Effect of absorbed dose on starch:PVA films irradiated with gamma rays

The films characterized by starch:PVA weight ratio equal to 45:55 were obtained by solution casting and irradiated with Co-60 gamma rays in vacuum applying doses of 5, 10, 20, 30, 50 and 75 kGy. The results have shown that irradiation with a dose of 5 kGy induces decrease in surface hydrophilicity shown by increase in contact angle to water with no special impact of using the higher doses. Tensile strength was not affected by irradiation performed with doses in all the range of 5-75 kGy, however using doses of 20 kGy or higher might result in decrease in the films' flexibility. Decrease in capacity to swell in water accompanied by increase in solubility of the material was also observed after irradiation. A reduced gel content together with an increased solubility of the irradiated material have shown that degradation prevails over crosslinking under gamma irradiation. It can be concluded that radiation modification carried out with gamma rays using doses up to 10 kGy may find application in manufacturing better films in the starch:PVA system, and that using doses of 5 kGy is sufficiently effective for this purpose. Simultaneously, the starch:PVA (45:55) films turn out to be suitable for packing of food intended for radiation decontamination using doses up to 10 kGy.