临界外推滑移长度的解析、测量及其流变学意义

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吴其晔， 李鹏， 慕晶霞， 张娜

（青岛科技大学 高分子科学与工程学院，山东 青岛 266042）

 摘要： 给出用恒速型毛细管流变仪研究熔体挤出畸变时，计算熔体壁滑速率和外推滑移长度的原理和方法，采用2种聚合物样品HDPE（高密度聚乙烯）和EPDM（三元乙丙橡胶）验证计算方法。求得样品的壁滑速率在每秒几厘米的量级，临界外推滑移长度在毫米数量级。由此进一步探讨壁滑的分子机理和界面机理，指出发生显著熔体壁滑、压力振荡和挤出物表面畸变的前提条件是，熔体具有线形分子链且发生强缠结以及熔体/模壁间具有强吸附边界。

 关键词： 挤出畸变； 壁滑； 外推滑移长度； 高密度聚乙烯； 三元乙丙橡胶

 中图分类号： TU 45文献标志码： A

 收稿日期： 20140412

基金项目： 国家自然科学基金资助项目（50973050）.

作者简介： 吴其晔(1943—)，男，教授，博士生导师.

 Analysis， Measurement of Critical Slide Length and Its Rheological Meaning

 WU Qiye, LI Peng, MU Jingxia, ZHANG Na

 (College of Polymer Science and Engineering，Qingdao University of Science and Technology, Qingdao 266042，China)

 Abstract: The calculation principle and method of melt slide speed at wall and critical slide length were provided for a capillary rheometer constant speed type by research of extrudate distortion of polymer melts. This method was verified with two samples of HDPE and EPDM. The melt slide speeds were in order of magnitudes of several centimeter per second and critical slide length of millimeter. From this the molecular mechanism and boundary mechanism of melts slide at wall were discussed deeply. And it is indicated that the melts with linear entangled chains and the strong boundary adsorption between melts and wall were the important precondition for a remarkable melts slide at wall and for extrusion pressure oscillation and for extrudate surface distortions.

Key words: extrudate distortion; melt slide at wall; critical slide length; HDPE; EPDM