperfine splitting structure (Figure a–d).…”

“…Hereby, the EPR-detected paramagnetic species should be from o -CFER. According to the presumption from the reported literature , and our experimental results, the spin species should be oxygen-centered as these fragmental structures in Figure d–f. Figure d,e shows the representative phenoxy-type free radicals, whose ESDs are mainly located on the oxygen atoms and aromatic carbon atoms according to the 0.005 isosurface, more specifically for carbon atoms, on the ortho - and para -carbon atoms.…”

“…Radiolysis and failure are inevitable when epoxy materials are suffering from long-term high-energy radiation such as gamma ray and neutron and electron beam. The dose rate effect, namely, low dose rate causing more serious damage, was found to play an important role in the radiolysis of polymers for both ionizing radiation − and nonionizing radiation . This was probably attributed to the spatial correlation-induced heterogeneity of radiochemical kinetics, species concentration-induced competition reactions, diffusion-controlled reactions, and synergistic/antagonistic effects derived from complicated coupling of environment conditions. ,,− So far, the radiolysis behaviors and mechanisms of o -CFER are seldom reported.…”

“…The dose rate effect, namely, low dose rate causing more serious damage, was found to play an important role in the radiolysis of polymers for both ionizing radiation − and nonionizing radiation . This was probably attributed to the spatial correlation-induced heterogeneity of radiochemical kinetics, species concentration-induced competition reactions, diffusion-controlled reactions, and synergistic/antagonistic effects derived from complicated coupling of environment conditions. ,,− So far, the radiolysis behaviors and mechanisms of o -CFER are seldom reported. Furthermore, the dose rate effect on epoxy materials is far from being sufficiently studied, although this is an all-important challenge faced by nuclear and aerospace industries.…”