Melting mechanisms in corotating twin-screw extrusion: a critical review

Abstract Corotating twin-screw extrusion is widely used for many applications in mixing and compounding. While the flow conditions in the different screw elements are now well known and accurately modeled, the melting mechanisms, i.e. the transition between solid and molten polymer, are much less understood and are still the subject of debates. In this review paper, experimental observations from the literature are first presented and commented, followed by the proposed theoretical approaches. It will be concluded that a satisfactory model considering the different mechanisms involved in the melting step has yet to be elaborated, unlike what exists for the single screw extrusion.