中文摘要：

以壳聚糖和海藻酸钠为原料、10％柠檬酸钠和3％氯化钙溶液为交联剂，制备1种可降解复合膜，研究交联时间和交联pH对复合膜机械性质和抗水性的影响，并通过X-射线衍射（XRD）和差示扫描量热法（DSC）对其结构和热稳定性进行分析。结果发现，复合膜的厚度（24．2μm）小于壳聚糖膜和海藻酸钠膜厚度相加的总和（39μm），表明在复合膜的制备过程中，壳聚糖与海藻酸钠在界面处部分混合并可能存在相互作用；柠檬酸钠和氯化钙分别对壳聚糖和海藻酸钠产生离子交联作用，且交联降低了二者的结晶度，提高了复合膜的热稳定性；在交联溶液pH为7、交联时间30min时，复合膜性质最好，机械强度最高可达到120MPa，水溶性仅为8．25％；复合膜改善了单一膜机械性能不足及抗水性差等缺点，有望应用于食品的保鲜包装。

英文摘要：

A biodegradable composite film was made from chitosan and alginate, cross-linked by 10% sodium citrate and 3% calcium chloride solution. Effects of cross-linking time and pH on the mechanical properties and water resistance of the composite film were investigated. Besides, X-ray diffraction （XRD） and differential scanning calorinetry （DSC） were applied to characterize and analyze the thermal stability of the film. The results showed that the thickness of the composite film （24.2 μm） was less than the sum of thickness of chitosan film and alginate film （39 μm）. This result indicated that chitosan and alginate partially mixed at the interface and might interact with each other during the film preparation. XRD and DSC showed that sodium citrate and calcium chloride cross-linked chitosan and alginate respectively, and the cross-linking decreased crystalline and improved thermal stability of the composite film. The best properties of the composite film could be achieved under a cross-linking time of 30 min and pH 7.0, with the highest tensile strength （120 MPa）, while lowest water solubility （only 8. 25 %）. The composite film overcame the drawbacks of single chitosan and alginate film, such as low mechanical properties and poor water resistance. The composite film was expected to replace low-density polyethylene, as a new food preservation packaging film.