Non-isothermal transient flow and molecular orientation during injection mold filling

• Published in: Rheologica acta Vol. 40; no. 1; pp. 67 - 73
• Main Authors: NGUYEN-CHUNG, Tham, MENNIG, Günter
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.01.2001; Springer Nature B.V
• Subjects: Applied sciences; Constitutive relationships; Deformation; Exact sciences and technology; Finite element method; Injection molding; Injection moulding; Kinematics; Machinery and processing; Microstructure; Molds; Moulding; Orientation; Particle tracking; Plastics; Polymer industry, paints, wood; Polymer melts; Technology of polymers; Unsteady flow; Viscous fluids; Non isothermal flow; Rheological model; Molecular orientation; Thermoplastics; Shear flow; Transient flow; Theoretical study; Injection molding; Polymer; Numerical simulation; Mold filling; Modeling
• ISSN: 0035-4511; 1435-1528
• DOI: 10.1007/s003970000121

The properties of injection molded products are directly related to the microstructure which in turn strongly depends on the flow kinematics and thermal history of the polymer melt during the filling process. In this study the mold filling process has been analyzed by using an FEM-code (FIDAP) to solve the equation of continuity, momentum, and energy under transient and non-isothermal conditions. As constitutive relation for a purely viscous fluid, the Bird-Carreau and Arrhenius model was chosen. The phenomenon at the flow front, its flow kinematics, and its significant implication on the microstructure of the part have been investigated in detail. Computed particle tracking showed good agreement with experiments under real processing conditions. Furthermore, a rather simple but effective and useful method for predicting the orientation distribution in an injection molded part was proposed. It was found that the local deformation near the solid wall may be considered as the main source for a typical layer of high orientation on the surface of the part.