CONICET | Buscador de Institutos y Recursos Humanos

In this work we studied the formation of biocomposite films through attaching of chitosan (CS) on polypropylene (PP) modified with grafted acrylic acid (AAc) and their use in the fixation of methylene blue (MB) like a model substrate. Methylene blue, a molecule with anti-oxidizing and antibacterial activity, was attached to the film surface in order to analyze its incorporation performance at different superficial levels. Firstly, surface of PP film was modified with AAc using a photo-graft polymerization at room temperature, and benzophenone (BP) was used as radical initiator. Here, the effect of the reaction time was analyzed on the AAc grafting degree (G) during the reaction. Later, we analyze the effect of the AAc grafting degree (G) on the reaction of CS immobilization (I) and final properties of the biocomposite films attained. It was found that the surface modification of PP films with 16% of G shows the more suitable properties to develop the CS-immobilization reaction, wich consists in electrostatic bond onto the carboxyl groups of the grafted film (PP-g-AAc), obtaining also the biocomposite films (PP-g-AAc-CS). The maximum value of CS immobilization obtained at room temperature was a 8%. The MB dye was fixed to films modified using three techniques, where in a case the MB molecule was attached to PP-g-AAc by electrostatic interaction with carboxyl groups (A). On the other hand, the dye was fixed into the PP-g-AAc-CS film by diffusion (B), and finally, methylene blue was mixed with CS and then anchored to PP-g-AAc (C). Keywords: chitosan, films, packaging, polypropylene