Modeling of water sorption isotherms of chitosan blends

The blends obtained on the basis of biodegradable chitosan were investigated taking into consideration possible miscibility of their components due to the presence of hydrogen bonds leading to formation of complexes. However, the components of chitosan blends with hydroxypropyl cellulose, poly(ethylene oxide), poly(vinyl alcohol) and starch show good miscibility only on a domain scale of micron or less size. The Authors proposed the formula which considers the dependence of moisture content on the weight fraction of the blend components and taking into account the observed lack of additivity resulting from the presence of some molecular interactions (the parameter partial derivative) of functional groups in the presence of water. Modelling of water sorption isotherms of polymer blends using the parameter d leads to good correlations with the experimental results simultaneously indicating that the greatest deviation from the moisture additivity occurs in case of high water activity (water humidity). (C) 2010 Published by Elsevier Ltd.