Moisture Sorption Characteristics of Chitosan/Polyethylene Oxide Blended Films

Abstract

Studies on the moisture sorption characteristics of chitosan/polyethylene oxide (PEO) blended films have been carried out at 27 °C for water activity (aw) from 0.1 to 0.9. The sorption data at different aw were used to fit 12 different sorption isotherm models proposed in the literature. The model constants were determined by linear fitting of the sorption equations. The ranges of applicability of water activity for the isotherms reported in the article lie between 0.11 to 0.44 (monomolecular layer) for the BET model and between 0.11 to 0.86 (monolayer & multilayer’s) for Smith, Caurie, Bradley and Oswin. The water activity for Halsey and Chung & Pfost models lies between 0.44 to 0.86 (multilayer) and 0.33 to 0.86 for Henderson and Freundlich models and 0.11 to 0.65 for Kuhn, Linear and Iglesias & Chirife models. The high coefficient of determination R2 (ranges from 0.82 to 1) confirms the applicability of the equations employed. The study on the application of such water activity data of chitosan/PEO blended films on different model equations will be helpful in prediction of durability and functional behavior of moisture sensitive biopolymeric films