Flow of polymer melts through a well‐lubricated, conical die
Flow of polymer melts through a well‐lubricated, conical die
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聚合物熔体流过润滑良好的锥形模具
DOI：
10.1002/app.1975.070191016
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发表时间：
1975
期刊：
影响因子：
--
通讯作者：
M. Shaw
中科院分区：
文献类型：
--
作者：
M. Shaw
在这项工作中，通过观察到聚乙稀挤出物在完全润滑锥形收敛挤出模时熔体断裂急剧增加，支持了聚合物熔体在口模入口区作为拉伸破坏的概念。根据弗洛姆粘弹性模型的分析，在100秒−1的非常适中的出口剪切速率(无润滑剂)下，这种流动能够在挤出物中产生超过106dynes/cm~2的轴向拉应力。计算的应力水平约为5×106dynes/cm~2，导致挤出物中出现尖锐的、深的横向切割。这种强度的拉应力对熔体断裂的能力是通过在熔化棒上进行简单拉伸的单独实验来证明的，这些实验使用相似的速率和总变形。在这两个实验中，高密度聚乙烯和低密度聚乙烯之间的质量差异很大。
The concept of gross melt fracture of polymer melts as a tensile failure in the die entry region was supported in this work by the observation of a dramatic increase in the melt fracture of poly-ethylene extrudates upon lubricating thoroughly a conical, converging extrusion die. This flow, according to an analysis using a Fromm viscoelastic model, was found capable of producing axial tensile stresses in the extrudate in excess of 106 dynes/cm2 at the very moderate exit shear rate (no lubricant) of 100 sec−1. A calculated stress level of about 5 × 106 dynes/cm2 caused sharp, deep transverse cuts to appear in the extrudate. The ability of tensile stresses of this magnitude to fracture melts was demonstrated by separate experiments run in simple tension on molten rods, using similar rates and total deformations. A large qualitative difference between high and low-density polyethylene in both these experiments was noted.