大学化学 >> 2026, Vol. 41 >> Issue (4): 400-408.doi: 10.12461/PKU.DXHX202502033

化学实验 上一篇    下一篇

混合可溶盐对黏度曲线线性关系的改进研究

张小艳, 陈子愉, 蒋想凤, 刘坤, 马忠云   

  1. 湘潭大学化学学院, 湖南 湘潭 411105
  • 收稿日期:2025-02-08 录用日期:2025-05-13 发布日期:2026-04-24
  • 通讯作者: 马忠云 E-mail:zhyma@xtu.edu.cn Zhongyun Ma
  • 基金资助:
    湖南省普通高等学校教学改革研究项目(HNJG-20230310)。

Improvement of Linear Relationship in Viscosity Curves Using Mixed Soluble Salt Systems

Xiaoyan Zhang, Ziyu Chen, Xiangfeng Jiang, Kun Liu, Zhongyun Ma   

  1. College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province, China
  • Received:2025-02-08 Accepted:2025-05-13 Published:2026-04-24
  • Contact: Zhongyun Ma E-mail:zhyma@xtu.edu.cn

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摘要： 黏度法是一种便捷、常用的测量高分子聚合物相对分子质量的方法，在物理化学、高分子物理与化学、生物化学等大学本科基础实验课程中都有开展相关实验。但是学生在使用黏度法测量高聚物(例如聚乙烯醇)相对分子质量的实验中，往往会出现黏度曲线的线性极差的情况。本文通过向高聚物溶液中添加单个或混合可溶盐体系，利用其带来的“上弯”和“下弯”的趋势对黏度曲线的线性关系进行调控，并考察有效毛细管内径、动能校正等影响因素，得到了线性相关系数R2在0.95以上的最佳盐组合体系(0.125 mol·L-1 LiCl + 0.25 mol·L-1 KCl)。此外，通过添加该混合可溶盐体系，测定了葡聚糖20、葡聚糖100和聚乙二醇的相对分子质量，进一步验证了上述改进方法的适用性。改进后的黏度法实验可启发学生将多领域理论知识应用到实际实验分析中，引导学生深入思考问题，培养学生科学研究的浓厚兴趣，大大提高他们的实验动手能力与科研创新能力。

关键词: 黏度法, 高聚物, 相对分子质量, 混合盐体系

Abstract: The viscosity method serves as a convenient and widely adopted technique for determining the relative molecular weight of polymeric materials, with relevant experiments being incorporated into undergraduate curricula including physical chemistry, polymer physics and chemistry, and biochemistry. However, students frequently encounter issues with poor linearity in viscosity curves when applying this method to measure the relative molecular weights of polymers such as polyvinyl alcohol. This study demonstrates that the linearity of viscosity curves can be significantly improved by introducing single or mixed soluble salt systems into polymer solutions, which modulate the curve's characteristics through “upward” and “downward” bending effects. Through systematic investigation of influencing factors including effective capillary inner diameter and kinetic energy correction, we identified an optimal mixed salt system (0.125 mol·L-1 LiCl + 0.25 mol·L-1 KCl) that achieves a linear correlation coefficient (R2) exceeding 0.95. The method's applicability was further validated by determining the relative molecular weights of dextran 20, dextran 100, and polyethylene glycol using this optimized salt system. This improved viscosity method not only enhances experimental outcomes but also encourages students to integrate multidisciplinary theoretical knowledge into practical analysis, stimulates deeper scientific inquiry, fosters research interest, and significantly develops experimental skills and innovative research capabilities.

Key words: Viscosity method, Superpolymer, Relative molecular weight, Mixed salt system