Estudo e caracterização de filmes de quitosana reticulados com dialdeído de amido (DAS) e ácido tânico

Abstract

The aim of this work was to formulate polymer films based on commercial chitosan and chitosan hydrochloride, using starch dialdehyde (DAS) and tannic acid as crosslinking agents to improve film properties, such as resistance, water vapor permeability and solubility. The use of chitosan as the basis for the formulation of biodegradable films is interesting, because it has low toxicity and biocompatibility. Films based on biopolymers have gained a lot of interest in the scientific community and industry for their potential toreplace conventional non-biodegradable materials for structures and packaging materials. However, the low solubility of chitosan motived the interest in using one of its derivatives, chitosan hydrochloride, which, beinga salt,is soluble in water, facilitating the process of making films. Few studies have reported the use of chitosan hydrochloride, being a differential of this study. However, polymer films usually have low resistance, and their mechanical and barrier properties are weak, which may be improved by adding to the film formulation crosslinking agents, which are capable of improving these properties. In this work, starch dialdehyde (DAS) and tannic acid, which had already been used efficiently, were used as crosslinking agents. For the characterization of chitosan, the techniques of Proton Nuclear Magnetic Resonance(¹H NMR) and Carbon Nuclear Magnetic Resonance (¹³C NMR), Fourier Transform Infrared Spectroscopy (FTIR), thermo gravimetric analysis and viscosimetry. The crosslinking agents were identified by Fourier Transform Infrared Spectroscopy (FTIR), as well as films with and without cross linkers. In addition, mechanical tests and water vapor permissibility were performed for the films. Therefore, it can be determined that the chitosan used can be classified as high purity chitosan with a degree of deacetylation of 97.08%. Viscosity determined that chitosan has a low molar mass: 2.818 × 104mol -1. The characterization analyzes confirmed the chitosan structure and its purity. The thermogravimetric analysis showed three characteristic decomposition events of chitosan. The mechanical tests showed that the cross linkers were able to improve the mechanical properties of the films, except for the reistance. In addition, they were able to decrease the permeability to water vapor. And the FTIR spectra suggested that the cross linkers were incorporated into the structure of the films.