Abstract: The properties of poly-(vinyl alcohol) (PVA) films added with chitosan (CS) and chitosan nanoparticles (NCS) were evaluated. A colorimeter and an ultraviolet (UV) spectrophotometer were used to investigate the optical properties. A gas permeability tester and a water vapor permeability tester were used to test the gas permeability and water vapor permeability, respectively. The moisture absorption capacity was measured under isothermal conditions, and the experimental data were fitted with various common isotherm models. Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC) were used to characterize the molecular structure and crystallinity. The results showed that the addition of CS enhanced the UV barrier properties of PVA film and the effect of NCS was more prominent. The addition of CS or NCS reduced the gas permeability and improved the water vapor permeability. Moisture absorption isotherms of PVA, PVA/CS and PVA/NCS films could be best fitted with the GAB equation (R2 > 0.98). FT-IR results indicated that PVA/CS and PVA/NCS films were homogenous with intermolecular hydrogen bonds being formed between PVA and CS. DSC analysis showed that the addition of CS or NCS slowed down the crystallization rate, reduced the degree of crystallinity, and increased the endothermic enthalpy of PVA.

Key words: chitosan, chitosan nanoparticles, poly-(vinyl alcohol) film, optical properties, moisture absorption isotherm