Intramolecular transfer of high energy in cellulose

Abstract

AbstractThe intramolecular transfer of high energy in purified cotton cellulose has been demonstrated to occur over distances several times greater than the length of the b axis of a cellobiose unit. The electron spin resonance spectra of fibrous benzoylated cotton cellulose have shown that the concentrations of free radicals initiated in the cellulosic molecule by γ‐radiation from Co60 are decreased by the presence of substituted benzoyl groups spaced at least as far apart as 70–80 A. The retention of the breaking strength of fibrous cotton cellulose on exposure to γ‐radiation is increased by substitution of benzoyl groups on the cellulose molecule. The substitution of benzoyl groups, spaced at least as far apart as 10–20 A., results in about 80% retention of the initial strength of the fibrous cellulose at dosages as high as 1.3 × 1021 e.v./g. cellulose, as compared with about 20% retention of the initial strength of unsubstituted cellulose at the same dosage. Based on the breaking strengths of the irradiated fibrous celluloses, at a dosage of 1.3 × 1021 e.v./g. cellulose, the average calculated distances between molecular cleavages are increased from about 500 A. for unsubstituted cellulose to about 3000 A. for benzoylated cellulose (degree of substitution 2.0). These energy transfer effects in cellulose of high molecular weight indicate that polymeric carbohydrates can be radioprotected.