Chitosan dissolved in CH3 COOH／NaCl aqueous solution was irradiated at various conditions

and the influence of H2O2

N2O

isopropanol

pH and molecular weight of chitosan on the radiation degradation of chitosan in aqueous solutions was investigated．In acidic solutions(pH=3)

the degradation of chitosan in aqueous solutions might be attributed to the interaction with both·H and·OH radicals．The degradation of chitosan was slightly faster in the presence of H2O2 or N2O

because the concentrations of·OH radicals increased slightly．The degradation of chitosan was inhibited obviously after adding isopropanol

due to the decrease of both·H and·OH radicals in the presence of isopropanol．With the pH of the solution approaching neutral

the concentration of ·H decreased and the·OH radicals increased rapidly with the presence of H2O2 or N2O．The chain scission of chitosan was promoted significantly after adding H2O2 or saturated with N2O．In addition

it was found that the rate constant of radiation degradation of chitosan increased with the decrease of molecular weight of ehitosan．UV and FTIR analyses of radiation-degraded chitosan manifested that except for carbonyl groups generated at the ends of molecular chains

no obvious change in the main chain structure of radiation—degraded chitosan

comparing with unirradiated chitosan．Therefore

gamma irradiation can be expected as an effective way to control the molecular weight of chitosan without obvious change in its backbone structure．