Influence of Glutaraldehyde Crosslinking and Alkaline Post-treatment on the Properties of Chitosan-Based Films

Depending on the modifications proposed, chitosan films present different characteristics, for instance correlated to hydrophilicity, chemical and mechanical properties. The aim of this study was to evaluate the influence of glutaraldehyde crosslinking and an alkaline post-treatment with NaOH on the characteristics of chitosan based films. Films were obtained by casting and characterized by thickness, swelling degree, mechanical and thermal properties and chemical structure. The water vapor permeability (WVP) was also evaluated for food packaging application. It was observed that crosslinking and NaOH post-treatment have great influence on the chitosan films characteristics. Crosslinking reduced the swelling degree of films and increased its fragility, whereas NaOH treatment also reduces the swelling degree and changes mechanical properties, acting in the same way as a crosslinker. The WVP analyses showed that the basic treatment could substitute the glutaraldehyde crosslinking for film water stability, without greatly compromising the barrier properties of chitosan based films.