Alkschbirs Melissa I, Bizotto Vanessa C, de Oliveira Marcelo G, Sabadini Edvaldo
Instituto de Química, Universidade Estadual de Campinas, Caixa Postal 6154, CEP 13084-862, Campinas, SP, Brazil.
Langmuir. 2004 Dec 21;20(26):11315-20. doi: 10.1021/la0489007.
The presence of very small amounts (ppm) of high-MW polymers in solution produces high levels of drag reduction in a turbulent flow. This phenomenon, often termed as the Toms effect, is highly dependent not only on MW, but also on the flexibility of the macromolecular chain. The Toms effect can be studied through the images of the structures produced after the drop impact against shallow solution surfaces. The splash structures composed of crown, cavity, and Rayleigh jet are highly dependent on the elongational properties of the solution. This work presents the effects of Congo red on the drag reduction properties of poly(ethylene oxide) in aqueous solutions through the analysis of splash structures. Results obtained in this analysis indicate that Congo red molecules act as physical cross-linking agents, decreasing the polymer elasticity and its drag reduction capacity. It was observed that the maximum height of the Rayleigh jet can be used as a sensitive parameter to the complexation between the dye and the polymer molecules.
溶液中极少量（ppm级）的高分子量聚合物会在湍流中产生高水平的减阻效果。这种现象通常被称为汤姆斯效应，它不仅高度依赖于分子量，还取决于大分子链的柔韧性。汤姆斯效应可以通过液滴冲击浅溶液表面后产生的结构图像来研究。由冠部、空腔和瑞利射流组成的飞溅结构高度依赖于溶液的拉伸性能。这项工作通过对飞溅结构的分析，展示了刚果红对聚环氧乙烷水溶液减阻性能的影响。该分析得到的结果表明，刚果红分子起到物理交联剂的作用，降低了聚合物的弹性及其减阻能力。据观察，瑞利射流的最大高度可作为染料与聚合物分子之间络合作用的敏感参数。
