Experimental Investigation of the Development of Interfacial Instabilities in Two Layer Coextrusion Dies
Experimental Investigation of the Development of Interfacial Instabilities in Two Layer Coextrusion Dies
复制标题
两层共挤模具中界面不稳定性发展的实验研究
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
J. Agassant
中科院分区：
文献类型：
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作者：
R. Valette;P. Laure;Y. Demay;J. Agassant
摘要实验研究了聚乙烯和聚苯乙烯在不同几何形状和不同流量比下的双层流动稳定性。第一共挤出装置允许停止非常长的狭缝通道中的共挤出流动，冷却聚合物样品并拆除模具以提取挤出物，然后对其进行仔细分析。第二个设备允许观察整个狭缝流通过透明的侧壁，并记录在自发和受控的不稳定条件下的界面波。这两种装置都清楚地指出，界面缺陷在特定的流动距离后开始生长，然后迅速放大。这说明了界面波的对流特性。透明模具中受控的不稳定处理条件允许精确测量线性区域中的缺陷生长速率，并显示非线性区域的快速发生。
Abstract The stability of two-layer flow of polyethylene and polystyrene is experimentally studied in different flow geometries and for various flow rate ratios. A first coextrusion device allows to stop the coextrusion flow in a very long slit channel, to cool down the polymer sample and to dismantle the die in order to extract extrudate which is then carefully analyzed. A second device allows to observe the whole slit flow through transparent lateral walls and to record the interfacial waves in both spontaneous and controlled unstable conditions. Both devices point clearly out that the interfacial defect begins to grow after a specific flow distance and is then quickly amplified. This demonstrates the convective character of interfacial wave. Controlled unstable processing conditions in transparent die allow to measure accurately growth rate of defect in the linear regime and show quick occurrence of non linear regime.