Studies of chitosan. 1. Preparation and characterization of chitosan/poly(vinyl alcohol) blend films

Various blending ratios of chitosan/poly(vinyl alcohol) (CS/PVA) blend films were prepared by solution blend method in this study. The thermal properties and chemical structure characterization of the CS/PVA blend films were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and Fourier transform infrared (FTIR). Based upon the observation on the DSC thermal analysis, the melting point of PVA is decreased when the amount of CS in the blend film is increased. The FTIR absorption characteristic is changed when the amount of CS in the blend film is varied. Results of X-ray diffraction (XRD) analysis indicate that the intensity of diffraction peak at 19 degrees of PVA becomes lower and broader with increasing the amount of CS in the CS/ PVA blend film. This trend illustrates that the existence of CS decreases the crystallinity of PVA. Although both PVA and CS are hydrophitic biodegradable polymers, the results of water contact angle measurement are still shown as high as 68 degrees and 83 degrees for PVA and for CS films, respectively. A minimum water contact angle (56 degrees) was observed when the blend film contains 50 wt % CS. (c) 2007 Wiley Periodicals, Inc.