Effect of molecular weight reduction by gamma irradiation on chitosan film properties

• Published in: Materials Science & Engineering C 2015-10, Vol.55, p.174-180
• Main Authors: García, Mario A., Pérez, Liliam, de la Paz, Nilia, González, Juan, Rapado, Manuel, Casariego, Alicia
• Format: Article
• Language: English
• Subjects: Chitosan; Chitosan - chemistry; Chitosan - radiation effects; Elongation; Food Packaging - instrumentation; Gamma irradiation; Gamma Rays; Glass; Irradiation; Lactic Acid - chemistry; Materials science; Mechanical properties; Molecular Weight; Permeability; Polysorbates - chemistry; Reduction; Solubility; Steam; Tensile Strength; Water vapor; Water vapor permeability
• ISSN: 0928-4931; 1873-0191
• DOI: 10.1016/j.msec.2015.05.009

The present work aimed the influence of molecular weight (MW) reduction by irradiation with 60Co and polymer concentration on some physical properties of chitosan films. Irradiation of chitosan with a MW of 275.221kDa and 74.74% of deacetylation degree was performed using a 60Co source to provide doses of 5, 10, 20 and 50kGy to obtain chitosans with molecular weights of 247.847, 221.563, 126.469 and 77.063kDa, respectively. Films were prepared via the solution casting method. Film-forming solutions (FFS) of chitosan irradiated or not, were prepared at 1.5 and 2% (w/v) in a solution of lactic acid at 1% (v/v) and 0.1% (v/v) of Tween 80. The FFS were poured into glass plates of 400cm2 and dried at 60°C during 10h without airflow. The decrease of MW and increase of chitosan concentration increased the tensil strength and water vapor permeability while decreased the elongation at break of the films. The chitosan MW did not significantly influence (p>0.05) the water solubility of films within a same polymer concentration. There was a decrease in the films' brightness with the increase of concentration and a decrease of the MW of irradiated chitosan, while the b* values of films increased and there was an increasing tendency of their apparent opacity. [Display omitted] •MW reduction by 60Co irradiation increased the tensil strength of chitosan films.•MW reduction increased the water vapor permeability of chitosan films.•MW did not affect the films' water solubility within a same chitosan concentration.•Films' brightness decreased with the chitosan molecular weight reduction.