聚合物双螺杆挤出的流变行为及模拟

In the study of rheological behavior of polymer melt in twin-screw extrusion, numerical simulation technique has great advantages over traditional method. Numerical simulation technique could provide a rapid, accurate and omprehensive insight into the flow field, thus reducing R&D cost and time-to-market, which represents research trends in the flow analysis of polymer processing. In this project, twin-screw extrusion mechanism is studied with CFD package POLYFLOW, three-dimensional noniso-thermal flow of polymer melt in twin-screw extruder is simulated and the fields of flow velocity, pressure, temperature, viscosity and shear rate is presented. Flow patterns in the conveying element, kneading blocks and screw assemblies are investigated. Influence of processing conditions，rheological properties of polymer melt, geometrical parameters of screw element and screw configurations on the conveying and mixing capability of twin-screw extruders are discussed. Particle trajectories in twin-screw extruders are visualized and mixing status of polymer melt along the extruder is statistically analyzed. Wall slip on the screw surfaces is also investigated. Experiments of twin-screw extrusion are carried out. Die swell phenomenon is modeled. Rheological properties of a nonvulcanic rubber EPDM have been tested. Constitutive equations are fitted out with the experimental data. With the fitted constitutive model, extrusion process in a rubber sealing profile die is simulated and numerical design methods of extrusion dies are explored.

研究挤出加工中聚合物的速度场、压力场和温度场; 分别研究螺杆、模头、啮合盘在不同几何参数、工艺参数及物性参数的条件下，挤出加工中聚合物熔体输送特性和流变行为，进行双螺杆工艺实验。研究双螺杆挤出机理对双螺杆挤出机的设计、控制产品的质量、实现双螺杆挤出机柔性制造技术提供理论依据。