Thermo-rheological phenomena at wall boundary layers during color and material changes in plastics extrusion

塑料挤出颜色和材料变化过程中壁边界层的热流变现象

• 批准号: 234828979
• 负责人: Professor Dr.-Ing. Johannes Karl Wortberg
• 金额: --
• 依托单位: Lehrstuhl für Konstruktion und Kunststoffmaschinen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/234828979?language=en
• 关键词: Thermo; rheological; phenomena; wall; boundary

Colour and material changes are very common in industrial processing of polymers. Especially at continuous polymer extrusion, the efforts in production for time and material are high. As a result of the lower flow velocity at the wall of the flow channel, the molten plastic has a long resistance time in the barrier layer and dominates the changeover time. To make the changeover process more efficient, it is necessary to achieve an improved understanding of the process, concerning the influences on fluid-mechanical properties as well as the thermo-rheological material behavior.The aim of this project is to expand the understanding of the thermal-rheological material behavior of thermal sensitive materials. In addition to the physical shear- and temperature dependent changes of the shear viscosity, the influence quantiies like time or temperature dependent reactive influences are investigated. To characterize the material behavior, different measuring methods are used. The new results of these measurements are used for an analytical model to depict the time dependent changes of the shear viscosity. Currently, a purely thermally induced change is considered for the calculation of the material behavior and will now be elaborated for a consideration of shear. Furthermore, the influence of the surface topology of the flow channel surface reflects the focus of the study of color and material change processes.After that, the knowledge of the preceding thermo-rheological investigation as well as the influence of the flow channel surface topology, are integrated into a numerical calculation method. For this purpose, the analytical model for the material change must be implemented in the simulation tool. For the calibration of CFD simulations, the results are compared with practical experiments.

颜色和材料变化在聚合物的工业加工中非常普遍。特别是在连续聚合物挤出时，时间和材料的生产努力很高。由于流动通道壁的下流速度较低，熔融塑料在屏障层中具有很长的电阻时间，并主导了转换时间。为了使转换过程更加有效，有必要提高对过程的理解，涉及对流体机械特性的影响以及热得主材料行为。除了剪切粘度的物理剪切和温度依赖性变化外，还研究了诸如时间或温度依赖性反应性影响的影响量。为了表征材料行为，使用了不同的测量方法。这些测量结果的新结果用于分析模型来描述剪切粘度的时间依赖性变化。当前，考虑计算材料行为的纯热诱导变化，现在将详细说明剪切。此外，流道表面的表面拓扑的影响反映了颜色和材料变化过程的研究的重点。此后，对先前的热得益研究的了解以及流道表面拓扑的影响，都集成了数值计算方法。为此，必须在模拟工具中实现材料更改的分析模型。对于CFD模拟的校准，将结果与实际实验进行了比较。