Evaluation of the effects of additives on the properties of starch-based bioplastic film

The adverse environmental effects of petroleum-based packaging plastics have necessitated the need for eco-friendly bioplastics. Most bioplastics are starch-based and are not without drawbacks, hence there is the need for their properties to be improved. In this study, the effect of varying concentrations of dialdehyde starch and silica solutions on the physical, mechanical, biodegradable, surface topology, and thermal properties of the bioplastic films was examined. The additive concentrations were varied from 60 to 100%. The bioplastic films produced with dialdehyde starch solution recorded better moisture content (6.62–11.85%), bioplastic film solubility (4.23–7.90%), and tensile strength (1.63–3.06 MPa), against (11.24–14.26%), (7.77–19.27%) and (0.53–0.73 MPa) respectively for bioplastic films produced with silica solution. The atomic force microscopy analysis; root-mean-square roughness, kurtosis, and skewness revealed better miscibility and compatibility between the starch matrix and the dialdehyde solution than between the starch matrix and the silica solution. Bioplastic with added dialdehyde starch solution has better tensile strength and long biodegradability than that with silica solution. The research has demonstrated that bioplastic film produced with starch and dialdehyde starch solution has better properties than the one produced with starch and silica solution. The properties evaluation results of the bioplastic films thus demonstrated their aptness for food packaging applications. Graphic abstract

Physical Properties of Films Based on Gelatin and Dialdehyde Starch with Different Oxidation Degrees

In this study, dialdehyde starch (DAS) was prepared by oxidizing corn starch using potassium periodateas the oxidant.The aldehyde contentsin DAS weredetermined using titration with hydroxylamine and were found proportional to the molar ratio of KIO4:C6H10O5.Fourier transform infrared spectroscopy was used to confirm the breakage of the bond between C2 and C3in anhydroglucose units and the formation of -CHO group in DAS. X-ray diffractometry showed a decrease in crystallinity of starch after periodate oxidation. Thermogravimetric analysis showed reduced thermal stability of DASin comparison with the native starch. The prepared DAS was blended with gelatin to form films by casting method. Increasing aldehyde contents in DAS from 0 to 12.2% resulted in decreased moisture contents, solubility in water, and the swelling capacity of gelatin-DAS films. The value of tensile strength and elongation at break of the gelatin-DAS films rose when the aldehyde content was low (0-3.5%), but declined when the aldehyde content was high (3.5-12.2%). Slight periodate oxidation is, therefore, an effective way to enhance the mechanical characteristics of blend films from DAS and other biopolymers.