N,O-羧化壳聚糖溶液的流动性、触变性以及动态粘弹性研究

The flow behavior,thixotropy and dynamical viscoelasticity of N,O- carboxymethyl chitosan solutions

通过分析25℃条件下N,O-羧化壳聚糖溶液的流动性、触变性以及动态粘弹性来研究其流变性能,并利用Power-law和Cross模型对其流动性进行了拟合分析。结果表明：低浓度的N,O-羧化壳聚糖溶液（0.01%~1%）表现为牛顿流体的特性,较高浓度的溶液体系（5%~15%）表现为剪切变稀的假塑性流体的特性,其流动性符合流变学的Cross模型,且浓度越高,临界剪切速率越小;随着溶液浓度的增大,触变性越强,结构不易恢复,表明溶液体系对时间的依赖性越大;在整个动态测试中,低频率下,G″〉G＇,表现出类似于液体的粘弹性行为,随着频率的增大,溶液体系表现为类似于固体的弹性行为（G＇〉G″）,G″与G＇交点的出现依赖于N,O-羧化壳聚糖溶液浓度的变化。

The flow behavior,thixotropy and dynamical viscoelasticity of N,O- carboxymethyl chitosan solutions were measured by steady- shear and small- amplitude oscillatory experiments,respectively.Power- law and Cross models were used to analyze the flow properties of the systems. The results showed that N,O- carboxymethyl chitosan solutions exhibited two different flow behaviors due to the variation of concentration. When the N,O-carboxymethyl chitosan solutions was in low concentrations（ 0.01% ~ 1%）,the systems exhibited obvious characteristics of Newton fluid.However,shear- thinning regions were observed and found to be well correlated to the Cross model for high concentrations of N,O- carboxymethyl chitosan solutions（ 5% ~15%）.The variation of the hysteresis loops area suggested a stronger thixotropic behavior as the polymer concentration increased.Dynamical viscoelastic properties showed a transition from fluid- like（ G″ G＇） to gel- like（ G＇ G″） structure with the increase of frequency,and the appearance of cross point was dependent on the concentrations of N,O- carboxymethyl chitosan solutions.