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首页> 外文期刊>Journal of Applied Polymer Science >Orientation and crystalinity in film casting of polypropylene
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Orientation and crystalinity in film casting of polypropylene

机译：聚丙烯薄膜浇铸中的取向和结晶度

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In the cast film process a polymer melt is extruded through a slit die, stretched in air, and cooled on a chill roll. During the path in air the melt cools while being stretched. Film casting experiments were carried out with an isotactic polypropylene resin. The temperature and width distributions were measured along the draw direction. Further, the crystallinity and Hermans orientation factor were measured on the final film. The process was described by a simple thermomechanical model derived elsewhere. The evolution of the molecular orientation parameters was calculated on the basis of a dumbbell model coupled with velocity and temperature distributions provided by the thermomechanical model. The experimental crystalline orientations of the final films collapsed into a single step-shaped curve (from low to high orientation) if plotted versus the stress calculated by the model at the frozen line. The experimental values of the crystallinity and Hermans orientation factors are discussed on the basis of predictions of the dumbbell model for melt orientation at the frozen line and the crystallinity data obtained in quiescent conditions under the same cooling rate. (C) 2002 whey Periodicals, Inc. [References: 23]
机译：在流延膜方法中，将聚合物熔体通过狭缝模头挤出，在空气中拉伸，并在激冷辊上冷却。在空气流动的过程中，熔体在拉伸时会冷却。用全同立构聚丙烯树脂进行薄膜流延实验。沿拉伸方向测量温度和宽度分布。此外，在最终膜上测量结晶度和赫曼斯取向因子。通过在其他地方获得的简单热力学模型描述了该过程。在哑铃模型的基础上，结合由热力学模型提供的速度和温度分布，计算了分子取向参数的变化。如果将最终膜的实验晶体取向与冷冻线处的模型所计算的应力作图，则可以将其压缩成一条阶梯状曲线（从低到高）。根据对冷冻线熔体取向的哑铃模型的预测以及在相同冷却速率下在静态条件下获得的结晶度数据，讨论了结晶度和Hermans取向因子的实验值。 （C）2002 Whey Periodicals，Inc. [参考：23]

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