Chitosan Film Mechanical and Permeation Properties as Affected by Acid, Plasticizer, and Storage

The effects of acid (acetic, formic, lactic, propionic) concentrations, plasticizer concentrations, and storage time (up to 9 wk) on mechanical properties, water vapor permeability, and oxygen permeability of solution‐cast chitosan films were determined. Measured water vapor permeability coefficients ranged from 5.35 to 13.20 × 10 −1 g/m·day·atm. Oxygen permeated coefficients ranged from 0.08 to 31.67 × 10 −3 cc O 2 m·day·atm. Neither property was affected by storage time. Tensile strength (6.85–31.88 Mpa) also was not time dependent, but elongation (14–70%) decreased with storage time. Lactic acid solutions produced the lowest oxygen permeability values, formic acid the highest. Films formed with 7.5% lactic acid solutions had uniquely high values for elongation at break.