Thermal treatment of chitosan in various conditions

Chitosan acetate film prepared by casting from solution was stored and heated in vacuum or oxygen atmosphere up to 600 °C. The chitosan carbonizate, maintaining the shape of origin film, was obtained in vacuum pyrolysis. FTIR spectroscopy results for samples heated under isothermal conditions were compared to data from thermogravimetric analysis conducted in nitrogen and oxygen atmospheres. It was found that the adsorbed water is evolved into at least two stages before chitosan thermal degradation because of different interaction of H2O molecules with the polysaccharide. The changes in the degree of deacetylation of chitosan proves that the decomposition in side groups takes place during sample heating. The presence of water (impossible to remove during drying at atmospheric pressure) disturbs the proper calculation of the degree of deacetylation.