Effects of convergent flow on in situ fibrillation of TLCP in PEN
Effects of convergent flow on in situ fibrillation of TLCP in PEN
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DOI：
10.1002/app.13330
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发表时间：
2004-02
影响因子：
3
通讯作者：
Li Li-Li;C. Chan;C. Yue;Y. Lam;K. Tam
中科院分区：
文献类型：
--
作者：
Li Li-Li;C. Chan;C. Yue;Y. Lam;K. Tam
从圆筒进入毛细管口模的聚合物熔体经历了一种收敛流动，其中存在拉伸流动和剪切流动的复杂组合。热致性液晶聚合物（TLCP）在热塑性基体熔体中的聚集流动在控制其原位成纤过程中起着重要作用。本研究探讨了收敛流对TLCP/聚萘二甲酸乙二醇酯（PEN）共混物中TLCP原纤发展的影响。使用毛细管流变仪，并通过改变毛细管尺寸和剪切速率来改变会聚流的程度。在给定的毛细管口模条件下，由于TLCP液滴的变形量增加，TLCP原纤化随剪切速率的增加而增加。通过使用相对长的模具建立充分发展的剪切速度分布被认为是必要的，以保留在会聚流动区域中引发的TLCP原纤。在给定的高剪切速率下，TLCP原纤化随着毛细管直径（≤2 mm）的增加而改善，这是因为毛细管和圆柱体之间的速度差增加。© 2003 Wiley Periodicals，Inc.应用聚合物科学杂志91：1505-1513，2004
A polymer melt entering a capillary die from a cylinder undergoes a convergent flow in which there is a complex combination of extensional and shear flows. The convergent flow plays an important role in controlling the in situ fibrillation of thermotropic liquid crystalline polymer (TLCP) in a thermoplastic matrix melt. This study examines effects of the convergent flow on development of TLCP fibrils in a TLCP/poly(ethylene naphthalate) (PEN) blend. A capillary rheometer was used and the extent of the convergent flow was varied by changing capillary dimension and shear rate. With a given capillary die, the TLCP fibrillation was found to increase with increasing shear rate because of the increased deformation of TLCP droplets. The establishment of a fully developed shear velocity profile by using a relatively long die is considered to be necessary to retain the TLCP fibrils initiated in the convergent flow region. At a given high shear rate, TLCP fibrillation improves with increasing capillary diameter (≤2 mm) because of the increased difference in velocity between the capillary and the cylinder. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1505–1513, 2004