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Electron spin resonance studies of γ‐irradiated cellulose. II. Free radicals in accessible regions to water in cellulose I and cellulose II
Author(s) -
Shimada Machiko,
Nakamura Yoshio,
Kusama Yasuo,
Matsuda Osamu,
Tamura Naoyuki,
Kageyama Eiichi
Publication year - 1974
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1974.070181118
Subject(s) - radical , cellulose , electron paramagnetic resonance , crystallinity , irradiation , singlet state , photochemistry , amorphous solid , materials science , chemistry , spectral line , cellulose fiber , polymer chemistry , analytical chemistry (journal) , crystallography , nuclear magnetic resonance , organic chemistry , excited state , atomic physics , physics , astronomy , nuclear physics
The types of free radicals produced in the water‐accessible regions of cellulose I and cellulose II fibers by γ‐irradiation in nitrogen atmosphere at room temperature were studied by ESR spectroscopy. The ESR spectra of the irradiated cellulose I and II change by contacting the fibers with water, and after immersion in water the spectral shape depends on the orientation of the fiber axes to the magnetic field. These spectra are probably related to the free radicals generated in the highly ordered regions inaccessible to water in irradiated cellulosic fibers. The ESR spectrum of free radicals generated in decrystallized cellulose after irradiation consists of a singlet and a doublet. When the ESR spectra of free radicals formed in the highly ordered regions of cellulose I and II and the singlet and the doublet are combined in adequate ratio, the constructed spectra are similar to those of the radicals scavenged by water in the irradiated cellulose I and II fibers. From these facts, the spectra due to the free radicals in the water‐accessible regions in irradiated cellulose I and II are considered to consist of the singlet and the doublet formed by free radicals in the typical amorphous regions and the spectra of other types of radicals generated in the semicrystalline regions.