ABSTRACT
Heat transfer and thermal homogeneity are important considerations in reactive extrusion. In many extrusion polymerization processes a considerable amount of reaction enthalpy is released, heating up the polymermonomer mixture to high temperatures that may lead to product deterioration. The heat transfer coeffcient depends on rotational speed, flight clearance, the number of thread starts of the screws, and the properties of the polymer. The most important heat resistance in extrusion occurs between polymer and barrel wall. The oldest model for this heat transfer is based on the theory of a scraped heat exchanger and was suggested in 1953 by C. H. Jephson. The heat transfer coeffcient in the Ganzeveld model is slightly smaller than the heat transfer coeffcient predicted by the H. Janeschitz-Kriegl model, and it is also more sensitive to the actual size of the flight gap. Heat transfer is a well-known problem during all extrusion processes and in particular during reactive extrusion.
