Insight into crosslinked chitosan/soy protein isolate /PVA plastics by revealing its structure, physicochemical properties, and biodegradability

Abstract

Biodegradable plastics are attracting attention for their excellent performance and eco-friendliness. In this study, various ratios of cross-linked chitosan/soybean protein isolate (SPI)/PVA ternary hybrid plastics were prepared by casting, and their structures and physicochemical properties were characterized. Due to hydrogen bonding, FT-IR and XRD results indicated good compatibility between the hybrid plastics. The hybrid plastics surface and cross-section were smoother and evener with few cracks and small free particles at chitosan to SPI ratios of 1:3 and 1:1. AFM results further verified that the relative roughness of the hybrid plastic was lower. In addition, the light transmission and water absorption gradually decreased. Also, with increasing the ratio of chitosan and SPI, the hybrid plastic thermal properties, e.g., crystallization temperature, crystallization enthalpy, melting temperature and melting enthalpy were enhanced. Moreover, blended plastics chroma values exhibited differences under various ratios. Also, the ratio increases of chitosan and SPI improved the plastics' tensile strength and elastic modulus and reduced the elongation at break. Furthermore, the hybrid plastics after soil burial possessed more pores and cracks, implying better degradability. The results obtained in this study can help expand the application and fabrication of crop-based biomacromolecules to meet various packaging requirements such as water resistance, excellent bearing capacity, and favor biodegradability. • Adding chitosan and SPI can reduce plastic surface roughness by promoting compatibility. • Hybrid plastic exhibits superior water resistance compared to pure PVA . • The addition of chitosan and SPI enhances the mechanical properties of hybrid plastics. • After soil burial, the hybrid plastic exhibited desirable degradability.