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Using microwave (MW) irradiation, polyacrylonitrile was grafted onto chitosan with 170% grafting yield under homogeneous conditions in 1.5 min in the bsence of any radical initiator or catalyst. Under similar conditions a maximum grafting of 105% could be achieved when the K 2 S 2 O 8 /ascorbic acid redox system was used as radical initiator in a thermostatic water bath at 35 Ϯ 2°C. The representative graft copolymer was characterized by Fourier transform infrared spectra, thermogravimetric analysis, and X-ray diffraction measurement, taking chitosan as a reference. The effects of such reaction variables as monomer/ chitosan concentration, MW power, and exposure time on the graft co polymerization were studied. A probable mechanism for grafting without the redox system under microwaves was proposed.

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