An extensive experimental study has been performed for starve fed single screw extrusion of polymer blends. Several materials have been used in the study: PP/PS, PP/PMMA, and HDPE/PS blends of composition of 85%/15%. “Screw Pulling-out Technique” has been used to study the melting mechanism and flow in the machine. CSM melting mechanism (contiguous solids melting) has been observed for flood fed extrusion with an obvious presence of minor component inclusions. This mechanism has not been observed for starve fed extrusion. A new melting mechanism for starve fed extrusion of polymer blends has been proposed. This includes conductive melting in a starve fed region, and dispersed melting in a fully filled region, and takes into account the solid and molten phases of major and minor components. A new computation approach has been proposed for modeling of the polyblend melting process. Moreover, a forward/backward scheme of computation has been applied for global modeling of the extrusion process of polymer blends. A new global SSEM_SF computer model has been applied for simulation of experimental runs.