The Numerical Simulation Of Polymer Gas-assisted Co-extrusion

Gas-assisted co-extrusion molding (shortened as GACEM) is a new multiphase-polymer molding technique. The basic mechanism of GACEM is that the gas-assisted extrusion is applied to the polymer co-extrusion, which will exert the advantages of both gas-assisted extrusion and co-extrusion. But up to now, the study on such a processes is very rare. In this paper, the influence of rheological characters of polymer and the parameters of processing have been investigated with respect to the dies well, the stability of the interfaces and die pressure drop.The main work conducted in the paper is listed below:(1) Based on technique characteristics of GACEM and theories of polymer rheology, hydrokinetics and thermodynamics etc., isothermal viscoelastic theoretical models of describing GACEM process were established by means of reasonable assumption.(2) On the base of the FEM numerical analysis software POLYFLOW, the established grid model has been simulated. The distribution of velocity field, the pressure field as well as the shear rate have been studied in the process of GACEM. Based on that, the Mechanism of the die pressure drop and die swell in the co-extrusion explained.(3) The influence of characters of polymer and parameters of process on the distribution of various fields have been studied also.