Electron spin resonance study of γ‐irradiated nylon 6

Abstract

SynopsisThe free radicals trapped in oriented nylon 6 filaments after y-irradiation under vacuum at room temperature were studied by ESR spectroscopy. The ESR spectrum measured after irradiation gradually changed to a broad singlet spectrum with decrease in the intensity. The ESR spectrum consisted of radicals with different orientation effects with respect to the outer magnetic field, and saturation effects in reference to microwave power. The simulation of the ESR spectrum from a Gaussian function gave a better fit to the observed spectrum than the calculation from a Lorentzian function. From the resolution of the spectrum from a Gaussian function, the observed spectrum is generated from three kinds of radicals: The relative radical concentration for the first, second, and third radical is about 75%, 6%, and 19% of the total radical concentration, respectively. With regard to the stability of the radicals, the third radical shows a comparatively long lifetime. The first and second radicals show almost identical lifetime, and their concentrations reduce to about 40% of the initial value during the 2 days at room temperature.

ESR study of gamma irradiated 2-methyl nylon3

“…The singlet spectrum is most probably due to the unpaired electron on the oxygen atom (R2). A similar broad singlet observed in polyamides reported by some authors (Takigami et al (1981); Shinohara and Ballantine (1961) and Simon et al (1977)). Simon et al (1977) was assigned to the conjugating structures as in our present study.…”