Effects of plasticizer type and concentration on rheological, physico-mechanical and structural properties of chitosan/zein film.

Abstract

The purpose of this study was to evaluate the effect of plasticizer type (glycerol, PEG-400, and sorbitol) and concentration (0%, 15%, 30% and 45%, w/w dry polymer weight) on rheological and physico-mechanical and structural properties of chitosan/zein blend film. Based on the analysis of rheological properties of chitosan/zein film-forming solutions, all film-forming solutions exhibited non-Newtonian behavior. The flow index of film-forming solution increased and apparent viscosity decreased with the increase of plasticizer concentration. The storage modulus (G ) and the loss modulus (G″) decreased when plasticizer was added. The permeability of films increased significantly with the increase of plasticizer concentration, but the C/Z-P film (plasticized chitosan/zein film with PEG-400) had better barrier performance compared with the other two. The C/Z-P film had better mechanical properties and light transmission. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) revealed chitosan and zein had good compatibility due to the addition of the plasticizer, and crystallinity decreased with the increase of plasticizer concentration.