Structural, physical and degradation characteristics of polyvinyl alcohol/esterified mung bean starch/gliadin ternary composite plastic

Abstract

Biodegradable composite plastics with better performance can replace synthetic polymer materials in packaging fields such as food and industry. In this study, solvent casting produced different proportions of composite plastics based on polyvinyl alcohol (PVA), esterified starch, and gladin. Pure PVA plastics had high elongation at break value and light transmittance. The PVA/starch/ gliadin plastics had lower hydrophilicity, higher tensile properties, and higher biodegradability despite having a lower elongation at break than the pure PVA plastics. Scanning Electron Microscope, Atomic Force Microscopy, X-ray diffraction, Fourier Infrared Spectra, and light transmittance showed that the PVA/starch/gliadin plastic had good compatibility through the hydrogen bond formation. Various proportions of plastics exhibited different colors due to the different component ratios. Simultaneously, as the content of esterified starch increased, the melting enthalpy and crystallization enthalpy of composite plastics showed an increasing trend. When the PVA accounted for 25% and the starch/gladin was 75%/25%, the hydrophilicity of composite plastics was the lowest, and significantly lower than that of PVA plastics. When PVA accounted for 50% and starch/gladin was 75%/25%, the tensile properties of ternary composite plastics were the highest; when PVA accounted for 75%, and starch accounted for 25%, the elastic modulus of PVA/starch plastics was the highest. Moreover, composite plastics had a higher biodegradability than pure PVA plastics. The outstanding advantages of environment-friendly PVA/starch/gliadin plastics in different proportions can meet various aspects of actual production, such as water-sensitive goods packaging and heavy object bearing.