An Experimental and Theoretical Investigation of Sharkskin Melt Fracture

小行星9422108 许多挤出的聚合物熔体表面上的缺陷，被认为是由熔体固化时的流变性引起的，通常用描述性术语“鲨鱼皮”缺陷来识别。 根据经验，已知这种表面缺陷可以在较低的挤出速率下消除，因为这减少了被认为是鲨鱼皮化原因的应力。 这些研究人员提出了一个分析和实验计划，以确定和理解控制鲨鱼皮形成的机制。 有了这种理解，他们应该能够消除鲨鱼皮或设计一个特定的鲨鱼皮表面纹理。 沿着一系列分析测试，他们将在挤出模头中使用光散射装置，以实验方式测量挤出聚合物的流变特性。 这一点，沿着建模和计算程序将确定流动的力学，结合各种流变模型，预测压力和输出波动，可以与鲨鱼皮的发展。 这项研究的影响将是更好地了解鲨鱼皮，这是一种今天无法预测的现象，消除鲨鱼皮通常需要降低挤出速度和降低生产率。 ***

9422108 Shaw Defects on the surface of a number of extruded polymer melts, thought to be caused by the rheology of the melt as it solidifies, are often identified by the descriptive term "sharkskin" defects. Empirically, it is known that this surface defect can be eliminated at lower extrusion rates, because this reduces the stresses that are assumed to be the cause of sharkskinning. These investigators propose an analytical and experimental program to identify and understand the mechanisms to control sharkskin formation. With this understanding, they should be able to eliminate sharkskin or design a specific sharkskin surface texture. Along with a number of analytical tests, they will use a light scattering device in an extrusion die to measure the rheological properties of the extruded polymer experimentally. This, along with a modeling and computional program will determine the mechanics of the flow, incorporating various rheological models, to predict pressure and output fluctuations that can be correlated with the development of sharkskin. The impact of this research will be a better understanding of sharkskinning, a phenomenon that today is unpredictable, and its elimination usually requires lower extrusion speeds and reduced productivity. ***