Numerical Simulation And Experimental Study On Plastic Profile Gas-assisted Coextrusion

Plastic profile is extruded product with irregularity and complex section whichdiffer from circular tube, film, slice and bar. It is lighter, more environmental andenergy-efficient than other profile which is made of other texture. Coextrusion is atechnology that need two or more extruders to provide materials with differentcharacteristics, these materials gather in the coextrusion die, so this technology canproduce composite structure product with multilayer. Coextrusion is widely used inprofile extrusion, but it is limited by some defects. Gas-assisted extrusion is a newtechnology, in this process, a stable gas layer is established between die wall and themelt, and the no-slip adhesive shearing extrusion mechanism is transfered to fully slipextrusion mechanism. A lot of advantages and enormous application prospect wasfound in former study. Numerical simulation and experimental study on profilegas-assisted coextrusion was performed in this paper based on single componentgas-assisted extrusion and bi-component gas-assisted coextrusion directed by formerscholars. What follows in the passage is the main content of this paper.(1) The profile gas-assisted coextrusion finite model was established based onrheology and fluid dynamics, the model was simplified appropriately in considerationof some characteristic of gas-assisted coextrusion. The viscoelastic constitutiveequation was used in numerical simulation. The melt flow inner and outer the die wasanalyzed.(2) The influence of technological and material parameters on gas-assistedcoextrusion and conventional coextrusion was computed, such as flow rate, viscosity,relaxation time, material parameters and, wall slip, matarial combination. Theresults of gas-assisted coextrusion and conventional coextrusion were analyzed andcompared.(3) A L-shaped profile gas-assisted coextrusion die was designed andmanufactured, the experimental platform was established and the experiments wereperformed successfully. The feasibility of profile gas-assisted coextrusion wastestified and the influence of technological conditions was studied by a lot of experiments. At last, some suggestions were proposed to improve the experimentalplatform.