Preparation and characterization of chitosan membranes

The present study investigates a new solvent system for the dissolution of chitosan and a new method for preparing chitosan membranes. First, aqueous tartaric acid was used to pretreat chitosan. Then, the chitosan was precipitated with ethanol or other regenerating agents, and 1.5 mL of 1-ethyl-3-methylimidazolium acetate ([EMIM]AC) was added to obtain translucent suspensions. The chitosan membranes were prepared by casting the suspensions on glass plates and allowing solvent evaporation. The structure and properties of the films were investigated by SEM, FT-IR, XRD and TGA. Also, the mechanical properties, as well as physical and chemical characteristics, of the chitosan films were evaluated. The results indicated that the optimum dissolution time was 10 min and the most suitable drying temperature was 60 °C. The thus-prepared film was moderately thick (about 0.02 mm) and had a smooth surface, without curling. The chitosan film prepared by ethanol regeneration had a tensile strength of up to 24 MPa, a minimum swelling degree of 78%, and a water vapor transmission rate of 270 g m^-2 d^-1 without the addition of plasticizer.