Regulation Mechanism of Intersection Angle of Three-Layer Co-Extrusion Die on Single Layer Thickness and Die Swell

The structure of polymer co-extrusion die has an important influence on the forming quality of products, especially the intersection angle of die has a significant influence on the melt thickness and die swell. In this paper, the Carreau viscosity model and Picard iterative calculation method were used to study the numerical simulation of the coextrusion process of three-layer microtubes with the outer layer of polydodecylamide (PA12), middle layer of ethylene-vinyl acetate copolymer (EVA) and inner layer of polypropylene (PP). The results show that when the intersection angle of the outer melt increases, the thickness of PA12 increases, the thickness of EVA and PP decreases, the inner and outer diameters decrease, and the swelling ratio increases. When the intersection angle of the middle melt increases, the thickness of EVA increases, the thickness of PA12 and PP decreases, the inner and outer diameters decrease, and the swelling rate decreases. When the intersection angle of the two melts increases at the same time, the thickness of PA12 and EVA increases, the thickness of PP decreases, the inner and outer diameters decrease, and the swelling rate increases. The three-layer co-extrusion experiment proves the correctness and effectiveness of the simulation results. The research results can provide important guidance value for the flow channel structure design of polymer multi-layer coextrusion die. © 2023 Chengdu University of Science and Technology. All rights reserved.