Characterization and potential applications of gamma irradiated chitosan and its blends with poly(vinyl alcohol).

Naturally available chitosan (CHI), of high molecular weight, results in reduced efficiency of these polymers for antibacterial activity. In this regard, irradiation is a widely used method for achieving reduction in molecular weight of polymers, which may improve some of its characteristics. Chitosan was extracted from crab shells and degraded by gamma radiations. Effect of radiation dose on chitosan was analyzed by Fourier transform infrared (FTIR) spectroscopy. Furthermore, the irradiated chitosan was blended with poly(vinyl alcohol) (PVA) and crosslinked with tetraethylorthosilicate (TEOS) into membranes. The membranes were found to be smooth, transparent and macroporous in structure, exhibiting high tensile strength (TS: 27-47 MPa) and elongation at break (EB: 292.6-407.3%). The effect of molecular weight of chitosan and chitosan blends on antibacterial activity was determined. Irradiated low molecular weight chitosan and membranes showed strong antibacterial activity against Escherichia coli and Bacillus subtilis.