羧甲基纤维素钠在醇水混合溶剂中的流变性研究

Research on the rheological properties of sodium carboxymethyl cellulose in glycerol-water mixed solvents

采用Anton Paar MCR 302流变仪,研究了羧甲基纤维素钠在甘油质量分数分别为0%,20%,40%,60%和80%的甘油-水混合溶剂中的流变特性。发现甘油-水混合CMC溶液为无屈服力非牛顿流体,具有剪切稀化特性;随甘油质量分数的增加,CMC溶液黏度增大、剪切稀化特性逐渐明显、结构恢复变慢;溶液从黏弹性流体逐渐向黏弹性固体转变,内部结构增强,刚性增大。经高温处理后,CMC混合溶液的黏度均会显著增加,且增加值随甘油量增加而增大。亲水性多糖类聚合物的分子主链带有羟基,具有形成氢键的能力。甘油带3个醇羟基,与水形成氢键比水与水之间的氢键更强,可促进体系中羟基间氢键形成,增加氢键数量以及氢键作用力,增大了聚合物分子链缠绕、分子链段缠结。

The rheological properties of sodium carboxymethyl cellulose(CMC)in glycerol-water mixed solvents with different mass fractions of glycerol were studied on an Anton Paar MCR 302 Rheometer.The mass fractions of glycerol were 0%,20%,40%,60% and 80%,respectively.The results showed that the CMC in different mixed solvents showed no yield stress and they were pseudoplastic fluids with shear-thinning behavior.With the increase of glycerol content,the viscosity of the CMC solution gradually increased;the shear-thinning properties became more obvious;the recovery of solution structure became slow;and the CMC solution gradually changed from a viscoelastic fluid to a viscoelastic solid,in which the internal structure was strengthened and the rigidity was increased.After high-temperature treatment,the viscosities of CMC solutions in the mixed solvents were significantly increased,and the increment was increased with the increase of glycerol content.The molecular backbones of hydrophilic polysaccharide polymers such as CMC have hydroxyl groups and can form hydrogen bonds.The glycerol molecule contains three hydroxyl groups,and its ability of formation of hydrogen bonds with water is strong.Therefore,glycerol can promote the hydrogen bonding between hydroxyl groups in the system,i.e.,increase the number of hydrogen bonds and the strength of hydrogen bonding,and thus increase the entanglement of molecular chains and molecular segments.