Properties of chitosan-poly(vinyl alcohol) blends in films and solutions

The viscosity of dilute and moderately concentrated solutions (up to 6 wt %) of chitosan blends with PVAL deviates from values predicted by the additive scheme and varies in a nonmonotonic manner with a maximum at 10-15 mol % PVAL. Transparent chitosan films with PVAL (up to 20 mol %) possess higher strength and plasticity as compared to chitosan. According to DTA, X-ray diffraction, and scanning probe microscopy data, the films are microheterogeneous and have a fine-grain crystalline structure similar to that of chitosan with a grain size of ∼50 nm.