Effect of ethanol content on rheology of film-forming solutions and properties of zein/chitosan film

The paper focused on the role of ethanol on rheological properties of zein/chitosan film-forming solutions, thermo-mechanical and structural characterization of films. The steady rheological results indicated that the film-forming solutions showed non-Newtonian behavior, and ZC-3 solution (zein treated with 90% ethanol and chitosan dissolved with acetic acid) had higher flow index (0.882 ± 0.003). Based on dynamic rheological analysis, ZC-3 solution showed the highest G′ value and the crossover point at the lowest frequency, representing the strongest entanglement and hydrogen bonding. ZC-3 film showed the highest tensile strength and elongation at break (16.72 MPa and 76.80%). The film prepared from high ethanol content improved water vapor, oxygen and carbon dioxide barrier properties. The X-ray diffraction (XRD) demonstrated zein and chitosan had good compatibility. Differential scanning calorimetric (DSC) indicated that the endothermic peak temperature of ZC-3 film was 148.83 °C. The thermogravimetric (TGA) results indicated that ZC-3 film had excellent thermal stability.