Melting in single screw extruders

A model for the melting of granules in a single screw extruder is presented in Part I. It is consistent with observations of earlier workers and retains some of the ideas introduced by Tadmor in his model; however, it assumes that the solid bed of granules cannot stand large differences of principal stresses and so account has to be taken explicitly of the downstream force balance on the solid bed and in the melt pool. Detailed quasi-analytic results are given for a Newtonian (constant viscosity) fluid in Part II. These illustrate the model for a particularly simple case and have relevance for some materials. A more elaborate numerical scheme is described in Part III for a non-Newtonian model and results are presented for comparison with the predictions of other theories and with experiments.