高低温处理对乙基纤维素稀溶液特性的影响

Influence of Heating and Freezing on the Hydrodynamic Properties of Ethyl Cellulose Dilute Solution

利用自行设计的封闭式粘度计以及体积排除色谱 ( SEC)研究了循环冷冻及加热处理对四氢呋喃( THF)稀溶液中乙基纤维素 ( EC)分子流体力学性质的影响 ,探讨了处理前后溶液中 EC分子组成及构象变化 ,发现对 EC的 THF稀溶液进行循环冷冻后溶液的粘度有所减小 ,但样品的 SEC保留体积没有明显变化 .这说明溶质分子的流体力学体积略有下降 ,这种下降主要是冷冻处理促使溶质分子结晶所致 .加热处理可使溶液中 EC分子的流体力学体积下降更为明显 ,溶液的粘度有较大的减小 .这说明加热可能会引起 EC分子发生侧基脱除 ,增大了分子形成氢键的能力 ,导致溶质分子发生团聚 .

A closed viscometer was designed for viscosity measurement of volatile solvent-based solutions. The influence of freezing-thawing and heating on the hydrodynamic properties of EC molecules was studied by viscometry and size exclusion chromatographic (SEC) analysis. The change of molecular structure and conformation of EC molecules in solution after treatments is discussed. Freezing-thawing treatment reduces the viscosity of EC dilute solutions. However, it doesn′t make any significant change of the SEC retention volume of EC sample in THFsolvent. This suggests that the apparent hydrodynamic volume of EC molecules slightly decrease. Heating treatment reduces the apparent hydrodynamic volume of EC molecules more evidently. The viscosity of EC solution decreases obviously after heating treatment.