Effect of UV-treatment on the properties of biodegradable rice starch films

Rice starch biodegradable films were prepared by casting film solution on leveled trays and ultra violet (UV) irradiation for 10 min was applied. The influence of content (3%, 6% and 9 wt. %) of the photosensitizer (sodium benzoate) on the properties of rice starch films was investigated. The tensile strength and gel fraction increased but elongation at break, water barrier properties, degree of swelling and crystalline peak structure of rice starch films decreased with additional and increasing content of the photosensitizer. However, too high a level of photosensitizer (9%) yielded lowering properties in the resulting films, but it was still much higher than untreated rice starch films. It was observed that incorporation of photosensitizer into the rice starch films increased lightness and made it yellowish but decreased transparency. The results showed that the carboxylate group band of sodium benzoate in the FTIR spectrum was present in the rice starch films. These results pointed out that there was an interaction between starch molecules induced by the photosensitizer. In addition, the highest absorption band resulted from cross linking reaction activity was observed when 6% photosensitizer was applied.