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

Zhang, Liming, Liu, Zhanli, Han, Xiangbo, Sun, Yang, Wang, Xiangyou
International journal of biological macromolecules 2019 v.134 pp. 807-814
X-ray diffraction, acetic acid, carbon dioxide, chitosan, differential scanning calorimetry, endothermy, ethanol, hydrogen bonding, oxygen, rheological properties, rheology, temperature, tensile strength, thermal stability, thermogravimetry, water vapor, zein
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 (16.72MPa 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.