Screw-type mixers or extruders of which there are numerous design configurations are widely employed for the extrusion of molten or plasticized polymers to semifinal and final product forms. Although these machines have found wide application, up to now there has been no rigorous theory of polymer melting in screw channels, hence the need for the mathematical treatment of the process. Presented in this paper is a mathematical model capable of describing the polymer movement and heat and mass transfer in the zone of polymer melting delay. The coupled nonlinear partial differential equations describing the phenomenon have been decoupled using the perturbation method and solved analytically using direct integration. The results obtained revealed that the Reynolds number and Eckert number have significant effects on the velocities, polymer temperature and mass flow rate.
Keywords: Plasticating extruder, screw, polymer, Melting delay zone, analytical solution