Study on the Synergic Effect of Chitosan Degradation in Homogeneity with Hydroperoxide and Gamma Co-60 Radiation

Chitosan with deacetylation degree (DD) 70.3% and mass average molecular weight (Mw0) 9.15 x 104 in dilute lactic acid solution of 5% (w/v) was effectively degraded by hydroperoxide (1%) under irradiation with gamma Co-60 radiation (1.33 kGy/h) in low dose range up to 16 kGy. The degradation effect was studied by measurement of Mw with gel permeation chromatography. Based on Mw results, it indicated that the synergic effect of degradation was of 56% at 4 kGy and gradually decreased to zero at 16 kGy. Values of scission yield (Gs) were found out to be Gs = 22.51 x 10-7 mol/J and Gs = 2.83 x 10-7 mol/J for 5% chitosan with and without 1% hydroperoxide, respectively. In addition, the structure of the degraded product was characterized by Fourier transform infrared (FTIR) spectroscopy. The DD value of chitosan calculated from FTIR spectra was almost not changed by irradiation of chitosan solution either with or without 1% hydroperoxide