Films of chitosan and N-carboxymethylchitosan. Part II: Effect of plasticizers on their physiochernical properties

摘要

Chitosan (Ch) and N-carboxymethylchitosan (N-CMCh) films were prepared by the casting method at concentrations of 1% and 2% of polymer, with or without plasticizer: polyethylene glycol (PEG-400) and glycerol (G), at 15% (w/w). The influence of composition on mechanical properties, water vapour transmission rate (WVTR), water saturation, and aqueous dissolution of the films was analysed. The thermal stability of the mixture (polymer:plasticizer, 1: 1) was evaluated by thermogravimetric analysis (TGA). In general, all the properties were affected by the plasticizers. The plasticized films showed lower strength and a higher percentage of elongation (%E), in the following order: G > PEG-400 > unplasticized film. The total WVTR increased with Ch concentration, with a different WVTR profile for Ch and N-CMCh. While the PEG-400 addition did not significantly modify the WVTR profile of films, the glycerol enhanced the transport of water vapour through both polymers. The plasticizer addition increased the time of water film saturation, in the following order: G > PEG-400 > unplasticized film; this was more pronounced in the N-CMCh films, probably due to the formation of hydrogen bonds. The solubility of the films was also affected by their composition. (C) 2006 Society of Chemical Industry.