RELATIONSHIPS BETWEEN THE CHAIN FLEXIBILITIES OF CHITOSAN MOLECULES AND THE PHYSICAL-PROPERTIES OF THEIR CASTED FILMS

Relationships between the chain flexibilities of chitosan molecules in solutions and the physical properties (gel swelling index, maximum melting temperature, and tensile strength) of their casted films were studied in order to manipulate the conditions to tailor the physical properties of the films made. The chain flexibilities of chitosan molecules in solutions were manipulated by using chitosans with different degrees of deacetylation (DD), pH and ionic strength of the media, and solvent systems. The results show the gel swelling index was independent of the media pH, and decreased with increasing DD of chitosans used, whereas maximum melting temperature and tensile strength increased with the increase of DD of the chitosan molecules. The differences were attributed to different crystalline regions in the films.