Effect of Oleic Acid on the Properties of Chitosan/Zein Blend Film

In order to improve the mechanical properties of chitosan/zein blend film, firstly, chitosan solution and zein solution were blended, then, oleic acid as plasticizer was added into the above solution to prepare a series of chitosan/zein film-forming solutions containing different mass fraction of oleic acid (0, 15%, 30%, 45%, based on the total mass of chitosan and zein solutions, the same below). The particle size, Zeta potential, static and dynamic rheological properties of film-forming solutions were analyzed. The effects of oleic acid on the barrier properties, mechanical properties and compatibility of blend films were evaluated. The results showed that the addition of oleic acid made the particle size of film-forming solution increase and disperse evenly. The film-forming solution containing 30% oleic acid exhibited better dispersion property with a PDI of 0.34 and a particle size of 1307.5 nm. With the increase of oleic acid content, the viscosity of film-forming solution decreased and the flow index increased, and the elastic modulus and viscosity modulus increased. The blend film containing 30% oleic acid had better mechanical properties, its tensile strength was 36.37 MPa and its elongation at break was 22.32%. Moreover, the barrier property of this blend film was enhanced. The water vapor transmittance and oxygen transmittance of the film-forming containing 45% oleic acid reduced by 44.21% and 67.52% compared with the film without addition of oleic acid. In the blend film, chitosan and zein molecules demonstrated good compatibility, and the surface of film was flat. © 2019, Editorial Office of FINE CHEMICALS. All right reserved.