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Effect of the Hydrophobic Modification of the Capillary Wall Surface upon the Viscosity Measurement Yang Haiyang, Zhang Huming, Xu Xiaoyun, Zhu Pingping, He Pingsheng* Abstract The surface property of the viscometer could be changed
dramatically by the monolayer of octadecyltrichlorosilane (OTS) via the hydrogen bonding
on the wall surface. As a result, the original hydrophilic surface of the viscometer
became hydrophobic. The flow time of the pure solvent, therefore, reduced from 120.69s to
118.78s. By measuring the contact angle of the pure water on the glass surface, together
with the geometric parameter of the viscometer, the additional pressure originated from
the curved surface of the liquid could be calculated. It was noted that the decrease of
the flow time of the pure water did not originate from the change of the flow model of the
fluid. In fact, the no-slip condition of the fluid was still satisfied on such an
occasion.
杨海洋 张胡铭 徐小云 朱平平 何平笙* 摘要 Octadecyltrichlorosilane(OTS)在玻璃表面自组装成单分子膜可以显著改变粘度计毛细管表面性质。实验结果表明，当毛细管管壁从亲水表面变成憎水表面时，纯水在粘度计中的流过时间由120.69s减小到118.78s。通过测定改性之前和之后纯水在玻璃表面接触角，结合乌式粘度计的几何尺寸参数，可以定量研究流体在流动过程中因液面弯曲产生的附加压强对流过时间的影响，计算结果表明界面性质的变化可能不会使流体在毛细管中的流动模式发生改变，剪切无滑移条件仍然是成立的。关键词 粘度计 表面改性 剪切无滑移条件 接触角 表面张力 杨海洋 男，38岁，博士，副教授，从事高分子和胶体溶液性质的研究。E-mail:yhy@ustc.edu.cn安徽省自然科学基金(00046310)和中国科学技术大学青年基金(KB3009)资助项目 2002-10-18收稿，2002-12-26修回 |