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series of chitosan samlpes with 91% deacetylation but different molecular weight were obtained by varying the time of chitosan solution in acetic acid aqueous solution at 70℃.The viscosities and flow behavior of the concentrated solutions of chitosan were investigated in 10% (vol%) formic acid aqueous solution after the solutions were prepared for two days by using RPX-705 Rheopexy Analyzer.For each chitosan sample,at the concentration of 3.5 g/100ml,the log (ηr/η0)versus lgγη0,M curves superimpose each other within the same rheogramme. Then the relationship between log nr and lgM was studied under different shear rates.For the highest M sample, the experimental data deviate from the straight lines greatly. This was because the chitosan chain degradated in acid solution during dissolving. The molecular weights were measured in acid solution after two days of dissolving, they were right on their own straight lines. However,no obvious degradation was observed after two days in the same solution for the other lower M chitosan sam-ples. In addition, the plot of nr against M was not a straight line,probaly due to particular interaction of chitosan. 相似文献
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壳聚糖浓溶液流变性质研究──分子量的依赖性 总被引:1,自引:0,他引:1
壳聚糖浓溶液流变性质研究──分子量的依赖性王伟,徐德时(中国科学院长春应用化学研究所高分子物理开放实验室长春130022)关键词壳聚糖,浓溶液,粘度,零剪切粘度,分子量作者曾研究了一些外部条件对壳聚糖浓溶液流变学性质的影响,如浓度、温度、溶剂性质、外... 相似文献
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壳聚糖浓溶液流变性质研究──零剪切粘度的测定和外推 总被引:1,自引:0,他引:1
用落球法测定了不同溶剂体系和浓度的壳聚糖浓溶液的零剪切粘度η0,用RPX-705多功能流变仪同轴圆筒方法测定了各浓溶液的粘度随剪切速率的变化关系,并用Perrr、Cross和Ballauff方法进行了求η0的外推.将外推结果与落球法结果进行了比较,认为Cross方法的结果与实际测得结果更接近,可以代替落球法,这样可以简单地得到壳聚糖浓溶液η0的信息. 相似文献
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壳聚糖浓溶液流变学性质研究-溶剂性质的依赖性 总被引:4,自引:0,他引:4
用不同pH值的HCOOH, CH~3COOH, HCl,0.1mol.dm^-3CH~3COONa+0.2mol.dm^-3CH~3COOH水溶液为溶剂, 进行了壳聚糖浓溶液的流变学性质研究。实验结果表明, 溶剂pH值相同时, 壳聚糖在各种酸中的溶解性和溶液沾度差别较大。同一种酸中, 在可溶范围内, pH值增加, 溶剂变劣, 粘度-浓度的幂律方程指数α增大。外加盐使溶剂变劣程度增加。在任何一种酸中, 浓溶液粘度都随存放时间的延长而下降, 流动指数n减小, 流动活化能基本不变。 相似文献
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