Abstract:

Chitosan （CS）/corn starch （St）/citric acid （CA） crosslinked films were prepared by a tape casting method using CS and St as raw materials and CA as a crosslinking agent. The effects of CS and ST contents on the thermal stability， water solubility， moisture resistance， and mechanical properties of the crosslinked films were investigated. The results indicated that the addition of CA generated a significant impact on the performance of the crosslinked films， and the as⁃prepared films exhibited the best comprehensive performance when the mass ratio of CS/St was 2∶1 and the mass fraction of CA in the solution was 2. In this case， the films presented a maximum thermal decomposition temperature of 366.3 ℃， a mass residue rate of 28.3 %， a water content of 8.16 wt%， a water solubility of 28.48 %， a swelling degree of 18.72 %， a water contact angle of 101.5 ° on the film surface. Their water vapor permeability was determined to be 8 g/（m²·24 h）， which was reduced by 12.25 times. The films also exhibited a water vapor permeability coefficient of 0.488×10^-13 g·cm/（cm²·s·Pa）. Their tensile strength was increased from 3.7 to 12.5 MPa， and their elongation at break was increased from 85.3 % to 113.2 %.

Key words: chitosan, corn starch, citric acid, crosslinked film, moisture barrier property