Polyamide-6 polymerization and its melt flow in the VK tube reactor with optimized baffle structure

The flow mechanism of Polyamide-6 (PA6) melt over conical perforated baffles in the VK tube is elucidated by computerized analysis based on a rational assumption of Stokes' flow. The governing equations for a two-dimensional flow are solved by the finite difference method to generate the stream function profile, velocity field and residence time distribution. Optimization of the geometries of the baffle structure brings about a uniform residence time distribution, so as to ensure a homogeneous extent of reaction for the final product. The complete mathematical model for PA6 polymerization while flowing through the VK tube was established according to PA6 hydrolytic polymerization kinetics. The optimized baffle structure was shown to be compatible with the desired polymerization variables.