Isothermal Pseudo-2D Analysis of Reactive Extrusion in Single-Screw Extruders

Reactive extrusion involves the continuous synthesis and modification of polymers in a screw extruder. Over the years, it has received a lot of attention both in academic research and industrial applications. It remains a potential source for further development of new products and processes. The present analysis is focused on power-law fluids undergoing isothermal homogeneous and heterogeneous reactions simulating reactive extrusion in a single-screw extruder. The assumption of shallow screw geometry enables the flow to be modeled as that occurring between infinitely long parallel plates, the analytical solutions of which are available in the literature. For the concentration problem, the reaction is taken to be first order, and the equation of conservation of component species is transformed into an eigenvalue problem. The eigenvalues and eigenfunctions are determined using the Runge–Kutta method. Analytical solutions are developed for the concentration distribution in the extruder and expressions for the conversion of the reactant, and Sherwood number are presented. The accuracy of the solutions is established and the concentration profiles at different axial locations in the extruder are presented for various values of power-law index, flow rate, and the homogeneous and heterogeneous reaction rate parameters. The effects of these parameters on the Sherwood number, reactant conversion and, bulk and wall concentration are also investigated.