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Química Nova

Print version ISSN 0100-4042On-line version ISSN 1678-7064


GARCIA, Rosangela Balaban et al. Evaluation of gels obtained from acetylation of chitosan in heterogeneous medium. Quím. Nova [online]. 2008, vol.31, n.3, pp.486-492. ISSN 0100-4042.

Chitosan was acetylated during 2, 5 and 10h and physical gels were obtained at different polymer concentrations in N,N-dimethylacetamide containing 5% of LiCl. Acetylation was confirmed by infrared spectroscopy and 13C NMR, and degrees of acetylation in the range of 0.82-0.91 were determined by NMR. The O-acetylation degree (0.12-0.15) was exclusively determined by a volumetric method. Rheological studies showed that the storage modulus values were smaller for the more acetylated samples and increased with the temperature and the polymer concentration. All the gels presented storage modulus superior to loss modulus, evidencing more elastic than viscous characteristics. The results obtained in this work suggest a gelation process based on a balance between O and N-acetylation and intermolecular bonds.

Keywords : chitosan; gel; rheology.

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