| Abstract: | Synthetic polymers are rarely degraded in nature and cause environmental pollution. Biodegradable films have been developed to alleviate the pollution. Many countries have great interests in biodegradable food packaging films. Poly (3‐hydroxy butyric acid) (PHB) is a natural biodegradable plastic with biocompatibility. However, PHB has some problems of application to the food system because it is brittle and stiff. Because PHB has a poor site for chemical modification, the blends of PHB with flexible polymers can overcome these undesirable properties. Therefore, we prepared the blend films of PHB with chitosan, analysed the mechanical properties and barrier properties against water vapour, oxygen and lipid and monitored biodegradability of PHB/chitosan films in this study. The degree of crystallinity of PHB/chitosan films by X‐ray diffraction decreased with increasing chitosan concentration. The granular sizes of the films were reduced with the addition of chitosan to the film in the micro structural observation by a scanning electron microscope. Mechanical properties, including tensile strength and percent elongation of the blend films increased with increasing chitosan ration in the films. It is demonstrated that mechanical properties of the films were improved by the addition of chitosan. The water vapour permeability (WVP) of the PHB film was the highest and WVP was decreased by the addition of chitosan. Oxygen permeability of the films decreased as chitosan amount increased. The films had very good barrier property against lipid. The consumed oxygen of PHB film was greater than that of chitosan film for incubation on the biodegradability determination of the films. Therefore, the blend films could be expected to increase the rate of degradation in natural environments. |
