Effect of the carbonyl content on the properties of composite films based on oxidized starch and gelatin

To improve the properties of gelatin, oxidized starch (OS) with different carbonyl content was introduced into the gelatin. In this study, we researched the influence of the carbonyl content of OS on the rheological characteristics, swelling behavior, thermal properties, and wettability of the modified gelatin film (MGF). The MGF samples were prepared by the casting of a 10% w/w solution of gelatin and OS with 18.9, 38.7, and 49.3% carbonyl content, respectively. The results of the dynamic viscosity demonstrated that the influence of the temperature on the rheological characteristics of native gelatin film (NGF) was more obvious than that of MGF. Meanwhile, the viscosity of the samples decreased with increasing carbonyl content in OS. Both the differential scanning calorimetry and thermogravimetry curves indicated that the denaturation and pyrogenic decomposition temperatures of the MGF samples were higher than those of NGF; this meant that the crosslinking between NGF and OS improved the physicochemical properties of gelatin. Compared with the NGF sample, MGF was less hydrophilic because the hydrophilic groups of gelatin could be shielded by OS. Meanwhile, the acid–base and salt sensitivity of the MGF samples were very obvious; therefore, the MGF samples could potentially be used as biomedical materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3809–3815, 2013