Electron Spin Resonance Spectrum of Irradiated Cellulose II

Abstract

AN asymmetric electron spin resonance spectrum has usually been reported for the free radicals produced by the γ-irradiation of cellulose^1,2. During the course of an investigation on the effect of crystallinity and cross-linking on the degradation of cellulose by γ-radiation we noticed that while specimens of ramie and cotton (cellulose I) gave the familiar asymmetric electron spin resonance spectrum (Fig. 1B), all the samples of regenerated cellulose (cellulose II) gave the more symmetric pattern (Fig. 1A). While the cause of this difference has not been further investigated, its relationship to the differences in the X-ray fibre diagram³ is of interest. We have recently shown from the relationship between the radical concentration and the degree of crystallinity that the stable radicals in cellulose are in the ordered regions. It follows that the differences in electron spin resonance pattern reported here must be a reflexion of the differences in molecular arrangement in cellulose I and cellulose II crystallites and might be expected to yield further information about these structures.