In order to obtain the chitosan oligomers

chitosan was irradiated in the solid state with and without H2O2 as a radiation degradation sensitizer

respectively. At room temperature

the viscosity average-molecular weight (Mη) of chitosan was decreased from 1.6 × 106 to 2.2 × 105 at an absorbed dose of 72 kGy without H2O2

and decreased to 2.7 × 104 at 2 kGy in the presence of an appropriate H2O2 content. In addition

the radiation degradation rate of chitosan containing 38.2wt% H2O2 is 59 times higher than that in the solid state without H2O2. FT-IR analysis suggests that there is no obvious change in the chemical structure of irradiated chitosan with and without H2O2 at a dose below 20 kGy

compared with unirradiated chitosan. On the other hand

the degree of deacetylation (DD) of irradiated chitosan in the studied dose range changed slightly

while DD of irradiated chitosan with H2O2 increased significantly. The XRD pattern indicates that the irradiated chitosan with H2O2 has more perfect crystalline structure than unirradiated chitosan. Therefore

it could be expected that irradiation of chitosan using H2O2 as a sensitizer would be a very effective method to prepare low molecular weight chitosan

because of its feasibility and benignancy to environment.