三维壳聚糖材料中水的状态与其性能的关系  

THE EFFECT OF WATER STATES ON MECHANICAL PROPERTIES OF 3-DIMENSIONAL CHITOSAN MATERIALS

作　　者：吕佳[1] 胡巧玲[1] 沈家骢[1] 

机构地区：[1]浙江大学高分子复合材料研究所,杭州310027

出　　处：《高分子学报》2006年第8期1019-1023,共5页Acta Polymerica Sinica

基　　金：国家自然科学基金资助项目(基金号50173023);国家自然科学基金重点资助项目(基金号50333020);国家重点基础研究发展计划(973计划)(项目号2005CB623902)资助项目

摘　　要：利用原位沉析法制备了具有层状结构的高强度三维壳聚糖(chitosan,CS)材料,由于CS分子结构中存在大量的亲水基团,容易吸附水分子.通过热分析(TGA,DSC)测试发现吸水后的CS材料中的水分是以3种不同的状态存在,结合水、中间态水和自由水.结合力学性能的方法分析不同状态的水对材料性能的影响.结果表明,结合水和CS以氢键紧密结合,有较好的热稳定性,对材料的力学性能有增强作用;CS棒材在环境中吸附的中间态水相当于一种增塑剂,随着水含量的增加,材料力学性能的下降符合Fermi经验公式;中间态水达到饱和之后,自由水开始出现,自由水和CS之间的作用力很弱,温度较低时会结晶成冰.自由水的渗透与中间态水比对材料的力学性能没有明显的影响.3-Dimensional ehitosan （CS） materials with high mechanical properties have been prepared via in-situ precipitated method. Owing to the existence of hydrophilic groups, the structure and properties of CS materials is easily affected by the hydrated water. Water sorption in the CS material is Fickian in nature. Thermal analyses revealed the existence of up to three energetically distinct states of water： bound water, intermediate water and free water in the water saturated CS rod, each type of water have different effects on the mechanical properties of the material. Initially, there exists thermal stable bound water that can not be easily removed. Interaction between water and CS results in a strengthening of the hydrogen bond network. Subsequent absorbed intermediate water of CS material in the water environment acts as a plasticizer, forming water-water bridges that loosen the hydrogen bonding network. Modeling of the modulus and strength of CS rods with the Fermi＇ s equation for the fall in the modulus and strength as a function of water content under isothermal condition was fitted. Differ to other CS blends, this intermediate water is non-freezing. In the later stage of water sorption, water enters the CS and loosely adhered as free water which is freezing, undergoes no thermal phase transition over the range of temperatures normally associated with bulk water, having few effects on the mechanical properties of the CS rod.

关 键 词：壳聚糖 水的状态 吸水过程 氢键作用 

分 类 号：TQ317[化学工程—高聚物工业]