Property improvement of biodegradable citric acid-crosslinked rice starch films by calcium oxide

Due to several important limitations for packaging applications of starch film such as strength and hydrophilicity, rice starch (Oryza sativa) film was crosslinked with citric acid and modified by different contents of calcium oxide. FTIR spectra showed the evidence of crosslinking by citric acid and the presence of calcium oxide in the modified rice starch films. After the crosslinking, the decrease of degree of crystallinity and swelling including the increase of film smoothness and strain at maximum load were observed. The application of both citric acid and calcium oxide caused greater decrease of swelling, moisture uptake as well as higher stiffness and antibacterial activity than those of the use of only the citric acid. The highest stiffness and antibacterial activity were found for the crosslinked film added by 5 wt% calcium oxide. Moreover, the effect of calcium oxide contents on morphological, thermal and biodegradable properties of the crosslinked films was also investigated.

Automated summary

In this study, rice starch film was crosslinked with citric acid and modified with different contents of calcium oxide to improve its packaging applications. The combination of citric acid and calcium oxide resulted in decreased swelling and moisture uptake, increased stiffness, and enhanced antibacterial activity. The film added with 5 wt% calcium oxide showed the highest stiffness and antibacterial activity, demonstrating the potential for improved properties in packaging materials.